Molecular characterization and typing of enrofloxacin-resistant clinical isolates of Mycoplasma gallisepticum.
Emergence of resistance to fluoroquinolones is mainly due to chromosomal mutations in genes encoding the subunits of the drug's target enzymes, DNA gyrase and topoisomerase IV, which are essential for DNA replication. The quinolone resistance-determining regions (QRDRs) of these genes were characterized in 25 Mycoplasma gallisepticum strains isolated from commercial poultry flocks during 1997-2007, which exhibited different levels of susceptibility to fluoroquinolones. All enrofloxacin-resistant isolates harbored amino acid substitutions in the QRDRs of each of three proteins (GyrA, GyrB, and ParC). Molecular typing of those strains by random amplification of polymorphic DNA and gene-targeted sequencing supports ongoing, stepwise selection of resistant strains from the existing reservoir of susceptible M. gallisepticum strains.
Lysnyansky
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I
Division of Avian and Aquatic Diseases, Kimron Veterinary Institute, Bet Dagan 50250, Israel. innal@moag.gov.il
Gerchman
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I
Perk
S
S
Levisohn
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S
D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001483:Base Sequence; D002645:Chickens; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D000077422:Enrofloxacin; D024841:Fluoroquinolones / Q000494:pharmacology*; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D045686:Mycoplasma gallisepticum / Q000145:classification / Q000187:drug effects* / Q000235:genetics*; D019105:Random Amplified Polymorphic DNA Technique / Q000662:veterinary; D014422:Turkeys
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D024841:Fluoroquinolones; D000077422:Enrofloxacin; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase