Antimicrobial resistance profile and presence of class I integrongs among Salmonella enterica serovars isolated from human clinical specimens in Tehran, Iran

Salmonella is one of the leading causes of food-borne diseases. Increasing occurrence of antimicrobial resistance, especially multidrug-resistance, in Salmonella serovars is a major public health problem worldwide. This study was carried out to detect class I integrons and antibiotic resistance profiles in clinical isolates of Salmonella serovars collected from seven hospitals in Tehran during November 2009 to June 2010. Antibiotic susceptibility profile of 19 antibiotics against 58 Salmonella isolates commonly used in humans was determined using disk diffusion assay. Minimum inhibitory concentration against ceftriaxone and ciprofloxacin was studied. PCR assays were used to detect class I integrons. Among 58 Salmonella isolates, 72.4% were Salmonella enterica serovar Enteritidis, 8.7% were Salmonella enteric serovar Typhimurium and 18.9% were other serovars. Of the total 58 Salmonella serovars, 43 [74.1%] were multidrug resistant and showed resistance to three or more antibiotic families. Class I integrons were identified in 38 [88.3%] MDR Salmonella isolates. Ciprofloxacin minimum inhibitory concentration ranged between 0.125-2 microg/ml for four isolates and other four isolates exhibited resistance to ceftriaxone [MIC 64-256 microg/ml]. The high prevalence of class I integrons was seen in our MDR Salmonella isolates and class I integrons might play an important role in the dissemination of antimicrobial resistance determinants