Thread: new EHEC strain persisting?

Maybe you have heard of the big EHEC case in Germany. Two EHEC strains have combined and formed a much more dangerous strain. Do you think that this strain will now threaten humanity "forever"? What I want to say is, whether the disease caused by this strain is established in the "disease world", from now on? Or will it disappear after removing the contaminated food? On what does it depend whether a certain disease is persisting in the human population?

Hey, this is my first post... I've recently just finished a BSc in Microbiology and I think there's a few points I could pick up on here.

With any disease outbreak it's important to identify the source, it can then be compared to past diseases with a similar epidemiology. I heard on the news last night that the Escherichia coli strain originated from bean sprouts. I immediately thought this was incorrect. E. coli is an enterobacteria that has optimal-growth close to the physicochemical conditions of the mammalian gut (i.e., 37 degrees C, high water-availability, plentiful resources/nutrition); therefore, the strain most likely came from manure that was used to fertilise the bean sprouts. I also heard that many farm animals are increasingly being treated constitutively with antibiotics, this means that there is a natural selection for antibiotic resistant strains of enterobacteria within the gut of the animal - if manure from these animals is used to fertilise vegetables, then the antibiotic-resistant strains may become associated with the food, hence treating patients that are infected with the new strain with well-used antibiotics is ineffective (I have no reference for this, it is purely speculative).

You said that

Originally Posted by neird

Two EHEC strains have combined and formed a much more dangerous strain.

Such terminology is more widely used in reference to virology, strictly speaking, bacteria cannot "combine", however, what I assume has happened is that an E. coli strain that was able to grow well within humans, but had low pathogenicity (generally not able to cause disease) obtained a novel set of pathogenic genes from a bacterium (not necessarily E. coli), therby transforming it to the new strain that can cause the haemolytic uraemic syndrome described in infected patients. The new genes would be a very small percentage of the total E. coli genome, but could drastically change the phenotype.

The strain will persist as long as it has a host. If it is contained within animals that are regularly used for their manure, then the strain will continue to be spread onto crops. However, I assume that the source is by now identified and the animals may be culled to prevent disease spread (assuming that this is indeed the source). It is very unlikely with the high-hygeine standards of today for such disease to travel from human to human via the faecal-oral route, and only from contaminated foods. I imagine that the strain will become controlled in a short period of time (through the action of the Health Protection Agency, food standards, and other such government bodies in different countries), and hopefully, if one good thing is to come out of it, then the pathogenesis from the strain could be studied to identify novel antibiotics that could be used in a future recurrence of the strain, or a similar strain.

My internet access is restricted to a smartphone at the moment so I can't write too much at the moment. Just wanted to point out that there has been some recent speculation that this strain has made an appearance before not too long ago. Check out Mike the Mad Biologists blog and Aetiology blog for details (can't provide links with this phone).