Group "B" Strep--As If Pregnant Patients Didn't Have Enough To Worry About

December 14, 2007

One of the newest "official" concerns of pregnancy is a flimsy little bacterium called Group B streptococcus. Harmless in the vagina of the prospective mother, it could present a significant risk of infection to a baby coming through the birth canal. It is common to find women who are carriers of it. In the mother it is usually without symptoms; in the newborn, it is quite a different story.

Premature rupture of membranes, resulting in complications of premature birth, has been associated with Group B strep in the mother. Also, meningitis can develop in the baby due to a mother's vaginal strep, causing devastating complications or even death to the newborn. It's no wonder that a few years ago the American Academy of Pediatrics invaded the domain of the American College of Obstetricians and Gynecologists by recommending routine screening of all pregnant mothers with a simple swab culture. Soon, most Ob-Gyns began this simple screening method. A Q-tip-like sampler is used to take a gentle swab that is then sent to a lab for growth. Called a "culture," it is usually done at 35 to 37weeks into the pregnancy, and the result is added to the list of items that are already on a prenatal check list.

If the culture is negative, nothing need be done, of course. If the culture is positive, treatment is still not done at that time. This is because the patient is a carrier, meaning if it were treated then, it would only come back. Actually, the value of the culture is in being forewarned. The strep is ignored until time for delivery, for that is the time to eliminate it. The antibiotics are given during labor (usually a simple penicillin will do--or another antibiotic, if allergic), and the baby allowed to deliver normally.

Strep's Presence

Sometimes strep can present in sneaky ways. Occasionally a woman may have a negative culture but have had a history of a bladder infection caused by this very same bacterium. In my practice, I lump these patients into the same category as ones whose vaginal cultures were positive. I also treat them right then and there, in addition to during the time of labor, because it's not just a "carrier" status I'm noting--it's an actual urinary tract infection in which treatment is indicated.

When a pregnant patient presents in labor without the benefit of a Group B strep culture--if she has had no prenatal care, for instance--the treatment is so simple and safe that an obstetrician and the baby are best served by giving treatment anyway. Since a certain percentage of all pregnant patients are carriers, I often wonder how many patients exposed their babies to Group B strep in the years before it was sought. Yet the infection rate in those years remained extremely low. This is reassuring, for although the one baby that contracts Group B strep meningitis is in grave danger, the chances of any baby actually developing this complication is actually quite unlikely--even in mothers who are carriers. The screening cultures are only another simple item included in modern obstetrical prenatal care.

But there's controversy now. The American College of Obstetricians and Gynecologists advise that cultures, while a good idea, are not crucial in determining those at risk. Instead, this organization recommends treating any pregnant patient as if she had Group B strep when she presents with certain delineated risk factors, like premature rupture of membranes, a fever, or premature labor. Medicolegally, we follow these guidelines and get the cultures. We like to think we're doing everything we can possibly do to stack the deck in our favor toward a healthy, happy baby.

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