Abstract: 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.

Key words: retail meat, Salmonella, Proteus mirabilis, integron, drug resistance