Abstract
The quinolone-resistance determining-region of gyrA was 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 aspartic 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.
Highlights
Pseudomonas aeruginosa is a clinically important pathogen
MIC values for the seven isolates for ampicillin, chloramphenicol, streptomycin, tetracycline, kanamycin, neomycin, ciprofloxacin and levofloxacin are shown in Tables 1 and 2
In Nigeria, it had been earlier reported that extensive use and often abuse/misuse of antimicrobial agents in livestock has resulted in emergence of resistant strains of bacteria in which some were found to habour R factors to commonly used antibiotics (Adetosoye, 1980)
Summary
It is usually incriminated as nosocomial pathogens (Sherertz and Sarubbi, 1983; Hooper and Wolfson, 1991) Infection with it is usually associated with significant morbidity and mortality, especially in patients with cystic fibrosis (Hancock and Speert, 2000; Obritsch et al, 2005). Fluoroquinolones in particular have been widely used for the treatment of nosocomial infection (Hooper, 1998; Yamaguchi et al, 2000) They are bactericidal members of the quinolone family, which acts by inhibiting the bacterial DNA gyrase and topoisomerase IV, causing the inhibition of the DNA transcription and replication (Gorgania et al, 2009). DNA gyrase is targeted in Gram-negative organisms, whereas for Grampositive organisms’ topoisomerase IV is the target (Jalal et al, 2000)
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