J. Perinat. Med. 37 (2009) 124–129 • Copyright  by Walter de Gruyter • Berlin • New York. DOI 10.1515/JPM.2009.020 Article in press - uncorrected proof Group B Streptococcus colonization in pregnancy: prevalence and prevention strategies of neonatal sepsis Alma-Verena Rausch 1 , Ariane Gross 1 , Sara Droz 2 , Thomas Bodmer 2 and Daniel V. Surbek 1, * 1 Department of Obstetrics and Gynecology, Inselspital, Bern University Hospital, and University of Bern, Switzerland 2 Institute of Infectious Diseases, Inselspital, Bern University Hospital, and University of Bern, Switzerland Abstract Early onset neonatal sepsis due to Group B streptococci (GBS) is responsible for severe morbidity and mortality of newborns. While different preventive strategies to identify women at risk are being recommended, the opti- mal strategy depends on the incidence of GBS-sepsis and on the prevalence of anogenital GBS colonization. We therefore aimed to assess the Group B streptococci prevalence and its consequences on different prevention strategies. We analyzed 1316 pregnant women between March 2005 and September 2006 at our institution. The preva- lence of GBS colonization was determined by selective cultures of anogenital smears. The presence of risk fac- tors was analyzed. In addition, the direct costs of screen- ing and intrapartum antibiotic prophylaxis were estimated for different preventive strategies. The prevalence of GBS colonization was 21%. Any maternal intrapartum risk factor was present in 37%. The direct costs of different prevention strategies have been estimated as follows: risk-based: 18,500 CHF/1000 live births, screening-based: 50,110 CHF/1000 live births, combined screening- and risk-based: 43,495/1000 live births. Strategies to prevent GBS-sepsis in newborn are nec- essary. With our colonization prevalence of 21%, and the intrapartum risk profile of women, the screening-based approach seems to be superior as compared to a risk- based approach. *Corresponding author: Prof. Daniel Surbek, MD Department of Obstetrics and Gynecology University Hospital Bern Effingerstr. 102 3010 Bern/Switzerland Tel.: q41 31 632 11 03 Fax: q41 31 632 11 05 E-mail: daniel.surbek@insel.ch Keywords: Costs; GBS-sepsis; intrapartum antibiotics; prevalence; screening and risk factor based strategies. Introduction Intrapartum vaginal presence of Group B Streptococcus (Streptococcus agalactiae, GBS), a facultative gram-pos- itive diplococcus, can cause severe neonatal infections including sepsis, pneumonia and meningitis, which gen- erally occur within the first week of life (early-onset dis- ease) or after seven days (late-onset disease) w 6, 15x . Infections with GBS have been recognized as the leading cause of early-onset neonatal sepsis with significant mortality. Epidemiologic studies in the pre-prevention era revealed an incidence of 1–3 cases of early-onset neo- natal GBS per 1000 with a case-fatality rate of 20–50% w 22, 28x . The risk of colonization of a neonate born to a colonized mother is between 40 and 70% w 5, 10, 13x and 1–2% of these colonized infants will develop an early- onset disease. At any given time, between 10–30% of women in the United States and between 5–15% in Europe are colonized with GBS w 24, 26, 27x . Thus, in the 1980s intensive research started with the goal to find a way of preventing GBSs vertical transmission. Random- ized controlled trials showed that intrapartum antibiotic treatment of colonized women prevents early-onset neonatal sepsis with 80% effectiveness w 8x . However, because no rapid GBS detection test with a high sensi- tivity and specificity exists to date, it was a matter of debate how to identify women who benefit from intra- partum antibiotic prophylaxis. Guidelines for intrapartum prophylaxis of neonatal GBS infections were issued in 1996 by the American College of Obstetricians and Gynecologists (ACOG) and the centers of disease control (CDC) w 4x , and in 1997 by the American Academy of Pediatrics (AAP) w 1x . These recommendations were that intrapartum antibio- tic prophylaxis is given based either on a risk- or on a screening-based approach. A risk-based approach is adapted from the presence of at least one maternal risk factor. Risk-factors associated with neonatal GBS dis- ease are: gestational age at delivery -37 weeks, intra- partum temperature G388C (100.48F), rupture of membranes for G18 h (G12 h), GBS bacteriuria during the current pregnancy or a previous delivery of a child affected by early-onset GBS sepsis. The screening- based approach includes universal screening of all preg- nant women for GBS colonization between 35 and