Most Escherichia coli strains live harmlessly in the intestines and rarely cause disease in healthy individuals. Nonetheless, a number of pathogenic strains can cause diarrhea or extraintestinal diseases both in healthy and immunocompromised individuals. Diarrheal illnesses are a severe public health problem and a major cause of morbidity and mortality in infants and young children, especially in developing countries. E. coli strains that cause diarrhea have evolved by acquiring, through horizontal gene transfer, a particular set of characteristics that have successfully persisted in the host. According to the group of virulence determinants acquired, specific combinations were formed determining the currently known E. coli pathotypes, which are collectively known as diarrheagenic E. coli. In this review, we have gathered information on current definitions, serotypes, lineages, virulence mechanisms, epidemiology, and diagnosis of the major diarrheagenic E. coli pathotypes.

To determine the prevalence and epidemiology of enteropathogens in acute infantile diarrhea, 500 infants ⩾12 months of age with diarrhea and 500 age-matched control subjects coming to a São Paulo emergency room were studied. Enteropathogens were identified in 55% of case infants and 10% of controls; enteropathogenic Escherichia coli (EPEC) of classic EPEC serotypes producing EPEC adherence factor (EAF) (26% of case infants), rotavirus (14%), Salmonella species (8%), enterotoxigenic E. coli (7%), and Shigella species (5%) were associated with diarrhea. Isolation of EAF⁺ classic EPEC decreased with increasing age of cases and peaked in spring, whereas rotavirus was least common in early infancy and peaked in fall and winter. Bloody stool had a 36% positive predictive value for Shigella infection. EAF⁺ classic EPEC were highly resistant to antimicrobial drugs. Among poor São Paulo infants, EAF⁺ classic EPEC equaled or exceeded rotavirus throughout the year as a cause of diarrhea bringing children to medical attention.

DiarrhoeagenicEscherichia coli(DEC) is a leading cause of infectious diarrhoea worldwide. In recent years,Escherichia albertiihas also been implicated as a cause of human enteric diseases. This study describes the occurrence ofE. colipathotypes and serotypes associated with enteric illness and haemolytic uremic syndrome (HUS) isolated in Brazil from 2011 to 2016. Pathotypes isolated included enteropathogenicE. coli(EPEC), enteroaggregativeE. coli(EAEC), enterotoxigenicE. coli(ETEC), enteroinvasiveE. coli(EIEC) and Shiga toxin-producingE. coli(STEC). PCR of stool enrichments for DEC pathotypes was employed, andE. albertiiwas also sought. O:H serotyping was performed on all DEC isolates. A total of 683 DEC and 10E. albertiistrains were isolated from 5047 clinical samples. The frequencies of DEC pathotypes were 52.6% (359/683) for EPEC, 32.5% for EAEC, 6.3% for ETEC, 4.4% for EIEC and 4.2% for STEC. DEC strains occurred in patients from 3 months to 96 years old, but EPEC, EAEC and STEC were most prevalent among children. Both typical and atypical isolates of EPEC and EAEC were recovered and presented great serotype heterogeneity. HUS cases were only associated with STEC serotype O157:H7. TwoE. albertiiisolates belonged to serogroup O113 and one had thestx2f gene. The higher prevalence of atypical EPEC in relation to EAEC in community-acquired diarrhoea in Brazil suggests a shift in the trend of DEC pathotypes circulation as previously EAEC predominated. This is the first report ofE. albertiiisolation from active surveillance. These results highlight the need of continuing DEC andE. albertiisurveillance, as a mean to detect changes in the pattern of pathotypes and serotypes circulation and provide useful information for intervention and control strategies.