Article

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

Department of International Health, Johns Hopkins University, Baltimore, Maryland, United States
Clinical Microbiology Reviews (Impact Factor: 17.41). 08/2005; 18(3):465-83. DOI: 10.1128/CMR.18.3.465-483.2005
Source: PubMed

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.

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    • "So far, a single small RCT documented an effect in carefully selected patients suffering from otitis externa ( " swimmer's ear " ) (Wright et al., 2009). E. coli is an important cause of diarrhea in children from developing countries (Qadri et al., 2005), resistant against many antibiotics (Jiang et al., 2002) while efficient E. coli diarrhea vaccines are not yet available (Ahmed et al., 2013). Other than zinc and oral rehydration solution, no specific, effective, safe and affordable treatment is available to reduce the severity or duration of illness caused by this bacterial agent. "
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    ABSTRACT: Antibiotic resistance of bacterial infections reached alarming levels. Phage therapy is a potential alternative antimicrobial. We demonstrated that two different oral phage preparations did not improve acute bacterial diarrhea in children from Bangladesh. We observed fecal excretion of the oral phage, but no major phage amplification in the gut. E. coli pathogen levels were low and the fecal microbiota showed a transient overgrowth with streptococci. Future phage trials should first verify the titer and association of the targeted pathogen with the disease.
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    • "In Bangladesh, ETEC infections in children and adults have a typical biphasic pattern with epidemic peaks in the warmer periods in April and in August–September, before and after the monsoon rains. The incidence of ETEC infections seems to correspond to increased average temperature but not to occurrence of heavy rainfall (Black et al., 1982; Qadri et al., 2005). Enterotoxigenic E. coli has also been detected in seawater where areas of lower salinity in marine environments seem to favour occurrence of ETEC (Akter et al., 2013). "
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    ABSTRACT: Enterotoxigenic Escherichia coli (ETEC) is a water and food borne pathogen that infects the small intestine of the human gut and causes diarrhea. ETEC adheres to the epithelium by means of colonization factors and secretes two enterotoxins, the heat labile toxin (LT) and/or the heat stable toxin (ST) that both de-regulate ion channels and cause secretory diarrhea. ETEC, as all E. coli, is a versatile organism able to survive and grow in different environments. During transmission and infection ETEC is exposed to various environmental cues that have an impact on survivability and virulence. The ability to cope with exposure to different stressful habitats is probably shaping the pool of virulent ETEC strains that cause both endemic and epidemic infections. This review will focus on the ecology of ETEC in its different habitats and interactions with other organisms as well as abiotic factors.
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    • "Enterotoxigenic Escherichia coli (ETEC) strains are a major cause of diarrheal disease in humans and animals (Zhu et al., 2011). ETEC is the most common cause of traveler's diarrhea and can be fatal for children (Qadri et al., 2005). The major virulence factors are bacterial fimbriae that mediate bacterial attachment to host enterocytes allowing its colonization and proliferation, and the production of enterotoxins, which stimulate fluid and electrolyte secretion by intestinal cells leading to diarrhea (Fairbrother et al., 2005). "
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    ABSTRACT: Quorum sensing (QS) is a signaling system among bacteria mediated by auto-inducer substances (AI). Whenever the concentration of these molecules reaches a threshold corresponding to a high cell density or quorum, the whole population starts a coordinated expression of specific genes. Studies have shown that epinephrine is also responsible for activating specific bacterial genes. This work aimed to investigate the role of conditioned medium (containing AI), epinephrine and their association on growth, motility, F4 fimbriae and heat-labile toxin (LT) expression on enterotoxigenic Escherichia coli (ETEC, E68). A significant increase in motility, F4 and LT expression, was observed in the ETEC culture supplemented with conditioned medium and epinephrine. These findings suggest that ETEC uses some components of conditioned medium (e.g., AI molecules), host molecules (epinephrine), and their association to modulate the expression of important virulence genes.
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