Background: 10-40% of pregnant women are colonized with Group B- Streptococci at the onset of labor in U.S. and Scandinavia. 50% will have perinatal transmission and 1-2% of these infants get early onset (< 7 days) neonatal infection. (Sepsis, meningitis, pneumonia). Almost all fatal cases occur within that first day of life (median age within 1 hours) mortality 5-20% and this is significantly higher in preterm infants. Neonatal symptoms: pneumonia, sepsis and meningitis, CRP increase and leucopeni. Late onset neonatal infection (sepsis, meningitis, osteomyelitis) mortality 2-6%. Complications: Colonization with GBS in the urogenital tract is associated with spontaneous abortion, intrauterine death, preterm labor delivery, preterm rupture of membranes and neonatal infection. Maternal perinatal GBS disease include chorioamnionitis, endometritis, sepsis and UTI. Other rare maternal complications include meningitis, abdominal abscess, endocarditis and necrotizing fasciitis. There is an increased risk for endometritis and bacteremia if the delivery is by cesarean section. The following factors increase the risk for neonatal infection and interpartum antibiotic should be given.
Some would give penicillin to women with a previous preterm rupture of membrane and a preterm GBS affected child but this is not evidence-based. Culture: Culture specimen taken both from the anal rectal region and distal part of the vagina increase the likelihood of GBS isolation. The sample should be identified for the laboratory as specifically for GBS culture (selective growth medium). Treatment: GBS in urine: penicillin po. 1 mill IE x 3 for 6 days. During labour, 5 million Penicillin and 2.5 million every 4 hours until delivery. Ampicillin 2 gm and then 1 gm every 3-4 hours. In case of allergy to Penicillin, Erythromycin 500 mg IV every 6 hours and/or Clindamycin 1 ½ gm every 8 hours but resistance is seen in about 10% in both drugs. The Child: If no symptoms at birth Full evaluation and treatment less than 34 weeks. If more than 34 weeks and mother has been treated more than 4 hours observation in 24 hours. If more than 34 weeks and less 4 hours treatment, start treatment and further treatment dependent on blood culture, etc. Screening Test on the Newborn: The optimal technique for GBS screening is obtaining a single vaginal anorectal swab and use of selective growth media. The disadvantages that it requires 18-24 h before the result is available which is an issue for woman presenting in? For this situation two rapid antigen detection methods: Latex particle agglutination test (LPA) and enzyme-linked immunoabsorbent assay (ELISA). The sensitivity and specificity for LPA test rate from 90-91% and 93.2-99.7%, respectively. Similar for ELISA with a sensitivity and specificity vary from 74-89% and 92-100%, respectively. References: (1) ACOG Committee Opinion, No. 173. June 1996. Washington, D.C. American College of Obstetricians and Gynecologists. (2) Allan MacLean, et al. Infection and Pregnancy, RCOG Press 2001. (3) Campbell, N et al. The prevention of early-onset neonatal group B streptococcus infection: technical report from the New Zealand GBS Consensus Working Party. N Z Med J. 2004 Aug 20;117(1200):U1023 (4) Larsen JW, Sever JL. Group B Streptococcus and pregnancy: a review. Am J Obstet Gynecol 2008 Jan 15 (Epub ahead of print) (5) www.infpregn.com (6) www.uptodate.com 2007
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