title: 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 μg/ml for seven isolates, 2 μg/ml for four isolates, and 1.5 μg/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.
authors: Institute of Microbiology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy.
authors: G
authors: G
authors: Piccinelli
authors: Institute of Microbiology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy.
authors: F
authors: F
authors: Gargiulo
authors: Institute of Microbiology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy.
authors: S
authors: S
authors: Corbellini
authors: Institute of Microbiology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy.
authors: G
authors: G
authors: Ravizzola
authors: Institute of Microbiology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy.
authors: C
authors: C
authors: Bonfanti
authors: Institute of Microbiology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy.
authors: A
authors: A
authors: Caruso
authors: Institute of Microbiology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy defrance@med.unibs.it.
authors: M A
authors: MA
authors: De Francesco
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D004264:DNA Topoisomerases, Type I / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics; D007558:Italy; D064704:Levofloxacin / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D009154:Mutation; D013292:Streptococcus agalactiae / Q000187:drug effects* / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D064704:Levofloxacin; D027101:DNA Topoisomerase IV; D004264:DNA Topoisomerases, Type I; D027081:DNA Gyrase