Enterobacteriales, a very large group, found in water, soil
or the intestines of humans and animals. The pathogenic genera include:
But they also include an exceedingly large number of dangerous pathogens
that cause bubonic plague, cholera, salmonella, tularemia, and urinary
tract and ear infections. Many cause secondary infections in ill or
hospitalized patients. The Gamma Proteobacteria include:
- Escherichia coli (occasionally pathogenic)
- Salmonella (food poisoning & typhoid fever)
- Shigella (bacterial dysentery)
- Yersinia (bubonic plague, which in the 14th century killed
over one-fourth of the population from China to Europe.)
- Serratia cause respiratory urinary & eye infections
and when flushed out to sea kill coral reefs
- Vibrionales cause cholera.
- Legionellales cause Legionaires' disease.
- Pasteurellales cause genital sores and ear infections.
- Chromatiales, or purple sulfur bacteria, consume hydrogen
- Methylococcales consume methane.
- Pseudomonadales spoil food, especially dairy products.
- Thiotrichales, the biggest bacteria in size, cause tularemia.