Prevalence, antimicrobial susceptibility, serotypes and risk factors of group B streptococcus rectovaginal isolates among pregnant women at Kenyatta National Hospital

Jisuvei Clayton Salano^1,2, Maina Anne Njeri¹, Osoti Alfred¹
¹University of Nairobi, ²Kenyatta National Hospital

Estimates of group B streptococcus (GBS) disease burden, antimicrobial susceptibility and its serotypes in circulation among pregnant women in many developing countries including Kenya, are limited, yet these data are required for prophylaxis and treatment of infections due to GBS. We evaluated the rectovaginal prevalence, antimicrobial susceptibility, serotypes and factors associated with GBS colonization among pregnant women receiving antenatal care at Kenyatta National Hospital (KNH) between August and November 2017. In this cross sectional study, 292 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. Two swabs; one from the anorectal canal the other from the lower vagina were collected and cultured on Granada agar for GBS isolation. Positive colonies were tested for antimicrobial susceptibility to penicillin G, ampicillin, vancomycin and clindamycin. Serotyping was done using Immulex Strep-B kit. We used logistic regression to identify factors associated with GBS colonization. Data analysis was done using STATA^® version 13. P values of <0.05 were considered significant. The median age of study participants was 30 years (IQR 26-35) with a median gestational age of 35 weeks (IQR 30-37). The prevalence of GBS in this study was 20.5%. Isolates were most resistant to penicillin G (72.4%) followed by ampicillin (55.2%), clindamycin (30.4%) and vancomycin (24.1%). All ten GBS serotypes were isolated. Serotype Ia was the most prevalent (75.9%) while serotype VIII (44.2%) was the least occuring. 37 (69.8%) participants carried more than one GBS serotype. None of the risk factors were associated with GBS colonization. The prevalence of GBS is high among mothers attending antenatal clinic at KNH. There is high prevalence of GBS isolates 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.

Funding source: National Research Fund-Kenya

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