Group B Strep Infection Causes, Symptoms, Diagnosis and Treatment on MedicineNet.com

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Group B Strep Infection

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Medical Author: Steven E. Doerr, MD
Medical Editor: Melissa Conrad Stöppler, MD

What is group B strep?

Group B strep (GBS) is a bacteria also known as Streptococcus agalactiae. This type of bacteria (not to be confused with group A strep which causes "strep throat") is commonly found in the human body, and it usually does not cause any symptoms. However, in certain cases it can be a dangerous cause of various infections that affect pregnant women and their newborn infants. Group B strep infection can also afflict adults with certain chronic medical conditions.

What causes group B strep infection?

Group B strep can normally be found in 10%-35% of all healthy adult women. It can commonly be found in the intestine, vagina, and/or rectal area. Most women who are carriers of the bacteria (colonized) will not have any symptoms; however, under certain circumstances, both infection of both the mother and/or newborn can develop.

How is group B strep transmitted?

In newborns, GBS infection is acquired through direct contact with the bacteria while in the uterus or during delivery; thus the infection is transmitted from the colonized mother to her newborn. However, not every baby born to a colonized mother will develop GBS infection. Statistics show that about one of every 100-200 babies born to a GBS-colonized mother will develop GBS infection. There are maternal risk factors, however, that increase the chance of transmitting the disease to the newborn:

labor or membrane rupture before 37 weeks

membrane rupture more than 18 hours before delivery

urinary tract infection with GBS during pregnancy

previous baby with GBS infection

fever during labor

positive culture for GBS colonization at 35-37 weeks

Group B strep infection is not a sexually transmitted disease (STD).

Next: What are the symptoms of group B strep infection? »

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