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The name chlamydiae is derived from the Greek word “chlamys” representing
the cloak-like mantle worn by men in Ancient Greece.1 Upon
initial discovery, chlamydiae were thought to be intracellular pathogens
that cloaked the nucleus of an infected cell. Scientists have since
discovered that chlamydiae are nonmotile, gram-negative, obligatory
intracellular bacteria. These organisms cannot produce energy and
thus survive by acting as a parasite using the energy mechanics
of its infected host. The appearance of the cloak is now known to
represent the host’s cytoplasmic vesicle with numerous
individual chlamydia organisms inside.
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The four recognized species within the genus of Chlamydia are C
psittaci, C pneumoniae, and C
trachomatis, all of which cause disease in humans (Table 259-1), and C pecorum which
causes disease in pigs, sheep, and cattle, but not in humans.1Chlamydia
psittaci is responsible for psittacosis (ornithosis). Chlamydia
pneumoniae causes pneumonia, pharyngitis, and bronchitis. Chlamydia
trachomatis has at least 15 different serotypes, known
as serovars, that are associated with a spectrum of diseases. Serovars
A to C are associated with trachoma, D to K with genital infections,
and L1 to L3 with lymphogranuloma venereum. The most common infections
of C trachomatis are those of the genital tract
which present as urethritis and epididymitis in the male and cervicitis and salpingitis in the
female. Neonates can present with conjunctivitis and pneumonia infection
acquired by passage through an infected mother’s genital
tract.
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Chlamydiae all have biphasic cycles of replication.1 The
elementary body that represents the “infectious” particle
enters the host cell and lives within the host’s cytoplasmic
inclusion particles. The organism then begins its secondary vegetative
state known as the reticulate body and replicates by binary fission. Each
inclusion body begins to form multiple progeny that will be extruded
as new infectious elementary bodies to begin the cycle once again.
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Chlamydia psittaci or the new proposed name Chlamydophila
psittaci is an obligate intracellular, gram-negative bacterium.2 The
pathogen causes psittacosis which is also referred to as ornithosis. Psittacosis
is contracted by human beings from infected birds and their contaminated
droppings All birds, including pet birds (parrots, parakeets, macaws,
and cockatiels) and poultry (turkeys, ducks, chickens, and other
fowl), are most frequently involved in transmission to humans; however,
mammals such as sheep, cattle, goats, and cats have also been shown
to transmit infection to humans.2-8 The birds show
a spectrum of disease as they can have no evidence of disease or could
appear ill and die. Birds transmit the disease to humans by the
respiratory route from feces, fecal dust, or ...