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Perinatal Group B Strep Guidelines Revised

The Centers for Disease Control (CDC) has published revised guidelines for prevention of perinatal group B streptococcal disease (MMWR 2010;59, No. RR-10). Despite an 80% decreased incidence of early-onset group B streptococcal (GBS) infections since prevention guidelines were issued in 1996 and revised in 2002, GBS disease remains the leading infectious cause of morbidity and mortality in U.S. newborns.Maternal recto-vaginal GBS colonization is the foremost risk factor for early-onset neonatal disease. According to the CDC, pregnant women with GBS colonization are >25 times more likely to have infants with early-onset GBS disease. An estimated 10% to 30% of pregnant women are recto-vaginally colonized with GBS, which can be transient, intermittent, or persistent. Some colonized women will develop GBS infections such as urinary tract infection, amnionitis, endometritis, sepsis, or meningitis. Infected infants most commonly have pneumonia or sepsis, or less frequently, meningitis. GBS can be transmitted through ruptured or intact membranes. Additional risk factors for early-onset infection include gestational age <37 weeks, prolonged rupture of membranes, intra-amniotic infection, young maternal age, black race, previous delivery of a GBS-infected infant, and heavy maternal colonization.Erythromycin is no longer recommended for treatment or prophylaxis of GBS under any circumstance, due to emergence of resistant strains (up to 32% of strains resistant). Of note, routine susceptibility testing of all GBS is unnecessary, except in penicillin allergic women, and is performed only by request for that reason. The revised guideline also addresses reporting of urine culture colony counts and states that little data is available regarding GBS disease risk in the presence of low colony-count GBS bacteriuria.The recommendation for GBS screening of all pregnant women at 35-37 weeks’ gestation screening is retained in the revised guideline. The preferred specimen is a recto-vaginal swab. GBS can be detected by culture and PCR. GBS PCR has superior sensitivity and specificity compared to culture.Other revisions to the guidelines include new algorithms for screening & prophylaxis for preterm labor or preterm rupture of membranes, changes in dosing for penicillin, and a revised algorithm for treatment of newborns. These new guidelines have been endorsed by the American College of Obstetricians and Gynecologists (ACOG) and the American Academy of Pediatrics.

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