title: Susceptibility of rapidly growing mycobacteria isolated from cats and dogs, to ciprofloxacin, enrofloxacin and moxifloxacin.
abstract: Rapidly growing mycobacteria (RGM) cause infections in cats and dogs which require prolonged antibacterial medication for resolution. In Australia, pathogens from the Mycobacterium fortuitum and Mycobacterium smegmatis clusters are responsible for most of the RGM infections in cats and dogs. As fluoroquinolones are often recommended for treating such infections, 14 M. fortuitum isolates, 51 isolates from the M. smegmatis cluster and 2 M. mageritense isolates, collected from feline and canine patients, underwent susceptibility testing to the second generation fluoroquinolones ciprofloxacin and enrofloxacin and the newer generation fluoroquinolone moxifloxacin. Using microbroth dilution, the MIC(90) of ciprofloxacin, enrofloxacin, and moxifloxacin that inhibited growth of M. fortuitum isolates were 0.500, 0.250 and 0.063 μg/mL respectively. For the M. smegmatis cluster isolates the corresponding MIC(90) was 0.500, 0.250 and 0.125 μg/mL respectively. E-test results showed similar trends but MICs were lower than those determined by microbroth dilution. Additionally, moxifloxacin was administered to 10 clinically normal cats (50mg per cat, once daily for 4 days). The plasma moxifloxacin concentration 2h after the last dose was determined by liquid chromatography as 2.2 ± 0.6 μg/mL. The plasma concentration at 2h:MIC(90) ratios for moxifloxacin for M. fortuitum and M. smegmatis cluster was 34.9 and 17.6 respectively which exceeded the recommended threshold of 10, indicating that moxifloxacin has good theoretical efficacy for treatment of those M. fortuitum and M. smegmatis infections in cats and dogs that have become refractory to other antibacterial drug classes.
authors.affiliation: Faculty of Veterinary Science, McMaster building, B14, The University of Sydney, NSW 2006, Australia. merran.govendir@sydney.edu.au
authors.forename: M
authors.initials: M
authors.lastname: Govendir
authors.forename: T
authors.initials: T
authors.lastname: Hansen
authors.forename: B
authors.initials: B
authors.lastname: Kimble
authors.forename: J M
authors.initials: JM
authors.lastname: Norris
authors.forename: R M
authors.initials: RM
authors.lastname: Baral
authors.forename: D I
authors.initials: DI
authors.lastname: Wigney
authors.forename: S
authors.initials: S
authors.lastname: Gottlieb
authors.forename: R
authors.initials: R
authors.lastname: Malik
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000009:adverse effects / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology*; D001315:Australia; D001372:Aza Compounds / Q000009:adverse effects / Q000097:blood / Q000493:pharmacokinetics; D002415:Cats; D002939:Ciprofloxacin / Q000494:pharmacology; D003967:Diarrhea / Q000139:chemically induced / Q000662:veterinary; D004285:Dogs; D000077422:Enrofloxacin; D005260:Female; D024841:Fluoroquinolones / Q000009:adverse effects / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology*; D008297:Male; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D000077266:Moxifloxacin; D009161:Mycobacterium / Q000187:drug effects* / Q000302:isolation & purification; D011804:Quinolines / Q000009:adverse effects / Q000097:blood / Q000493:pharmacokinetics
chemical_list: D000900:Anti-Bacterial Agents; D001372:Aza Compounds; D024841:Fluoroquinolones; D011804:Quinolines; D000077422:Enrofloxacin; D002939:Ciprofloxacin; D000077266:Moxifloxacin