German E.coli outbreak caused by new toxic strain: scientists
The E. coli epidemic in Europe is caused by a new, highly infectious and toxic strain of bacteria that carries genes giving it resistance to a few classes of antibiotics, researchers and public health experts believe.
Scientists at the Beijing Genomics Institute, who are collaborating with Germany’s University Medical Center Hamburg-Eppendorf, completed sequencing the genome of the bacterium in three days after receiving its DNA samples.
“This E. coli is a new strain of bacteria that is highly infectious and toxic,” they said in a press release issued by the Beijing Genomics Institute in Shenzhen city in southern China, adding that the bacterium was closely related to another E. coli strain, called EAEC 55989, which was previously isolated in central Africa and known to cause serious diarrhea.
Authorities are still hunting for the source of the new bacteria, which is believed to have contaminated raw vegetables. The E.coli outbreak has so far killed at least 18 people and (17 in Germany and one in Sweden) made more than 1 500 others ill in eight European countries.
University Medical Center Hamburg-Eppendorf, one of the largest hospitals in Hamburg, treated many of the infected patients from north Germany and found they did not respond to some of the antibiotics used, the Chinese scientists said.
“The analysis further showed that this deadly bacterium carries several antibiotic resistant genes, including resistance to aminoglycoside, macrolides and Beta-lactam antibiotics: all of which makes antibiotic treatment extremely difficult,” the scientists said.
This new strain of also bore the hallmarks of other E. coli strains that are known to cause symptoms such as bloody diarrhea, or hemorrhagic colitis, and hemolytic-uremic syndrome, which affects the kidneys.
The World Health Organisation said the variant had “never been seen in an outbreak situation before.”
The UK’s Health Protection Agency said it was likely to be a new variant of the rare strain O104 – possibly with a newly acquired ability to infect large numbers of people. In a statement it said: “While there is a lot more that we need to learn about this bacterium, the evidence that is already available tells us that the German authorities have been dealing with something new.”
Professor Gad Frankel, from Imperial College London, the Sanger Institute and the Medical Research Council, said: “This is a new combination and a deadly combination. It has a gene which produces a toxin and another which helps the bacterium colonise the gut more efficiently, which effectively means even more toxin is produced. “Research we published last year showed this same factor mediates attachment to the human gut and the surface of salad leaves.”
Health experts are recommending strict hygiene measures such as hand washing and thorough cleaning and cooking of food.
Source: National Post News; BBC News
Alarmingly high numbers of HUS in Europe
Europe’s E. coli outbreak is being monitored closely by doctors and public health authorities around the world, who are alarmed by the unprecedented number of hemolytic uremic syndrome cases, the acute kidney failure that has hospitalized hundreds in Germany and neighboring countries.
In most outbreaks of E. coli poisoning, about 5 to 10 percent of patients suffer this life-threatening complication — most of them younger children or seniors with weakened immune systems. Based on available information from Germany, more than 30 percent of the illnesses are developing into HUS. As of Wednesday, more than 1,500 people, many of them middle-aged women, were reported sick in Germany and adjacent countries, and nearly 500 of them were said to have been diagnosed with HUS.
Survivors of HUS describe the disorder as excruciatingly painful. “Try to remember the worst pain you’ve ever experienced, and then multiply it by at least a hundred,” says Laura Lucy who, as a college student in Alabama, survived a horrible case of HUS in 1993. “And there is absolutely no relief.”
Hemolytic uremic syndrome usually (but not always) begins with E. coli poisoning. In most cases, the culprit has been E. coli O157:H7, but the German outbreak has been identified as E. coli O104:H4, a rare strain that some believe may be the result of a recent mutation.
The human body is home to countless millions of perfectly healthy E. coli bacteria, which play important roles in digestion and other body functions. The emerging toxic strains, however, breed in cows and other animals and are shed in animal feces, which can then contaminate human food.
As few as 100 bacteria can cause the illness. Once ingested the bacteria multiply rapidly in the intestine, causing diarrhea, and attach themselves to the lining of the large intestine. There the poison is absorbed into the intestinal capillaries, clings to white blood cells and piggybacks with those cells to the kidneys. From there, the poison can be distributed to the brain, pancreas or other organs.
Meanwhile, the toxin attacks blood cells, triggering the platelets that cause blood to coagulate. The platelets, in turn, cause blood clots which block blood circulation and begin to shut down the kidneys.
With the colon inflamed, the patient is subjected to painful abdominal cramps and blood-saturated diarrhea. Urination ceases and the body begins to swell with bodily fluids that further increase the discomfort and toxicity.
HUS has been relatively rare, with just 60 cases per year in Germany — less than one in a million per year. The high numbers of HUS today could mean the overall size of the outbreak is larger than has been reported, or that E. coli O104:H4 is more likely to cause HUS.
Treating E. coli infections with antibiotics tends to increase the risk of HUS by killing the healthy bacteria needed to combat the toxic invasion. Once the symptoms of HUS appear, dialysis may be needed to prevent the kidneys from failing.
For many HUS survivors, the illness never ends. The illness has damaged their kidneys and other organs, weakened their immune systems, and they have a high risk of kidney failure later in life.
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