Prevalence of virulence genes in Escherichia coli isolated from food in Casablanca (Morocco) Samira Badri a, * , Ingrid Filliol b , Isabelle Carle b , Mohammed Hassar a , Aziz Fassouane c , Nozha Cohen a a Laboratoire de Microbiologie et d’Hygiène des Aliments et de l’Environnement, Institut Pasteur du Maroc, Casablanca, Morocco b Centre national de référence des Escherichia coli et Shigella, Unité de Biodiversité des Bactéries pathogènes émergentes, Institut Pasteur de Paris, France c Laboratoire de biochimie, Département de Biologie, Faculté des Sciences d’Eljadida, Université Chouaib Doukkali, Morocco article info Article history: Received 20 December 2007 Received in revised form 14 August 2008 Accepted 19 August 2008 Keywords: E. coli Prevalence Virulence gene Food abstract This study was undertaken to determine the frequency of potentially pathogenic Escherichia coli (E. coli) strains among E. coli isolated from Casablanca, Morocco. The E. coli strains were isolated from ground beef (n = 140), turkey (n = 200), sausage (n = 120), seafood (n = 60), domestic water (n = 35) and well water (n = 50). The prevalence of E. coli was 48%, 45%, 35.5%, 30%, 8.3%, 0%, for well water, ground beef, turkey, sausage, sea food and domestic water, respectively. Two hundreds E. coli isolates were tested for the pres- ence of 17 virulence genes associated with strains causing intestinal and extra-intestinal infections. The virulence genes included stx1, stx2, lt, st, hlyA, aggA, saa, astA, iucD, cnf1, eaeA, bfpA, ial, ipaH, afa, pap and sfa. PCR showed that 37% (74) of E. coli isolates carried one or more of these virulence genes. No virulence genes were found in E. coli strains isolated from sea food samples. In contrast, 10% of the ground beef samples, 18% of the turkey samples, 17.5% of sausage samples and 6% of well water contained specific factors for intestinal E. coli pathogens. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Morocco is one of the countries where food borne diseases rep- resent one of the main causes of morbidity. During 2000–2004, 7118 cases of food born diseases have been reported among which 86% were of bacteriological origin (Cohen & Karib, 2006). According to the same report, less than 1% of these food born diseases were due to E. coli. E. coli strains are normal inhabitants of the gut of warm- blooded animals including human beings enable them to cause intestinal infections such as diarrhea or hemorrhagic colitis, or to cause extra-intestinal infections such as neonatal meningitis, nos- ocomial septicaemia, haemolytic uremic syndrome, urinary tract and surgical site infections (Falagas & Gorbach, 1995). On the basis on their distinct virulence properties and the clinical symptoms of the host, pathogenic E. coli strains have been broadly classified into two major categories: the enteric pathogens and the extra-intesti- nal pathogens. Enteric pathogenic E. coli (Levine, 1987; Nataro & Kaper, 1998) have been broadly divided into enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), Shiga toxin-produc- ing E. coli (STEC), enteroinvasive E. coli (EIEC), enteroaggregative E. coli (EAEC) and diffusely adherent E. coli (DAEC). ETEC (Nataro & Kaper, 1998) are a major cause of diarrhea in young children from developing countries and in adults from indus- trialized countries traveling to these regions (traveler’s diarrhea). Fecal contamination of food and drinking water is the major route of infection of these pathogens for humans (Kuhnert, Boerlin, & Frey, 2000). EPEC represent another major cause of diarrhea in third world countries, they are usually transmitted by contaminated food and colonize the small intestine where they attach tightly to the epithelial cells of the villus tips and cause typical lesions called attaching and effacing lesions (Kaper, 1994). STEC (previously called Shiga-like toxin-producing E. coli or verotoxin-producing E. coli) cause a broad range of symptoms in humans (Griffin, 1999) including uncomplicated diarrhea, but also more severe dis- eases like hemorrhagic colitis and the often deadly hemorrhagic uremic syndrome. Cattle form the main reservoir of STEC and fecal contamination of food represents the usual source of infection for humans but due to an apparently low infectious dose, human to hu- man transmission has also been observed in outbreaks (Kuhnert et al., 2000). EIEC closely resemble Shigella and cause mainly watery diarrhea and dysentery in severe cases. Transmission seems to be mainly through contaminated food and water. EAEC present a typ- ical adherence pattern on cell cultures, with bacteria aligning in parallel clusters like bricks in a wall (Nataro, Steiner, & Guerrant, 1998). Typical is the persistence of diarrhea for often more than 14 days. The epidemiology and the exact pathogenic potential of DAEC are less well understood than those of EAEC. Extra-intestinal pathogenic E. coli have been categorized mainly into uropathogenic E. coli (UPEC) and neonatal meningitis E. coli (NMEC). UPEC represent by far the most frequent cause of urinary 0956-7135/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodcont.2008.08.015 * Corresponding author. Tel.: +212 68 30 67 18; fax: +212 22 98 50 63. E-mail address: samira_bdm@yahoo.fr (S. Badri). Food Control 20 (2009) 560–564 Contents lists available at ScienceDirect Food Control journal homepage: www.elsevier.com/locate/foodcont