Open AccessFluoroquinolone Resistance in Streptococcus dysgalactiae subsp. equisimilis and Evidence for a Shared Global Gene Pool with Streptococcus pyogenes
Author(s) -
Marcos D. Pinho,
José MeloCristino,
Mário Ramirez
Publication year - 2010
Publication title -
antimicrobial agents and chemotherapy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.07
H-Index - 259
eISSN - 1070-6283
pISSN - 0066-4804
DOI - 10.1128/aac.01377-09
Subject(s) - streptococcus dysgalactiae , streptococcus pyogenes , biology , microbiology and biotechnology , genetics , allele , gene , quinolone , streptococcus , bacteria , streptococcus agalactiae , antibiotics , staphylococcus aureus
Quinolone resistance is an emerging problem inStreptococcus pyogenes , and recombination withStreptococcus dysgalactiae DNA has been implicated as a frequent mechanism leading to resistance. We have characterized a collection ofS. dysgalactiae subsp.equisimilis isolates responsible for infections in humans (n = 314) and found a high proportion of levofloxacin-resistant isolates (12%). Resistance was associated with multipleemm types and genetic lineages, as determined by pulsed-field gel electrophoretic profiling. Since we could not find evidence for a role of efflux pumps in resistance, we sequenced the quinolone resistance-determining regions of thegyrA andparC genes of representative resistant and susceptible isolates. We found much greater diversity among theparC genes (19 alleles) than among thegyrA genes (5 alleles). While single mutations in either GyrA or ParC were sufficient to raise the MIC so that the strains were classified as intermediately resistant, higher-level resistance was associated with mutations in both GyrA and ParC. Evidence for recombination withS. pyogenes DNA was found in someparC alleles, but this was not exclusively associated with resistance. Our data support the existence of a common reservoir of genes conferring quinolone resistance shared betweenS. dysgalactiae subsp.equisimilis andS. pyogenes , while no recombination with the animal pathogenS. dysgalactiae subsp.dysgalactiae could be found.