ABSTRACT
Guidelines recommend universal screening of all pregnant women at 35-37 weeks of gestation for group B streptococcus (GBS) colonization and reserve a risk-factor-based approach for women who have no prenatal cultures. This study determines the prevalence of GBS among pregnant women in Lebanon and assesses the association between risk factors and vaginal flora in this patient population and antibiotic resistance pattern of the GBS isolates. Vaginal samples from women between 35-37 weeks of gestation were obtained and cultured on 5% sheep blood agar (BA), colistin nalidixic acid agar, Strep B Select chromogenic agar and Lim enrichment broth. Also, vaginal flora was evaluated on Gram-stained smears. Colonies on BA suggestive of GBS were identified by Gram staining, catalase test and agglutination in group B antiserum. Antimicrobial susceptibility to different antibiotics was tested on BA. Risk factors were obtained. The prevalence of vaginal GBS colonization was 18.4% (31/168). Evaluation of Gram-stained vaginal smears revealed an inverse relationship between the presence of lactobacilli and GBS colonization (p=0.029). Resistance of GBS to erythromycin and clindamycin was found to be 25.8% and 12.9%, respectively. Demographic and obstetric data did not reveal statistically significant differences in GBS colonization rates between age groups (p=0.498) or level of education (p=0.696) among these women. Prevalence of GBS remains high in this region with no identifiable risk factors for its acquisition. Furthermore, increase in resistance to erythromycin and clindamycin should prompt susceptibility testing of all GBS isolates. The resistance profile of these strains represents an emerging public health concern that needs further surveillance.
