Wednesday, September 11, 2013


Man's fight again pathogenic bugs seems to be never ending as the latter invariably outsmarthumans in outliving the traps laid for them! The increasing class of microbes that cock a snook at all antibiotics known to day provides a scary scenario than can spoil the peace of mankind in the coming years unless a more effective strategy is drawn up now to deal with this emerging danger. Who would have imagined 2-3 decades ago that an innocuous bacteria like Escherichia coli, so common in the human guts, would become deadly, capable killing people one day. This happened when the dangerous version of this microbe E.coli O157:H7 was implicated in many food poisoning cases a few years ago. Now comes the news about the emergence of another deadly strain of this species christened E.coli O104:H4 which created havoc in Europe in the year 2011 and about which more information is available now after its isolation, from fenugreek sprouts reported to have been imported from Egypt and its genetic mapping. Here is a take on this monster bacteria which is being suggested as the most dangerous future pathogen with potential for causing devastating consequences.     

As it turned out, E. coli O104:H4 evolved from a type of E. coli known to be harmless enteroaggregative E. coli and had acquired the genes to produce Shiga toxin from more virulent strains known as enterohemorrhagic E. coli. When the outbreak struck in May 2011, medical professionals only knew to screen for enterohemorrhagic strains of E. coli, adding another layer of confusion to the initial response. Like other enteroaggregative E. coli strains, O104:H4 groups together in defensive brick patterns within a host's intestines, inducing mucus production that both shields and feeds it. Combine that with the ability to produce Shiga toxin, and O104: H4 possesses the right cocktail of genes to become especially harmful in an outbreak.
That combination of traits could also explain why the German outbreak saw such a high proportion of HUS cases. Nearly 1,000 of the 4,000 ill – or one in four – developed HUS as part of their infection. Outbreaks of other E. coli strains typically result in about one in 10 patients developing HUS, predominantly children. What's more, the O104:H4 outbreak caused HUS in adults at the same rate it did in children. Rasko and other researchers suspect that the HUS cases were exacerbated by the early prescription of antibiotics to patients when doctors did not realize they were dealing with an E. coli outbreak. The use of antibiotics against Shiga toxin-producing E. coli has a well-established link with higher rates of HUS due to bacteria releasing additional toxin when killed. In July 2012, research from the University of New Mexico Children's Hospital found that treating children's E. coli infections with antibiotics tripled their risk of developing HUS.

Interestingly this microbe, in stead of responding to antibiotics, becomes more deadly after antibiotic treatment because the dying cells produce more shiga toxin in the GI tract leading to the so called Hemolytic Uremic Syndrome or HUS as it is better known damaging the kidney. The mechanism by which it resists efforts to destroy them has been recently uncovered and there is hope than pathologists will come out with ways and means of fighting this menace soon. The danger is all the more conspicuous for consumers who eat cold foods without heating such as salads. It is not known whether O104:H4 is capable of surviving irradiation treatment and if so what could be the optimum dosage needed. If pathogens like this keep emerging, mankind has to be ready with fast response before they can cause significant damage and mortality.


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