Abstract

Background: Penicillin is recommended as the first-line agent for intrapartum antibiotic prophylaxis, while ampicillin is considered as an acceptable alternative. Although GBS strains are generally susceptible to penicillin with only occasional resistance, they show varying resistance to erythromycin, clindamycin and tetracycline. Therefore, a knowledge of the resistance profile of GBS in the local environment will be useful for administration of appropriateintrapartumantibiotics prophylaxis. Methods & Materials: Rectovaginal swabs collected from pregnant women were cultured for GBS using conventional media.Kirby-Bauer disc diffusion method was performed according to the Clinical Laboratory Standards Institute (CLSI) guidelines on GBS isolates to determine the antibiotic susceptibility patterns of the isolates. Inducible clindamycin resistance was detected by using the D-zone test. Resistance determinants were discerned with conventional PCR. Streptococcus agalactiae control strainsIa (2008232728),Ib (2008232729),III (2008232582) andV (2008232731) from CDC were usedfor quality control of antibiotic susceptibility testing. Results: All 46 available strains of GBS colonizing the pregnant mothers were uniformly susceptible (100%) to penicillin, vancomycin and ceftriaxone, while 44 (95.7%) and 41 (89.1%) were resistant to tetracycline and trimethoprim- sulfamethoxazole respectively (Table 2). Only three (6.5%) of the isolates showed erythromycin-clindamycin inducible resistance. ermA gene was present in all three GBS isolates with erythromycin-clindamycin inducible resistance and absent in the only one strain with intermediate resistance. ermB was absent in all the four strains tested while the mefA/E gene was carried by two of the macrolide- clindamycin resistance isolates. tetM gene was carried by all isolates that showed tetracycline resistance phenotypes. Conclusion: In this study, all GBS isolates were susceptible to Penicillin G, the recommended antibiotic for intrapartum antibiotic prophylaxis. Also, a very low resistance rate recorded for erythromycin and clindamycin in this study implied that women allergic to -lactam antibiotics can alternatively receive intravenous clindamycin or erythromycin.