Abstract
BackgroundInvasive group B Streptococcus (GBS) disease in Chinese infants has gradually gained attention in recent years, but the molecular epidemiology of the pathogen is still not well known.MethodsThis multicenter study retrospectively investigated distribution of capsular serotypes, sequence types (STs), and hypervirulent GBS adhesin gene (hvgA) in clinical GBS isolates that caused invasive disease in infants aged < 3 months of age in southern mainland China between January 2013 and June 2016. Genes for antibiotic resistance to tetracycline, erythromycin, and clindamycin were also examined.ResultsFrom a total of 93 GBS isolates taken from 34 early-onset disease (EOD, 0–6 days after birth) and 59 late-onset disease (LOD, 7–89 days after birth) cases, four serotypes were identified: serotypes III (79.6%), Ib (12.9%), Ia (4.3%), and V (3.2%). Serotype III accounted for 73.5% of EOD and 83.1% of LOD and was responsible for 75.5% of cases involving meningitis. Fifteen STs were found, with the majority being ST17 (61.3%), ST12 (7.5%), ST19 (7.5%), and others (23.7%). 96.8% of STs belonged to only five clonal complexes (CCs): CC17 (64.5%), CC10 (12.9%), CC19 (9.7%), CC23 (6.5%), and CC1 (3.2%). The hvgA gene was detected in 66.7% of GBS isolates and 95% of CC17 isolates, all of which were serotype III except one serotype Ib/CC17 isolate. A large proportion of GBS isolates were found to be resistant to tetracycline (93.5%), clindamycin (65.5%), and erythromycin (60.2%). Genes of tetO (74.7%) and tetM (46.0%) were found in tetracycline resistant isolates, linB (24.6%) in clindamycin resistant isolates, and ermB (87.5%) and mefA (3.6%) in erythromycin resistant isolates.ConclusionOur results reveal higher prevalence of serotype III, ST17, CC17, hvgA expressing, and antibiotic resistant GBS isolates than previously reported in southern mainland China.This study provides guidance for appropriate measures of prevention and control to be taken in the future.
Highlights
Invasive group B Streptococcus (GBS) disease in Chinese infants has gradually gained attention in recent years, but the molecular epidemiology of the pathogen is still not well known
Jones et al analyzed GBS isolates with multilocus sequence typing (MLST) and reported that serotype III strains have been categorized to ST17 and belong to complex clone 17 (CC17) [8]
There were 49 GBS cases which were diagnosed with meningitis, 47% (16/34) of which were observed in early-onset disease (EOD) cases and 55.9% (33/59) in late-onset disease (LOD) cases
Summary
Invasive group B Streptococcus (GBS) disease in Chinese infants has gradually gained attention in recent years, but the molecular epidemiology of the pathogen is still not well known. Group B Streptococcus (GBS), called Streptococcus agalactiae, is a main causative pathogen of invasive neonatal bacterial infection, causing high morbidity and mortality [1,2,3]. A meta-analysis by Madrid et al found that the incidence of invasive GBS disease in infants. Only limited subtypes have been identified in infants with invasive infection, indicating that variation in expressed surface molecules is related to pathogenicity of strains. In the CC17 lineage, which is strongly associated with neonatal meningitis, the hvgA gene encoding a surface-anchored protein named hypervirulent GBS adhesin (HvgA) has been identified [9]. The HvgA surface-anchored protein acts as an important adhesion medium for destroying and penetrating the intestinal and blood-brain barriers, and mediates the migration of bacteria into the bloodstream and the central nervous system, which leads to infection [9, 10]
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