Abstract:

Objective: To characterize multi-drug resistant Salmonella isolates carrying integeon-1 and sulfonamides-resistant
genes from broiler slaughterhouse. Methods: The susceptibility of 84 Salmonella isolates from broiler slaughterhouse to
10 varieties of antibiotics was evaluated by K-B disc method. In addition, PCR was used to detect the presence of the int1,
sul1, sul2 and sul3 genes of multi-drug resistance in Salmonella isolates. Results: The resistant rates of these 84 Salmonella
isolates were 100% to ampicilin and nalidixic acid, and 39.29%, 35.71%, 35.71%, 35.71%, 22.62% and 14.29% to
ciprofloxacin, tetracycline, benzyl methyl oxygen/sulfamethoxazole, spectinomycin, fluorine benzene nicol and gentamicin,
respectively. It was found that 38 of these isolates exhibited resistance to at least three antibiotics as multi-drug resistant
strains. Among the 38 multi-drug resistant Salmonella strains, 20 carried integron-1. Sulfonamide resistant genes such as
sul1 or sul2 or sul3 genes were detected in 30 sulfonamides resistant Salmonella isolates, suggesting 100% consistency
between the results of drug sensitivity tests and PCR. The detection rates of the sulfonamides resistant genes sul1, sul2 and sul3
genes by PCR were 40%, 100% and 63.3%, respectively. Conclusion: These results implied that the antimicrobial resistance of
Salmonella isolates from broiler slaughterhouse is not optimistic. A close correlation exists between the multi-drug resistance and
the carrier condition of the integron-1, which may play a critical role in the sulphonamide resistance in Salmonella isolates.

Key words: Salmonella, integron-1, multi-drug resistance, sulfonamide-resistant genes