[Current situations and countermeasures regarding antimicrobial resistance in group B streptococcal isolates from patients, ranging from newborn to the elderly, with invasive infections].

Several group B streptococci (GBS) strains resistant to macrolides, lyncomycins, fluoroquinolones, or tetracyclines, are reported in isolates from children or adults patients with invasive infections. Some strains with reduced susceptibility to beta-lactams also are observed among subjects with invasive or noninvasive diseases. Constitutively expressed erm methylase gene confers resistance to both macrolides and lyncomycins, while the tetM gene carried on transposon Tn916 contributes to tetracycline resistance. Significant amino acid substitutions (GyrA, Ser81Leu; ParC, Ser79Phe) in topoisomerases induce resistance to fluoroquinolones, and other substitutions (PBP2X, Gln557Glu and Val405Ala; PBP2B, Gly613Arg) adjacent to significant motifs in penicillin-binding proteins produce decreased beta-lactam susceptibility. Therefore, current interventions concerning prophylaxis and treatment will need to re-evaluate in future.