Molecular characteristics of group B Streptococcus isolates from infants in southern mainland China

Abstract

Background 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. Methods This 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. Results From 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. Conclusion Our 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.

Predominance of III/ST19 and Ib/ST10 Lineages With High Multidrug Resistance in Fluoroquinolone-Resistant Group B Streptococci Isolates in Which a New Integrative and Conjugative Element Was Identified

“…Records were considered as the same episode if specimens were taken within 7 days and showed resistance to the same antibiotics and were thus merged accordingly to form a single record. Sampling, laboratory procedures, and identification of GBS were performed as previously described (Ji et al, 2019 ; Li et al, 2019 ).…”

“…Resistance genes for clindamycin ( lnuB ), erythromycin ( ermB ), and tetracycline ( tetO and tetM ) were detected by PCR as previously described (Gao et al, 2018 ; Li et al, 2019 ). Identification of the gyrA and parC genes in QRDR mutations was performed according to Hays et al ( 2016 ).…”

Rapid Classification of Multilocus Sequence Subtype for Group B Streptococcus Based on MALDI-TOF Mass Spectrometry and Statistical Models

“…The isolates were representative of the main epidemic ST clones in China. All isolates were recovered from blood or cerebrospinal fluid (CSF) cultures after routine identification in clinical microbiology laboratories of tertiary healthcare centers, and were characterized by MLST and serotyping (Ji et al, 2019;Li et al, 2019) (Table S1). Pre-analysis of the total dataset identified 31 types of STs, the most prevalent STs were ST10, ST12, ST17, ST19, ST23, the major serotypes were III, Ib, and Ia, as well as a strong association of serotype III with ST17/ST19, serotype Ib with ST10/ST12 and serotype Ia with ST23.…”

“…Multilocus sequence typing (MLST) has been widely used as another powerful tool to study the genetic lineages of GBS strains based on the gene sequence of seven housekeeping genes since 2003 (Jones et al, 2003). By using MLST, the majority sequence types (STs) of the human GBS isolates were ST1, ST10, ST12, ST17, ST19, ST23, and ST26 (Da et al, 2014;Wu et al, 2019;Li et al, 2019;McGee et al, 2020). Special GBS STs were found to be strongly associated with neonatal invasive diseases (Wu et al, 2019;Li et al, 2019).…”

“…By using MLST, the majority sequence types (STs) of the human GBS isolates were ST1, ST10, ST12, ST17, ST19, ST23, and ST26 (Da et al, 2014;Wu et al, 2019;Li et al, 2019;McGee et al, 2020). Special GBS STs were found to be strongly associated with neonatal invasive diseases (Wu et al, 2019;Li et al, 2019). For example, the ST17 clone, mostly serotype III, expressing hypervirulent adhesin (HvgA) as a signature virulence factor for this lineage, has a greater potential to cause invasive diseases like neonatal sepsis and meningitis, accounting for more than 80% of late-onset (LOD) meningitis cases (Manning et al, 2009;Landwehr-Kenzel and Henneke, 2014;Zhu et al, 2020).…”