title: Vegetables and Restaurant Salads as a Reservoir for Shiga Toxigenic Escherichia coli: Distribution of Virulence Factors, O-Serogroups, and Antibiotic Resistance Properties.
abstract: Close contact of vegetables with soil, polluted water, and animal manure and unsanitary conditions during processing of restaurant salads led us to study the distribution of virulence factors, O-serogroups, and antibiotic resistance properties in Shiga toxigenic Escherichia coli (STEC) isolated from vegetables and salads. Samples of vegetables and salad (n = 420) were collected and evaluated for the presence of E. coli using culture and a PCR assay. Total prevalence of E. coli in studied samples was 49.5%. E. coli was found in 49.6% of vegetable samples and 49% of salad samples. Leek and traditional salad had the highest incidence of E. coli. Significant differences in the incidence of E. coli were found between the hot and cold seasons. Of the 149 E. coli isolates from vegetable samples, 130 (87%) were STEC, and of the 59 E. coli isolates from salad samples, 50 (84%) were STEC. The most commonly detected virulence factors were stx1 and eaeA. A significant difference was found between the frequency of the attaching and effacing and the enterohemorrhagic E. coli subtypes. Serogroups O26 (46% of isolates), O157 (14%), O121 (10%), and O128 (9%) were the most commonly detected serogroups among the STEC strains. The tetA, sul1, aac(3)-IV, dfrA1, blaSHV, and CITM antibiotic resistance genes were found in 96, 47.7, 90, 51, 27, and 93% of isolates, respectively. The highest levels of resistance were found against ampicillin (96.6% of isolates), tetracycline (87%), and gentamicin (90%). This study shows the importance of vegetables and salads as potential sources of E. coli infection.
authors.affiliation: Department of Food Hygiene, Faculty of Veterinary Medicine, Shahrekord Branch, Islamic Azad University, P.O. Box 166, Shahrekord, Iran. amshakerian@yahoo.com amshakerian@iaushk.ac.ir.
authors.forename: Amir
authors.initials: A
authors.lastname: Shakerian
authors.affiliation: Department of Food Hygiene, Faculty of Veterinary Medicine, Shahrekord Branch, Islamic Azad University, P.O. Box 166, Shahrekord, Iran.
authors.forename: Ebrahim
authors.initials: E
authors.lastname: Rahimi
authors.affiliation: Department of Microbiology, Faculty of Basic Sciences, Shahrekord Branch, Islamic Azad University, P.O. Box 166, Shahrekord, Iran.
authors.forename: Pardis
authors.initials: P
authors.lastname: Emad
mesh_terms: D000818:Animals; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000302:isolation & purification; D004927:Escherichia coli Infections; D029968:Escherichia coli Proteins / Q000235:genetics; D005243:Feces; D012147:Restaurants; D065288:Serogroup; D054323:Shiga-Toxigenic Escherichia coli / Q000302:isolation & purification*; D014675:Vegetables; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D029968:Escherichia coli Proteins; D037521:Virulence Factors