Spotlight on the Escherichia coli bacteria
In May 2011, Germany had to cope with an outbreak of the « E. coli EHEC bacteria». Almost a year later, scientists published an analysis highlighting the real causes of this catastrophe which gave rise to many questions and approximations. In the publication, the researchers also suggest a new nomenclature which should make it possible to better distinguish the different strains of the bacteria which are sometimes confused with each other and which are in fact very different from each other.
Animal versus human strains
More than a year after the outbreak, a team of scientists who specialize in human and veterinary medicine published an article (1) summarizing its emergence and recontextualizing it from the point of view of human medicine in the broader sense and also from an epidemiological, veterinary medicine and bacteriology viewpoint. “The primary aim of the article was to set the record straight. There were a lot of rumors, mistakes and misunderstandings concerning the epidemic. Inundated by this flood of incomplete information, the wider public, just like a large part of the scientific community, did not have the key to an understanding of the causes of the catastrophe”, explains Jacques Mainil, Professor of bacteriology at the University of Liège’s Faculty of Veterinary Medicine.
The first mistake in the case of an epidemic is to systematically point the finger of blame at animals. This knee-jerk reflex is caused by the existence of a common strain of the E. coli bacteria, the EHEC O157:H7 strain. This strain can be found in the intestines of cattle and other ruminants that do not become ill due to the presence of the bacteria: the animals are known as “healthy carriers”. At the slaughter stage, the EHEC O157:H7 strain can unfortunately contaminate meat intended for human consumption. If the meat is not well cooked or properly refrigerated it can proliferate and once ingested by humans, will attack the intestines causing diarrhea which can become bloody before causing kidney lesions in some cases. This strain, which is crudely called “the hamburger bacteria”, often causes infection in men and women: it can involve isolated cases or epidemics according to the source of contamination.
(1) Piérard D., De Greve H., Haesebrouck F., Mainil J.G. O157:H7 and O104:H4 Vero/Shiga toxin-producing Escherichia coli: respective role of cattle and humans. Vet. Res., 2012, 43:13.