Epidemiology, Pathogenesis and Genetics of Diarrhoeagenic Escherichia coli Infections
T. Ramamurthy and M. John Albert
from: Foodborne and Waterborne Bacterial Pathogens: Epidemiology, Evolution and Molecular Biology (Edited by: Shah M. Faruque). Caister Academic Press, U.K. (2012)
There are five categories of diarrhoeagenic Escherichia coli (DEC) namely enterotoxigenic, enteropathogenic, enterohaemorrhagic, enteroinvasive and enteroaggregative. They have evolved from nonpathogenic commensal strains by acquisition of specific virulence genes through mobile genetic elements. Their pathogenesis differs and they produce distinct clinical syndromes and pathological lesions and have different epidemiological characteristics. The virulence genes are carried on plasmids, bacteriophages, transposons or pathogenicity islands. DEC produce an array of virulence factors which include colonization factors, enterotoxins, cytotoxins, haemolysins, invasins etc. The diseases they produce range from acute watery diarrhea to dysentery to bloody diarrhoea with haemolytic uraemic syndrome. Even though the major burden of the disease is in the developing world, no part of the world is free from them, and EHEC infections are predominant in developed countries. A variety of molecular tools have been developed to study the diversity and transmission of these pathogens. Even though attempts are being made, no ideal vaccine exists against any category of DEC, therefore maintaining appropriate food and water hygiene are the only ways to keep the infections under control. We must also be on guard against the emergence of new pathogenic strains. The recent emergence of a hybrid enteroaggregative-haemorrhagic E. coli with the rare serotype of O104:H4 in Germany that caused high mortality rates is a case in point read more ...