Nasopharyngeal Carriage of Drug-resistant Streptococcus pneumoniae in Children with Acute Otitis Media Evaluated by Polymerase Chain Reaction-based Genotyping of Penicillin-binding Proteins

Abstract

A polymerase chain reaction (PCR)-based genotyping of the penicillin-binding protein (PBP) genes pbp1a , pbp2x and pbp2b was used to characterize Streptococcus pneumoniae isolated from the nasopharynx of children with acute otitis media (AOM). Mutations were observed in pbp1a , pbp2x and pbp2b genes in 36.5% of the strains. Decreased susceptibility to g -lactam antibiotics was closely associated with the frequency of mutations in the three PBP genes. Of penicillin-intermediately-resistant S. pneumoniae strains, 54.5% appeared to be genetically similar to penicillin-resistant S. pneumoniae strains. Of penicillin-susceptible S. pneumoniae strains, 33.3% had mutations in the pbp2x gene and showed relatively high MICs to cephalosporins. Strains with mutations in the three PBP genes were often isolated from children h 2 years old. Evaluation of mutations in PBP genes using PCR will prove useful for studying the epidemiology of antibiotic resistance.