ObjectiveTo analyze epidemiological characteristics of serotypes, virulence factors, and resistance genes of group B streptococcus (GBS) colonized in pregnant women in Shenzhen City.MethodsPositive strains of prenatal GBS screening for pregnant women in three tertiary hospitals in Shenzhen City from October 2015 to September 2016 were collected, antimicrobial susceptibility testing was performed with KirbyBauer disk diffusion method, GBS serological typing, αlike surface protein, pili protein, and antimicrobial resistance genes were detected with multiplex polymerase chain reaction (multiplex PCR).ResultsA total of 56 GBS strains were isolated, 5 serotypes were detected (Ia, Ib, II, III, V), which was dominated by type III (60.7%). There was correlation between different serotypes and specific surface protein as well as pili protein distribution, such as serotype Ia and eps, Ib and bca, III and rib, V and alp2/3, serotype Ib and PI2a, III and PI2b, as well as V and PI2a+PI1( all P<0.05). 56 strains of GBS were all sensitive to penicillin, resistance rates to chloramphenicol, levofloxacin, erythromycin, clindamycin, and tetracycline were 14.3%, 23.2%, 75.0%, 67.9%, and 85.7%, respectively.ConclusionThe main type of GBS in pregnant women in Shenzhen City is type III, there is a significant correlation between different serotypes and specific virulence genes. GBS is generally sensitive to penicillin, resistance rates to erythromycin, clindamycin, and tetracycline are high.