Abstract

Avian pathogenic Escherichia coli strains (APEC) are responsible for major economic losses in poultry farms. The use of antibiotics has led to the emergence of resistant bacteria having direct impact on the food industry. In order to evaluate the resistance of 191 Tunisian APEC strains, we determined the antimicrobial resistance profile of these bacteria to 18 antibiotics by disk diffusion method. This study revealed high resistance towards most of the tested antibiotics. Indeed for 13 antibiotics over 50% of strains were resistant. The results also showed significant increase in time of resistance percentage and multidrug resistance; which may be related to the selection pressure due to the overuse of antimicrobial agents for treatment and as growth factors in poultry. Statistical tests revealed several statistical descriptive values, reflecting scattered distribution of resistance with normality dispersion. Phylogenetic analyses showered clustered strains. Data converge towards a heterogeneous distribution of resistance with increasing rates, suggesting considerable overlap between APEC strains.

Key words: APEC strains, colibacillosis, antimicrobial agents, resistance profile, Tunisia.