<unk>  is a genus of bacteria in the family Enterobacteriaceae.<unk>  are Gram-negative rod shaped bacteria, a few micrometers long and fractions of a micrometer in diameter, and are facultative anaerobes. Some members of<unk>  are pathogenic in humans. Rodents are the natural reservoirs of<unk> ; less frequently other mammals serve as the host. Infection may occur either through blood (in the case of Y. pestis) or in an alimentary fashion, through occasionally via consumption of food products (especially vegetables, milk-derived products and meat) contaminated with infected urine or feces.
Speculations exist as to whether or not certain<unk>  can also  be spread via  protozoonotic mechanisms, since<unk>  are known to be facultative intracellular parasites; studies and discussions of the possibility of amoeba-vectored (through  the cyst form of the protozoan)<unk>  propagation and proliferation are now in progress.
Yersinia
Salmonella
Shigella
Salmonella enterica
Campylobacter jejuni
Salmonella enteritidis
Vibrio cholerae
Clostridium difficile