Detection of Enteric Bacteria in Raw Food Samples from Vietnam ...

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CHAPTER 1: INTRODUCTION
has been reported for the first time from cows’ feaces by Nakasone et al. (2005). Infection
with EHEC strains may be asymptomatic or associated with a range of symptoms from non-
bloody diarrhoea, fever and vomiting through to hemorrhagic colitis (HC), hemolytic uraemic
syndrome (HUS), thrombotic thrombocytopenic purpura (TTP) and death (Desmarchelier and
Grau, 1997b; Coia, 1998; Phan et al., 2007). Transmission of outbreaks frequently occurs
through the ingestion of contaminated food such as meats in particular beef, unpasteurised
milk or water, by person-to-person contact or by zoonotic transmission (CDC, 1995a; CDC,
1995b; Bolton and Aird, 1998; Hashimoto et al., 1999; Clarke, 2001; Doorduyn et al., 2006;
Hughes et al., 2007; Honish et al., 2007). There is no specific treatment for EHEC infection
except drinking a lot of water, the use of antibiotics is not recommended.
Diffuse-adhering E. coli (DAEC) strains show a diffuse adherent pattern on Hep-2 cells.
Several studies have implicated DAEC as a cause of diarrhoea while other studies have not
recovered DAEC strains more frequently from diarrhoeal patients than from asymptomatic
controls (Nataro and Kaper, 1998a). Although there has been a dramatic increase in
knowledge about the pathogenesis of this pathotype (Servin, 2005), little is known about its
epidemiology and clinical profile. These strains have been associated with diarrhoea in
children outside infancy (Levine et al., 1993a; Desmarchelier and Grau, 1997b).
1.1.4.3. Diseases and symptoms caused by Vibrio spp.
Vibrios are Gram-negative, halophilic, non-spore-forming bacteria, autochthonous inhabitants
of the marine and estuarine environments. These strains are able to colonise the surface and
internal organs of marine vertebrates and invertebrates (Cavallo and Stabili, 2002; Hervio-
Heath et al., 2002; Potasman et al., 2002). The genus Vibrio includes at least 30 species, and