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Classification of group B streptococci with reduced β-lactam susceptibility (GBS-RBS) based on the amino acid substitutions in PBPs

2015; Oxford University Press; Volume: 70; Issue: 6 Linguagem: Inglês

10.1093/jac/dkv022

1460-2091

Kouji Kimura, Noriyuki Nagano, Yoshichika Arakawa,

Pneumonia and Respiratory Infections

Abstract All clinical isolates of group B Streptococcus (GBS; Streptococcus agalactiae) are considered uniformly susceptible to β-lactams, including penicillins. However, GBS with reduced penicillin susceptibility (PRGBS) were first identified by our group in Japan and have also been reported from North America. PRGBS are non-susceptible to penicillin because of acquisition of amino acid substitutions near the conserved active-site motifs in PBP2X. In particular, V405A and Q557E are considered the key amino acid substitutions responsible for penicillin non-susceptibility. We revealed that in addition to the substitutions in PBP2X, an amino acid substitution in PBP1A confers high-level cephalosporin resistance in GBS. As the number of publications on GBS with reduced β-lactam susceptibility (GBS-RBS), especially PRGBS, and concomitantly the need for a systematic classification of GBS-RBS is increasing, we propose here a classification of GBS-RBS based on the amino acid substitutions in their PBPs.