Susceptibility of rapidly growing mycobacteria and Nocardia isolates from cats and dogs to pradofloxacin

• Published in: Veterinary microbiology 2011-12, Vol.153 (3), p.240-245
• Main Authors: Govendir, M., Norris, J.M., Hansen, T., Wigney, D.I., Muscatello, G., Trott, D.J., Malik, R.
• Format: Article
• Language: English
• Subjects: Animals; Anti-Bacterial Agents - pharmacology; Bacteriology; Biological and medical sciences; Cat; Cat Diseases - microbiology; Cats; Ciprofloxacin - pharmacology; Dog; Dog Diseases - microbiology; Dogs; Fluoroquinolone; Fluoroquinolones - pharmacology; Fundamental and applied biological sciences. Psychology; Microbial Sensitivity Tests - veterinary; Microbiology; Miscellaneous; Mycobacteria; Mycobacterium - drug effects; Mycobacterium - growth & development; Mycobacterium fortuitum; Mycobacterium Infections - microbiology; Mycobacterium Infections - veterinary; Mycobacterium smegmatis; Nocardia; Nocardia - drug effects; Nocardia - growth & development; Nocardia farcinica; Nocardia Infections - microbiology; Nocardia Infections - veterinary; Nocardia nova; Pradofloxacin
• ISSN: 0378-1135; 1873-2542
• DOI: 10.1016/j.vetmic.2011.06.001

Rapidly growing mycobacteria (RGM) and Nocardiae can cause severe or refractory infections in cats and dogs. Prolonged antibacterial therapy is required to cure these infections. As fluoroquinolones have been used in combination therapy for treating RGM infections, isolates from the Mycobacterium smegmatis cluster ( n = 64), Mycobacterium fortuitum cluster ( n = 17), and M. mageritense cluster ( n = 2), collected from feline and canine patients, underwent susceptibility testing to pradofloxacin. The MIC 50, MIC 90 and tentative epidemiological cut-off (ECOFF) values as determined by microbroth dilution susceptibility testing that inhibited growth of the M. smegmatis and M. fortuitum clusters were 0.063, 0.125 and ≤0.25; and 0.125, 0.250 and ≤1.0 μg/mL, respectively. E-Test results showed similar trends but MICs were lower than those for microbroth dilution. In summary, pradofloxacin demonstrated effective in vitro activity against RGM isolates. Additionally, veterinary isolates of Nocardia nova ( n = 18), Nocardia farcinica ( n = 3) and Nocardia cyriacigeorgica ( n = 1) underwent microbroth dilution testing to ciprofloxacin, enrofloxacin and pradofloxacin. The MIC 50 and MIC 90 of pradofloxacin, ciprofloxacin and enrofloxacin that inhibited growth of Nocardia nova isolates were 2 (4), 8 (16), 16 (32) μg/mL, respectively. The tentative ECOFF values for pradofloxacin and ciprofloxacin were 32 μg/mL and for enrofloxacin 64 μg/mL. The MIC or MIC range for the three N. farcinica isolates of pradofloxacin, ciprofloxacin and enrofloxacin were 0.25–0.5, 2 and 2 μg/mL and for the single N. cyriacigeorgica isolate were 1, 4 and 4 μg/mL, respectively. On the basis on these results, fluoroquinolones appear to have limited therapeutic potential for most Nocardia infections.