Abstract

The development of antimicrobial resistance has been a public health issue worldwide. The aim of this study was to determine the antibiotic resistance pattern of Salmonellaspecies isolated from broiler chickens in Iran. 37 isolates of Salmonella recovered from broiler chicken carcasses were analyzed for resistance to 14 antimicrobial agents.Salmonella isolates were serogrouped by standard agglutination test using O and H antisera before antibiotic susceptibility testing. Serogroup screening showed 4 different serogroups (D1, B, C1 and C2) among 37 Salmonella isolates. Salmonella serogroup D1 with frequency 48.64% was the most prevalent serogroup. Antimicrobial susceptibility testing was performed by the standard disc diffusion method according National Committee for Clinical Laboratory Standards. The results showed that Amikacin, Cephalotin, Tylosin, and Chloramphenicol, were the most effective antibiotics (100% sensitivity). Antibiotics for which Salmonella isolates exhibited resistance were: Neomycin (10.81%), Amoxicillin (18.91%), Streptomycin (29.72%), Chlortetracycline (32.43%), Trimethoprim (13.51%), Nalidixic acid (18.91%), Tetracycline (29.72%), Kanamycin (16.21%), Ampicillin (13.51%). Also 51% of resistant isolates belonged to serogroup D1 and serogroups B, C1, and C2 included 37, 9 and 3% of resistant isolates respectively. Overall 28% of Salmonella isolates were resistant to more than 4 antibiotics (MDR). Findings of present study indicated that the development of antimicrobial resistance inSalmonella is an increasing problem in Iran and resistant strains are widespread.

Key words: Resistance, antimicrobial, Salmonella, chicken.