Interpretation of Group B strep (GBS) Test Results

Group B strep (GBS), a common name for Streptococcus agalactiae, are bacteria that come and go naturally in the body. Most of the time the bacteria are not harmful, but they can cause illness in people.

It rarely causes symptoms or problems in healthy adults but can cause infections and serious illness in newborns, especially before or during labor and delivery. GBS screening identifies the presence of the bacteria in the vaginal/rectal area of a pregnant woman.



  • A positive test for GBS in a healthy pregnant woman means that the bacteria are currently present in her vagina and/or rectum. This indicates that she is at risk of passing the bacteria to her infant. In this situation, she should be given antibiotics intravenously during labor to prevent spreading the bacteria to her baby. This treatment is known as intrapartum prophylaxis.
  • A negative result means that the woman is not likely to have GBS in the areas tested. In this situation, no intrapartum prophylaxis is recommended unless she has other risk factors.


Things Must Keep in Mind

Pregnant women who have a urine culture positive for significant numbers of GBS any time during their pregnancy should receive appropriate intrapartum prophylaxis to prevent disease in their infants.

Keywords: Group B strep; GBS; pregnant women; intrapartum prophylaxis

* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.