Detection of genetic diversity by pulsed-field gel electrophoresis among Escherichia coli O157 isolated from bovine faecal samples by immunomagnetic separation technique

• Published in: Letters in applied microbiology Vol. 44; no. 1; pp. 19 - 23
• Main Authors: Vali, L, Hamouda, A, Pearce, M.C, Knight, H.I, Evans, J, Amyes, S.G.B
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 2007; Blackwell Publishing Ltd
• Subjects: Animals; bovine; Cattle; Cattle Diseases - microbiology; CT‐SMAC media; Electrophoresis, Gel, Pulsed-Field; Escherichia coli Infections - microbiology; Escherichia coli O157; Escherichia coli O157 - classification; Escherichia coli O157 - genetics; Escherichia coli O157 - isolation & purification; faecal samples; Feces - microbiology; Genetic Variation; Immunomagnetic Separation; Phylogeny; pulsed‐field gel electrophoresis
• ISSN: 0266-8254; 1472-765X; 1365-2673
• DOI: 10.1111/j.1472-765X.2006.02034.x

Escherichia coli O157 is considered to be one of most important human pathogens of animal origin which causes serious clinical complications. One of the most common methods to isolate E. coli O157 is the immunomagnetic separation (IMS) technique which employs specific antibodies coupled to magnetic beads to bind and extract cells from enrichment broths followed by plating onto sorbitol MacConkey agar supplemented with cefixime and potassium tellurite (CT-SMAC) plates. The aim of this study was to determine strain variation by pulsed-field gel electrophoresis (PFGE) among E. coli O157 on IMS/CT-SMAC plates. Every suspect colony of E. coli O157 was tested following isolation by the IMS/CT-SMAC technique. From 124 colonies detected; six XbaI-PFGE profiles were identified. Our results demonstrate that mixed populations of E. coli O157 with distinguishable PFGE profiles that are simultaneously present in bovine faeces can be isolated with IMS/CT-SMAC technique. If the aim of the study was to analyse diversity of PFGE profiles of E. coli O157 in a faecal sample following isolation by the IMS/CT-SMAC technique, at least five colonies per sample should be analysed to detect different PFGE subtypes if present.