| Objectives To understand the incidence of group B Streptococcus(GBS)in 35 and 37 gestation pregnant women,and explore antibiotic susceptibility,serological types and molecular characteristics of the isolates,master the drug resistance,explore the differences of virulence genes and resistance characteristics among different serotype dist Ributions and molecular typing isolates,which may be meaningful for the prevention and GBS related diseases.Methods A cross-sectional analysis method was conducted in Tangshan Maternal and Child Health Care Hospital,where pregnant women in 35 and 37 gestation collected vaginal-rectal swabs.Strains were tested and analyzed by culture characteristics,catalase tests and CAMP tests.Drug sensitive analysis of antibiotics was conducted by E-tests and disk diffusio of D-tests.Serological typing was distinguished by latex agglutination experiments.Polymerase chain reaction was used to test drug resistance gene of erythromycin,clindamycin,tetracycline and virulence gene.MLST was conducted by DNA sequencing,e BURST was used to authenticate Clonal Complex.SPSS17.0 was used to analyze statistical sample results.Results 1 Relevance ratio 2292 swabs were collected among pregnant women in 35 and 37 gestation period.The prevalence of cultivated GBS was 4.8%.2 Results of serological typings Six serological typings were observed,the serological typing ware Ⅲ(34.5%),Ib(32.7%),Ⅴ(18.2%),Ia(8.2%),Ⅱ(3.6%)and NT(2.7%).3 Results of resistance 110 strains of GBS were sensitive to Cefotaxime,Linezolid,Chloramphenicol,Penicillin,Vancomycin,and the percentage of the 110 strains resistant to Erythromycin,Levofloxacin,Clindamycin and Tetracycline were 71.2%、68.5%、67.1% and 49.3% respectively.Three strains i MLSB and one strain M were conducted by disk diffusio of D-test.4 Results of MLST There were 11 STs among which the most common was ST19(34.5%),followed by ST10(29.1%),the other STs were ST23(9.1%),ST485(4.5%),ST1(6.4%),ST3(1.8%),ST328(0.9%),ST27(3.6%),ST12(2.7%),ST17(2.7%),ST325(0.9%).Comparative analysis was conducted by MLST data,ST485 was not in the clone group,others were dist Ributed in group1,group2 and group3,7 Clone complexes were found,CC19,CC10,CC23,CC1,CC12 and CC17,the proportion of these ware 39%,29.1%,10.0%,6.4%,2.7%,2.7%.5 Results of resistant genes Among the 110 GBS isolates,78 isolates of Erythromycin resistant strains were detected,7 Erythromycin resistant genes were tested,the prevalence of mreA carriage was 100%,ermB was 79.5%,mefE was 74.2%,mefA was 59.4%,ermTR was 16.2%,ermA was 0.8%,ermC was 0%.73 isolates of Clindamycin resistant strains were detected,lin B was not found.54 isolates of Testracycline resistant strains were detected,the drug resistant gene tet M carried the highest rate,59.2%,followed by tet O(25.9%),tet L(5.6%),tet K(0%).6 Results of virulance genes Virulence genes bca,scp B and hyl B existed in 110 strains,the carrier rate of Rid was 90%,and the carrier rate of bac was 26.4%.Conclusions The detection rate of GBS in perinatal female genital tract infection in Tangshan area was low,at 4.8%.GBS had a higher tolerance rate for antibiotics,mainly about Erythromycin,Clindamycin,Levofloxacin and Tetracycline resistance.As for Erythromycin mainly carried mreA,ermB,mefE and mefA.Tetracycline mainly carried tet M.bca,C5 a peptidase toxin gene(scpB)and hyaluronic acid(hylB)were carried totally,the carrying rate of Rib virulence genes were 90%.The predominant serotypes were Ⅲ and Ib.And the predominant MLST were ST19,ST10,ST23,the predominant clone complexes were CC19,CC10 and CC23.In this study,ST19 /Ⅲ and ST10 /Ib were the predominant isolates and there may be relations between serotypes and STs.Serological typings had respective relations with parts of antibiotic and resistant genes.The synergy of these factors,led to the strains of popular widely and seriously harm. |
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