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0:00
Hello, my name is
Michael Donnenberg,
and I'm at the University of
Maryland School of Medicine
in Baltimore,
where I'm Professor
of Medicine and
Professor of Microbiology
and Immunology.
I'm going to talk to
you today about E. coli
and the great diversity
of infections
that this microbe can cause.
0:21
Now E. coli, pictured in
this scanning
electron micrograph
really has a split personality.
On the one hand, it's
a ubiquitous microbe
present in the gut of humans and
other mammals and birds
almost from birth where it's
content to live a
commensal lifestyle
rarely causing any harm,
in fact, where it
can contribute to
colonization resistance
and produce beneficial
metabolites.
0:52
On the other hand, a plethora of
different pathotypes of E. coli
can cause a variety of
serious infections.
E. coli strains can cause
urinary tract infections
and can cause meningitis
in the newborn.
E. coli can cause diarrhea by
no less than six
different mechanisms.
Each of these types of
infections is caused by
a different pathogenic type
or pathotype of E. coli.
1:22
How is it that E. coli is able
to cause so many diseases?
Close examination of
the E. coli genome,
reveals evidence of enumerable
recombination events
in which E. coli strains
have conjugated with
one another and
foreign DNA has come
into the genome.
The distinct pathotypes have
different virulence genes that
allow them to cause the
different infections.
These virulence
factors are encoded on
mobile genetic elements such
as plasmids, bacteriophages,
and pathogenicity islands
which are large stretches
of DNA encoding
virulence factors
that clearly had an origin
outside of the host strain.
