title: In vitro susceptibilities of Leptospira spp. and Borrelia burgdorferi isolates to amoxicillin, tilmicosin, and enrofloxacin.
abstract: Antimicrobial susceptibility testing was conducted with 6 different spirochetal strains (4 strains of Leptospira spp. and 2 strains of Borrelia burgdorferi) against 3 antimicrobial agents, commonly used in equine and bovine practice. The ranges of MIC and MBC of amoxicillin against Leptospira spp. were 0.05 - 6.25 microgram/ml and 6.25 - 25.0 microgram/ml, respectively. And the ranges of minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of amoxicillin against B. burgdorferi were 0.05 - 0.39 microgram/ml and 0.20 - 0.78 microgram/ml, respectively. The ranges of MIC and MBC of enrofloxacin against Leptospira spp. were 0.05 - 0.39 microgram/ml and 0.05 - 0.39 microgram/ml, respectively. Two strains of B. burgdorferi were resistant to enrofloxacin at the highest concentration tested for MBC (>or=100 microgram/ml). Therefore, the potential role of tilmicosin in the treatment of leptospirosis and borreliosis should be further evaluated in animal models to understand whether the in vivo studies will confirm in vitro results. All spirochetal isolates were inhibited (MIC) and were killed (MBC) by tilmicosin at concentrations below the limit of testing (<or=0.01 microgram/ml).
authors.affiliation: College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Doo
authors.initials: D
authors.lastname: Kim
authors.forename: Dorsey
authors.initials: D
authors.lastname: Kordick
authors.forename: Thomas
authors.initials: T
authors.lastname: Divers
authors.forename: Yung Fu
authors.initials: YF
authors.lastname: Chang
mesh_terms: D000658:Amoxicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D025065:Borrelia burgdorferi / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D000077422:Enrofloxacin; D024841:Fluoroquinolones / Q000494:pharmacology; D007919:Leptospira / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D007922:Leptospirosis / Q000382:microbiology*; D008193:Lyme Disease / Q000382:microbiology*; D018942:Macrolides / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D015203:Reproducibility of Results; D015645:Tylosin / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D018942:Macrolides; D000077422:Enrofloxacin; D000658:Amoxicillin; C052319:tilmicosin; D015645:Tylosin