Serotype, Genotype, and Clinical Manifestations of Group B Streptococcus (GBS) Isolated from Neonates in China

Background: Group B streptococcus (GBS) is a common bacterial pathogen causing nenatal infections. This study aimed to determine the serotypes and genotypes of GBS isolated from neonates and to ascertain the association between the type and the antibiotic resistance of GBS strains. Methods: A total of 26 group B streptococcus (GBS) strains were isolated from neonates in our hospital between January, 2008 and August, 2014. Species identification was conducted with a VITEK system (BioMerieux) and conventional biochemical tests. A latex agglutination test was used to determine the serotypes of the GBS strains. The antibiotic resistance of GBS strains was then evaluated using a Kirby-Bauer disk susceptibility test and an Epsilometer test (E-test). Multilocus sequence typing (MLST) was used to determine the sequence types (STs) of all 26 GBS strains. Results and Conclusions: Serotype III and sequence type ST17 were the major GBS strain serotype and genotype causing invasive infections in neonates, respectively. These GBS strains exhibited a high rate of resistance to tetracycline, erythromycin, and clindamycin, confirming that penicillin should remain the first-line antibiotic for the treatment of GBS infection. In addition, we identified an association between serotype III and genotype ST17 with septicaemia, purulent meningitis and pneumonia in GBS infections in neonates.