Determination of antibiotic resistance patterns in Escherichia coli isolated from healthy and colisepticemic broiler chickens in Ahvaz

The knowledge about antibiotic resistance of common bacterial pathogens in any region is essential. Colibacillosis is one of the most common bacterial diseases in poultry caused by Escherichia coli and is responsible for significant economic losses. The aim of this study was to investigate the antibiotic resistance profile in Escherichia coli isolates recovered from broiler chickens in Ahvaz. For this reason, a total of 120 isolates from 12 broiler farms, 60 isolates from livers of chickens with colibacillosis, and the rest from cloaca of healthy birds were collected. Antibiotic resistance pattern to Doxycycline, Enrofloxacin, Florfenicol, Lincospectin and Trimethoprim-Sulphadiazine, the five common antibiotics in poultry industry of Iran, was investigated. According to disk diffusion test, the maximum resistance was to Enrofloxacin (90.8%), Florfenicol (83.3%), Doxycycline (82.5%), Sultrim (74.2%), and Lincospectin (66.7%), respectively. In the minimum inhibitory concentration (MIC) method, the order was: Enrofloxacin (91.7%), Florfenicol (90%), Doxycycline (87.5%), Sultrim (71.7%), and Lincospectin (69.2%). The results showed that fecal isolates were more resistant than septicemic isolates (p< 0.05). No significant deference was demonstrated between the two methods (disc diffusion and MIC) (p> 0.05). Also, the results showed that 88.3% and 90% of isolates were resistant to more than three antibiotics in disc diffusion test and MIC methods, respectively. It is concluded that for treatment of poultry colibacillosis, antibiotic sensitivity test should be performed routinely.