title: Distribution of genotypes and antibiotic resistance genes among invasive Streptococcus agalactiae (group B streptococcus) isolates from Australasian patients belonging to different age groups.
abstract: Serotype distribution and antibiotic resistance (AR) among group B streptococci (GBS) affect GBS disease prevention strategies, but vary among patient groups. A multiplex PCR-based reverse line blot (mPCR/RLB) hybridisation assay was used to compare the distributions of GBS serotypes, serotype III subtypes and AR-associated genes among 666 invasive isolates from 663 patients, divided into five age groups: infants, early-onset (EO; 0-6 days) and late-onset (LO; 7-90 days); children (aged 3 months to 14 years); women of childbearing age (WCBA; aged 15-45 years); and other adults (males aged >15 years; females aged >45 years). Serotypes Ia and V and serosubtype III-1 accounted for 60% of infections. Serosubtype III-2, which corresponds to a virulent clone belonging to sequence type (ST)17, was relatively uncommon overall (7%), but was associated strongly with LO infant infections, in which it was significantly more common than in adult infections (25/104 (24%) vs. 9/392 (2%), p <0.0001) or in EO infections (25/104 (24%) vs. 14/155 (9%), p <0.005). Erythromycin resistance genes were found in 8% of all isolates (ermB 3%, ermA 2.5% and mefA/E 2%), in 11-15% of isolates of serotypes II and V and subtype III-1, but in none of the isolates of serosubtype III-2 (III-2, 0/49 vs. all others, 54/618 (9%), p <0.04). In summary, the virulent serosubtype III-2 was associated strongly with LO infant GBS infection, but was less likely than other serotypes or serosubtype III-1 to carry AR genes.
authors.affiliation: Department of Dermatology, First Hospital, Peking University, Beijing, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Zhao
authors.forename: F
authors.initials: F
authors.lastname: Kong
authors.forename: X
authors.initials: X
authors.lastname: Zeng
authors.forename: H F
authors.initials: HF
authors.lastname: Gidding
authors.forename: J
authors.initials: J
authors.lastname: Morgan
authors.forename: G L
authors.initials: GL
authors.lastname: Gilbert
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001208:Asia / Q000453:epidemiology; D001315:Australia / Q000453:epidemiology; D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D002648:Child; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008780:Methyltransferases / Q000235:genetics; D008875:Middle Aged; D017720:Molecular Epidemiology; D009693:Nucleic Acid Hybridization / Q000379:methods; D016133:Polymerase Chain Reaction / Q000379:methods; D012703:Serotyping / Q000379:methods; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D013292:Streptococcus agalactiae / Q000145:classification* / Q000302:isolation & purification*
chemical_list: D001426:Bacterial Proteins; C111078:ErmTR protein, bacteria; D008780:Methyltransferases