"They're quite specialized, the pathogenic bacteria.
Each one recognizes a specific kind of host cell and does a specific thing.
Each one has its own gimmick, as it were, to be successful."
The plague bacillus, which Falkow also studies, enters
the cell very differently than Salmonella. First, it attaches to
little spikes, called phylopodia, on the surface of a host cell. Its target
is the epithelial cells that line the stomach and gut. Once attached, the
cell slurps up the bacteria like spaghetti.
"The bacteria live in the gut, which is a place of
privilege. It must be very nice for them, because what you see on the surface
of the cell is the growth of colonies of bacteria. Even though they never
go in, they subvert the host cell's biochemistry for their own betterment,"
In the process, one strain of e. coli also secretes
a potent toxin that causes bleeding in the small intestine. This strain
was behind the recent deadly outbreak of food poisoning in the Pacific Northwest
from eating undercooked hamburger.
By spying on the microscopic war between pathogens and their hosts, Falkow
and his colleagues hope to eventually disarm the microbes' weapons by developing
new vaccines or antibiotics. "It's really an exciting time now,"
says Falkow, "because we're getting to understand more about the strategies
pathogens use during infection. In the process, we learn as much about host
cell biology as we do about bacterial biology."