Prevalence of antimicrobial resistance, the intI1 andSul1 genes in Salmonella Enteritidis strains isolatedfrom livestock and poultry

Bacterial antibiotic resistance has become a worldwide public health problem with direct impact on food safety.Salmonella is an important cause of food-borne gastroenteritis in humans, and diarrhea and sometimes septicemiain animals. Integrons are genetic elements that recognize and capture mobile gene cassettes, which usuallyencode antimicrobial drug resistance determinants. Integrons are usually found in association with transposonsand plasmids. The study included 31 Salmonella Enteritidis isolates collected in Iran, in 2012. The isolates wererecovered from animal sources. All samples were assessed by culture method and standard biochemical tests fordiagnosis of Salmonella strains. After DNA extraction the presence of intI1 and Sul1 genes were examined byPCR. The most common resistance phenotypes were to cefalothin (100%), ampicillin (54/8%), chloramphenicol(51/6%), tetracycline (45/1%), sulfamethoxazole (41/9%), amoxicillin / clavulanate (38/7%). The intI1 gene wasfound in (47%) and (42/8%) and the sul1 gene in (35/2%) and (35/7%) of Salmonella isolates from livestock andpoultry respectively. Integron positive isolates had higher resistance to tetracycline, chloramphenicol, ampicillinsulfamethoxazole and amoxicillin / clavulanate compared with integron negative isolates. The ability of Integronsto integrate resistance gene to antimicrobial agents improves the diffusion of antibiotic resistance.