Prevalence, antimicrobial susceptibility and serotypes of group b streptococcus recto-vaginal isolates from pregnant women at Kenyatta National Hospital

Abstract

Background: Estimates of group B streptococcus (GBS) disease burden, antimicrobial susceptibility, and serotypes in pregnant women are limited for many resource-limited countries including Kenya. These data are required to inform recommendations for prophylaxis and treatment of infections due to GBS. Objective: We evaluated the recto-vaginal prevalence, antimicrobial susceptibility, serotypes and factors associated with rectovaginal GBS colonization among pregnant women at 12-40 weeks gestation receiving antenatal care at Kenyatta National Hospital (KNH) between August and November 2017. Method: In this cross-sectional study, consenting pregnant women between 12 and 40 weeks of gestation were enrolled. Interview-administered questionnaires were used to assess risk factors associated with GBS colonization. An anorectal swab and a lower vaginal swab were collected and cultured on Granada agar for GBS isolation. Positive colonies were tested for antimicrobial susceptibility to penicillin G, ampicillin, vancomycin, and clindamycin using disk diffusion method. Serotyping was performed using Immulex Strep-B kit. Logistic regression was used to identify factors associated with GBS colonization. Results: A total of 292 women were enrolled. Their median age was 30 years (interquartile range [IQR] 26-35) with a median gestational age of 35 weeks (IQR 30-37). Overall GBS was identified in 60/292 (20.5%) of participants. Among the positive isolates resistance was detected for penicillin G in 42/60 (72.4%) isolates, ampicillin in 32/60 (55.2%) isolates, clindamycin in 14/60 (30.4%) isolates, and vancomycin in 14 (24.1%) isolates. All ten GBS serotypes were isolated, and 37/53 (69.8%) of GBS positive participants had more than one serotype. GBS colonization was not significantly associated with maternal age (OR 1, CI 0.93-1.05; P 0.86), parity (OR 1.1, CI 0.77-1.51; P 0.65), gestation age (OR 1, CI 0.93-1.10; P 0.71), prior still births (OR 0.7, CI 0.45-1.16; P 0.18), history of pregnancy loss (OR 1.3, vii CI 0.76-2.19; P 0.33), history of preterm birth in prior pregnancies (OR 1, CI 0.64-1.51; P 0.94), past histoty of neonatal death (OR 2.1, CI 0.80-5.60; P 0.13), history of neionatal infection (OR 0.5, CI 0.14-1.60; P 0.23), history of membrane rapture in prior pregnacy (OR 0.7, CI 0.30-1.60; P 0.39). Conclusion: The prevalence of GBS colonization was high among mothers attending antenatal clinic at KNH. In addition, a high proportion of GBS isolates were resistant to commonly prescribed intrapartum antibiotics. Hence, other measures like GBS vaccination is a potentially useful approaches to GBS prevention and control in this population. Screening of pregnant mothers for GBS colonization should be introduced and antimicrobial susceptibility test performed on GBS positive samples to guide antibiotic prophylaxis