ABSTRACT 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.

Enteropathogenic Escherichia coli (EPEC) are important human gastroenteritis agents. The prevalence of six non-LEE genes encoding type 3 translocated effectors was investigated. The nleC, cif and nleB genes were more prevalent in typical than in atypical EPEC, although a higher diversity of genes combinations was observed in atypical EPEC.

Amostras de Escherichia coli isoladas de 24 psitacídeos doentes foram sorogrupadas e investigadas para a presença de genes que codificam os seguintes fatores de virulência: attaching e effacing (eae), plasmídeo EAF (EAF), pili associado à pielonefrite (pap), fímbria S (sfa), adesina afimbrial (afa), cápsula K1 (neu), curli (crl, csgA), hemaglutinina termosensível (tsh), enterotoxina termo-estável 1 de E. coli enteroagregativa (astA), toxina termolábil (LT) e toxina termoestável (STa e STb), Shiga-like toxinas (stx1 e stx2), fator citotóxico necrotizante 1 (cnf1), hemolisina (hly), produção de aerobactina (iuc) e resistência sérica (iss). Os resultados mostraram que os isolados pertenciam a 12 sorogrupos: O7; O15; O21; O23; O54; O64; O76; O84; O88; O128; O152 e O166. Os genes de virulência encontrados foram: crl em todos os isolados, pap em 10 isolados, iss em sete isolados, csgA em cinco isolados, iuc e tsh em três isolados e eae em dois isolados. A combinação dos genes de virulência revelou 11 perfis genotípicos distintos. Todas as amostras foram negativas para os genes que codificam EAF, EAEC, K1, sfa, afa, hly, cnf, LT, STa, STb, stx1 e stx2. Estes resultados demonstraram que algumas amostras de E. coli isoladas de psitacídeos apresentam os mesmos fatores de virulência presentes nos patotipos de E. coli patogênicas para aves (APEC), uropatogênicas (UPEC) e E. coli enteropatogênicas (EPEC).

Escherichia coli isolates from 24 sick psittacine birds were serogrouped and investigated for the presence of genes encoding the following virulence factors: attaching and effacing (eae), enteropathogenic E. coli EAF plasmid (EAF), pili associated with pyelonephritis (pap), S fimbriae (sfa), afimbrial adhesin (afa), capsule K1 (neu), curli (crl, csgA), temperature-sensitive hemagglutinin (tsh), enteroaggregative heat-stable enterotoxin-1 (astA), heat-stable enterotoxin -1 heat labile (LT) and heat stable (STa and STb) enterotoxins, Shiga-like toxins (stx1 and stx2), cytotoxic necrotizing factor 1 (cnf1), haemolysin (hly), aerobactin production (iuc) and serum resistance (iss). The results showed that the isolates belonged to 12 serogroups: O7; O15; O21; O23; O54; O64; O76; O84; O88; O128; O152 and O166. The virulence genes found were: crl in all isolates, pap in 10 isolates, iss in seven isolates, csgA in five isolates, iuc and tsh in three isolates and eae in two isolates. The combination of virulence genes revealed 11 different genotypic patterns. All strains were negative for genes encoding for EAF, EAEC, K1, sfa, afa, hly, cnf, LT, STa, STb, stx1 and stx2. Our findings showed that some E. coli isolated from psittacine birds present the same virulence factors as avian pathogenic E. coli (APEC), uropathogenic E. coli (UPEC) and Enteropathogenic E. coli (EPEC) pathotypes.