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Tuesday, July 5, 2011

Chilling E. coli scenarios arise
as probers close in on source

The tracking of deadly E. coli pathogens
carrying plague DNA to a single lot of spice seeds poses disturbing scenarios for investigators.

Because the E. coli strain, O104:H4, is believed to have originated in human intestines before mutating to an extremely antibiotic-resistant form, the contamination of the lot almost certainly stemmed from at least one human handler.

This handler is very likely to have either been someone in Germany at the import firm AGA SAAT GMBH or in Egypt or on a cargo line in order to have affected people some 750 miles apart.

Scenario 1:
The handler, who might have been resistant to the strain, inadvertently contaminated the fenugreek seeds, which in raw form are used as spices in curries and other dishes. In that case, there would be reason to believe that the strain was a hospital-bred strain that had not previously been identified.

Yet, European health authorities monitor hospitals for such strains, and no such strain has been reported as a hospital-borne problem. This would then lead to suspicion of Egyptian hospitals, which a decade ago were reported to be hotbeds for the breeding of super-bugs resistant to antibiotics. (Hospitals worldwide are contending with this problem.) But, Egyptian authorities said that the O104:H4 strain was unknown in Egypt. Its precursor is known, however, in Germany.

In 2008, the U.S. Centers for Disease Control published research saying that a study of Spanish hospital patients had shown that treatment with the antibiotic ampicillin appeared to be affecting human intestinal E. coli. This report may have triggered the initial suspicion that Spanish cucumbers were the infection carrier.

Scenario 2:
The handler was a terrorist, either acting alone or in concert with others, who sprinkled the bacteria onto the lot either when in Egypt or in Germany, or possibly during transit by ship and rail.

If the seeds were deliberately contaminated, investigators would then face the issue of how the strain was developed. There are methods of breeding antibiotic resistant strains. Researchers may try to provoke such resistance in order to study bacterial biology.

Dr. Helge Karch, a German E. coli expert, reported that “the O104:H4 bacteria responsible for the current outbreak are a so-called 'chimera' that contains genetic material" from various E. coli bacteria. The bug "also contains DNA sequences from plague bacteria which makes it particularly pathogenic.” He also has said he believed the strain to have originated in humans, rather than livestock.

The fact that the strain picked up resistance to such a wide spectrum of antibiotics in a relatively short span of perhaps less than a decade is a matter of concern.

No terrorist group is reliably reported to have claimed credit for the outbreak. However, a loner with sufficient biological training could well have pulled off such a deed. Al Qaeda and its allies have been urging individuals to exact revenge for the killing of Osama bin Laden.

Last year U.S. officials sought to play down a report that al Qaeda had been considering poisoning U.S. salad bars with ricin, a feared chemical warfare weapon.

At any rate, in either scenario, the world is facing a new era of troubles. The "global village" effect means that emergent diseases and biological warfare can have wide-ranging impact, as seen by the fact that the contaminated seeds were eaten by Europeans 750 miles (1,200 kilometers) apart.

A strain of E. coli isolated in South Korea showed similarity to the German and French serotype. However, researchers say the Korean serotype -- biological indicators of resistance to antibiotics and other bacteriacides -- is markedly different from that of the European killer strain, according to a paper published by the U.S. Centers for Disease Control.

The culprit pathogen seems to be an evolved and extremely toxic version of a microorganism first identified in Münster, Germany, in 2001, according to genetic analyses done by two separate teams of scientists, the Wall Street Journal has reported. This would tend to indicate that the source of contamination was a food handler at the German organic food firm AGA SAAT GMBH.

 "Everything we know so far indicates it is an evolved strain," the Journal quoted Alexander Mellmann of the University Hospital of Münster, as saying. Mellmann was involved in the genetic analysis. "If it was completely unknown, we'd struggle a lot more in our effort to fight it."

In addition to Mellmann's group, a separate team from BGI, formerly known as the Beijing Genomics Institute, and University Medical Center Hamburg-Eppendorf compared the genetic material of the 2001 and 2011 strains. They found that seven genes crucial to both bugs' survival are identical, as are 12 virulence/fitness genes shared by both, the Journal said.

The 2001 strain caused fewer than five identified cases world-wide, and scientists never did identify its natural reservoir—where a new strain of the E. coli bug can originate, such as in cattle. But the genetic analysis showed that as the 2001 bug likely swapped genetic material with other bacterial strains, some big changes occurred, the Journal said.

The 2011 version turns out to be resistant to eight classes of antibiotics, including penicillin, streptomycin and sulfonamide. The likely reason is that rapid evolution "resulted in the gain of more genes during the last 10 years" that conferred immunity against many more antibiotics, according to BGI, according to the Journal.

The introduction of plague genes into the strain would have occurred via recombination of genes, which occurs naturally, but which is also accomplished by the techniques of genetic engineering.

The European Centre for Disease Prevention and Control (ECDC) reports that the European toll in the outbreak of E. coli O104:H4 in Germany and France linked to the fenugreek seeds had risen to 4,173 illnesses and 49 deaths.

Those numbers include 892 hemolytic uremic syndrome (HUS) cases.

A single lot of seeds -- lot number 48088 -- from an Egyptian exporter appears to be the link between the German and French outbreaks, the European Food Safety Authority (EFSA) reports, even though microbiological tests carried out on the seeds have thus far been negative.

Food Safety News reports that EFSA cautions that those test results "cannot be interpreted as proof that a batch is not contaminated" with Shiga toxin-producing E. coli. Given that other lots may be implicated, and because exposure to a small quantity of the seeds can have a "severe health impact," the food-safety authority is recommending that all lots of fenugreek from the identified -- but unnamed -- exporter should be considered suspect, the news service said.

Fenugreek seeds from the suspect Egyptian lot - about 15,000 kilograms - were imported to one large German distributor, according to an AP report. Those seeds were then sold to 70 different companies, 54 of them in Germany, the center of the outbreak, and to 16 companies in 11 other European countries.

Meanwhile, the British company Thompson & Morgan said it is awaiting the results of lab tests on three kinds of its sprouting seeds - organic fenugreek, white mustard and rocket (arugula). It confirmed that its supplier had obtained organic fenugreek sprouting seed from Egypt, and that Thompson & Morgan in turn supplied seeds to a French garden center. That garden center was the source of the seeds used to grow sprouts served at a school event in the town of Bègles, where many of those sickened reported eating various cold soups garnished with sprouts.

However, as with the Egyptian exporter, Thompson & Morgan's supplier was not named. The German importer AGA SAAT GMBH has succeeded in having European authorities omit its name as the transhipment source of the infected seeds.

The French garden center was the source of the seeds used to grow sprouts served at a school event in the town of Bègles, where many of those sickened reported eating various cold soups garnished with sprouts.

Two new Wikileaks emulators operating

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