Abstract

The quinolone-resistance determining-region of gyrA was polymerase chain reaction (PCR)-amplified and sequenced in seven fluoroquinolone-resistant Pseudomonas aeruginosa (Nalidixic acid MICs ranging 8 to128 µg/ml, ciprofloxacin MICs ranging 8 to 32 µg/ml and  levofloxacin MICs ranged from 32 to 64 µg/ml) isolated from poultry that died of septicaemic clinical diseases in Ibadan, Oyo State, South Western Nigeria. The seven isolates were also multidrug resistant to various combinations of the commonly used antibiotics like streptomycin, ampicillin, tetracycline, kanamycin, neomycin and chloramphenicol. The entire seven isolates possessed the gyrA mutation encoding the histidine to tyrosine conversion at amino acid 150 (H150Y). Additional substitutions observed included: aspartic acid to tyrosine substitution at amino acid 87 (D87Y) in two isolates, aspartic acid to glycine D87G substitution in three isolates, another simultaneous seven substitutions: aspartic acid to alanine, D87A; alanine to proline, A62P; tyrosine to isoleucine, Y83I; methionine to leucine, M92L; leucine to methionine, L98M; L128M; and aspertic acid to proline D148P  in one of the isolate, whereas one of the seven isolates possessed only the H150Y substitution. The H150Y is typical of the quinolone resistant P. aeruginosa isolated from septic poultry in Nigeria, regardless of other resistance- patterns exhibited to other commonly used antibiotics. This study associate gyrA mutations with fluoroquinolone resistance in P. aeruginosa isolated from septicaemic poultry in Nigeria, where fluoroquinolone use in livestock is not strictly regulated and misuse/abuse of most antibiotics is rampart.

Key words: Pseudomonas aeruginosa, resistance, fluoroquinolone, poultry, Oyo state, Nigeria.