The epidemiology of nonenteric Escherichia coli infections: prevalence of serological groups.

Escherichia coli is an ubiquitous microorganism which is found in the gastrointestinal tract of every individual, where it usually forms a part of the normal gut flora. Extensive epidemiological, clinical, and bacteriological observations have documented the pathogenic significance of certain serological strains of E. coli in infantile diarrhea. However, although they are frequently isolated in infected sites closely related to the gastrointestinal tract, such as the appendix, gall bladder, and peritoneal cavity, little is known about the serological specificity of coliform bacteria in non-enteric infections, particularly those involving the urinary tract. Ewing (1) has emphasized that complete serological typing of E. coli should provide accurate information concerning the incidence of specific strains associated with disease and permit evaluation of nosocomial spread. The concept that some strains of gram-negative organisms may be associated with infection more often than others is not new. Kauffman (2) advanced the hypothesis that certain coliform serotypes are more prevalent in appendicitis, and he also noted that strains of certain serological groups were more frequently isolated from the urine than from feces. Others have reported that strains of certain serological groups are more commonly isolated from infected sites than from fecal specimens (3). Vahlne (4) and Sjdstedt (5) performed serological typing on strains of E. coli from a variety of normal and abnormal sources and found that certain types were more commonly associated with human infections but that these types were not limited to the urinary tract. More recently, Rantz (6) suggested that E. coli with certain group specific antigens are more invasive for the urinary tract than others. A preliminary report from this laboratory indicated