Group A Strep Infections

Group A Streptococcus, a computer-generated image based on electron microscopy. CDC image.

Group A Streptococcus, or group A strep, is a type of bacteria that can cause many different infections, from minor to deadly, as well as inflammatory diseases afterward. The bacteria are contagious.

What they cause

Usually mild:

• impetigo;
• scarlet fever;
• strep throat.

Potentially very serious or deadly:

• cellulitis;
• necrotizing fasciitis;
• streptococcal toxic shock syndrome.

Inflammatory diseases that can follow an infection: post-streptococcal glomerulonephritis and rheumatic fever. Both are thought to result from the immune system — normally the body's defense against infection — mistakenly attacking healthy tissue after an earlier strep infection.

Who is at higher risk of serious infection

Risk varies by condition, but in general serious group A strep infections are more likely in people who:

• have or recently had a viral infection such as flu or chickenpox;
• have cancer; chronic heart, kidney, liver or lung disease; diabetes; a weakened immune system; obesity; or wounds or skin disease;
• are American Indian, Alaska Native, Native Hawaiian or Pacific Islander;
• are 65 or older;
• inject drugs or are experiencing homelessness;
• live in long-term care facilities.

How it spreads

The bacteria spread easily, even from people who have no symptoms.

• Respiratory droplets. Group A strep often lives in the nose and throat, and infected people spread it by talking, coughing or sneezing. Others can catch it by breathing in the droplets, touching their mouth or nose after touching something with droplets on it, or sharing a plate, utensils or a glass with an infected person. Washed dishes are safe to share.
• Direct contact. Touching infected skin sores, or fluid from them, can spread the bacteria; once the sores heal they usually stop spreading.
• Food, rarely, if it is not handled properly.

Prevention

Prevention depends on the disease but generally aims to:

• limit exposure to and spread of the bacteria;
• treat infections promptly;
• use preventive antibiotics when appropriate.

CDC explains how to prevent group A strep infections. Talk with a health care provider if you have concerns.

Sources

• Centers for Disease Control and Prevention: "About Group A Strep Infection."