Enterohaemorrhagic Escherichia coli (EHEC) Attacks Europe

There are currently over 1,000 Europeans ill with a novel strain of the bacteria E. coli. Although outbreaks of illness due to this bacteria are common, the current outbreak in Europe is unusual in several respects. First, the outbreak has gotten progressively worse over an extended period of time. The first cases were reported May 2, 2011. Second, the number of people affected is large and growing. The exact number is difficult to determine, but is likely in the thousands. Third, this new pathogen is an unusual chimera of different bacteria. It is also surprisingly resistant to a wide variety of antibiotics. Finally, this new bacteria is extremely virulent. At least 18 people have died. Many others are in critical condition.

Although this illness appears to be spreading throughout Northern Europe, the focus appears to be in Northern Germany. Here’s what health care workers in German hospitals are facing (From Monsters and Critics, June 3, 2011):

‘It’s completely new to us, we’ve never experienced anything like it,’ says Michaela Kiemes, ward manager at Kiel University Clinic.

The 44-year-old and her colleagues have been caring for a flood of patients over the past two weeks who have been infected with the enterohaemorrhagic Escherichia coli (EHEC) bacteria, and are experiencing its alarming symptoms first hand.

The cause of the outbreak – which has spread across Europe but is centred in northern Germany – remains unclear, and little research has been done on its treatment.

Doctors and nurses, patients and their relations have all been pushed to their limits.

‘We’re sleeping badly, and have bad dreams,’ Kiemes says quietly. ‘We can’t get the images of suffering patients out of our heads.’

The neurological breakdowns of patients are particularly concerning. ‘When their condition gets worse, then it’s dramatic.’

The clinic is currently treating around 180 patients suffering from EHEC, of whom 95 have life-threatening haemolytic-uraemic syndrome (HUS), a form of kidney failure caused by E coli. Around every other HUS patient suffers serious neurological complications.

The patients become disoriented, have difficulty expressing themselves, suffer convulsions. Some become apathetic, others make strange noises. Some get such strong cramp attacks they have to be restrained.

Since the first EHEC patients arrived in the hospital, the wards treating them have been on a ‘complete emergency footing,’ Kiemes says.

Doctors and co-workers have worked through weekends and days off, delaying their holidays in order to help out.

The bacteria causing these disturbing symptoms was sequenced in record time by the Beijing Genomics Institute in Shenzhen, China. Their early analysis suggests the new bacteria is an extremely odd mixture of multiple bacteria. From Science, June 2, 2011:

Just from the high number of deaths and severe cases, scientists and public health experts battling Germany’s massive E. coli outbreak knew they were up against something unusual. Now, early results from sequencing projects of the enterohemorrhagic Escherichia coli(EHEC) strain appear to confirm that a never-before-seen hybrid, combining the worst of several bacterial strains, is causing the havoc.

The Beijing Genomics Institute (BGI), in Shenzhen, China—which today announced that it has sequenced the microbe’s entire 5.2-million-base-pair genome—says that its acquisition of several virulence genes make this EHEC strain “supertoxic.”

[snip]

BGI, meanwhile, says that the microbe’s genome—which it says took just 3 days to sequence, also using Life Technologies equipment—reveals that it shares 93% of its sequence with EAEC 55989 E. coli, a strain isolated in the Central African Republic and known to cause serious diarrhea. It appears to have acquired several genes that make it more pathogenic, however, probably in a process called horizontal gene transfer, by which microbes exchange bits of genetic information.

In an e-mail to ScienceInsider, Yang Bicheng, director of BGI’s marketing department, wrote that one gene fragment appears to have come from another food-borne pathogen, Salmonella enterica, while other genes are highly homologous to those found in other, phylogenetically distinct E. coli strains, including a strain called O25:H4-ST131.

BGI, which has made the sequence available for researchers to download, says the analysis also confirmed that the microbe is resistant to many antibiotics. These include aminoglycoside, the macrolides, and the beta-lactams—”all of which makes antibiotic treatment extremely difficult,” according to the press release. However, German EHEC patients aren’t treated with antibiotics; most scientists believe they make matters worse, because killing EHEC results in the release of more toxin.

BGI is to be commended for both sequencing this novel organism so rapidly and for releasing the sequences, apparently without any restrictions.

The source of the new bacteria is currently unknown. More discussion of this in the next blog in this series.

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Filed under Outbreak, public health, Science

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