Prevalence and Antibiotic Susceptibility Pattern of Streptococcus agalactiae Among Pregnant Women at Adigrat Zonal Hospital and Adigrat Health Center, Tigray, Ethiopia

Abstract

Back ground: Streptococcus agalactiae or Lancefield group B Streptococci (GBS) is part of the microbiota of the mucous membranes of humans and animals, mainly colonizing the intestinal and genitourinary tracts. This study was undertaken to determine the carriage rate of S. agalactiae and to assess their antimicrobial susceptibility pattern. An attempt has been also made to identify the possible risk factors related with S. agalactiae colonization. Methods: Rectal and vaginal swabs were obtained from 150 pregnant women at 35-37 weeks of gestational period that attended antenatal clinic at Adigrat Zonal Hospital and Adigrat Health Center, Tigray, Ethiopia. Then the specimen was cultured on selective CHROMagarTMStrepB. In cases of positive cultures obtained, antibiotic susceptibility tests were carried out on all S. agalactiae isolates using the disc diffusion technique on Mueller-Hinton agar supplemented with 5% sheep blood. A univariate and multivariate binary logistic regression model was used to ascertain the association between the frequencies of colonization in relation to the different variables. Results: The prevalence of rectovaginal S. agalactiae colonization was (11.3%). Bacterial resistance was detected to erythromycin (11.8%) and clindamycin (17.6%). By multi variant logistic regression analysis, prolonged rupture of membrane was associated with a higher colonization rate of S. agalactiae (OR=5.864, 95% CI= 1.395 – 24.643, P-value= 0.016). Conclusion: The carriage rate of S. agalactiae among pregnant women in the present and a previous study in Gondar, remain low. The rates, risk factors of maternal GBS colonization may vary in different communities and need to be thoroughly evaluated in each country to allow the most appropriate preventive strategy to be selected.