Escherichia coli is a gram positive, facultative anaerobe that occupies a symbiotic relationship with the large intestine of several animals including that of humans. This mutually beneficial arrangement provides adequate nutrition and safe haven for the encapsulated bacteria while providing the host with vitamin K and B-complexes (Tierney et al., 1998). E. coli is rapidly introduced into the sterile newborn through food, water and as a direct result of the birthing process. The host's colon is rapidly colonized by these and other bacteria that compete among themselves for position and acquisition of resources.
E. coli is the most common cause of urinary tract infections and gram-negative rod sepsis (Levinson and Jawetz, 1996). It has been readily associated with neonatal meningitis, and diseases like the ever-dreaded Montezuma's Revenge (Traveler's diarrhea). Once established within its environment, this rod shaped unicellular organism is able to respond to environmental pressures such as chemical, pH, osmosis and temperature changes, by moving to regions of the large intestine where more suitable conditions exist (Baron et al., 1994)
Morbidity caused by this organism is a direct result of the virulence factors present, which provide a means for categorizing E.coli into different groups. These differences in the way they cause disease not only help in identification, but aid researchers in targeting mechanisms capable of preventing the usually benign bacteria form becoming pathogenic.
According to Levine (1989) there are 3 main antigens utilized in order to serotype E. coli. The O antigen is located within the cell wall; H is a flagellar antigen and the K antigen is located within the capsule. Since there are numerous types of each antigen and various combinations of these antigens are possible in any one organism, the result is over 1000 antigenic types of E.coli. Classification into major groups is usually done...