Roger Cunningham, associate professor of microbiology, is director of UB's Ernest Witebsky Center for Immunology. He has been a member of the UB faculty since 1973.

How many strains of E. coli are there? Are they all dangerous?
The number of strains will vary according to who is counting and what method they use. The most common involve the use of what is termed serological typing. Once having determined that a given isolate is Escherichia coli based on certain morphological and biochemical properties, i.e. proper rod shape and staining properties, and ability to ferment the sugar lactose, the organism is tested with antiserum that has been prepared in animals specifically to detect the various serotypes. The different serotypes are determined by the particular structures present on the surface of different strains of E. coli. There are two kinds of these structures (antigens). One is called O antigen and these are composed of complex carbohydrate structures on the surface of the bacterial cell. At present, there are about 200 different kinds (strains) of Escherichia coli known. Each of these, when given as a vaccine to (for example) a rabbit, will produce a specific antibody that will detect that particular antigen and no other. A second type of antigen is usually, but not always, present on E. coli cells. This is a protein structure termed a flagellum that is responsible for motility. These are termed H antigens. In the present case, the E. coli are of the serotype 0157:H7. These are organisms that carry a toxin gene that has been acquired from a cousin of E. coli called Shigella. Shigella are always pathogenic. The vast majority of E. coli are non-pathogenic and inhabit the intestinal tract (colon) of humans and animals, where they probably play a beneficial role.

What are some of the more common sources of E. coli?
These organisms are common inhabitants of the intestinal tract of humans and animals. They can, however, also be found in soil, water, food or anything else that becomes contaminated with feces from these sources.

What are the symptoms once you have become infected?
The symptoms are those of an acute gastroenteritis that develops into a cramping, often grossly bloody diarrhea. Fever is low-grade or absent. Many cases are self-limiting, and resolve in eight to 10 days without specific treatment. A serious, sometimes fatal, complication may develop in some patients in which the kidneys become affected, presumably by the Shigella toxin, particularly in children. This is known as hemolytic uremic syndrome that can lead to kidney failure and sometimes an associated hemolytic anemia.

How do you treat E. coli infection?
Antibiotics, fluid and salt replacement, and bed rest are the usual treatment. Some physicians omit antibiotics but, depending on the patient, will do supportive care as warrants.

Are more outbreaks occurring or has media publicity made it seem that way?
As is so often the case in infectious disease, the first recognition of what are termed STEC (Shigella toxin-producing Escherichia coli) in 1982 led to the recognition of an association between an unusual serotype, 0157:H7, and hemolytic uremic syndrome and bloody diarrhea further led to additional cases being recognized in the ensuing years. The most spectacular episode occurred in 1993 on the West Coast in a chain of fast-food restaurants. The outbreak was associated with consumption of undercooked ground beef. More than 700 cases were identified, of which 55 developed hemolytic uremic syndrome and four died. As of this moment, most public health laboratories have initiated active surveillance programs for these organisms among dysentery cases admitted to hospitals, but they do not examine ground beef in packing plants.

Is increasing use of antibacterial cleaners actually making us more susceptible to bacterial infections?
This is not likely for several reasons. Most products that are advertised as antibacterial are weak in their action. A brisk swipe with brand whatever is very unlikely to kill because outside of incineration, the chemical killing of organisms takes time, more time than the average person is willing to wait. The principle effect of such swabbing is due to simple washing of the surface being treated. Another reason is that the antibacterial materials are not antibiotics. They exert their effect by chemical denaturing of the bacteria, thus the death of an organism is an all-or-none phenomenon. In contrast, antibiotics affect the metabolism of the bacteria and interfere with it. If the bacteria develop an alternative metabolic pathway, then the antibiotic will no longer have a target, whereas an antibacterial will always be able to denature its target, be it protein, lipid or carbohydrate.

How do you protect yourself and your family from an outbreak of this type?
If you frequent restaurants, particularly of the fast-food persuasion, you must rely on the vendor. At home, the rules are simple: Cook all ground meats to 160 degrees Fahrenheit or until the juices run clear. It is probably time for all the backyard chefs to invest in a good meat thermometer. In addition, because one never knows the history of fruits and vegetables, they should be thoroughly washed. For the pessimist, soaking in a solution of one teaspoon of bleach in a gallon of water will help disinfect produce.

What question do you wish I had asked, and how would you have answered it?
What's ahead? We must expect more "manmade" situations, such as E. coli 0157:H7, to emerge. To be sure, the "creation" of an ordinary E. coli that acquired a toxin gene from the Shigella bacillus is not the fault of humans. But the capacity to propagate enormous amounts of tainted food surely is a human activity. The number of carcasses that comprise a single lot of ground beef these days must simply be seen to be believed. Now, consider a single contaminated animal's meat being ground into meat from, say 10-12 other cattle. An entire batch of hundreds of pounds of ground beef now is contaminated and if not properly cooked, will lead to disease, if not tragedy. Furthermore, we must be more aware of the real dangers that careless disposal of fecal material can easily lead to disaster. The final point to make is ground meat must be properly cooked and fruits and vegetables properly washed. Your mother told you all about it. So do it