Short communication Isolation and characterization of verocytotoxin-producing Escherichia coli O157 from Turkish cattle O ¨ zkan Aslantas ¸ a , Suat Erdog ˘an b , Zafer Cantekin a ,I ˙ rem Gu ¨lac ¸tN c , Gu ¨lsu ¨ m A. Evrendilek d, * a Faculty of Veterinary Medicine, Department of Microbiology, Mustafa Kemal University, 31034 Hatay, Turkey b Faculty of Veterinary Medicine, Department of Biochemistry, Mustafa Kemal University, 31034 Hatay, Turkey c Faculty of Veterinary Medicine, Department of Virology, Fy ´rat University, ElazNg ˘, Turkey d Faculty of Agriculture, Department of Food Engineering, Mustafa Kemal University, 31034 Hatay, Turkey Received 22 March 2005; received in revised form 13 July 2005; accepted 7 August 2005 Abstract The objective of this study was to collect rectal swabs from the cattle in a slaughterhouse located in Hatay (Turkey) immediately after slaughter for the isolation and characterization of verotoxin-producing Escherichia coli O157 in each month during a 1-year period. The rectal swab samples were analyzed for the isolation of E. coli O157 through preenrichment, immunomagnetic separation and selective plating on CT-SMAC agar. E. coli O157 was isolated from 77 (13.6%) of the samples. The presence of E. coli O157 changed during a 1-year period, in that the occurrence of E. coli O157 was the highest in July and November and lowest in February. A total of 66 isolates out of 77 were seroytpe O157:H7 and 11 were serotype O157:NM. PCR analysis of E. coli O157 virulence genes revealed that all O157:H7/NM were positive for rbf O157 , 74 positive for EhlyA, 72 positive for eaeA, 62 positive for vtx2 , and 3 positive for both vtx1 and vtx2 . It was presented by cytotoxicity tests that many of E. coli O157 isolates showed high cytotoxicity on Vero cells. All of the isolates containing EhlyA showed enterohaemolysin production. D 2005 Elsevier B.V. All rights reserved. Keywords: Escherichia coli O157; Turkey; Cattle; IMS; PCR 1. Introduction Verocytotoxin-producing Escherichia coli (VTEC) strains is the most important recently emerged food-borne pathogens (Armstrong et al., 1996). VTEC may belong to many serotypes, but most severe human infections are caused by strains of E. coli O157:H7 (Mead and Griffin, 1998). Ruminants, especially cattle, are known to be the most important resevoir of VTEC, including VTEC O157. Contam- inated milk and beef were the first recognized sources of human VTEC O157 infections (Armstrong et al., 1996); however, other routes of transmission are important for human sporadic infections as well as outbreaks, e.g., direct contact with animals, contaminated drinking or swimming water, and person-to-person infections (Karch et al., 1999). Several virulence factors have importance for the pathogen- esis of the VTEC infections (Paton and Paton, 1998). VTEC produce either or both of two phage-encoded toxins, VT1 and VT2. VTs are thought to cause the vascular endothelial damage observed in HC and HUS patients (Mead and Griffin, 1998). Several studies were conducted to determine occurrence of E. coli O157:H7 in cattle. Non-O157 VTEC strains were detected in dairy and meat processing environment in Northern Ireland by McKee et al. (2003). E. coli O157 was isolated in the ratio of 21% in a cattle slaughterhouse located in Belgium (Tutenel et al., 2003). Similar studies were conducted to determine occurrence of E. coli O157 in different countries. However, except for the results reported by YNlmaz et al. (2002) and C ¸ abalar et al. (2001), not enough data are available for the presence of E. coli O157 in slaughterhouses located in Turkey. Therefore, the aim of the study was to investigate the frequency of E. coli O157 in cattle slaughtered in Hatay, Turkey, characterize the isolates with respect to the presence and variation in virulence genes, determine seasonal variation, and detect the cytotoxicity and enterohemolysin production. 0168-1605/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.ijfoodmicro.2005.08.005 * Corresponding author. Tel.: +90 326 245 57 35; fax: +90 326 245 58 32. E-mail addresses: gevrendilek@mku.edu.tr, gevrendilek@yahoo.com (G.A. Evrendilek). International Journal of Food Microbiology 106 (2006) 338 – 342 www.elsevier.com/locate/ijfoodmicro