The Different Types of Streptococci (Strep Bacteria)

Here’s what to know about how the different types of streptococcal infections are transmitted, treated, and prevented.

Group A strep, sometimes called GAS, tends to affect the throat and the skin. People may carry GAS in these areas yet not show any symptoms of illness.

Group A strep infections spread through direct contact with mucus from the nose or throat, or through contact with infected wounds or sores.

Illnesses caused by infection with group A strep include:

Strep Throat

• A sore throat that comes on very quickly
• Pain when swallowing
• Fever
• Red and swollen tonsils (sometimes with white patches or streaks of pus)
• Small red spots on the roof of the mouth
• Swollen lymph nodes in the front of the neck

Strep throat may also be accompanied by headache, abdominal pain, nausea, or vomiting, especially in children. Illness typically manifests two to five days after exposure.

A doctor cannot tell if someone has strep throat just by looking, so a diagnostic test is needed. A rapid strep test involves swabbing the throat and running a lab test to see if GAS is the cause of the illness.

While most sore throats are caused by viruses, strep throat is caused by bacteria and therefore can be treated with antibiotics.

“If throat pain becomes more severe instead of improving after the first couple of days on antibiotics, it's important to seek follow up care,” says Christian Nechyba, MD, a pediatrician with Duke Health in Wake Forest, North Carolina, “It's also important to seek care right away if you have difficulty drinking, have significant neck swelling, or have fevers that last longer than a couple of days after starting treatment.”

Scarlet Fever

• A very red sore throat
• A rough, red rash on the skin
• A “strawberry,” or red and bumpy, tongue
• Fever
• Swollen glands in the neck
• A whitish coating on the tongue
• Bright red skin in the underarm, elbow, or groin

The illness typically begins with a fever and sore throat. The rash, caused by a toxin made by group A strep bacteria, usually appears a day or two later, although it can begin before the illness or up to seven days later. Untreated cases of strep throat can turn into scarlet fever.

The availability of rapid strep throat testing, which allows for early treatment, has made scarlet fever less common over time, says Dawn Sokol, MD, a pediatric infectious disease specialist at Ochsner Children’s Health Center in New Orleans.

Symptoms of rheumatic fever include:

• Swelling and pain in the joints
• Skin rashes
• Fever

In serious cases, there can be damage to the heart valves. This is known as rheumatic heart disease.

Like strep throat, scarlet fever is more common in children than adults, particularly those ages 5 through 15. Close contact with someone who has the infection is the biggest risk factor for getting the illness.

• Using a tissue to cover the mouth when sneezing or coughing
• Washing hands frequently
• Using alcohol-based hand sanitizer if soap and water are unavailable
• Coughing or sneezing into the upper sleeve or elbow, rather than the hands, if a tissue is not available

Impetigo

Symptoms begin as itchy, red, or pimple-like sores surrounded by red skin, usually on the face, arms, or legs, that are filled with pus.

Post-Streptococcal Glomerulonephritis

Also referred to as PSGN, this is a kidney disease that can develop after a GAS infection. But PSGN is not a GAS infection of the kidneys — it’s a result of the body’s immune system fighting off the group A strep infection.

• Dark, reddish-brown urine
• Swelling in the face, hands, and feet
• Decreased amount of urine or decreased need to urinate
• Fatigue

The condition is treated by managing symptoms, including limiting salt and water intake or prescribing medication to reduce swelling. Antibiotics can also help kill any strep A bacteria left in the body.

Very rare, but potentially life-threatening, manifestations of strep A infection include:

Necrotizing Fasciitis

Symptoms often begin with sudden pain, swelling, and redness in the affected area, which may look like a simple skin injury at first. As the infection spreads, the skin may turn dark, blister, or die. Necrotizing fasciitis is not contagious.

Streptococcal Toxic Shock Syndrome

Streptococcal toxic shock syndrome (STSS) is a rare but life-threatening illness caused by toxins produced by group A strep bacteria.

Symptoms begin suddenly and include fever, chills, low blood pressure, muscle aches, and confusion. As it progresses, it can lead to organ failure and shock.

Group B streptococcus, also known as group B strep or GBS, is a type of bacteria that can cause illness in people of all ages, though it can be particularly severe in newborns, most commonly causing sepsis, pneumonia, and meningitis.

• Urinary tract infections
• Skin infections
• Bloodstream infections
• Pneumonia
• Skin and soft-tissue infections
• Bone and joint infections

Group B Streptococcus in Babies

In babies, group B strep infections occur as either early-onset (younger than 1 week old) or late-onset (1 week to 3 months old).

“The source of infection is often unknown for infants with group B strep illness that begins more than a week after birth,” Sokol says. “There are effective strategies to prevent early-onset infection but not late-onset disease.”

“There is no preventive antibiotic given to the infant or special testing required,” Sokol says.

Symptoms of GBS infection in newborn babies usually develop within the first few hours or days after giving birth and include being floppy or unresponsive, poor feeding, grunting when breathing, and unusually fast or slow breathing and heartbeat.

Group B Streptococcus in Adults

Group B strep infection occurs less frequently in adults than in babies, but it can affect anyone. The sources of disease caused by GBS in adults are unknown, but the gastrointestinal and genitourinary tracts may be the source of infection.

• Fever
• Cough
• Ear pain
• Shortness of breath
• Stiff neck

The CDC recommends pneumococcal vaccination for:

• All children younger than 5 years old
• People 5 through 49 years old with certain risk conditions
• Adults 50 years or older

Groups C and G streptococci are much less well-understood than strep A and B because the diseases caused by these bacteria are far less common.

The best way to prevent common strep infections is through good hygiene — regular handwashing, covering coughs and sneezes, and avoiding close contact with people who have strep, says Sokol.

Most strep infections can be treated with antibiotics, which help reduce symptoms, prevent complications, and lower the risk of spreading the infection to others. Prompt treatment is especially important for more serious cases, and taking the full course of antibiotics as prescribed is essential.

• There are several different types of streptococcus bacteria. Groups A and B are the most common types.
• Group A strep is responsible for strep throat, scarlet fever, impetigo, and a few rare but potentially life-threatening infections.
• Group B most commonly affects newborns during birth.
• Prevention measures include good hand hygiene and avoiding sharing drinking glasses and utensils with others.