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Group B Strep Infection in Adults

While the rates of serious group B strep infections are much higher among newborns than among any other age group, serious group B strep infections occur in other age groups in both men and women.

The most common problems caused by group B strep in adults are:

  • Bloodstream infections
  • Pneumonia (infection in the lungs)
  • Skin and soft-tissue infections
  • Bone and joint infections

Rarely in adults, group B strep can cause meningitis (infection of the fluid and lining surrounding the brain).

Nurse talking with man using walker device

Transmission and Prevention

The source of infection for adults is unknown. Since group B strep is a common organism in the gastrointestinal tract of men and women, this may be a source of some infection.


If doctors suspect an adult has an invasive group B strep infection, they will take a sample of sterile body fluids, such as blood or spinal fluid. Group B strep disease is diagnosed when the bacteria are grown in the laboratory from samples of those fluids. Samples take a few days to grow. Sometimes group B strep can cause mild disease in adults, such as urinary tract infections (UTIs, also called bladder infections), which also can be diagnosed in the lab with a sample of urine.


Group B strep infections are usually treated with penicillin or other common antibiotics. Sometimes soft tissue and bone infections may need surgery. Treatment will vary according to the kind of infection with group B strep someone has, and patients should ask their doctor about specific treatment options.

Disease Trends

The rate of serious group B strep disease increases with age. The average age of cases in non-pregnant adults is about 60 years old. The rate of invasive disease is approximately 7 cases per 100,000 non-pregnant adults. The rate is highest among adults 65 years of age and older — 20-25 cases per 100,000. Most adult group B strep disease occurs in adults who have other medical conditions. These include: diabetes mellitus; cardiovascular disease; congestive heart failure; history of cancer; and obesity.

Serious group B strep infections in adults can be fatal. On average, 8% of adults with invasive group B strep infections (infections where the bacteria have entered a part of the body that is normally not exposed to bacteria) die. Risk of death is lower among younger adults, and adults who do not have other medical conditions.


  • Skoff TH, Farley MM, Petit S, et al. Increasing Burden of Invasive Group B Streptococcal Disease in Non-Pregnant Adults, 1990-2007. Clin Infect Dis. 2009;49:85-92.
  • Farley, M M. Group B streptococcal disease in nonpregnant adults. Clin Infect Dis. 2001;33:556-61.
  • Jackson LA, Hilsdon R, Farley MM et al. Risk factors for group B streptococcal disease in adults. Ann Intern Med. 1995;B123:415-20.

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