Emergence of the first levofloxacin-resistant strains of Streptococcus agalactiae isolated in Italy.

ABSTRACT: Of 901 group B streptococcus strains analyzed, 13 (1.4%) were resistant to levofloxacin (MICs of >32 ?g/ml for seven isolates, 2 ?g/ml for four isolates, and 1.5 ?g/ml for four isolates). Mutations in the quinolone resistance-determining regions (QRDRs) of gyrase and topoisomerase IV were identified. A double mutation involving the Ser-81 change to Leu for gyrA and the Ser-79 change to Phe or to Tyr for parC was linked to a high level of fluoroquinolone resistance. In addition, two other mutational positions in parC were observed, resulting in an Asp-83-to-Tyr substitution and an Asp-83-to-Asn substitution. Different mutations were also observed in gyrB, with unknown significance. Most levofloxacin-resistant GBS strains were of serotype Ib and belonged to sequence type 19 (ST19) and clonal complex 19 (CC-19). Most of them exhibited the epsilon gene.

SUBMITTER: Piccinelli G 

PROVIDER: S-EPMC4356756 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature