Sidd
Staff
Junior
45 posts
"Sustainable dairy business."
Posted on 22. Dec 2023
Escherichia coli belongs to the Enterobacteriaceae family. They are gram negative rods up to 3um in length, ferment glucose and wide range of sugars. Produce pink colonies on McConkey agar. Hemolytic activity on blood agar is a character of certain strains of E. coli.It is motile with peritrichous flagella and often fimbriate (Jay, 2000). E. coli 0157:H7 is an important serotype and seems to be predominate in most areas. The strains producing verotoxin are shiga-like toxin (SLT) which produces diarrhoea in humans and animals.Source of infection
Contamination of food by human and animal faeces. The organism can persist in manure, water trough and other farm location. The association of E. coli 0157:H7 with raw meat, under cooked ground beef and raw milk lead to investigation of the role of cattle as a reservoir of the pathogens (Buchanan & Doyle, 1997).Pathogenesis
Enterohemorrhagic E. coli (EHEC) strain may produce one or more types of cytotoxins which are collectively referred as shiga-like toxins (SLTs) since they are antigenically and functionally similar to shiga toxin produced by Shigella dysenterica.However, new terminology has been applied, and what was SLT is now Stx. All Stxs consists of a single enzymatically active A subunits and multiple B subunits. Stx-sensitive cells possess the toxin receptor, globotriaosyceramide (Gb3), and sodium butyrate appears to play a role in sensitizing cells to Stxs.Once toxins bind toGb3, internalization follows with transport to the trans-Golgi network. Inside the host cells, the A subunits binds to and releases and adenine residue that inhibits protein synthesis. The B subunits form pentamers in association with a single A subunit and thus are responsible for the binding of the toxin to the neutral glycolipid receptors (Ibid).Symptoms
The incubation period is 72-120 hours. The clinical signs initially may be diarrhoea in a few days. However, there is no fever. The symptoms of E. coli septicaemia are mainly referable to bacteraemia, end toxaemia and the effect of bacteria localization in a variety of tissue spaces throughout the body (Quinlan, 2013).Detection of toxin
Laboratory diagnoses involve culturing the food on McConkey agar or sorbitol. Strains can be identified by serotyping using specific antisera. Stxs can be detected by ELISA and gene coding can be detected by DNA hybridization techniques. Sorbitol McConkey agar is recommended for isolation of E. coli 0157:H7 from food and faeces samples.Control and Prevention
The prevention of food borne illnesses caused by E. coli can be prevented by the same method as prevention of other food borne illness caused by bacteria. Food should be properly cooked since the organism is heat sensitive.Occurrence is worldwide with most incidences in developing countries. Case fatality ratio for EPEC, ETEC, EIEC infections in industrialized countries <0.1%, for EHEC infection about 2%.Case fatality ratio of E. coli infections in infants and children much higher in developing countries. Children and the elderly are particularly vulnerable and may suffer more severely. Most cases of EHEC infections are reported in summer.References
- Buchanan, R., & Doyle, M. (1997). Food Borne Disease: Significance oof E. coli O157:H7 and other Enterohaemorrhagic E. coli. Food Technology, 5, 69-76.
- Jay, J. (2000). Modern Food Microbiology (6th ed.). Gaithersburg, Maryland: Aspen Publications.
- Quinlan, J. J. (2013). Foodborne Illness Incidence Rates and Food Safety Risks for Populations of Low Socioeconomic Status and Minority Race/Ethnicity: A Review of the Literature. International Journal of Environmental Research and Public Health, 10, 3634-52.
For people, planet and profits.
