Detection of Extended Spectrum Beta Lactamase Producing Salmonella spp. and Multidrug Resistance Pattern

Abstract

Background: and Objectives: <em>Salmonella</em> infections are endemic in many developing countries with poor sanitary conditions, but emerge sporadically as a serious public health threat in developed countries. Infections with multidrug resistant (MDR) strains of <em>Salmonella</em> have been associated with treatment failures. <em>Salmonella</em> spp. resistant to extended spectrum cephalosporins are increasing in prevalence worldwide. The aim of this study was to determine the antimicrobial susceptibility, multidrug resistance and extended spectrum beta lactamase (ESBL) production among clinical isolates of <em>Salmonella</em> spp. during 2007 in Tehran, Iran. Patients and Methods: In this cross-sectional study, fifty <em>Salmonella</em> spp. were identified by API 20E system and serotyped by the slide agglutination test. Disk diffusion test was performed. Double disk synergy test was used as a screening test for ESBL production, using disks of cefotaxime and ceftazidime with and without clavulanic acid. Results: From 50 <em>Salmonella</em> spp. 12 (24%) were <em>S. enterica </em>serotype paratyphi B, 24 (48%) <em>S. enterica </em>serotype paratyphi C and 14 (28%) were <em>S. enterica </em>serotype Typhi. The most susceptibility and resistance were observed to ceftazidime (98%) and amoxicillin-clavulanic acid (96%), respectively. 28(56%) were resistant to 5 or more antibiotics. ESBL production was detected by double disk synergy test in one isolate (2%). Conclusion: Results showed increase in antibiotic and multidrug resistance pattern of <em>Salmonella</em> spp. comparing to previous studies in Iran and other countries.It seems that this is the first report of <em>Salmonella</em> spp. ESBL producing in Iran.