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Browsing by Subject "EAEC"

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  • Martikainen, Outi (2011)
    Diarrheagenic Escherichia coli (DEC) can cause diarrheal disease in humans. Like commensal E. coli, DEC are present in the human and mammalian, especially ruminant, and avian gut. They can also be present in soil and water environments. The food of animal origin can act as a transmission vehicle to infect humans. Infection may also be gained by drinking water contaminated by animal or human feces. DEC can be devided into five pathogroups based on their virulence traits: enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enterohaemorrhagic E. coli (EHEC), enteroinvasive E. coli (EIEC) and enteroaggregative E. coli (EAEC). EPEC typically causes children’s diarrhea in developing countries. ETEC is a typical cause for tourist’s diarrhea and infantil diarrhoea in developing countries. EHEC causes bloody or non-bloody diarrhea that might lead to kidney dysfunction called hemolytic uremic syndrome (HUS) especially in young children. EIEC causes Shigella-like diarrhea which can be bloody. EAEC is mainly associated with prolonged diarrhea. This study was conducted to find out the prevalence of diarrheagenic E. coli in humans and food in Burkina Faso, on which there was no previous knowledge. Fecal samples were collected from children under five years of age suffering from diarrhea in two villages, Boromo and Gourcy, and in the capital Ouagadougou (110 samples). Raw meat samples (chicken, beef, mutton and bovine intestines used for human consumption) were collected from open markets in Ouagadougou (120 samples). Primary mixed bacterial cultures obtained from the samples were studied using multiplex PCR-method, which detects the virulence genes of the five pathogroups. In addition, 20 EHEC strains were isolated from meat samples using colony hybridization based on the detection of Shiga toxin gene stx and PCR-screening, and were characterized to reveal the possible virulence properties. The study demonstrated that DEC-infections in small children are common in Burkina Faso. Of the studied fecal samples, 59 % were positive for DEC. The most prevalent pathogroups were EAEC (32 %), ETEC (31 %) and EPEC (20 %). EIEC (2 %) and EHEC (1 %) were found only in a few samples. Mixed infections with more than one pathogroup were common (24 %). The difference in DEC prevalence between the different sampling locations was statistically significant. There were more DEC-infections in Gourcy than in Ouagadougou and Boromo. The study also showed that DEC occur commonly in raw meats sold at open markets in Ouagadougou. Of the studied meat samples, 43 % were positive for DEC. The most prevalent were EHEC (28 %), EPEC (20 %), ETEC (8 %) and EAEC (5 %). EIEC was not detected. Mixed contaminations with more than one pathogroup were relatively common (17 %) in meat. There was no statistical significance in DEC-prevalence between the different meats. When prevalence was considered by each pathogroup, EHEC was absent in chicken and the difference was statistically significant when compared to the other meats. The 20 EHEC strains isolated from the meat samples were grouped into 14 serotypes, some of which have previously been isolated from humans suffering from diarrheal disease and HUS. All the strains were positive for stx1 and half of them also for stx2, which is considered to be the more virulent form of Shiga toxin. Two EHEC strains were also positive for an ETEC-related gene of heat-stable enterotoxin Ia. Hence, the two strains were a mixture of two pathogroups and an evidence of gene transfer between different pathogroups. The youngest children do not consume meat but meat can be thought to represent a sample from their living environment, because food for children might be prepared in the same environment where raw meat products are handled. Thus contaminated meat can be a source of DEC-infections in little children.