Biomedical Engineering Reference
In-Depth Information
to blood infection, may cause a septicemic form of plague; and infection
by aerosolized droplets may produce the pneumonic form of plague.
Class Plesiomonaceae is the second subclass contained in Class
Enterobacteriales. It contains one genus, with one currently recognized human
pathogenic species: Plesiomonas shigelloides, an organism found in diverse
animals, including fish and shellfish. Plesiomonas shigelloides was thought to
be an exclusively opportunistic pathogen, producing a gastroenterities, capable
of developing into sepsis, in immune-compromised patients. It has now been
found to be associated with a significant number of cases of mild enteritis in
otherwise healthy individuals [37].
Readers should not confuse Plesiomonas shigelloides, containing the
species name “shigelloides,” with the genus name “Shigella” (see above).
Gamma Proteobacteria
Cardiobacteriales
Cardiobacteriaceae
*Cardiobacterium
Genus Cardiobacterium contains one pathogenic species: Cardiobacterium
hominis, a pleomorphic but often rod-shaped bacteria that causes some cases
of endocarditis. It is included with the HACEK organisms. See Glossary item
HACEK.
Gamma Proteobacteria
Legionellales
Coxiellaceae
*Coxiella
Legionellaceae
*Legionella
*Fluoribacter (formerly Legionella)
Whereas most subclasses of the Gamma Proteobacteria live extracellular lives,
the members of Class Legionellales that infect humans live inside cells.
Genus Coxiella contains one human pathogen: Coxiella burnetii, the
cause of Q fever. Coxiella burnetii is an obligate intracellular organism that
is capable of reverting to a small cell variant of itself, that is resistant to
intracellular degradation by lysosomes. This highly infectious zoonosis is
transmitted by inhaling aerosolized respiratory material, or from direct con-
tact with secretions from an infected animal (including cattle, sheep, goats,
dogs, and cats). A flu-like syndrome results, which may progress to chronic
pneumonia, ARDS (acute respiratory distress syndrome) and various sys-
temic sequelae, including endocarditis.
Genera of Class Legionellaceae are facultative intracellular organisms
and include Legionella and Fluoribacter [38].
Legionella species live within amoeba in the environment. Infection
occurs after inhalation of the bacteria, and epidemics of Legionnaire's
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