RESUMEN
In the present study, 470 children less than 72 months of age and presenting acute diarrhea were examined to identify associated enteropathogenic agents. Viruses were the pathogens most frequently found in stools of infants with diarrhea, including 111 cases of rotavirus (23.6 percent of the total diarrhea cases) and 30 cases of adenovirus (6.3 percent). The second group was diarrheogenic Escherichia coli (86 cases, 18.2 percent), followed by Salmonella sp (44 cases, 9.3 percent) and Shigella sp (24 cases, 5.1 percent). Using the PCR technique to differentiate the pathogenic categories of E. coli, it was possible to identify 29 cases (6.1 percent) of enteropathogenic E. coli (EPEC). Of these, 10 (2.1 percent) were typical EPEC and 19 (4.0 percent) atypical EPEC. In addition, there were 26 cases (5.5 percent) of enteroaggregative E. coli, 21 cases (4.4 percent) of enterotoxigenic E. coli, 7 cases (1.4 percent) of enteroinvasive E. coli (EIEC), and 3 cases (0.6 percent) of enterohemorrhagic E. coli. When comparing the frequencies of diarrheogenic E. coli, EPEC was the only category for which significant differences were found between diarrhea and control groups. A low frequency of EIEC was found, thus EIEC cannot be considered to be a potential etiology agent of diarrhea. Simultaneous infections with two pathogens were found in 39 diarrhea cases but not in controls, suggesting associations among potential enteropathogens in the etiology of diarrhea. The frequent association of diarrheogenic E. coli strains was significantly higher than the probability of their random association, suggesting the presence of facilitating factor(s).