Frequency of Antibiotic Resistance and Virulence Factors in <i>Streptococcus agalactiae</i> Isolated from Vaginal and Urine Samples of Pregnant Women in Yazd, Iran: A Cross-sectional Study

Background: Streptococcus agalactiae, or group B Streptococcus (GBS), is part of the normal flora of the female vagina and gastrointestinal tract. The capsular serotype, virulence factors, and antibiotic resistance determine the pathogenic properties of this bacterium. Objectives: This cross-sectional study aims to determine the frequency of antibiotic resistance and virulence factor genes in GBS isolated from vaginal and urine samples of pregnant women in Yazd, Iran. Methods: A cross-sectional study was conducted from January 2021 to May 2022 in Yazd, Iran. Ninety GBS isolates from pregnant women were subjected to analysis. The Kirby-Bauer method was performed to assess antibiotic resistance of GBS to penicillin, clindamycin, erythromycin, tetracycline, and levofloxacin. Genotypic investigation of resistance to erythromycin, tetracycline, and clindamycin genes, as well as adhesion and invasion protein genes, was also evaluated by molecular methods. Results: The highest resistance was related to tetracycline (93.3%), and the resistance rates to clindamycin and erythromycin were 13.3% and 12.2%, respectively. The frequencies of scpB, laminin-binding protein (lmb), fbsA, and fbsB genes in vaginal samples were 97.8%, 93.3%, 96.7%, and 83.3%, respectively, and in urine samples were 100% for all genes; however, the hvgA gene was not found in any vaginal or urine isolates. The distribution of antibiotic resistance genes was tetM (87%), int-Tn (72.2%), ermA (42.2%), ermB (12.2%), tetO (7.8%), tetK, linB (1.1%), and tetL (0%). Conclusions: This study revealed that most isolates had more than three virulence genes, and the frequency distribution of these genes in vaginal and urine samples was almost the same.