Class Ⅰ Integron and Antibiotic Resistance of Salmonella and Proteus mirabilis in Retail Meat from Shaanxi Province

SHEN Jin-ling1,YANG Bao-wei1,XI Mei-li1,MENG Jiang-hong1,2(1.College of Food Science and Engineering,Northwest A&F University,Yangling 712100,China;2.Department of Nutrition and Food Science,University of Maryland,College Park MD20742,USA)

retail meat;Salmonella;Proteus mirabilis;integron;drug resistance

Sixty-three Salmonella and twenty-nine Proteus mirabilis isolates were detected in retail meat from Shaanxi Province during the period of 2007—2008.Class Ⅰ integrons were identified by DNA sequence analysis and restriction enzyme digestion.The antibacterial susceptibility of class Ⅰ integron-positive strains were further tested by using fourteen antibiotics and the agar dilution method recommended by the Clinical Laboratory and Standard Institute(CLSI).The results indicated that two kinds of class Ⅰ integrons were identified in 10 Salmonella isolates(16%),with 1281 bp integron containing IntI1-blaPSE-1 and 1842 bp integron containing dhfrXII-orf-aadA2.Of twenty-nine Proteus mirabilis isolates,seven(24%) contained class Ⅰ integrons with 1123,1526 and 1590 bp harboring IntI1-blaPSE-1,aadB-aadA2 and dfr17-aadA5 genes.All class Ⅰ integron-postitive isolates were multi-drug resistant strains.The antibiotic resistant genes in these integrons could mediate resistance to β-lactams,trimethoprim and aminoglycosides.More class Ⅰ integrons existed in Proteus mirabilis than in Salmonella.