Antimicrobial Susceptibility of Escherichia Coli Isolated from Traditional Ice cream in Gonabad

Ice cream is a good growth-medium for microbes due to its nutrients and nearly neutral pH of 6-7. Ice cream contaminated with E.coli is the source of diarrhea and E.coli is an important pathogen that has shown an increasing antimicrobial resistance to most antibiotics. The aim of this study was to determine antibiotic resistance pattern of E.coli isolated from traditional ice-cream in Gonabad city. A cross-sectional study was carried out on 126 E.coli isolated from 523 samples of traditional ice cream which were collected randomly from the retail stores in Gonabad during March 2007 through November 2008. The antibiograms of E.coli isolates were determined using the Kirby-Bauer disc diffusion on Muller Hinton Agar against 17 selected antibiotics. In this research, 126 (24/9%) samples were positive for E.coli. All E.coli isolates (100%) were found to be resistant to Amoxicillin and Amoxyclav; in addition, 99.2% of the isolates were resistant to Erythromycin. However, 89.68% isolates were susceptible to ceftizoxim followed by 64.85% susceptible to ceftriaxon. The results of this study showed that in order to treat diarrhea due to ice cream contaminated with E.coli the best choices for beginning empiric treatment are ceftizoxim and ceftriaxon.