Staphylococcal Infections Health Article

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 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.

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