Staphylococcal infections

Definition

Staphylococcus is the name of a genus of Grampositive bacteria responsible for a number of serious illnesses. There are 31 species of staphylococci that have been identified as of 2008; most of them, however, are harmless to humans. Staphylococci are widespread in all parts of the world; they are

commonly found in the soil as well as on the skin and mucous membranes of humans and domestic animals. The name of the genus comes from two Greek words meaning “bunch of grapes” and “round,” as these bacteria look like clumps or clusters of round objects under a microscope.

Description

Staphylococci are usually commensal organisms, which means that they can live on or in humans without necessarily causing harm. They can, however, cause disease in humans and other animals either by direct destruction of tissue or by releasing toxins into the digestive tract or bloodstream.

The following are the species of staphylococci most likely to cause disease in humans:

• S. aureus. S. aureus is generally considered the most dangerous staphylococcus, causing a range of infections from pneumonia and endocarditis to food poisoning and eye infections. Methicillin-resistant S. aureus, or MRSA, has become a major public health concern since the 1990s.
• S. epidermidis. S. epidermidis usually lives on the skin, as its name suggests, but can also cause infections in indwelling catheters and in HIV-positive patients or others with weakened immune systems. As with S. aureus, there are antibiotic-resistant strains of S. epidermidis, known as MRSE. This staphylococcus can be additionally difficult to treat because it produces a slimy biofilm that allows it to cling to the surfaces of prostheses and other implanted medical devices.
• S. saprophyticus. S. saprophyticus is found in the vaginal tract of some women and is a common cause of urinary tract infections in sexually active women, including seniors.
• S. lugdunensis and S. caprae. These are recently discovered species of staphylococci that have been found to cause endocarditis as well as infections of the bones and joints.

Demographics

Staphylococci are commonplace organisms. In humans, they can be found on the scalp, skin (particularly the armpits and genital areas), or outer nasal passages. Biologists refer to the formation of groups or clumps of bacteria on a human or animal as colonization. Some species of staphylococci colonize the vaginas of about 10 percent of premenopausal women. Staph is found in 80 percent of the general population intermittently and 20–30 percent of the population on an ongoing basis. People who harbor staphylococci most of the time are called “staph carriers.” An estimated 2 billion people are colonized by some form of S. aureus; of these persons, as many as 53 million, or 2.7 percent of carriers, are thought to carry MRSA, the drug-resistant form of S. aureus. It is possible for a senior (or younger adult) to carry staphylococci for many years without becoming sick; in addition, such domestic animals as cats, dogs, chickens, and horses can carry MRSA strains as well as less virulent staphylococci.

As far as is known as of 2008, people of either sex, any age group, or any race are equally likely to carry staphylococci. Newborns may be colonized by staphylococci from the mother during childbirth. Some groups, however, are more susceptible than others to staph infections, including diabetics, African Americans, gay men who practice anal intercourse, and very young children as well as seniors and persons with prosthetic devices.

Causes and symptoms

The causes and symptoms of staphylococcal infections vary somewhat according to the species or strain involved and the tissues or body organs infected.

Skin and soft-tissue infections

Staphylococcal infections of the skin and soft tissues are most commonly caused by S. aureus; however, the number of such infections caused by S. epidermidis has been rising rapidly since the early 2000s. Skin infections caused by staph often look like spider or other insect bites. Infected wounds or surgical incisions typically ooze pus or another discharge. Many of these skin infections develop from scratching insect bites or patches of eczema; after the skin is broken, the bacteria can enter the tissues beneath the surface and form large pus-filled abscesses. In patients with weakened immune systems, the staphylococci can enter the bloodstream. This condition, which is known as bacteremia , can carry the organisms to other parts of the body, including the heart, lungs, and eyes.

Endocarditis

Infective endocarditis is an inflammation of the valves and other tissues lining the heart, caused when staphylococci form colonies on the surface of the valves. Patients with artificial or damaged heart valves have a higher risk of bacterial endocarditis than patients with normal heart valves. The staphylococci typically enter the body through a surgical incision, a urinary tract infection , intravenous drug use, or indwelling catheters Although some forms of endocarditis develop slowly, others mdash; particularly those caused by S. aureus—may develop in days or a few weeks. The patient usually runs a fever, and the staphylococci can be detected in a blood culture. The patient will often have a heart murmur or some other abnormality of blood flow in the heart that can be detected on an echocardiogram .

Some elderly patients may develop rapid-onset dementia as a symptom of infective endocarditis. About 40 percent of patients will develop skin problems, ranging from small tender nodules in the fingertips to pinpoint hemorrhages in the tissues lining the mouth or on the skin above the shoulder blades. Some patients will develop the signs of a stroke if the endocarditis is not detected early; this complication develops when the bacteria growing on the heart tissue form clumps that travel through the bloodstream and block some of the blood vessels in the brain.

Pneumonia

Most cases of pneumonia in seniors are caused by streptococci; however, staphylococcal pneumonia accounts for about 3 percent of severe cases acquired outside the hospital. S. aureus was identified as the cause of a number of severe cases of pneumonia following influenza during the 2003–2004 flu season. The patients had the typical symptoms of pneumonia: fever, chest pain , cough, and production of sputum. Community-acquired pneumonia (CAP) following influenza is more likely to affect seniors than younger adults; seniors with diabetes are particularly susceptible.

Joints and prosthetic devices

Infections of the joints may be caused by staphylococci entering the joints from the bloodstream or through contamination of artificial joints. S. aureus and S. epidermidis are the species usually involved in joint infections. The knee is the most commonly affected joint, but the wrist, ankle, or hip may also be involved; about 20 percent of patients have two or more joints affected by the infection.

The most common symptom of a joint infection is sudden swelling and pain in the affected joint due to the accumulation of pus and tissue fluid. The patient may or may not have a fever.

Endophthalmitis

Endophthalmitis is an inflammation of the tissues on the inside of the eye. It can be caused by bacteria entering these tissues via the bloodstream (endogenous endophthalmitis) or following eye surgery (exogenous endophthalmitis). Endogenous endophthalmitis is rare, accounting for about 15 percent of cases. Most cases of eye infection from staphylococci result from trauma to the eye or following cataract surgery. S. epidermidis is the most common staphylococcus involved in bacterial endophthalmitis, followed by S. aureus. These organisms usually live on the eyelid and other tissues surrounding the eye, and are introduced into the interior of the eye during surgery or when the eye is injured.

The early symptoms of staphylococcal endophthalmitis include pain, swelling, and redness in the affected eye and partial loss of vision. They usually begin within a week of the injury or operation. The patient may also have a headache and be sensitive to bright light. In some cases there is a noticeable discharge from the affected eye.

Food poisoning

Staphylococcal food poisoning is the result of toxins secreted by the organisms rather than by tissue damage caused by invasion of the bacteria themselves. The staphylococci usually get into food from the hands of food workers or from contaminated cheese or milk products. S. aureus is tolerant of salt and can grow in salty foods like ham. The staphylococci produce at least seven different toxins that cannot be destroyed by cooking. Foods most likely to be contaminated are those made by hand and that require little or no cooking, such as sandwiches, cold cuts, and certain types of pastry.

The symptoms of staphylococcal food poisoning include nausea, vomiting, and diarrhea . They usually begin between one and six hours after eating the contaminated food, but may cause vomiting in as little as 30 minutes after eating. Most people feel better in one to three days, although seniors may take a few more days to recover fully.

Diagnosis

Diagnosis of a staphylococcal infection in seniors is based on a combination of the patient's medical history, symptoms, an examination of the skin or other affected body parts, and a blood culture that is positive for a specific staphylococcus species. For example, S. aureus can be distinguished from S. epidermidis by its effects on the blood agar used to culture bacteria in the laboratory. S. aureus is a hemolytic bacterium, which means that it destroys the blood cells suspended in the agar and leaves a clear or colorless area beneath and under its colonies.

Another test that is used to distinguish S. aureus from other staphylococci is the coagulase test. Coagulase is an enzyme produced by S. aureus that causes blood to clot, whereas most other staphylococci do not produce this enzyme. S. aureus is thus said to be coagulase-positive while other staphylococci are coagulase-negative. The test is important because S. aureus is usually more virulent than other species of staphylococci and early identification is critical.

Samples for a bacterial culture may be obtained from a skin injury, from drawing a blood sample, from a urine sample, or by having the patient cough up sputum (matter from the lungs) if pneumonia is suspected. Although a standard blood culture for a staph infection takes a day or two to yield results, rapid diagnostic methods using amplification and probe-based molecular techniques provide results in hours, thus allowing treatment to be started earlier and improving the patient's chances of recovery.

Although S. aureus can be identified in stool samples or vomit from a patient with food poisoning, doctors do not usually test for the organism unless there is an outbreak involving several people. The diagnosis of staphylococcal food poisoning is usually made on the basis of the patient's symptoms.

X-rays and other imaging tests may be performed as part of the diagnosis of joint infections, endocarditis, and pneumonia.

Staphylococcal infections of the eye are diagnosed by an examination of the eye with a slit lamp and a vision test. In most cases the patient will be referred to an ophthalmologist for further testing of the affected eye while a blood culture or urine culture is performed to identify the organism involved.

Treatment

Treatment depends on the specific type and location of staphylococcal infection. In most cases the doctor will start antibiotic therapy when a staphylococcal infection is suspected as soon as the sample of tissue, blood, sputum, or urine has been sent to the laboratory. Specific types of infections are treated as follows:

• Skin infections: The doctor will usually make an incision to drain the pus and other infected fluid out of the wound. In some cases a topical antibiotic may be applied after the wound has been cleansed, or the patient may be given systemic oral or intravenous antibiotics.
• Staphylococcal pneumonia following influenza is usually treated with intravenous antibiotics following hospitalization. Severely ill seniors may require treatment with supplemental oxygen in an intensive care unit (ICU).
• Indwelling catheters and similar devices are removed when staphylococcal infection is suspected or proved. If the infection is located in a joint with a prosthetic appliance, the artificial joint must be removed and the patient given a four- to six-week course of antibiotics. Infected joints without a prosthetic appliance are usually drained of fluid and the patient is given a four-week course of antibiotic therapy to clear the infection. Physical therapy is encouraged to maintain the range of motion in the joint.
• Infected artificial heart valves may or may not require removal. Endocarditis does, however, require long-term antibiotic therapy, particularly in seniors.
• Staphylococcal eye infections require emergency treatment. The patient is given antibiotics and the vitreous humor of the eye is removed and replaced with sterile fluid. An ophthalmologist (specialist in eye disorders) usually injects antibiotics into the tissues around the eye as well as giving antibiotics by mouth or intravenously. In extreme cases the entire eye may need to be removed.

QUESTIONS TO ASK YOUR DOCTOR

• What is the risk of a staphylococcal infection following surgery on the eye or a joint?
• Should I consider having a flu shot to lower the risk of pneumonia following flu?
• Is it safe for elderly family members to visit friends in the hospital? Should they take any special precautions to lower their risk of contracting an infection?

Nutrition/Dietetic concerns

Seniors who become sick from staphylococcal food poisoning usually recover with bed rest, plenty of fluids, and antinausea drugs prescribed by the doctor. Antibiotics cannot be used to treat food poisoning because the toxins that cause the nausea and vomiting are not affected by these drugs. Seniors who become severely ill from the toxins produced by the bacteria may require hospitalization and treatment with intravenous fluids.

KEY TERMS

Agar —A gel-like substance derived from red seaweed that is used to make a culture medium for growing bacteria on laboratory plates.

Bacteremia —The presence of bacteria in the bloodstream.

Coagulase —An enzyme produced by S. aureus that causes blood to clot. Testing for this enzyme can be used to distinguish S. aureus from most other species of staphylococci.

Colonization —In biology, the process by which a species moves into and populates a new area. It is also used the describe the process by which bacteria and other microorganisms form colonies in or on the bodies of humans and other animals.

Commensalism —In biology, a relationship in which a member of one species lives on or in a member of another and derives benefit from the relationship while the member of the other species is unharmed. Staphylococci are commensal organisms that can live on or in humans without necessarily causing disease.

Endocarditis —An inflammation of the tissues lining the inside of the heart and its valves.

Endophthalmitis —Inflammation of the tissues inside the eyeball.

Gram-positive —A term that refers to the amount of a crystal violet dye picked up by a bacterium during the Gram stain process. A Gram-positive organism looks blue or violet under a microscope whereas Gram-negative bacteria look red or pink. Staphylococci are Gram-positive bacteria.

Sepsis —The presence of bacteria or their toxic products in the bloodstream or other tissues, causing whole-body inflammation. Sepsis is a serious medical condition.

Sputum —Matter from the lungs or throat that is brought up by coughing.

Strain —A genetic variant or subtype of a bacterium (or other microorganism).

Superbug —Informal term for an antibiotic-resistant bacterium.

Virulence —The relative ability of a disease organism to overcome the body's defenses. A highly virulent organism is one that can readily overcome the immune system.

Vitrectomy —The surgical removal of the vitreous humor. The gel is replaced with saline or another clear fluid.

Vitreous humor —The clear gel that fills the space between the lens and the retina of the eye.

Therapy

Therapy for staphylococcal infections consists of administration of appropriate antibiotics by mouth or intravenously as appropriate, with surgical removal of infected tissue or medical devices as necessary.

Prognosis

The prognosis of staphylococcal infections varies according to the specific illness. Untreated S. aureus infections of the bloodstream can have a mortality rate as high as 80 percent. Endocarditis and pneumonia caused by antibiotic-resistant staphylococci have mortality rates around 11 percent in patients without other diseases or disorders, but the rate may be as high as 44 percent in patients with diabetes, HIV infection, or other disorders that weaken the immune system . Seniors with staphylococcal pneumonia have a worse prognosis than younger adults. In patients over the age of 70, community-acquired staph infections are associated with a mortality rate of 21 percent in the year following diagnosis.

The prognosis for staphylococcal endophthalmitis depends on timely diagnosis and treatment. In general, patients with postoperative endophthalmitis do better than those with endogenous infections. Seniors with weak immune systems, HIV infection, diabetes, or other disorders have a poor prognosis for full recovery of vision.

Most patients with staphylococcal food poisoning or staphylococcal urinary tract infections recover completely; fatalities are rare except in the very old.

Prevention

Preventive measures against staphylococcal infections include the following:

• Avoid scratching insect bites or other areas of irritated skin; see a doctor about a boil filled with pus or a similar skin lesion that will not heal.
• Wash hands carefully before and after preparing food.
• Cover infected skin or skin draining pus with waterproof dressings, and dispose of soiled dressings carefully. Clean cuts and scratches promptly and keep them bandaged.
• People with infections on their hands or wrists should avoid preparing or serving food until the infection has been cleared.
• Avoid sharing such personal items as combs, brushes, cosmetics, cell phones, razors, and towels. Be particularly careful in gyms and health clubs, as staphylococci prefer warm, moist environments.
• Wipe down kitchen countertops, athletic equipment, and hospital equipment with alcohol-based sanitizers.
• Avoid direct contact with other people's wounds or injuries whenever possible.

Caregiver concerns

Caregivers of seniors should be concerned about the following:

• Carefully monitor all indwelling catheters or similar devices and notify the doctor at once if there are signs of infection.
• If the senior has recently had eye surgery, watch for a discharge or other signs of infection in the eye that was treated This precaution is particularly important if the senior has diabetes.
• Look for signs of skin injury and be careful to keep the senior's skin clean and dry. Notify the doctor at once if even a small wound looks infected or the tissue around it seems to be dying.
• Wash hands carefully before and after giving the senior a bath or other body care, and use a hand sanitizer as well. Clean kitchen countertops and other hard surfaces with an alcohol-based cleaning agent.
• Do not use or serve food that may be contaminated, and do not prepare food for the senior if you have been diagnosed with a skin or eye infection. Keep hot foods hot (over 140°F) and cold foods cold if they must be stored for longer than 2 hours.

Resources

books

Rhinehart, Emily, and Mary McGoldrick. Infection Control in Home Care and Hospice. Sudbury, MA: Jones and Bartlett, Publishers, 2006.

Wilson, Michael. Bacteriology of Humans: An Ecological Perspective. Malden, MA: Blackwell Publishing, 2008.

periodicals

Appelbaum, P. C. “Microbiology of Antibiotic Resistance in Staphylococcus aureus.” Clinical Infectious Diseases 45 (September 15, 2007): S165–S170.

Bamberger, David M., and Sarah E. Boyd. “Management of Staphylococcus aureus Infections.” American Family Physician 72 (December 15, 2005): 2474–2481.

Hageman, Jeffrey C., Timothy M. Uyeki, John S. Francis, et al. “Severe Community-Acquired Pneumonia Due to Staphylococcus aureus, 2003–04 Influenza Season.” Emerging Infectious Diseases 12 (June 2006): 894–899.

Liu, G. Y., A. Essex, J. T. Buchanan, et al. “Staphylococcus aureus Golden Pigment Impairs Neutrophil Killing and Promotes Virulence through Its Antioxidant Activity.” Journal of Experimental Medicine 202 (July 18, 2005): 209–215.

Miller, D. M., A. S. Vedula, H. W. Flynn, Jr., et al. “Endophthalmitis Caused by Staphylococcus epidermidis: In Vitro Antibiotic Susceptibilities and Clinical Outcomes.” Ophthalmic Surgery, Lasers and Imaging 38 (November-December 2007): 446–451.

Mody, L., S. Maheshwari, A. Galecki, et al. “Indwelling Device Use and Antibiotic Resistance in Nursing Homes: Identifying a High-Risk Group.” Journal of the American Geriatrics Society 55 (December 2007): 1921–1926.

Noskin, G. A., R. J. Rubin, J. J. Schentag, et al. “The Burden of Staphylococcus aureus Infections on Hospitals in the United States: An Analysis of the 2000 and 2001 Nationwide Inpatient Sample Database.” Archives of Internal Medicine 165 (August 8–22, 2005): 1756–1761.

other

Centers for Disease Control and Prevention (CDC). Staphylococcal Food Poisoning. Available online at http://www.cdc.gov/ncidod/dbmd/diseaseinfo/staphylo-coccus_food_g.htm [cited March 9, 2008].

Egan, Daniel J., and Jessica R. Peters. “Endophthalmitis.” eMedicine, December 21, 2007. http://www.emedicine.com/emerg/topic880.htm [cited March 9, 2008].

Fraser, Susan L. “Enterococcal Infections.” eMedicine, July 5, 2006. http://www.emedicine.com/med/topic680.htm [cited March 8, 2008].

Herchline, Thomas. “Staphylococcal Infections.” eMedicine, May 8, 2007. http://www.emedicine.com/med/topic2166.htm [cited March 7, 2008].

organizations

Centers for Disease Control and Prevention (CDC), 1600 Clifton Road, Atlanta, GA, 30333, (404) 498-1515, (800) 311-3435, http://www.cdc.gov/.

Food and Drug Administration (FDA), 5600 Fishers Lane, Rockville, MD, 20857, (888) 463-6332, http://www.fda.gov/default.htm.

National Institute of Allergy and Infectious Diseases (NIAID), 6610 Rockledge Drive, MSC 6612, Bethesda, MD, 20892, (301) 496-5717, (866) 284-4107, (301) 402 3573, http://www3.niaid.nih.gov/.

Rebecca J. Frey Ph.D.

Staphylococcal infections

Definition

Staphylococcal (staph) infections are communicable infections caused by staph organisms and often characterized by the formation of abscesses. They are the leading cause of primary infections originating in hospitals (nosocomial infections) in the United States.

Description

Classified since the early twentieth century as among the deadliest of all disease-causing organisms, staph exists on the skin or inside the nostrils of 20–30% of healthy people. These bacteria are sometimes found in breast tissue, the mouth, and the genital, urinary, and upper respiratory tracts.

Although staph bacteria are usually harmless, when injury or a break in the skin enables the organisms to invade the body and overcome the body's natural defenses, consequences can range from minor discomfort to death. Infection is most apt to occur in:

• Newborns (especially those born prematurely).
• Women who are breast-feeding.
• Persons whose immune systems have been weakened by radiation treatments, chemotherapy, HIV, or medication.
• Intravenous drug users.
• Those with surgical incisions, skin disorders, and serious illness like cancer , diabetes, and lung disease.
• The elderly, particularly those who are confined to nursing homes.

Types of infections

Staph skin infections often produce pus-filled pockets (abscesses) located just beneath the surface of the skin or deep within the body. Risk of infection is greatest among the very young and the very old.

A localized staph infection is confined to a ring of dead and dying white blood cells and bacteria. The skin above it feels warm to the touch. Most of these abscesses eventually burst, and pus leaking onto the skin can cause new infections.

A small fraction of localized staph infections enter the bloodstream and spread through the body. In children, these systemic (affecting the whole body) or disseminated infections frequently affect the ends of the long bones of the arms or legs, causing a bone infection called osteomyelitis. When adults develop invasive staph infections, bacteria are most apt to cause abscesses of the brain, heart, kidneys, liver, lungs, or spleen.

TOXIC SHOCK. Toxic shock syndrome is a life-threatening infection characterized by severe headache, sore throat, fever as high as 105°F (40.6°C), and a sunburn-like rash that spreads from the face to the rest of the body. Symptoms appear suddenly; they also include dehydration and watery diarrhea .

Inadequate blood flow to peripheral parts of the body (shock) and loss of consciousness occur within the first 48 hours. Between the third and seventh day of illness, skin peels from the palms of the hands, soles of the feet, and other parts of the body. Kidney, liver, and muscle damage often occur.

SCALDED SKIN SYNDROME. Rare in adults and most common in newborns and other children under the age of five, scalded skin syndrome originates with a localized skin infection. A mild fever and/or an increase in the number of infection-fighting white blood cells may occur.

A bright red rash spreads from the face to other parts of the body and eventually forms scales. Large, soft blisters develop at the site of infection and elsewhere. When they burst, they expose inflamed skin that looks as if it had been burned.

MISCELLANEOUS INFECTIONS. Staphylococcus aureus can also cause:

• arthritis
• bacteria in the bloodstream (bacteremia)
• pockets of infection and pus under the skin (carbuncles)
• tissue inflammation that spreads below the skin, causing pain and swelling (cellulitis)
• inflammation of the valves and walls of the heart(endocarditis)
• inflammation of tissue that enclosed and protects the spinal cord and brain (meningitis)
• inflammation of bone and bone marrow (osteomyelitis).
• pneumonia

Types of staph infections

STAPHYLOCOCCUS AUREUS. Named for the golden color of the bacterium when grown under laboratory conditions, S. aureus is a hardy organism that can survive in extreme temperatures or other inhospitable circumstances. About 70–90% of the population carry this strain of staph in the nostrils at some time. Although present on the skin of only 5–20% of healthy people, as many as 40% carry it elsewhere, such as in the throat, vagina, or rectum, for varying periods of time, from hours to years, without developing symptoms or becoming ill.

S. aureus flourishes in hospitals, where it infects healthcare personnel and patients who have had surgery; who have acute dermatitis , insulin-dependent diabetes, or dialysis-dependent kidney disease; or who receive frequent allergy-desensitization injections. Staph bacteria can also contaminate bedclothes, catheters, and other objects. In many cases, staph contamination in hospitals is made worse by overprescribing and misuse of antibiotics. The result is the emergence of strains of S. aureus that are resistant to antibiotics.

S. aureus causes a variety of infections. Boils and inflammation of the skin surrounding a hair shaft (folliculitis) are the most common. Toxic shock syndrome (TSS) and scalded skin syndrome (SSS) are among the most serious. S. aureus is also emerging as a leading cause of infective endocarditis and of a higher mortality rate from this disorder.

Together with S. pyogenes, S. aureus is known to be a major producer of superantigens, which are bacterial exotoxins that trigger abnormal and excessive activation of T-cells. T cells are produced in the thymus gland and regulate the human immune system's response to infection. Superantigens are being studied intensively for their roles in causing disease. Staphylococci are responsible for at least 19 different superantigens.

S. EPIDERMIDIS. Capable of clinging to tubing (as in that used for intravenous feeding, etc.), prosthetic devices, and other non-living surfaces, S. epidermidis is the organism that most often contaminates devices that provide direct access to the bloodstream.

The primary cause of bacteremia in hospital patients, this strain of staph is most likely to infect cancer patients, whose immune systems have been compromised, and high-risk newborns receiving intravenous supplements.

S. epidermidis also accounts for two of every five cases of prosthetic valve endocarditis. Prosthetic valve endocarditis is an infection that develops as a complication of the implantation of an artificial valve in the heart. Although contamination usually occurs during surgery, symptoms of infection may not become evident until a year after the operation. More than half of the patients who develop prosthetic valve endocarditis die.

STAPHYLOCOCCUS SAPROPHYTICUS. Existing within and around the tube-like structure that carries urine from the bladder (urethra) of about 5% of healthy males and females, S. saprophyticus is the second most common cause of unobstructed urinary tract infections (UTIs) in sexually active young women. This strain of staph is responsible for 10-20% of infections affecting healthy outpatients.

Causes & symptoms

Staph bacteria can spread through the air, but infection is almost always the result of direct contact with open sores or body fluids contaminated by these organisms.

Warning signs

Common symptoms of staph infection include:

• Pain or swelling around a cut or an area of skin that has been scraped.
• Boils or other skin abscesses.
• Blistering, peeling, or scaling of the skin. This symptom is most common in infants and young children.
• Enlarged lymph nodes in the neck, armpits, or groin.

A family physician should be notified whenever:

• A boil or carbuncle appears on any part of the face or spine. Staph infections affecting these areas can spread to the brain or spinal cord.
• A boil becomes very sore. Usually a sign that infection has spread, this condition may be accompanied by fever, chills , and red streaks radiating from the site of the original infection.
• Boils that develop repeatedly. This type of recurrent infection could be a symptom of diabetes.

Diagnosis

Blood tests that show unusually high concentrations of white blood cells can suggest staph infection, but diagnosis is based on laboratory analysis of material removed from pus-filled sores, and on analysis of normally uninfected body fluids, such as blood and urine. Also, x rays can enable doctors to locate internal abscesses and estimate the severity of infection. Needle biopsy (removing tissue with a needle, then examining it under a microscope) may be used to assess bone involvement.

Treatment

Superficial staph infections can generally be cured by keeping the area clean and antiseptic and applying warm moist compresses to the affected area for 20 to 30 minutes three or four times a day.

Among the therapies believed to be helpful for the person with a staph infection are yoga (to stimulate the immune system and promote relaxation ), acupuncture (to draw heat away from the infection), and herbal remedies. Herbs that may help the body overcome, or withstand, staph infection include:

• Garlic (Allium sativum ). This herb is believed to have antibacterial properties. Herbalists recommend consuming three garlic cloves or three garlic oil capsules a day, starting when symptoms of infection first appear.
• Cleavers (Galium aparine ). This anti-inflammatory herb is believed to support the lymphatic system. It may be taken internally to help heal staph abscesses and reduce swelling of the lymph nodes. A cleavers compress can also be applied directly to a skin infection.
• Goldenseal (Hydrastis canadensis ). Another herb believed to fight infection and reduce inflammation, goldenseal may be taken internally when symptoms of infection first appear. Skin infections can be treated by making a paste of water and powdered goldenseal root and applying it directly to the affected area. The preparation should be covered with a clean bandage and left in place overnight.
• Echinacea (Echinacea spp.). Taken internally, this herb is believed to have antibiotic properties and is also thought to strengthen the immune system.
• Thyme (Thymus vulgaris ), lavender (Lavandula officinalis ), or bergamot (Citrus bergamot ) oils. These oils are believed to have antibacterial properties and may help to prevent the scarring that may result from skin infections. A few drops of these oils are added to water and a compress soaked in the water is then applied to the affected area.
• Tea tree oil (Melaleuca spp., or ylang ylang). Another infection-fighting herb, this oil can be applied directly to a boil or other skin infection.

Allopathic treatment

Severe or recurrent staphylocoecal infections may require a seven- to 10-day course of treatment with penicillin or other oral antibiotics. The location of the infection and the identity of the causal bacterium determines which of several effective medications should be prescribed. In recent years, doctors have turned to such newer medications as vancomycin or the fluoroquinolones to treat staph infections because strains of S. aureus have emerged that are resistant to penicillin and the older antibiotics.

In case of a more serious infection, antibiotics may be administered intravenously for as long as six weeks. Intravenous antibiotics are also used to treat staph infections around the eyes or on other parts of the face.

Surgery may be required to drain or remove abscesses that form on internal organs, or on shunts or other devices implanted inside the body.

Expected results

Most healthy people who develop staph infections recover fully within a short time. Others develop repeated infections. Some become seriously ill, requiring long-term therapy or emergency care. A small percentage die.

Prevention

Healthcare providers and patients should always wash their hands thoroughly with warm water and soap after treating a staph infection or touching an open wound or the pus it produces. Pus that oozes onto the skin from the site of an infection should be removed immediately. This affected area should then be cleansed with antiseptic or with antibacterial soap.

To prevent infection from spreading from one part of the body to another, it is important to shower rather than bathe during the healing process. Because staph infection is easily transmitted from one member of a household to others, towels, washcloths, and bed linens used by someone with a staph infection should not be used by anyone else. They should be changed daily until symptoms disappear, and laundered separately in hot water with bleach.

Children should frequently be reminded not to share:

• brushes, combs, or hair accessories
• caps
• clothing
• sleeping bags
• sports equipment
• other personal items

A diet rich in green, yellow, and orange vegetables can bolster natural immunity. A doctor or nutritionist may recommend vitamins or mineral supplements to compensate for specific dietary deficiencies. Drinking eight to 10 glasses of water a day can help flush diseasecausing organisms from the body.

Because some strains of staph bacteria are known to contaminate artificial limbs, prosthetic devices implanted within the body, and tubes used to administer medication or drain fluids from the body, catheters and other devices should be removed on a regular basis if possible and examined for microscopic signs of staph. Symptoms may not become evident until many months after contamination has occurred, so this practice should be followed even with patients who show no sign of infection.

A vaccine against S. aureus was developed in the late 1990s for use with patients with low resistance to infection. A trial of the vaccine in hemodialysis patients indicates that it offers partial protection against bacteremia for about 40 weeks.

Resources

BOOKS

Bennett, J. Claude, and Fred Plum, eds. Cecil Textbook of Medicine. Philadelphia, PA: W. B. Saunders Company, 1996.

Civetta, Joseph M., et al, eds. Critical Care. Philadelphia, PA: Lippincott-Raven Publishers, 1997.

Fauci, Anthony, et al, eds. Harrison's Principles of Internal Medicine. New York, NY: McGraw-Hill, Inc., 1998.

PERIODICALS

Al-Ghamdi, S., M. Gedebou, and N. E. Bilal. "Nosocomial Infections and Misuse of Antibiotics in a Provincial Community Hospital, Saudi Arabia." Journal of Hospital Infection 50 (February 2002): 115-121.

Amir, L. "Breastfeeding and Staphylococcus aureus :Three Case Reports." Breastfeeding Review 10 (March 2002): 15-18.

Bradley, S. F. "Staphylococcus aureus Infections and Antibiotic Resistance in Older Adults." Clinical Infectious Diseases 34 (January 15, 2002): 211-216.

Cabell, C. H., J. G. Jollis, G. E. Peterson, et al. "Changing Patient Characteristics and the Effect on Mortality in Endocarditis." Archives of Internal Medicine 162 (January 14, 2002): 90-94.

Llewelyn, M., and J. Cohen. "Superantigens: Microbial Agents That Corrupt Immunity." Lancet Infectious Diseases 2 (March 2002): 156-162.

Shinefeld, H., S. Black, A. Fattom et al. "Use of a Staphylococcus aureus Conjugate Vaccine in Patients Receiving Hemodialysis." New England Journal of Medicine 346 (February 14, 2002): 491-496.

Paula Ford-Martin

Rebecca J. Frey, PhD

Staphylococcal infections

Definition

Staphylococcal (staph) infections are communicable diseases caused by certain bacteria and generally characterized by the formation of abscesses. They are the leading cause of primary infections originating in hospitals in the United States.

Description

Classified since the early twentieth century as among the deadliest of all disease-causing organisms, staphylococcal bacteria exist on the skin or inside the nostrils of 20 to 30 percent of healthy people. It is sometimes found in breast tissue, the mouth, and the genital, urinary, and upper respiratory tracts.

Staph bacteria are usually harmless; however, when an injury or a break in the skin enables the organisms to invade the body and overcome the body's natural defenses, consequences can range from minor discomfort to death.

Demographics

Infection is most apt to occur in newborns; children whose immune systems have been undermined by radiation treatments, chemotherapy , or medication; those with surgical incisions or skin disorders; and among people with serious illnesses such as cancer , diabetes, and lung disease. Children are also more at risk for staph infections if they have HIV/AIDS or other diseases that compromise immune function, have a catheter or implanted prosthetics, are hospitalized, have open wounds , or live in close quarters with a large group of others. It is not clear exactly how many staph infections occur each year, but it is the most common infection that begins in the hospital.

Causes and symptoms

Staph infections produce pus-filled pockets (abscesses) located just beneath the surface of the skin or deep within the body. A localized staph infection is confined to a ring of dead and dying white blood cells and bacteria. The skin above it feels warm to the touch. Most of these abscesses eventually burst, and pus that leaks onto the skin can cause new infections.

A small fraction of localized staph infections enter the bloodstream and spread through the body. In children, these systemic (affecting the whole body) or disseminated infections frequently affect the ends of the long bones of the arms or legs, causing a bone infection called osteomyelitis. Other abscesses that can develop from staph infection include those of the brain, heart, kidneys, liver, lungs, or spleen.

Staphylococcus aureus

Named for the golden color of the bacteria grown under laboratory conditions, Staphylococcus aureus is a hardy organism that can survive in extreme temperatures or other inhospitable circumstances. About 70 to 90 percent of the population carry this type of staph in their nostrils at some time in their lives. Although present on the skin of only 5 to 20 percent of healthy people, as many as 40 percent of individuals carry it elsewhere, such as in the throat, vagina, or rectum, for varying periods of time, from hours to years, without developing symptoms or becoming ill.

S. aureus flourishes in hospitals, where it infects healthcare personnel and infects patients who have had surgery, have open wounds, have acute dermatitis , insulin-dependent diabetes, or dialysis-dependent kidney disease, or who receive frequent allergy-desensitization injections. Staph bacteria can also contaminate bedclothes, catheters, and other objects.

S. aureus causes a variety of infections. Boils and inflammation of the skin surrounding a hair shaft (folliculitis) are the most common. Toxic shock (TSS) and scalded skin syndrome (SSS) are among the most serious.

TOXIC SHOCK Toxic shock syndrome is a life-threatening infection characterized by severe headache , sore throat , fever as high as 105°F (40.5°C), and a sunburn-like rash that spreads from the face to the rest of the body. Symptoms appear suddenly. They also include dehydration and watery diarrhea .

Inadequate blood flow to peripheral parts of the body (shock) and loss of consciousness occur within the first 48 hours. Between the third and seventh day of illness, skin peels from the palms of the hands, soles of the feet, and other parts of the body. Kidney, liver, and muscle damage often occur.

SCALDED SKIN SYNDROME Rare in adults and most common in newborns and other children under the age of five, scalded skin syndrome originates with a localized skin infection. A mild fever and/or an increase in the number of infection-fighting white blood cells may occur.

A bright red rash spreads from the face to other parts of the body and eventually forms scales. Large, soft blisters develop at the site of infection and elsewhere. When they burst, they expose inflamed skin that looks as if it had been burned.

MISCELLANEOUS INFECTIONS S. aureus can also cause the following:

• arthritis
• bacteria in the bloodstream (bacteremia)
• pockets of infection and pus under the skin (carbuncles)
• tissue inflammation that spreads below the skin, causing pain and swelling (cellulitis)
• inflammation of the valves and walls of the heart (endocarditis)
• inflammation of tissue that encloses and protects the spinal cord and brain (meningitis)
• inflammation of bone and bone marrow (osteomyelitis)
• pneumonia

Other strains of staphylococci

S. EPIDERMIDIS Capable of clinging to tubing (such as that used for intravenous feeding), prosthetic devices, and other non-living surfaces, S. epidermidis is the organism that most often contaminates devices that provide direct access to the bloodstream.

The primary cause of bacterial infection in hospital patients, this strain of staph is most likely to infect cancer patients, whose immune systems have been compromised and high-risk newborns receiving intravenous supplements.

S. epidermidis also accounts for two of every five cases of prosthetic valve endocarditis. Prosthetic valve endocarditis is inflammation that occurs as a complication of the implantation of an artificial valve in the heart. Although contamination usually occurs during surgery, symptoms of infection may not become evident until a year after the operation. More than half of the patients who develop prosthetic valve endocarditis die.

Causes and symptoms

Staph bacteria can spread through the air, but infection is almost always the result of direct contact with open sores or body fluids contaminated by these organisms. Staph bacteria often enter the body through inflamed hair follicles or oil glands. Or they penetrate skin damaged by burns , cuts and scrapes, infection, insect bites , or wounds.

Multiplying beneath the skin, bacteria infect and destroy tissue in the area where they entered the body. Staph infection of the blood (staphylococcal bacteremia) develops when bacteria from a local infection infiltrate the lymph glands and bloodstream. These infections, which can usually be traced to contaminated catheters or intravenous devices, cause persistent high fever. They may cause shock. They also can cause death within a short time.

When to call the doctor

The following are common symptoms of staph infection:

• pain or swelling around a cut or an area of skin that has been scraped
• boils or other skin abscesses
• blistering, peeling, or scaling of the skin (This symptom is most common in infants and young children.)
• enlarged lymph nodes in the neck, armpits, or groin

A family physician should be notified whenever the following symptoms are present:

• Lymph nodes in the neck, armpits, or groin become swollen or tender.
• An area of skin that has been cut or scraped becomes painful or swollen, feels hot, or produces pus. These symptoms may mean the infection has spread to the bloodstream.
• A boil or carbuncle appears on any part of the face or spine. Staph infections affecting these areas can spread to the brain or spinal cord.
• A boil becomes very sore. Usually a sign that infection has spread, this condition may be accompanied by fever, chills, and red streaks radiating from the site of the original infection.
• Boils develop repeatedly. This type of recurrent infection could be a symptom of diabetes.

Diagnosis

Blood tests that show unusually high concentrations of white blood cells can suggest staph infection, but diagnosis is based on laboratory analysis of material removed from pus-filled sores and on analysis of normally uninfected body fluids such as blood and urine. Also, x-rays can enable doctors to locate internal abscesses and estimate the severity of infection. Needle biopsy (removing tissue with a needle, then examining it under a microscope) may be used to assess if any bones are infected.

Treatment

Superficial staph infections can generally be cured by keeping the area clean, using soaps that leave a germ-killing film on the skin, and applying warm, moist compresses to the affected area for 20 to 30 minutes three or four times a day.

Severe or recurrent infections may require a seven to 10 day course of treatment with penicillin or other oral antibiotics . The location of the infection and the identity of the causal bacteria determine which of several effective medications should be prescribed.

In case of a more serious infection, antibiotics may be administered intravenously for as long as six weeks. Intravenous antibiotics are also used to treat staph infections around the eyes or on other parts of the face.

Surgery may be required to drain or remove abscesses that form on internal organs or on shunts or other devices implanted inside the body.

Alternative treatment

Alternative therapies for staph infection are meant to strengthen the immune system and prevent recurrences. Among the therapies believed to be helpful for the person with a staph infection are yoga (to stimulate the immune system and promote relaxation), acupuncture (to draw heat away from the infection), and herbal remedies. Herbs that may help the body overcome, or withstand, staph infection include the following:

• Garlic (Allium sativum ). This herb is believed to have antibacterial properties. Herbalists recommend consuming three garlic cloves or three garlic oil capsules a day, starting when symptoms of infection first appear.
• Cleavers (Galium aparine ). This anti-inflammatory herb is believed to support the lymphatic system. It may be taken internally to help heal staph abscesses and reduce swelling of the lymph nodes. A cleavers compress can also be applied directly to a skin infection.
• Goldenseal (Hydrastis canadensis ). Another herb believed to fight infection and reduce inflammation, goldenseal may be taken internally when symptoms of infection first appear. Skin infections can be treated by making a paste of water and powdered goldenseal root and applying it directly to the affected area. The preparation should be covered with a clean bandage and left in place overnight.
• Echinacea (Echinacea spp.). Taken internally, this herb is believed to have antibiotic properties and is also thought to strengthen the immune system.
• Thyme (Thymus vulgaris ), lavender (Lavandula officinalis ), or bergamot (Citrus bergamot ) oils. These oils are believed to have antibacterial properties and may help to prevent the scarring that may result from skin infections. A few drops of these oils are added to water and then a compress soaked in the water is applied to the affected area.
• Tea tree oil (Melaleuca spp.). Another infection-fighting herb, this oil can be applied directly to a boil or other skin infection.

Prognosis

Most healthy people who develop staph infections recover fully within a short time. Others develop repeated infections. Some become seriously ill, requiring long-term therapy or emergency care. A small percentage die.

Doctors and researchers are becoming increasingly concerned about staph infections that are resistant to antibiotics. A bacterium that is considered resistant is one that can no longer be treated effectively using the antibiotics that are commonly prescribed for that type of infection. Resistant staph infections can usually be treated effectively with other antibiotics. Children who are most at risk for resistant staph infections are those who have been in the hospital or have serious underlying medical conditions. According to the Centers for Disease Control, although it is not clear how many cases of resistant staph infections occur each year, they are thought to be very rare. They recommend treating all infections promptly and only prescribing antibiotics when there is an underlying bacterial cause for the disease (antibiotics are not effective against viruses) to help reduce the occurrence of bacteria becoming resistant to antibiotics.

Prevention

Healthcare providers and patients should always wash their hands thoroughly with warm water and soap after treating a staph infection or touching an open wound or the pus it produces. Pus that oozes onto the skin from the site of an infection should be removed immediately. This affected area should then be cleansed with antiseptic or with antibacterial soap.

To prevent infection from spreading from one part of the body to another, it is important to shower rather than bathe during the healing process. Because staph infection is easily transmitted from one member of a household to others, towels, washcloths, and bed linens used by someone with a staph infection should not be used by anyone else. They should be changed daily until symptoms disappear, and laundered separately in hot water with bleach. Children should frequently be reminded not to share brushes, combs, or hair accessories.

Parental concerns

Staph infections are most likely to occur after a child has had surgery or a wound of some kind. A good way to help prevent staph infections of wounds is to keep the wound clean and dry. Children who have staph infections, especially skin infections, should be kept away from others whom they are likely to infect, and their bedding, clothes, and other things that may have touched the wound should be cleaned with hot soapy water and bleach.

KEY TERMS

Abscess —A localized collection of pus in the skin or other body tissue caused by infection.

Endocarditis —Inflammation of the inner membrane lining heart and/or of the heart valves caused by infection.

Resources

BOOKS

Honeyman, Allen, Herman Friedman, and Mauro Bendinelli, eds. Staphylococcus Aureus Infection and Disease. New York: Kluwer Academic, 2001.

PERIODICALS

Zoler, Mitchell L. "Community-Acquired MRSA Infections Rising: Pediatric, Soft Tissue Infections." Family Practice News 34, no. 11 (June 2004): 7–8.

Tish Davidson, A.M. Maureen Haggerty

Staphylococcal Infections

Definition

Staphylococcal (staph) infections are communicable conditions caused by certain bacteria and generally characterized by the formation of abscesses. They are the leading cause of primary infections originating in hospitals (nosocomial infections) in the United States.

Description

Classified since the early twentienth century as among the deadliest of all disease-causing organisms, staph exists on the skin or inside the nostrils of 20-30% of healthy people. It is sometimes found in breast tissue, the mouth, and the genital, urinary, and upper respiratory tracts.

Although staph bacteria are usually harmless, when injury or a break in the skin enables the organisms to invade the body and overcome the body's natural defenses, consequences can range from minor discomfort to death. Infection is most apt to occur in:

• newborns
• women who are breastfeeding
• individuals whose immune systems have been undermined by radiation treatments, chemotherapy, or medication
• intravenous drug users
• those with surgical incisions, skin disorders, and serious illness like cancer, diabetes, and lung disease

Types of infections

Staph infections produce pus-filled pockets (abscesses) located just beneath the surface of the skin or deep within the body. Risk of infection is greatest among the very young and the very old.

A localized staph infection is confined to a ring of dead and dying white blood cells and bacteria. The skin above it feels warm to the touch. Most of these abscesses eventually burst, and pus that leaks onto the skin can cause new infections.

A small fraction of localized staph infections enter the bloodstream and spread through the body. In children, these systemic (affecting the whole body) or disseminated infections frequently affect the ends of the long bones of the arms or legs, causing a bone infection called osteomyelitis. When adults develop invasive staph infections, bacteria are most apt to cause abscesses of the brain, heart, kidneys, liver, lungs, or spleen.

Staphylococcus aureus

Named for the golden color of the bacteria grown under laboratory conditions, S. aureus is a hardy organism that can survive in extreme temperatures or other inhospitable circumstances. About 70-90% of the population carry this strain of staph in the nostrils at some time. Although present on the skin of only 5-20% of healthy people, as many as 40% carry it elsewhere, such as in the throat, vagina, or rectum, for varying periods of time, from hours to years, without developing symptoms or becoming ill.

S. aureus flourishes in hospitals, where it infects healthcare personnel and patients who have had surgery; who have acute dermatitis, insulin-dependent diabetes, or dialysis-dependent kidney disease ; or who receive frequent allergy-desensitization injections. Staph bacteria can also contaminate bedclothes, catheters, and other objects.

S. aureus causes a variety of infections. Boils and inflammation of the skin surrounding a hair shaft (folliculitis ) are the most common. Toxic shock (TSS) and scalded skin syndrome (SSSS) are among the most serious.

TOXIC SHOCK. Toxic shock syndrome is a life-threatening infection characterized by severe headache, sore throat, fever as high as 105°F, and a sunburn-like rash that spreads from the face to the rest of the body. Symptoms appear suddenly; they also include dehydration and watery diarrhea.

Inadequate blood flow to peripheral parts of the body (shock) and loss of consciousness occur within the first 48 hours. Between the third and seventh day of illness, skin peels from the palms of the hands, soles of the feet, and other parts of the body. Kidney, liver, and muscle damage often occur.

SCALDED SKIN SYNDROME. Rare in adults and most common in newborns and other children under the age of five, scalded skin syndrome originates with a localized skin infection. A mild fever and/or an increase in the number of infection-fighting white blood cells may occur.

A bright red rash spreads from the face to other parts of the body and eventually forms scales. Large, soft blisters develop at the site of infection and elsewhere. When they burst, they expose inflamed skin that looks as if it had been burned.

MISCELLANEOUS INFECTIONS. S. aureus can also cause:

• arthritis
• bacteria in the bloodstream (bacteremia )
• pockets of infection and pus under the skin (carbuncles)
• tissue inflammation that spreads below the skin, causing pain and swelling (cellulitis)
• inflammation of the valves and walls of the heart (endocarditis )
• inflammation of tissue that enclosed and protects the spinal cord and brain (meningitis )
• inflammation of bone and bone marrow (osteomyelitis)
• pneumonia

Other strains of staph

S. EPIDERMIDIS. Capable of clinging to tubing (as in that used for intravenous feeding, etc.), prosthetic devices, and other non-living surfaces, S. epidermidis is the organism that most often contaminates devices that provide direct access to the bloodstream.

The primary cause of bacteremia in hospital patients, this strain of staph is most likely to infect cancer patients, whose immune systems have been compromised, and high-risk newborns receiving intravenous supplements.

S. epidermidis also accounts for two of every five cases of prosthetic valve endocarditis. Prosthetic valve endocarditis is endocarditis as a complication of the implantation of an artificial valve in the heart. Although contamination usually occurs during surgery, symptoms of infection may not become evident until a year after the operation. More than half of the patients who develop prosthetic valve endocarditis die.

STAPHYLOCOCCUS SAPROPHYTICUS. Existing within and around the tube-like structure that carries urine from the bladder (urethra) of about 5% of healthy males and females, S. saprophyticus is the second most common cause of unobstructed urinary tract infections (UTIs) in sexually active young women. This strain of staph is responsible for 10-20% of infections affecting healthy outpatients.

Causes and symptoms

Staph bacteria can spread through the air, but infection is almost always the result of direct contact with open sores or body fluids contaminated by these organisms.

Staph bacteria often enter the body through inflamed hair follicles or oil glands. Or they penetrate skin damaged by burns, cuts and scrapes, infection, insect bites, or wounds.

Multiplying beneath the skin, bacteria infect and destroy tissue in the area where they entered the body. Staph infection of the blood (staphylococcal bacteremia) develops when bacteria from a local infection infiltrate the lymph glands and bloodstream. These infections, which can usually be traced to contaminated catheters or intravenous devices, usually cause persistent high fever. They may cause shock. They also can cause death within a short time.

Warning signs

Common symptoms of staph infection include:

• pain or swelling around a cut, or an area of skin that has been scraped
• boils or other skin abscesses
• blistering, peeling, or scaling of the skin; this is most common in infants and young children
• enlarged lymph nodes in the neck, armpits, or groin

A family physician should be notified whenever:

• Lymph nodes in the neck, armpits, or groin become swollen or tender.
• An area of skin that has been cut or scraped becomes painful or swollen, feels hot, or produces pus. These symptoms may mean the infection has spread to the bloodstream.
• A boil or carbuncle appears on any part of the face or spine. Staph infections affecting these areas can spread to the brain or spinal cord.
• A boil becomes very sore. Usually a sign that infection has spread, this condition may be accompanied by fever, chills, and red streaks radiating from the site of the original infection.
• Boils that develop repeatedly. This type of recurrent infection could be a symptom of diabetes.

Diagnosis

Blood tests that show unusually high concentrations of white blood cells can suggest staph infection, but diagnosis is based on laboratory analysis of material removed from pus-filled sores, and on analysis of normally uninfected body fluids, such as, blood and urine. Also, x rays can enable doctors to locate internal abscesses and estimate the severity of infection. Needle biopsy (removing tissue with a needle, then examining it under a microscope) may be used to assess bone involvement.

Treatment

Superficial staph infections can generally be cured by keeping the area clean, using soaps that leave a germ-killing film on the skin, and applying warm, moist compresses to the affected area for 20-30 minutes three or four times a day.

Severe or recurrent infections may require a seven to 10 day course of treatment with penicillin or other oral antibiotics. The location of the infection and the identity of the causal bacteria determines which of several effective medications should be prescribed.

In case of a more serious infection, antibiotics may be administered intravenously for as long as six weeks. Intravenous antibiotics are also used to treat staph infections around the eyes or on other parts of the face.

Surgery may be required to drain or remove abscesses that form on internal organs, or on shunts or other devices implanted inside the body.

Alternative treatment

Alternative therapies for staph infection are meant to strengthen the immune system and prevent recurrences. Among the therapies believed to be helpful for the person with a staph infection are yoga (to stimulate the immune system and promote relaxation), acupuncture (to draw heat away from the infection), and herbal remedies. Herbs that may help the body overcome, or withstand, staph infection include:

• Garlic (Allium sativum ). This herb is believed to have anitbacterial properties. Herbalists recommend consuming three garlic cloves or three garlic oil capsules a day, starting when symptoms of infection first appear.
• Cleavers (Galium aparine ). This anti-inflammatory herb is believed to support the lymphatic system. It may be taken internally to help heal staph abscesses and reduce swelling of the lymph nodes. A cleavers compress can also be applied directly to a skin infection.
• Goldenseal (Hydrastis canadensis ). Another herb believed to fight infection and reduce imflammation, goldenseal may be taken internally when symptoms of infection first appear. Skin infections can be treated by making a paste of water and powdered goldenseal root and applying it directly to the affected area. The preparation should be covered with a clean bandage and left in place overnight.
• Echinacea (Echinacea spp.). Taken internally, this herb is believed to have antibiotic properties and is also thought to strengthen the immune system.
• Thyme (Thymus vulgaris ), lavender (Lavandula officinalis ), or bergamot (Citrus bergamot ) oils. These oils are believed to have antibacterial properties and may help to prevent the scarring that may result from skin infections. A few drops of these oils are added to water and then a compress soaked in the water is applied to the affected area.
• Tea tree oil (Melaleuca spp.). Another infection-fighting herb, this oil can be applied directly to a boil or other skin infection.

Prognosis

Most healthy people who develop staph infections recover fully within a short time. Others develop repeated infections. Some become seriously ill, requiring long-term therapy or emergency care. A small percentage die.

Prevention

Healthcare providers and patients should always wash their hands thoroughly with warm water and soap after treating a staph infection or touching an open wound or the pus it produces. Pus that oozes onto the skin from the site of an infection should be removed immediately. This affected area should then be cleansed with antiseptic or with antibacterial soap.

KEY TERMS

Abscess— A cavity containing pus surrounded by inflamed tissue.

Endocarditis— Inflammation of the lining of the heart, and/or the heart valves, caused by infection.

Nosocomial infections— Infections that were not present before the patient came to a hospital, but were acquired by a patient while in the hospital.

To prevent infection from spreading from one part of the body to another, it is important to shower rather than bathe during the healing process. Because staph infection is easily transmitted from one member of a household to others, towels, washcloths, and bed linens used by someone with a staph infection should not be used by anyone else. They should be changed daily until symptoms disappear, and laundered separately in hot water with bleach.

Children should frequently be reminded not to share:

• brushes, combs, or hair accessories
• caps
• clothing
• sleeping bags
• sports equipment
• other personal items

A diet rich in green, yellow, and orange vegetables can bolster natural immunity. A doctor or nutritionist may recommend vitamins or mineral supplements to compensate for specific dietary deficiencies. Drinking eight to 10 glasses of water a day can help flush disease-causing organisms from the body.

Because some strains of staph bacteria are known to contaminate artificial limbs, prosthetic devices implanted within the body, and tubes used to administer medication or drain fluids from the body, catheters and other devices should be removed on a regular basis, if possible, and examined for microscopic signs of staph. Symptoms may not become evident until many months after contamination has occurred, so this practice should be followed even with patients who show no sign of infection.

Resources

BOOKS

Civetta, Joseph M., et al., editors. Critical Care. Philadelphia: Lippincott-Raven Publishers, 1997.

Staphylococcal Infections

What Are Staphylococcal Infections?

How Common Are They?

Are They Contagious?

What Are Some Types of Staph Infections?

How Is a Staph Infection Diagnosed?

What Is the Treatment for Staph Infections?

How Long Does Infection Last?

What Are the Complications of Staph Infection?

Can Staph Infections Be Prevented?

Resource

Staphylococcal (stah-fih-lo-KAH-kul) infections are infections caused by Staphylococcus aureus (stah-fih-lo-KAH-kus ARE-ree-us) and related species of bacteria.

KEYWORDS

for searching the Internet and other reference sources

Antibiotic resistance

Cellulitis

Food poisoning

Impetigo

Methicillin-resistant staphylococcus aureus (MRSA)

Scalded skin syndrome

Staphylococcus aureus

Toxic shock syndrome

Vancomycin intermediate staphylococcus aureus (VISA)

What Are Staphylococcal Infections?

They cannot be seen with the naked eye, but bacteria cover the skin’s surface. Staphylococcus aureus bacteria, also called staph bacteria, often live on people’s skin, particularly around openings such as the nose, mouth, genitals*, and rectum* and sometimes inside the nose and mouth, without causing disease. But when a person’s skin is broken or cut, the bacteria can enter the wound and cause an infection. Staph infections range from minor skin infections to joint, bone, or lung infections to widespread or systemic infections. Some strains* of staph produce a toxin (or poison) that causes illness.

*genitals

(JEH-nih-tuls) are the external sexual organs.

*rectum

is the final portion of the large intestine, connecting the colon to the anus.

*strains

are various subtypes of organisms, such as viruses or bacteria.

Newborns, elderly people, and people with immune systems weakened by diseases such as cancer and AIDS* are at greater risk of serious staph infections. Some serious infections can be acquired in a hospital when a patient is being treated for another condition.

*AIDS ,

or acquired immunodeficiency (ih-myoo-no-dih-FIH-shen-see) syndrome, is an infection that severely weakens the immune system; it is caused by the human immunodeficiency virus (HIV).

How Common Are They?

Some species of staph bacteria are present on people’s skin all the time. The more dangerous Staphylococcus aureus may come and go regularly from people’s noses and skin. Skin infections caused by staph, such as boils, are quite common. Many staph infections are minor and do not require treatment; serious staph infections are less common.

Are They Contagious?

Sometimes staph infections of the skin are contagious. If a person touches another person who has a staph infection of the skin and then touches his or her own mouth or nose or an area of broken skin, the staph infection can spread. A person also can spread the bacteria from one part of the body to another through touch. Staph can be transmitted via contaminated surfaces and food and through the air as well.

What Are Some Types of Staph Infections?

Impetigo (im-pih-TEE-go) is a skin infection that usually occurs around the nose and mouth. In impetigo, fluid-filled blisters develop and often burst and form yellowish crusts. Impetigo is a contagious infection that can spread if a person scratches the blisters and then scratches or touches another area of the body.

The Evolution of Antibiotic-Resistant Staph

Antibiotics are used widely to treat infections such as those caused by staph. Over time, staph bacteria may become stronger so that the antibiotics may not be as effective against the germ, which is known as antibiotic resistance. When Alexander Fleming discovered penicillin in 1928, staph bacteria were highly sensitive to it. Now, few staph bacteria are killed by penicillin. These bacteria often are resistant to many antibiotics. The more important strains of antibiotic-resistant staph are known as methicillin-resistant staphylococcus aureus (MRSA). MRSA is resistant to commonplace antibiotics, but it is still susceptible to the last-resort, more powerful medications. A more serious strain of staph infection, vancomycin intermediate staphylococcus aureus (VISA), can resist vancomycin, one of the most powerful (and last-resort) antibiotics available. Although all strains of the bacteria found so far have been treatable with some type of antibiotic, VISA potentially could defy all medication currently available to treat such infections. MRSA and VISA infections usually develop only in a hospital or health care facility, where prolonged treatment of patients with several antibiotics is common.

Carbuncles (KAR-bung-kulz) and furuncles (FYOOR-ung-kulz), also known as boils, are staph infections that produce a red, swollen bump filled with pus* in the skin surrounding a hair follicle*. With boils pus forms in a single hair follicle, whereas carbuncles form from grouped furuncles and have several small chambers, like a series of connected boils.

*pus

is a thick, creamy fluid, usually yellow or greenish in color, that forms at the site of an infection. Pus contains infection-fighting white cells and other substances.

*hair follicle

(FAH-lih-kul) is the skin structure from which hair develops and grows.

Cellulitis (sel-yoo-LYE-tis) is an infection of the deeper layers of the skin and the connective tissues below the skin’s surface. People with cellulitis usually have an area of red, swollen, tender, warm skin. They also may have fever, swollen lymph nodes*, and a general feeling of illness. Cellulitis is most common on the face and lower legs.

*lymph

(LIMF) nodes are small, bean-shaped masses of tissue that contain immune system cells that fight harmful microorganisms. Lymph nodes may swell during infections.

Scalded skin syndrome (also known as Ritter disease) is a staph infection that typically occurs in infants and children less than 5 years old and causes large portions of skin to be shed from the body. In this condition the staph bacteria produce a toxin that damages skin. Fluid collects beneath the skin and loosens it so that large portions slip off when rubbed. When the skin slips off, it leaves raw areas that eventually crust over. When the area under the skin is exposed, the child is at risk of excessive fluid loss and additional bacterial infections. Other symptoms include fever and skin redness and tenderness. Babies with this condition may become extremely ill.

Toxic shock syndrome (TSS) is a severe infection that, like scalded skin syndrome, is caused by a toxin produced by staph bacteria. It was first recognized in the late 1970s and early 1980s, mostly among women who were using certain types of very absorbent tampons, but it can occur in people of both sexes and in both children and adults. Because this type of absorbent tampon is no longer available, TSS now usually develops after surgery or in wounds that, in most cases, do not look infected but contain the toxin-producing staph. Skin abscesses* or other staphylococcal infections also may lead to TSS. Symptoms of TSS include sudden fever, low blood pressure, very red rash, vomiting, diarrhea (dye-uh-REE-uh), and muscle pain.

*abscesses

(AB-seh-sez) are localized or walled off accumulations of pus caused by infection that can occur anywhere within the body.

Staph bacteria can produce other types of toxins that cause food poisoning if a person eats contaminated food (usually meats, poultry, eggs, and dairy products) that has not been heated or refrigerated at the proper temperature. Symptoms include belly pain, nausea (NAW-zee-uh), and vomiting. If the food poisoning is severe, a person may experience headaches, muscle aches, and blood pressure changes.

Some staph infections affect internal organs. Staph is a common cause of the bone infection osteomyelitis (ah-stee-o-my-uh-LYE-tis). Staph infections also may cause pneumonia (nu-MO-nyah), an inflammation of the lungs; blood infection (sepsis); and, more rarely, meningitis (meh-nin-JY-tis), an inflammation of the membranes that surround the brain and the spinal cord (the meninges, meh-NIN-jeez). The bacteria may spread from an infection elsewhere in the body, or they can come from a medical device, such as a catheter*, that has been colonized* by staph bacteria. Staphylococcus aureus also may infect the heart valves, where it causes inflammation and gives rise to a condition called endocarditis (endo-kar-DYE-tis).

*catheter

(KAH-thuh-ter) is a small plastic tube placed through a body opening into an organ (such as the bladder) or through the skin directly into a blood vessel. It is used to give fluids to or drain fluids from a person.

*colonized

means that a group of organisms, particularly bacteria, are living on or inside the body without causing symptoms of infection.

How Is a Staph Infection Diagnosed?

A doctor may diagnose and treat a staph infection based on its appearance, but a definite diagnosis is made by identifying the organism under a microscope or by culture*. Samples are taken from the site of the infection, which may be the skin, the blood, or an abscess. Staph food poisoning generally is diagnosed based on symptoms, dietary history, and sometimes illness in other people who have eaten the same food or eaten at the same place.

*culture

(KUL-chur) is a test in which a sample of fluid or tissue from the body is placed in a dish containing material that supports the growth of certain organisms. Typically, within days the organisms will grow and can be identified.

What Is the Treatment for Staph Infections?

Minor skin infections caused by staph bacteria often can be treated with an over-the-counter antibiotic ointment, or they can heal on their own. If a person has an abscess that stems from a staph infection, surgery to drain the pus may be necessary in addition to antibiotics, to allow the infection to heal.

More serious staph infections, such as endocarditis, osteomyelitis, TSS, and scalded skin syndrome, usually require hospitalization and supportive care, such as antibiotics, intravenous fluids to prevent dehydration, and other medications. Endocarditis caused by staph may require surgery in which the infected, damaged heart valve is removed and an artificial valve is inserted.

Because antibiotics are used widely to treat both minor and serious infections caused by staph and other bacteria, some strains of bacteria have become resistant to common antibiotics. New medications and forms of treatment will be important in the future, and scientists are working to develop a Staphylococcus aureus vaccine that might help people with weakened immune systems resist staph infection.

How Long Does Infection Last?

Minor skin infections caused by staph bacteria usually clear up within a week, whereas more serious widespread illnesses may take several weeks to more than a month to get better.

What Are the Complications of Staph Infection?

Minor staph skin infections rarely result in complications, but some can produce more widespread infection, such as sepsis, a serious systemic infection caused by bacteria invading the bloodstream. TSS can lead to shock*, organ failure, and death. Scalded skin syndrome can give rise to other infections, dehydration, and sepsis. Osteomyelitis can cause permanent bone damage and may require surgical treatment.

*shock

is a serious condition in which blood pressure is very low and not enough blood flows to the body’s organs and tissues. Untreated, shock may result in death.

Can Staph Infections Be Prevented?

There are several ways to help prevent the spread of staph infections:

• washing hands before eating and after using the toilet, or touching the nose
• washing any cuts, scrapes, or open sores
• keeping wounds covered with a clean bandage

Food poisoning can be prevented by washing hands before food preparation, storing food properly before cooking, cooking food to the appropriate temperatures, using clean utensils and dishes, and refrigerating or freezing food as soon as possible after cooking. To lessen the risk of TSS, women are advised to use less-absorbent tampons, to change them frequently, and not to use only tampons during a menstrual period, or to avoid tampons altogether.

See also

Abscesses

Endocarditis, Infectious

Intestinal Infections

Meningitis

Osteomyelitis

Sepsis

Skin and Soft Tissue Infections

Resource

Organization

U.S. Centers for Disease Control and Prevention (CDC), 1600 Clifton Road, Atlanta, GA 30333. The CDC provides information about infections such as staph, how often they occur, and how to prevent them.

Telephone 800-311-3435 http://www.cdc.gov