OBJECTIVE: To probe into the sensitivity

serotype and molecular genetic background of group B Streptococcus（ GBS） in Liuzhou

so as to provide evidence for prevention and treatment of GBS infection in neonates.METHODS: Neonates born in Liuzhou Maternity and Child Health Care Hospital were monitored daily. Immediately after birth

sterile sampler was applied to ears

mouth and umbilical cord

and transportation medium was placed. For the cultured strains

further antibiotics susceptibility test was performed to detect the drug-resistant gene

virulence gene

serotype and multi-sequence genotyping of the strains after identification. RESULTS: A total of 50 strains of GBS were detected

among which 28（ 56. 0%） were found in male neonates. And 26 strains（ 52. 0%） were detected in neonates at first delivery

19 strains（ 18. 0%） were detected in neonates with natural delivery. There were 16 strains and 4 strains（ 32. 0% and 8. 0%

respectively） detected in neonates with pneumonia and asphyxia. 80. 0% of GBS strains showed multi-drug resistance; all GBS strains were sensitive to penicillin

ceftriaxone

linezolid and vancomycin

and were resistant to erythromycin and clindamycin. 60. 0% of GBS strains carried both erythromycin and tetracycline resistance genes

and the main resistance genes were ermA and tetM. The serotypes of GBS strains were mainly type Ⅰa（ 21 strains

42. 0%）

type Ⅲ（ 21 strains

42. 0%） and type IB（ 8 strains

16. 0%）. All strains carried the virulence genes scpB and hlyB. The genes carried by different serotype strains were inconsistent. For example

among serotype Ⅰ a strains

the proportion of strains carrying the resistance gene tetT accounted for the highest（ 8 strains

38. 1%

P = 0. 005）; Among the serotype Ⅲ strains

the proportion of strains carrying alp surface localization protein antigen gene rib accounted for the highest（ 14 strains

66. 7%

P < 0. 001）; the proportion of strains carrying alphaC in serotype Ⅰ a strains was significantly higher than that of serotypes Ⅰ b and Ⅲ

and the difference was statistically significant（ P < 0. 001）. Among the 50 GBS strains

the most common gene sequences were ST12（ 15 strains

30. 0%）

ST19（ 10 strains

20. 0%）

ST17（ 9 strains

18. 0%） and ST23（ 5 strains

10. 0%）.ST17 and ST19 were mainly related to serotype Ⅲ and resistant to tetracycline

erythromycin and clindamycin

and carried resistance gene tetM and ermA

virulence gene rib; ST12 and ST23 were mainly related to the serum type Ⅰtype a

carried carried resistance gene tetM and ermA

virulence gene alphaC and epsilon. CONCLUSIONS: The multi-drug resistance of neonatal GBS strains highlights the importance of continuous monitoring of GBS resistance to antibiotics in the future. The specific serotypes of GBS are highly associated with specific ST types

drug-resistant phenotypes

genotypes and virulence genes

suggesting that the potential pathogenic abilities of isolates are inconsistent with different characteristics

which underscores the value of monitoring multiple characteristics to detect new epidemiologic trends and provide implications for the formulation of multivalent GBS vaccines.