title: Persistence of Mycoplasma synoviae in hens after two enrofloxacin treatments and detection of mutations in the parC gene.
abstract: The ability of Mycoplasma synoviae, an avian pathogen, to persist despite fluoroquinolone treatments was investigated in hens. Groups of Mycoplasma-free hens were experimentally infected with the M. synoviae 317 strain and treated twice with enrofloxacin at the therapeutic dose. The results show that the two treatments did not have any influence on this strain of M. synoviae recovery from tracheal swabs. Mycoplasmas were isolated from tracheal swab cultures, but not from inner organs such as the liver or spleen, suggesting that this strain of M. synoviae was not able to cross the mucosal barrier to disseminate throughout the host. A significant increase of the resistance level to enrofloxacin of five re-isolated mycoplasma clones, was observed after the second treatment. This increase was associated in two clones to a Ser81-->Pro substitution, found in the ParC quinolone-resistance determining region (QRDR) of DNA topoisomerase IV. This is the first time that a mutation in a gene coding for topoisomerase IV is described in M. synoviae after in vivo enrofloxacin treatments in experimentally infected hens.
authors.affiliation: Agence Française de Sécurité Sanitaire des Aliments, Laboratoire d'Etudes et de Recherches Avicoles et Porcines, Unité de Mycoplasmologie-Bactériologie, BP 53, 22440 Ploufragan, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Le Carrou
authors.forename: Anita K
authors.initials: AK
authors.lastname: Reinhardt
authors.forename: Isabelle
authors.initials: I
authors.lastname: Kempf
authors.forename: Anne V
authors.initials: AV
authors.lastname: Gautier-Bouchardon
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001483:Base Sequence; D002645:Chickens; D027101:DNA Topoisomerase IV / Q000235:genetics; D004269:DNA, Bacterial / Q000032:analysis; D024881:Drug Resistance, Bacterial / Q000235:genetics; D000077422:Enrofloxacin; D005260:Female; D024841:Fluoroquinolones / Q000494:pharmacology / Q000627:therapeutic use*; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D009154:Mutation; D009175:Mycoplasma Infections / Q000188:drug therapy / Q000382:microbiology / Q000662:veterinary*; D045805:Mycoplasma synoviae / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D011201:Poultry Diseases / Q000188:drug therapy / Q000382:microbiology*; D011897:Random Allocation; D014132:Trachea / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D024841:Fluoroquinolones; D000077422:Enrofloxacin; D027101:DNA Topoisomerase IV