Group B strep disease

Group B streptococcus (strep) is a common bacterium often carried in your intestines or lower genital tract. Group B strep is usually harmless in adults. In newborns, however, it can cause a serious illness known as group B strep disease.

Group B strep can also cause dangerous infections in adults with certain chronic medical conditions, such as diabetes or liver disease. Older adults are at increased risk of illness due to group B strep, too.

If you're a healthy adult, there's nothing you need to do about group B strep. If you're pregnant, get a group B strep screening test during your third trimester. If you have group B strep, antibiotic treatment during labor can protect your baby.

Symptoms Causes Risk factors Complications Prevention


Most babies born to women carrying group B strep are healthy. But the few who are infected by group B strep during labor can become critically ill.

In infants, illness caused by group B strep can take two forms: early onset or late onset.

Early-onset group B strep disease. A baby with early-onset group B strep disease becomes sick within one week after birth. Signs and symptoms may include:

  • Fever
  • Difficulty feeding
  • Lethargy

Late-onset group B strep disease. Late-onset group B strep disease develops within a week to a few months after birth, usually within the first month. Signs and symptoms may include:

  • Difficulty breathing
  • Fever
  • Difficulty feeding
  • Lethargy
  • Irritability


If you're like many adults, you may carry group B strep in your body, usually in your bowel, vagina, rectum, bladder or throat. Most adults simply carry the bacterium and have no signs or symptoms.

In some cases, group B strep may cause a urinary tract infection or more serious infections such as blood infections (bacteremia) or pneumonia.

When to see a doctor

As an adult, if you experience any signs or symptoms of group B strep infection — particularly if you're pregnant, you have a chronic medical condition or you're older than 65 — contact your doctor right away.

If you notice your infant has any of the signs or symptoms of group B strep disease, tell your baby's doctor immediately.

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