Background & Objectives : The early-onset form of GBS (Group B Streptococci) disease typically occurs in the first 24 hours of life, with fulminant sepsis or pneumonia and has associated to high mortality (5-20 %) and morbidity. In prenatal infections GBS is transmitted vertically to the newborn during labor and delivery from the vagina of a typically asymptomatic colonized woman. Preventive strategies can be done with screening program and this study has been done for determination of carriage prevalence and antimicrobial resistance of GBS in pregnant women of Ardabil.

  Methods :�For determination of carriage�prevalence 420 pregnant women selected stratified proportionally from 11 clusters of obstetric clinics of Ardabil. Sampling was done in pregnant women at 35-37 weeks' gestation with a vaginal and rectal swab for culture. Swabs were inoculated into a selective broth medium (Todd-Hewitt broth with colistin, 10mg/L and nalidixic acid 15 mg/L = LIM broth), incubated overnight at 35-37°C, and subcultured onto sheep blood agar. Isolated bacteria identified by standard microbiological tests.

 Results: Out of 420 subjects 62 positive cultures were established (14.8%), 19 of them (4.5%) from anus, 19 of them (4.5%) from vagina and 24 of them (5.8%) from both.

 All of isolates were sensitive to Ampicillin and Vancomycin. There were 1 case of resistance 15 case of semi sensitivity and 46 cases of sensitive versus Erythromycin, these pattern also checked for Clindamycin, and results were respectively 11, 5, 46. All isolated GBS were sensitive to penicillin among them 3 (4.83%) isolates showed reduced susceptibility.

  Conclusion: Because of high prevalence rate we recommend screening of all pregnant women for Group B Streptococcus at 35-37 weeks' gestation with a vaginal and rectal swab. Based on antibiogram drug of choice for treatment is Ampicillin, and in cases of drug hypersensitivity Vancomycin may be choice.