Enterotoxigenic Escherichia coli in Developing Countries: Epidemiology, Microbiology, Clinical Features, Treatment, and Prevention

Abstract

ETEC is an underrecognized but extremely important cause of diarrhea in the developing world where there is inadequate clean water and poor sanitation. It is the most frequent bacterial cause of diarrhea in children and adults living in these areas and also the most common cause of traveler's diarrhea. ETEC diarrhea is most frequently seen in children, suggesting that a protective immune response occurs with age. The pathogenesis of ETEC-induced diarrhea is similar to that of cholera and includes the production of enterotoxins and colonization factors. The clinical symptoms of ETEC infection can range from mild diarrhea to a severe cholera-like syndrome. The effective treatment of ETEC diarrhea by rehydration is similar to treatment for cholera, but antibiotics are not used routinely for treatment except in traveler's diarrhea. The frequency and characterization of ETEC on a worldwide scale are inadequate because of the difficulty in recognizing the organisms; no simple diagnostic tests are presently available. Protection strategies, as for other enteric infections, include improvements in hygiene and development of effective vaccines. Increases in antimicrobial resistance will dictate the drugs used for the treatment of traveler's diarrhea. Efforts need to be made to improve our understanding of the worldwide importance of ETEC

Increased prevalence of pathogenic bacteria in the gut microbiota of infants at risk of developing celiac disease: The PROFICEL study

“…26 Moreover, in NOD-DQ8 mice the colonization with E. coli ENT CAI:5 isolated from one CD patient increased the sensitivity to gluten-induced immunopathology and suggested that this could be a contributing factor to the disease. 18 The ETEC type is a major cause of diarrhoea, 40 , 41 but it has also been detected in asymptomatic subjects acting as carriers, 42-44 who would presumably have an increased risk of developing gastrointestinal disorders.…”

Comparison of virulence markers and antibiotic resistance in enterotoxigenic Escherichia coli isolated ten years apart in Tehran

“…Katouli et al showed that ST-only with a 78% rate was the most frequent toxin type followed by LT-only (14%) and LTST (8%) [19]. Dominance of the ST-expressing ETEC has been documented in Egypt, Bangladesh, and Tunisia [11,20,21]. However, a recent study conducted in Bangladesh concluded that ETEC strains have shifted from ST-producers to significantly more LTproducing strains similar to those observed in Latin American countries, such as Mexico, Peru, and Argentina, which have shown a high prevalence of LT-producing ETEC [22,11,23].…”

“…Dominance of the ST-expressing ETEC has been documented in Egypt, Bangladesh, and Tunisia [11,20,21]. However, a recent study conducted in Bangladesh concluded that ETEC strains have shifted from ST-producers to significantly more LTproducing strains similar to those observed in Latin American countries, such as Mexico, Peru, and Argentina, which have shown a high prevalence of LT-producing ETEC [22,11,23]. The results of this study also showed the predominance of the STproducing strains in the 1988 isolates, but a significant increase in the detection rate of the LTproducers was observed among the 1998 ETEC isolates, and those previously reported [19].…”

“…Variation in the prevalence of toxin types as well as CFs may occur from year to year and among different geographic areas. In Bangladesh, a study conducted in 1980 reported a 4% prevalence for LTonly, 34% for ST-only and 62% for LT and ST isolates; these ratios, however, for 1992 were 58%, 38% and 4% respectively, a significant change in the ratio of LT-producers [11]. Katouli et al showed that ST-only with a 78% rate was the most frequent toxin type followed by LT-only (14%) and LTST (8%) [19].…”

“…Of all the known CFs, the most frequently encountered are CFA/I, CS1, CS2, CS3, CS4, CS5, CS6, CS7, CS14, CS17, and CS21, of which to our knowledge only CS6, CS7 and CS21 are not regulated by the CfaD/Rns activators. Moreover, despite the important role that CFs play in the pathogenesis of ETEC, in approximately 30-50% of the isolates worldwide, no CF is detected [11]. ETEC fimbriae have generally been identified by agglutination or immunoblotting with poly or monoclonal antibodies, but these reagents are not widely available, leading to the publication of various genotypic methods, including mono-and multiplex PCRs for the identification of CFs [8,[12][13][14][15][16].…”