title: Molecular characterization and phylogeny of Shiga toxin-producing E. coli (STEC) from imported beef meat in Malaysia.
abstract: This study aimed at determining the presence and characterization of Escherichia coli and Shiga toxin-producing E. coli (STEC) from imported frozen beef meats. Seventy-four (74) frozen imported beef meat samples from two countries, India (42 samples) and Australia (32 samples), were collected and tested for E. coli. These samples were purchased from the frozen meat sections of five different supermarkets in different locations in Selangor, Malaysia, from April 2012 to October 2014. A total of 222 E. coli strains were isolated from the meat samples; 126 strains were isolated from country A (India), and 96 E. coli strains were from country of origin B (Australia), respectively. A total of 70 E. coli strains were identified and characterized. All E. coli strains were isolated into Fluorocult medium and identified using API 20E kit. All selected E. coli strains were characterized for Shiga toxin genes (stx1 and stx2). All biochemically identified E. coli in this study were further subjected to molecular detection through polymerase chain reaction (PCR) amplification and characterization using 16S ribosomal RNA (rRNA) gene of Shiga toxin-producing E. coli. Of the 70 E. coli strains, 11 strains were positive for both Shiga toxin genes (stx1 and stx2) and 11 (11/70) strains were positive for stx1 gene, while 25 (25/70) strains were positive for stx2 gene. The analysis of 16S rRNA gene of all the E. coli isolates in this study was successfully sequenced and analyzed, and based on sequence data obtained, a phylogenetic tree of the 16S rRNA gene was performed using Clustal W programme in MEGA 6.06 software. Phylogenetic tree showed that the E. coli isolates in our study cluster with the strain of E. coli isolated in other countries, which further confirm that the isolates of E. coli in this study are similar to those obtained in other studies. As a result, all the strains obtained in this study proved to be a strain of pathogenic E. coli, which may cause a serious outbreak of food-borne disease. The isolation of pathogenic E. coli strains from the imported meat samples calls for prudent management of imported meats by the relevant authorities.
authors.affiliation: School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Darul Ehsan, Malaysia. nawalnoureldaim@yahoo.com.
authors.forename: Nawal Nouridaim
authors.initials: NN
authors.lastname: Abuelhassan
authors.affiliation: School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Darul Ehsan, Malaysia.
authors.forename: Sahilah Abdul
authors.initials: SA
authors.lastname: Mutalib
authors.affiliation: Department of Pathology and Microbiology, University Putra Malaysia, Darul Ehsan, 43400, Serdang, Selangor, Malaysia.
authors.forename: Fufa Ido
authors.initials: FI
authors.lastname: Gimba
authors.affiliation: School of Bioscience and Biotechnology, School of Chemical Sciences and Food Technology, Faculty of Food Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Darul Ehsan, Malaysia.
authors.forename: Wan Mohtar
authors.initials: WM
authors.lastname: Yusoff
mesh_terms: D000818:Animals; D001315:Australia; D002417:Cattle; D029968:Escherichia coli Proteins / Q000235:genetics*; D007194:India; D008296:Malaysia; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D000069466:Red Meat / Q000382:microbiology*; D022603:Shiga Toxins; D054323:Shiga-Toxigenic Escherichia coli / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D029968:Escherichia coli Proteins; D012336:RNA, Ribosomal, 16S; D022603:Shiga Toxins
keywords: Escherichia coli; Shiga toxin-producing E. coli (STEC) beef meat