Investigation into the Quinolone Resistant E. coli Isolated from Commercial Broilers
M. A. R. Priyantha
*
Bacteriology Division, Veterinary Research Institute, P.O.Box 28, Peradeniya, Sri Lanka.
A. B. S. Pabasara
Bacteriology Division, Veterinary Research Institute, P.O.Box 28, Peradeniya, Sri Lanka.
P. S. Fernando
Bacteriology Division, Veterinary Research Institute, P.O.Box 28, Peradeniya, Sri Lanka.
N. Liyanagunawardhana
Bacteriology Division, Veterinary Research Institute, P.O.Box 28, Peradeniya, Sri Lanka.
P. S. De Alwis
Bacteriology Division, Veterinary Research Institute, P.O.Box 28, Peradeniya, Sri Lanka.
D. M. S. N. B. Dissanayake
Bacteriology Division, Veterinary Research Institute, P.O.Box 28, Peradeniya, Sri Lanka.
N. G. N. Samarakoon
Bacteriology Division, Veterinary Research Institute, P.O.Box 28, Peradeniya, Sri Lanka.
M. I. Wijemuni
Bacteriology Division, Veterinary Research Institute, P.O.Box 28, Peradeniya, Sri Lanka.
*Author to whom correspondence should be addressed.
Abstract
Antimicrobial resistance is an overwhelming issue in human and veterinary medicine. Association between usage of antimicrobials in livestock and the emergence of antimicrobial resistance in human medicine has been widely discussed. Antimicrobial resistant surveillance is the only method to know the exact situation among microbial population human and livestock. Quinolone is one of the common antimicrobial used in the poultry husbandry in Sri Lanka. Therefore, the objectives of this study were to determine quantitative quinolone resistance in E. coli isolated in commercial broilers and to investigate into common quinolone resistant genes in E. coli.
The samples were collected from a collection of E coli which were isolated and identified by a previous study published. A collection of E. coli (n=123) were shown resistant to quinolone by disk diffusion carried out previously. All isolates of the current study were again confirmed as E. coli by Gram test, TSI, Urease test, SIM and indole test as described. The phenotypic antimicrobials resistant of E. coli were determined by agar dilution test as described (EUCAST). Convectional PCR test carried out to identify the selected quinolone resistant genes in E. coli. EUCAST clinical breakpoint was used to interpret ciprofloxacin in E. coli and other guidelines were used for enrofloxacin and nalidixic acids.
Over 96.7% of isolates were shown high MIC as 64 µg/ml and 128 µg/ml against nalidixic acids. More than 86.2% were shown high MIC as 8 µg/ml against enrofloxacin. A 74.8% of E. coli were shown equivalent or more than 1 µg/ml for ciprofloxacin. qnrB was found in majority of isolates as 50.4% of quinolone resistant E .coli were positive for the gene. gyrA was found in 35.8% of E. coli and qnrC and aac(6')-Ib-cr were also found in small percentage in the study. None of isolates were shown positive for qnrA, qnrD, aqxAB and qepA in the study.
Emergence of plasmid mediated quinolone resistance is an alarming finding in the collection of isolate. Since quinolone is a critically importance antimicrobial in human medicine, minimizing emergence and spreading of antimicrobial resistance is vital importance in animal husbandry. Avoiding over usage and misusing quinolone and evidence based usage of antimicrobial is highly recommended to minimize risk of spreading quinolone resistance in poultry.
Keywords: Antimicrobial resistance, quinolone, E. coli, MIC distribution