Detection of class Ⅰ integron from foodborne salmonella and analysis on the drug resistance gene cassettes

Objective: To investigate the drug resistance, the distribution of class Ⅰ integron and drug resistance gene cassette of foodborne salmonella. Methods: K- B assay was applied to measure the drug resistance of foodborne salmonella isolated against fourteen antibiotics.The class Ⅰintegron and drug resistance gene cassette were detected by PCR sequencing of amplification products. Results: The highest drug resistance rate to β-lactams, aminoglycosides, quinonones and sulfa in foodborne salmonella was 18.75%, 12.5%, 6.25% and 25%. 59.4% ( 19 /32) of foodborne salmonella were positive for classⅠintegron.The product by PCR amplifying of classⅠ integron was 1009bp and 1664bp. In the drug resistance cassettes of variable regions of class Ⅰ integrons there were 3 types drug resistance genes, including aadA5, dfr17 and aadA2, which induced the resistance to aminoglycosides antibiotics spectinomycin, streptomycin and sulfonamides drugs trimethoprim. Conclusion: High multidrug resistance and class I integron carrying had been identified among the foodborne salmonella.The result stressed the need for continued surveillance of foodborne antibiotic resistance bacteria in the molecular level.