Determining the antibiotic resistance patterns of isolated Salmonella from broiler flocks to 28 antimicrobial agents used in Iran

The purpose of this study was to determine the serogroups of isolated Salmonella spp from broiler flocks and their drug resistance patterns to 28 antimicrobial agents commonly used in medicine and veterinary of Iran. One-hundred and eighty-nine samples were collected from liver, heart and intestine of slaughtered broiler flocks in Ardabil province for identification of salmonella. The antibiotic resistance rate of isolates was determined using Kirby-Bauer method. Out of 189 samples examined, Salmonella was isolated from 22 samples (11.6%). Out of 22 salmonella isolates, fourteen (63.7%), seven (31.8%) and one (4.5%) isolates belonged to serogroups D, C and B, respectively. Multiple resistance was observed among isolates. The highest resistance was to tetracycline (100%), chlortetracycline (91%), streptomycin (91%), doxycycline (86.5%), nalidixic acid (81.8%), neomycin (77.3%), kanamycin (68.3%), furazolidone (63.7%), lincospectin (59.1%), flumequine (54.6%), penicillin (45.5%) and sulfamethoxazole trimethoprim (40.9%). Ten resistance patterns to ten antimicrobial agents commonly used in Iranian poultry industry were found in 22 Salmonella isolates 81.82% of isolates were resistant to more than two antibacterials. The results of this study showed that the frequency of resistance to the antimicrobial agents among avian salmonella isolates is a major public health concern.