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Title:	Isolation and characterization of escherichia coli and shiga toxin-producing E. Coli (STEC) from imported beef meats
Authors:	Nawal Noureldaim Abuelhassan (P59310)
Supervisor:	Sahilah Abdul Mutalib, Assoc. Prof. Dr.
Keywords:	Escherichia coli Imported beef meats Shiga toxin-producing E. coli Dissertations, Academic -- Malaysia
Issue Date:	22-Jun-2016
Description:	Escherichia coli normally live in the intestines of animals and humans. Most E. coli are harmless but some E. coli are pathogenic, they can cause diarrhea and are referred to as diarrheagenic E. coli. The pathotype of E. coli associated with diarrhea are commonly recognized as Shiga toxin-producing E. coli (STEC) also referred to as verocytotoxinproducing E. coli (VTEC) or enterohemorrhagic E. coli (EHEC). This study aim to determine the presence and characterization of Shiga toxin-producing E. coli (STEC) from imported frozen beef meats marketed in Klang, Selangor. Seventy four meat (n=74) samples were purchased from hypermarkets from April 2012 to October 2014. Forty two samples were from India (A) and thirty two samples were from Australia (B). A total of 222 E. coli strains were isolated from 74 meat samples; 126 strains were isolated from country A and 96 E. coli strains were from country B, respectively. However, only 70 E. coli strains were identified and characterized. All E. coli strains were isolated into fluorocult medium and identified using biochemical test. All selected E. coli strains were characterized for shiga toxin genes (stx1 and stx2). Of 70 E. coli strains 11 strains were positive for both shiga toxin genes (stx1 and stx2), 11 strains were positive towards stx1 gene while 25 strains were positive to stx2 gene. Subtyping of the above E. coli strains were conducted using phenotypically antibiogram analysis (antibiotic resistance patterns) and genotypic approaches of Random amplified polymorphic DNA-polymerase PCR (RAPD-PCR), Enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) and plasmid profiling. Antibiotic resistance analysis showed that E. coli strains were highly resistant to carbenicillin (93%), cephalocillin (93%), sulphamethoxazole (91%) and kanamycin (81%) followed by resistance to novobiocin (11%) and penicillin (10%). None of the E. coli strains were resistant to streptomycin and bacitracin. Antibiogram patterns exhibited, 12 patterns and phenotypically less heterogenous when compared to PCRbased techniques using ERIC and RAPD-PCR. The result of the ERIC-PCR and RAPDPCR using Gel compare 11 software which was displayed in dendrograms, with primers ERIC1R and ERIC2 discriminated the E. coli isolates into 4 clusters and 2 single isolates at a similarity level of 80 %. RAPD-PCR with primer Gene 8 discriminated the E. coli into 15 clusters and 8 single isolate, RAPD-PCR using primer Gene 9 discriminated the E.coli into 16 clusters and 8 single isolate, while RAPD-PCR using primer Opar 8 discriminated the E. coli into 8 clusters and 3 single isolate, RAPD-PCR using primer OPAR 20 discriminated the E. coli into 7 clusters and 4 single isolate, RAPD-PCR using primer A1 discriminated the E. coli into 3 clusters and 6 single isolate, RAPD-PCR using primer A7 discriminated the E. coli into 12 clusters and 6 single isolate and RAPD using primer A10 discriminated the E. coli into 8 clusters and 4 single isolates at the same a similarity level examined (80%). Plasmid profiling showed 12 patterns. Combination of phenotypically and genotypically methods show a wide heterogeneity among imported beef isolates of E. coli. Results in the presence study demonstrated the presence of shigaproducing E. coli is at the level that should attract attentions by public health authorities of potential risk from imported beef meats.,Certification of Master's/Doctoral Thesis" is not available
Pages:	159
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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