Background: Group B streptococcus (Streptococcus agalactiae) is one of the most common pathogens causing meningitis, bacteremia and pneumonia. The drug resistance mechanisms of group B streptococcus in different countries and regions also show regional differences.Method: The study population was comprised of 1877 pregnant women of 34-38 weeks who underwent prenatal examination in the gynecology and obstetrics outpatient clinic of Xinjiang People's Hospital, between January 1, 2019 and January

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... 1, 2020. Clinic specimens were collected and identified by the API bacteria Rapid Identification card for the downstream group B Streptococcus (Streptococcus agalactiae) isolation. Drug susceptibility of the Streptococcus agalactiae isolated was detected by Kirby-Bauer disk diffusion method. Macrolide–lincosamide–streptogramin B (MLSB) resistance was determined by D test. Real-time quantitative polymerase chain reaction and Gene sequencing was performed for the resistance genes ermA, ermB, mreA, erm (47), mefA/E and Lin B.Results: 149 Streptococcus agalactiae-positive strains were identified by clinical isolation, with a positive rate of 7.94%. Group B Streptococcus showed 100% susceptibility to linezolid, penicillin, vancomycin, meropenem, ampicillin, ceftriaxone, 44.97%, 35.57%, 56.38% and 29.53% susceptibility to levofloxacin, erythromycin, tetracycline and clindamycin, respectively. Among the 149 isolates, 127 strains showed macrolide resistance phenotype. The detection rate of intrinsic resistance phenotype (cMLS) was 40.94% (59/127), active efflux resistance phenotype (MS) 9.45% (12/127), and induced resistance phenotype (iMLS) 22.83% (29/127).Conclusion: The ermB gene-mediated 50s ribosome target site change co-existing with mreA gene for macrolide resistance efflux may play a major role in the mechanism of Streptococcus agalactiae resistance macrolide resistance of in perinatal women in Xinjiang. The change of 50s ribosomal target site mediated by ermB gene may be the main reason for drug cross-resistance.