ISSN: 2223-2133 (Online), 1815-8986 (Print)
Vol. 8 Number 1, July 2008
Antimicrobial drug resistance and genetic diversity if commensal Escherichia coli from caeca of chickens in Grenada
Harry Hariharan, Simone Oliveira, Shiplap Sharma, Vanessa Matthew, Alfred Chikweto
The main goal of this study was to generate baseline data on resistance to 11 antimicrobial drugs of global importance among commensal Escherichia coli from healthy chickens in Grenada. For this purpose, a total of 183 commensal Escherichia coli isolates from 197 chickens (147 broilers and 50 layers) originating from 11 poultry farms in Grenada were studied using a standard disk duffusion method. The isolates were further studied for their haemolytic properties using sheep blood agar, and genotypes using the enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR). Sixty-six isolates were positive for alpha haemolysis, and the remaining were non-haemolytic. There was no difference in the antimicrobial susceptiblilty between haemolytic and non-haemolytic isolates. Resistance was highest against tetracycline (58.5%) followed by streptomycin (44.3%) and lowest to chloramphenicol(0.55%). Only three isolates (1.6%) showed resistance to fluoroquinolones. Resistance was highest against tetracycline, streptomycin, and gentamicin were significantly lower among isolates from layers, compared with those from broilers. Multiple resistance to three or more classes of drugs was found in 10.4% of total isolates; the most common R-profile was Amp,Str,Tet. Twenty genotypes were identified among 24 randomly isolates that originated from 11 unrelated farms and 5 geographical locations. Isolates sharing similar genomic diversity figerprints by ERIC-PCR had different resistance profiles, whereas isloates that originated from 11 unrelated farms and 5 geographical locations. Isolates sharing similar genomic fingerprints by ERIC-PCR had different resistance profiles, whereas isolated with different genotypes shared similar profiles. In conclusion, this study showed the genetic diversity of chicken isolates from Grenada, and that E. coli isolates from layers had lower resistance rates to certain drugs when compared with isolates from broilsers. The haemolytic patterns of E.coli isolates of chicken-origin, and their significance, and the epidemiologial significance of ERIC-PCR genotypes among among poultry isolates need further study.