QUINOLONE SUSCEPTIBILITY AND PHYLOGENETIC ANALYSIS OF ESCHERICHIA COLI STRAINS ISOLATED FROM HUMAN AND CALVES

Background and Aim:It has been suggested that widespread use of antibiotics is a driving force for the emergence of resistant bacterial strains, and epidemiologic evidence supports the view that there is a link between resistant human pathogen and farm animals. Recent findings indicate that phenotypic characterizations including resistant to quinolones are associated with genotypic characterization such as phylogenetic groups and virulence factors.Methods:A total of 80 Escherichia coli isolates from human with urinary tract infection and healthy calves (40 isolates from each samples) were used. Triplex PCR was used to determine the phylogenetic groups of isolates. Antimicrobial susceptibility testing was performed by disc diffusion method.Results:Phylogroup A isolates from calves were significantly more resistant to nalidixic acid than human isolates (P= 0.034). Also, Phylogroup B2 strains from human were significantly more resistant to ciprofloxacin than calves isolates (P= 0.028). There were no ciprofloxacin resistant E. coli from calves belonged to phylogroup B1.Conclusion:The presence of cross resistance among fluoroquinolones used in veterinary and human medicine is a source of debate on the use of these antibiotics for the treatment of infections in animals. Calves can be a source for nalidixic acid resistant phylogroup B2 isolates. It may represent an emerging problem in public health, perhaps due to transfer of such strains from calves to humans.

کلیدواژه ها:

Quinolone susceptibility ، phylogenetic analysis ، Escherichia coli strains