PCR Detection of Microbial Pathogens PCR Detection of Microbial ...

STEC PCR 163
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Detection and Subtyping of Shiga Toxin-Producing
Escherichia coli (STEC)
Peter Gallien
1. Introduction
When the Japanese microbiologist Shiga discovered a bacterium causing dysentery
in humans in 1898, the organism was designated Shigella dysenteriae
type 1. The toxin produced by the germ was found to have enterotoxic and neurotoxic
properties. Later on, it became clear that, in most countries,
Shigella dysenteriae type 1 does not play an important role in human infectious
diseases. Nevertheless, this microorganism has spread a genetic message among
other bacterial species, namely Escherichia coli and Citrobacter freundii.
Meanwhile, cases of diarrhea have been associated to an increasing extent
with E. coli, a generally harmless occupant of the gut in humans and animals.
Although these optionally anaerobic, Gram-negative, motile, rod-shaped bacilli
only make up less than one percent of the total bacterial population in the gut,
they play an important part in the symbiosis between host and intestinal flora as
a consequence of their oxygen-consuming metabolism (1). Alongside these nonpathogenic
E. coli, there may be toxigenic representatives of the same species
present in the host organism. Pathogenic E. coli can possess specific adhesins,
which are genes encoding toxins and other factors of virulence. This group of
pathogens is associated with intestinal and extra-intestinal diseases (2).
Among the representatives residing in the intestinal tract are shiga toxin-producing
E. coli (STEC), which can cause hemorrhagic colitis (HC), toxic extraintestinal
complications, such as the hemolytic-uremic syndrome (HUS) (3–7),
and thrombotic thrombocytopenic purpura (TTP) (8) in humans. In addition, the
central nervous system can be affected (9,10).
From: Methods in Molecular Biology, vol. 216: PCR Detection of Microbial Pathogens: Methods and Protocols
Edited by: K. Sachse and J. Frey © Humana Press Inc., Totowa, NJ
163