| Staining |
Short rods,
usually 0.2-0.4 um by 0.4-1.0 um, resembling organisms of
the genus Rickettsia in staining properties, dependence
on host cells for growth, and close natural association
with arthropod and vertebrate hosts. Grows preferentially
in the vacuoles of the host cell (rather than in the
cytoplasm or the nucleus as do the species of
Rickettsia). Unlike Chlamydia, Coxiella does not prevent
the formation of phagolysosomes. Grows well in the yolk
sac of chicken embryos, where it undergoes a cycle of
development which includes formation of an endospore-like
body. Has high resistance to chemical agents and elevated
temperatures that generally kill Rickettsia species.
Although axenic growth has not been obtained, outside the
host Coxiella metabolizes glutamate, glucose, and other
substrates, provided the pH is low. This property may
reflect an adaptation to the environment of the
phagolysosome. The distribution in ticks and various
mammals is worldwide and infection is particularly
prevalent in cattle, sheep and goats. Etiological agent
of the aerosolborne human disease Q fever. The mol% G + C
of the DNA is 43 (chemical analysis; Smith and Stoker
(1951). |