title: Acquired resistance to the 16-membered macrolides tylosin and tilmicosin by Mycoplasma bovis.
abstract: The molecular mechanism of acquired resistance to the 16-membered macrolides tylosin (Ty) and tilmicosin (Tm) was investigated in Mycoplasma bovis field isolates. Sequence analysis of domains II and V of the two 23S rRNA alleles and ribosomal proteins L4 and L22 was performed on 54 M. bovis isolates showing different minimal inhibitory concentrations (MIC). The presence of any one of the point mutations G748A, C752T, A2058G, A2059G or A2059C (Escherichia coli numbering) in one or both alleles of the 23S rRNAs was correlated with decreased susceptibility to Ty (8-1024 μg/ml) and to Tm (32 to >256 μg/ml) in 27/27 and 27/31 M. bovis isolates, respectively. Although a single mutation in domain II or V could be sufficient to cause decreased susceptibility to Ty, our data imply that a combination of mutations in two domains is necessary to achieve higher MICs (≥ 128 μg/ml). The influence of a combination of mutations in two domains II and V on enhancement of resistance to Tm was less clear. In addition, the amino acid (aa) substitution L22-Q90H was found in 24/32 representative M. bovis isolates with different MICs, but no correlation with decreased susceptibility to Ty or Tm was identified. Multiple aa substitutions were also identified in the L4 protein, including at positions 185-186 (positions 64 and 65 in E. coli) which are adjacent to the macrolide-binding site. This is the first description of the molecular mechanism of acquired resistance to the 16-membered macrolides in M. bovis.
authors.affiliation: Mycoplasma Unit, Division of Avian and Fish Diseases, Kimron Veterinary Institute, Israel; Department of Microbiology and Molecular Genetics, The Hebrew University of Jerusalem, Israel.
authors.forename: Uri
authors.initials: U
authors.lastname: Lerner
authors.affiliation: Mycoplasma Unit, Division of Avian and Fish Diseases, Kimron Veterinary Institute, Israel; Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Israel.
authors.forename: Eytan
authors.initials: E
authors.lastname: Amram
authors.affiliation: Animal Health and Veterinary Laboratories Agency, Weybridge, UK.
authors.forename: Roger D
authors.initials: RD
authors.lastname: Ayling
authors.affiliation: Mycoplasma Unit, Division of Avian and Fish Diseases, Kimron Veterinary Institute, Israel.
authors.forename: Inna
authors.initials: I
authors.lastname: Mikula
authors.affiliation: Mycoplasma Unit, Division of Avian and Fish Diseases, Kimron Veterinary Institute, Israel.
authors.forename: Irena
authors.initials: I
authors.lastname: Gerchman
authors.affiliation: Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Israel.
authors.forename: Shimon
authors.initials: S
authors.lastname: Harrus
authors.affiliation: Department of Microbiology and Molecular Genetics, The Hebrew University of Jerusalem, Israel.
authors.forename: Dina
authors.initials: D
authors.lastname: Teff
authors.affiliation: Department of Microbiology and Molecular Genetics, The Hebrew University of Jerusalem, Israel.
authors.forename: David
authors.initials: D
authors.lastname: Yogev
authors.affiliation: Mycoplasma Unit, Division of Avian and Fish Diseases, Kimron Veterinary Institute, Israel. Electronic address: innal@moag.gov.il.
authors.forename: Inna
authors.initials: I
authors.lastname: Lysnyansky
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy / Q000382:microbiology; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics; D008826:Microbial Sensitivity Tests; D009175:Mycoplasma Infections / Q000188:drug therapy / Q000662:veterinary; D045682:Mycoplasma bovis / Q000187:drug effects* / Q000235:genetics*; D017354:Point Mutation; D012338:RNA, Ribosomal, 23S / Q000235:genetics; D012269:Ribosomal Proteins / Q000235:genetics; D015645:Tylosin / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D012338:RNA, Ribosomal, 23S; D012269:Ribosomal Proteins; C056368:ribosomal protein L4; C052319:tilmicosin; D015645:Tylosin
keywords: Acquired resistance; Mycoplasma bovis; Tilmicosin; Tylosin