Group B Streptococcus Prevalence, Antibiotic Susceptibility and Risk Factors for Colonization among Antenatal Women at Mbagathi Hospital, Nairobi City County, Kenya

Abstract

Group B Streptococcus is recognized as the leading cause of neonatal sepsis as well as a significant cause of maternal post-partum sepsis globally. Maternal genitourinary colonization with the bacteria in pregnancy is the most significant risk factor for neonatal infection due to the risk of transmission to neonates during delivery. There is a gap in knowledge in the developing countries, Kenya included, regarding the prevalence of group B Streptococcus among the antenatal women. Therefore this study determined the prevalence of group B Streptococcus isolates and their antibiotic susceptibility patterns as well as identified the risk factors associated with group B Streptococcus colonization among antenatal women. The study was conducted at Mbagathi hospital, Nairobi City County, over a period of three months, adopting a cross- sectional study design. It included 323 systematically selected pregnant women. These participants provided 30-40 mls of mid-stream urine specimens which were then enriched in Todd-Hewitt broth and later cultured in strep B chromogenic agar and blood agar for bacteria isolation. The isolates were later identified using Gram staining and microscopy as well as a series of biochemical tests including the Christie Atkins and Munch Petersen test, catalase and pyrollidonyl arylamidase tests. The vitek 2 system was used to carry out antibiotic susceptibility testing and the resulting minimum inhibitory concentration values interpreted as either sensitive, intermediate or resistant with reference to Clinical and Laboratory Standards Institute 2020 guidelines. A questionnaire was used to collect data regarding the risk factors associated with maternal colonization with group B Streptococcus. The data was analyzed using the statistical packages for social sciences version 17. Percentages were used to show the prevalence of group B Streptococcus among participants and the differences in antibiotic susceptibility patterns of the isolates towards the various antibiotics that they were tested against. The Chi square test was used to test the association between the risk factors associated with maternal colonization with group B Streptococcus and the colonization status of the participants. The overall prevalence of group B Streptococcus established by this study was 15.2%, with 49 participants testing positive for group B Streptococcus. All isolates were 100% sensitive to Penicillin, Ampicillin, Ceftriaxone, Cefipime, Cefuroxime, Linezolid and Vancomycin. However, the isolates exhibited resistance towards Erythromycin 15 (30.6%), Azithromycin 9 (18.4%), Levofloxacin 7 (14.3%), Clindamycin 10 (20.4%) and Tetracycline 4 (8.2%). In addition, 10 (20.4%) of the isolates exhibited intermediate susceptibility towards Tetracycline. Age of a participant, place of residence and marital status (P= 0.000) were found to be significant. All obstetric related risk factors were also found to be significant; having a history of neonatal sepsis (P= 0.017), the parity status, history of: still birth, miscarriage, neonatal death and preterm delivery (P= 0.000). The human immunodeficiency virus status and dysuria (P= 0.000), lower abdominal pain (P= 0.001) and any form of vaginal infection (P=0.009) were also found to have significant associations with GBS colonization. No significant associations were found with the level of education of participants (P= 0.075) and the number of sexual partners (P= 0.083). Penicillin remains the antibiotic of choice for treatment of GBS infections and risk factors without individual routine screening are not sufficient for identifying candidates for intrapartum antibiotic prophylaxis. The study provided information regarding the most current effective antibiotics for group B streptococcal infections and advised on the criteria to identify candidates for intrapartum antibiotic prophylaxis. Further research is recommended to come up with a vaccine that would prevent women from being colonized with group B Streptococcus during pregnancy.