en Microbiology Microbiology پژوهشي Research <strong>Introduction:</strong> Group B<em> Streptococcus </em>(GBS) is one of the most causes of neonatal infections. The bacterium colonizes genitourinary tracts of pregnant women and transmits to infants. The aim of this study was investigating colony PCR and culture methods to detection of GBS in pregnant women.<br> <strong>Materials and methods:</strong> Hundred pregnant women, at the 35^th and 37^th weeks of pregnancy, were selected from the Obstetrics and Gynecology Unit of the Moatazedi and Shahid Chamran Hospitals in Kermanshah province. Specimens were collected from vaginal introitus and investigated by selective culture and colony PCR methods. Then, antibiotic resistance tests were performed according to the latest guidelines of Clinical and Laboratory Standards Institute (CLSI).<br> <strong>Results:</strong> Prevalence of GBS colonization was shown to be 5% and 6% by the culture and colony PCR methods, respectively. Also, resistance rate to erythromycin, penicillin, vancomycin, and the clindamycin were determined to be 50%, 16.66%, 16.66% and 33.33 %, respectively. Moreover, the highest resistance was for erythromycin and the appropriate antibiotics were penicillin and then vancomycin.<br> <strong>Conclusion:</strong> A higher prevalence of GBS colonization in pregnant women in the Kermanshah city of Iran was detected using colony PCR method compared to culture method. Antibiotic Resistance, BCA gene, Colony-PCR, GBS 27 32 http://jbrms.medilam.ac.ir/browse.php?a_code=A-10-168-5&slc_lang=en&sid=1 Aazam Khani Daramroodi gol.keshavarzi@gmail.com 10031947532846003004 10031947532846003004 No Department of Biology, Kurdistan Science and Research Branch, Islamic Azad University, Sanandaj, Iran Fatemeh Keshavarzi gol.keshavarzi@gmail.com 10031947532846003005 10031947532846003005 Yes Department of Genetics, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran Farshid Raissi gol.keshavarzi@gmail.com 10031947532846003006 10031947532846003006 No Department of Pathology, Faculty of Medicine, Kermanshah University of Medical Science, Kermanshah, Iran