title: Overall decrease in the susceptibility of Mycoplasma bovis to antimicrobials over the past 30 years in France.
abstract: Mycoplasma (M.) bovis is frequently implicated in respiratory diseases of young cattle worldwide. Today, to combat M. bovis in Europe, only antimicrobial therapy is available, but often fails, leading to important economical losses. The antimicrobial susceptibility of M. bovis is not covered by antimicrobial resistance surveillance networks. The objectives of this study were to identify resistances that were acquired over the last 30 years in France and to determine their prevalence within contemporary strains. The minimum inhibition concentration (MIC) values of 12 antimicrobials, considered active on M. bovis, were compared, using an agar dilution method, between 27 and 46 M. bovis isolates respectively obtained in 1978-1979 and in 2010-2012 from 73 distinct respiratory disease outbreaks in young cattle all over France. For eight antimicrobials, resistances were proven to be acquired over the period and expressed by all contemporary strains. The increase of the MIC value that inhibited 50% of the isolates (MIC50) was: i) substantial for tylosin, tilmicosin, tulathromycin and spectinomycin, from 2 to >64, 2 to >128, 16 to 128 and 4 to >64 µg/mL, respectively, ii) moderate for enrofloxacin, danofloxacin, marbofloxacin and oxytetracycline, from 0.25 to 0.5, 0.25 to 0.5, 0.5 to 1, 32 to >32 µg/mL, respectively. No differences were observed for gamithromycin, tildipirosin, florfenicol and valnemulin with MIC50 of 128, 128, 8, <0.03 µg/mL, respectively. If referring to breakpoint MIC values published for respiratory bovine pathogens, all contemporary isolates would be intermediate in vivo for fluoroquinolones and resistant to macrolides, oxytetracycline, spectinomycin and florfenicol.
authors: ANSES, Laboratoire de Ploufragan/Plouzané, Unité Mycoplasmologie-Bactériologie, Ploufragan, France ; Université Européenne de Bretagne, Rennes, France.
authors: Anne V
authors: AV
authors: Gautier-Bouchardon
authors: ANSES, Laboratoire de Ploufragan/Plouzané, Unité Mycoplasmologie-Bactériologie, Ploufragan, France ; Université Européenne de Bretagne, Rennes, France.
authors: Séverine
authors: S
authors: Ferré
authors: ANSES, Laboratoire de Lyon, UMR Mycoplasmoses des Ruminants, Lyon, France ; Université de Lyon, VetAgro Sup, UMR Mycoplasmoses des Ruminants, Marcy L'Etoile, France.
authors: Dominique
authors: D
authors: Le Grand
authors: ANSES, Laboratoire de Lyon, UMR Mycoplasmoses des Ruminants, Lyon, France ; Université de Lyon, VetAgro Sup, UMR Mycoplasmoses des Ruminants, Marcy L'Etoile, France.
authors: Agnès
authors: A
authors: Paoli
authors: ANSES, Laboratoire de Lyon, Unité Epidémiologie, Lyon, France.
authors: Emilie
authors: E
authors: Gay
authors: ANSES, Laboratoire de Lyon, UMR Mycoplasmoses des Ruminants, Lyon, France ; Université de Lyon, VetAgro Sup, UMR Mycoplasmoses des Ruminants, Marcy L'Etoile, France.
authors: François
authors: F
authors: Poumarat
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology*; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000382:microbiology*; D024881:Drug Resistance, Bacterial; D005602:France / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D009175:Mycoplasma Infections / Q000662:veterinary*; D045682:Mycoplasma bovis / Q000187:drug effects*; D015995:Prevalence; D015203:Reproducibility of Results
chemical_list: D000890:Anti-Infective Agents