This study aimed to assess the prevalence of aminoglycoside resistance genes in S. Typhimurium isolated from poultry carcasses in Iran, and to reveal the most prevalent patterns of antimicrobial resistance. A total number of 300 samples of poultry carcasses were analyzed. Salmonella was isolated from 245 samples (81.66%). Multiplex PCR showed that 56.3% of the samples belonged to serovar S. Typhimurium and the remainder (43.6%) contained the rest of serovars. The highest rate of drug resistance was observed for tetracycline (97.0%), nalidixic acid (87.0%) and amoxicillinclavulanic acid (67.4%). These serovars, however, were sensitive to cefotaxime (84.8%), sulfamethoxazole trimethoprim (77.6%) and gentamicin (71.0%). aadA1 gene was detected in 63 isolates (45.6%), aadA2 in 48 isolates (34.7%), aadB in 43 isolates (31.1%), strA in 52 isolates (37.6%) and strB in 31 isolates (22.4%). High prevalence of aminoglycoside resistance genes in S. Typhimurium was shown. Furthermore, there was a significant association (P < 0.02) between the presence of aadA1, aadA2, strA and strB genes and resistance to streptomycin. Also, there was a significant association (P < 0.001) between the presence of aadB gene and resistance to kanamycin and gentamicin.
