OK; who "is" the bad guy? The rare strain of E. coli that is getting a lot of "press" lately because it is indeed a bad bug, is E. coli O157:H7, a member of the EHEC - enterohemorrhagic E. coli group. Enterohemorrhagic means an intestinally-related (here we are at the Greek word enterikos again) organism which causes hemorrhaging - and therefore, loss of blood. The image shown below is a picture of an electron microscope visualization (an electron micrograph) of O157:H7 (compliments of David Graham, University of Illinois at Urbana/Champaign). How then do we "pick up" this organism? Basically, here is the problem: E.coli bacteria are everywhere in the environment. But, since they are such a common occupant of all animals, anytime we eat something, drink something, or touch our hands to something that has been either a part of or has been near where animals are, there is always the potential to ingest these bacteria - is a good reason for washing your hands now and then, huh? How did this strain of E. coli come to be? Since bacterial cells are all over the place, it is possible for them to acquire genetic information from other sources (bacterial viruses, plasmids, or just naked pieces of DNA floating around and about) - bacteria are "pretty good" at this - this information has nothing to do with the original genetic information necessary for the survival of the bacterium - although in some cases, acquisition of this information may provide an advantage for survival. In the case of E.coli O157:H7, a long-ago cell appears to have been infected with a bacterial virus. This particular virus had the ability to insert its own DNA into the bacteria's chromosome without harming the bacterium - and to remain there. Now, every time this bacterial cell divided, the virus DNA, being now a part of the bacterial DNA, was passed on to every daughter cell - and now, we have the E.coli strain, O157:H7.... This virus's genetic information (genes) unfortunately (for us) contained information for the production of a toxin, called Shiga-like toxin (SLT), or is sometimes called, Vero toxin. Consequently, this strain of E.coli, and all of its progeny produce this toxin. The toxin is a protein which causes severe damage to intestinal epithelial cells (the cells that line the wall of the intestine). The damage is so severe that if we acquire this bacterial strain, not only do we lose water and salts, blood vessels are damaged, and bleeding occurs - lots of bleeding - hemorrhaging. This condition is particularly dangerous to small children - may be lethal - children are too small to tolerate much blood and fluid loss. It is for this reason that small children should not be allowed to become dehydrated, even in mild cases of diarrhea. Too, in some cases another syndrome is involved which is called hemolytic uremic syndrome (HUS), which is characterized by kidney failure and loss of red blood cells. Approximately 5% to 10% of little kids progress to this stage of disease - which is very dangerous for them. In severe cases, the disease can cause permanent kidney damage. The presence of this bacterium can also be very dangerous to the elderly or infirm. There can be a combination of HUS and some other things which involve the blood system, which can be lethal to the elderly in 50% of the cases. So, E.coli O157:H7 is a dangerous organism, for sure. Recent News: 1. As of August, 1997, various "lots" of hamburger meat produced for shipment by Hudson Foods were found to be contaminated with a harmful strain of E. coli. The strain of E. coli involved is again O157:H7. The Hudson Foods plant in Nebraska responsible for the contaminated beef is now closed. Approximately 25 million pounds of beef are being recalled - all of the beef shipped from this plant. And, all beef presently at the plant is being destroyed. Interestingly, the USDA as no authority to force an industry to recall food which threatens the safety of the population in the US. The government can only recommend that the meat be recalled. The Secretary of Agriculture states that he is planning to see that Congress again consider legislation to increase the authority of the USDA - the arm of the Federal Government which is responsible for the safety of food products in the nation.