Investigation of Shiga Toxin Producing Escherichia coli from Imported Beef from Malaysia Sukhumungoon P.1), Nakaguchi Y.2), Iwade Y.3), Seto K.4), Nishibuchi M.2), Pradutkanchana J.5), Radu, S.6),Vuddhakul V.1) 1 Department of Microbiology, Faculty of Science, Prince of Songkla University, Thailand, 2 Center for Southeast Asian Studies, Kyoto University, Kyoto, Japan, 3 Mie Prefecture Health and Environmental Research Institute, Mie, Japan, 4 Osaka Prefectural Institute of Public Health, Osaka, Japan, 5 Department of Pathology, Faculty of Medicine, Prince of Songkla University, Thailand, 6 Department of Biotechnology, Faculty of Food Science and Biotechnology, University of Putra Malaysia, Malaysia The southern part of Thailand has a common border with Malaysia and some foods are being exported from Malaysia to Thailand through this border. Beef is popular in this area because of the Muslim population. Therefore, a quick and easy method to screen the imported beef for potential pathogens is needed to assure the safety of the beef in this area. Shiga toxin-producing Escherichia coli (EHEC) is an important foodborne pathogen. Especially, EHEC belonging to serotype O157:H7 and carrying the stx (stx1 and/or stx2) gene and the eae gene can be a causative agent of hemorrhagic colitis and/or hemolytic-uremic syndrome. This organism is often a contaminant of beef. In this study, we examined in southern Thailand, the beef exported from Malaysia to Thailand and those produced in Thailand for EHEC with special emphasis on the stx1, stx2, and eae genes to help establish future microbiological safety measures in this area. Using an immunomagnetic separation technique and CHROMagar O157, 36 and 31 beef samples from Thailand and Malaysia, were investigated respectively. Four (11.1%) and seven (22.6%) samples from Thai and Malaysian beef were positive for both stx2 and eae genes, respectively. All 6 positive isolates from Thai were O157:H7 but 13 isolates from Malaysian were O157:H7 and 1 isolates (stx1+ stx2+ and eae+) belongs to O116:H31. All EHEC O157 isolates obtained in this study produced very low Stx2 (titer <1:2 - 1:2). Antibiogram of all EHEC isolates against 14 antibiotics revealed 2 isolates (33.3%) from Thai samples were resistant to ceftriazone and cephalothin, whereas 8 isolates (57.1%) from Malaysian samples were resistant to ceftriazone, cephalothin and ampicillin. DNA fingerprinting of Malaysian and Thai EHEC isolates was determined by IS-printing using multiplex PCR technique. Different DNA profiles between EHEC isolates from Thai and Malaysian indicated that they were from different origins. It was concluded that some imported Malaysian beef is contaminated with EHEC and most of them are O157 serotype; however, they were the toxin-nonproducing type. Nevertheless, they may cause diarrhea and are of public health importance.
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