Phylotypes, antimicrobial susceptibility phenotypes and virulence determinants of Escherichia coli isolates from broiler chickens infected with colibacillosis

Document Type : Original Articles


1 El- gomohoria street

2 Department of Bacteriology, Mycology, and Immunology, Faculty of Veterinary Medicine, Mansoura University, Mansoura 35516, Egypt


Objectives: The aim of this study was to isolate APEC from diseased broiler chickens, assess their virulence-associated genes (VAGs) and to determine their antimicrobial susceptibility profiles.

Design: Descriptive study

Samples: Forty-four APEC isolates were isolated from 115 colibacillosis suspected broiler chickens collected from Dakahalyia poultry farms.

Procedures: Polymerase chain reaction (PCR) was carried out to investigate the presence of eleven virulence- associated genes (VAGs). E.coli isolates were tested against ten antimicrobial agents including, ampicillin, amoxicillin, doxycycline, colistin, imipenem, clindamycin, ciprofloxacin, cefuroxime, amikacin and chloramphenicol by Kirby-Bauer disc diffusion method.

Results: Concerning VAGs, the detection rate of ompT, hly, iuc,irp, astA, iorN, iutA, cva/cvi, tsh, iss, papC was 88.60,% 97.70%, 86.40%, 81.80%, 95.50%, 93.20%, 84.10%, 15.90%, 27.30%, 88.60% and 34.10% respectively. Among APEC isolates, 42 isolates (95.45%) carried five or more virulence genes and 41 isolates harbored 3 or more APEC virulence genes (hlyA, iut, ompT, iss, iorN). The in-vitro antimicrobial susceptibility testing revealed that all retrieved APEC isolates showed multidrug resistance (MDR) phenotypes. The highest levels of multidrug-resistant APEC were found to ampicillin, amoxicillin, cefuroxime, clindamycin and doxycycline. While, E. coli isolates were highly susceptibility to colistin, imipenem, ciprofloxacin and amikacin.

Conclusion and clinical relevance: the present study highlighted the need for the frequent monitoring of poultry farms for the presence of VAGs and the antimicrobial susceptibility of APEC to control the spreading of colibacillosis and the potential public health hazard resulted from the spreading of MDR strains.


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