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.
[Article by: Paula Ford-Martin; Rebecca J. Frey, PhD]
