Unit 4 - Chlamydia Flashcards
What is the morphology of the organisms in the genus Chlamydia?
small, pleomorphic coccobacillary bacteria
Are organisms in the geus Chlamydia gram negative or positive?
gram negative but they stain poorly with gram stain
Chlamydiae can survive _____ of host cells but have to be ______ to grow.
outside; intracellular
What is the main difference between Chlamydiae and Rickettsiae species?
Chlamydiae have a developmental cycle while Rickettsiae do not and Rickettsiae almost always require vectors for their transmission while Chlamydiae do not
Describe the family Chlamydiaceae.
They are a family of small, obligately intracellular bacteria parasites. They infect a wide spectrum of vertebrate hosts including birds, mammals, and man
What species in the genus Chamydia are strictly human pathogens?
Chlamydia trachomatis and Chlamydia pneumoniae
What are the two distinct growth forms of chlamydiae?
the elementary body (EB) and the reticulate body (RB)
What is the general morphology of both forms of chlamydiae?
nonmotile, lack flagella, and are nonfimbriated
What growth form of chlamydiae is the infectious form?
the EB
What is the specific morphology of the EB?
it is a small, dense spherical body with a rigid cell wall which protects the EB outside of the host. The cell wall consists of an inner and outer cell membrane without peptidoglycan in between. Cell rigidity is believed to be due to disulfide bond cross-linking among the major outer membrane proteins. The genome is compacted in a central nucleoid
What is the RB?
it is the intracellular, metabolically active form that divides by binary fission
What is the RB dependent on the host for?
ATP
What are the steps of the development cycle for the genus Chlamydia?
- Attachment and penetration of host cells by the EB. 2. Transition of the metabolically inert EB into a metabolically active RB. 3. Division of RB and production of many progeny begins by 10-15 hours post infection. 4. Maturation of the noninfectious RB and EB occurs at 20-30 hours after infection. 5. Release of EB from the cell
How do Chlamydial species attach and penetrate host cells?
Penetration may be similar to receptor-mediated endocytosis but the exact mechanism is not understood. Endosome fusion with the lysosome is prevented and the chlamdiae remain bounded and protected by the endosomal membrane throughout the intracellular stage
When does step 2 of the developmental cycle of chlamydiae occur?
within a few hours after endocytosis
When does step 3 of the developmental cycle of chlamydiae occur?
10-15 hours post infection
When does step 5 of the developmental cycle of chlamydiae occur?
within 48 hours of initial infection
What does Chlamydia trachomatis cause?
infections primarily of eye and genital tract in humans only
What strains comprise Biovar I of Chlamydia trachomatis?
the lymphogranuloma venereum strains which produce invasive infections beyond the mucous membranes and can infect many cell types
What is the activity of biovar II of Chlamydia trachomatis?
the organisms are not systemically invasive and infections are limited largely to mucosal epithelial cells of the conjunctiva and urogenital tract
What diseases do strains of Biovar II of Chlamydia trachomatis cause?
Trachoma and Urogenital tract infections
What is Trachoma?
Chronic keratoconjunctivitis which is the leading cause of preventable blindness in the world
What specific urogenital tract infections does Chlamydia trachomatis cause?
urethritis in males, and urethritis and infertility in females
What does Chlamydia pneumoniae cause?
pneumonia and encephalitis that is transmitted from human to human with no intervening avian or animal host
What has human infection with Chlamydia pneumoniae been linked with?
atherosclerosis and thus strokes and heart attacks
What cells does Chlamydia psittaci infect?
epithelial and other cells including M-cells, fibroblasts, macrophages, and synovial cells in birds and mammals
What does serovar A of Chlamydia psittaci infect?
Psittacine
What does serovar B of Chlamydia psittaci infect?
pigeon
What does serovar C of Chlamydia psittaci infect?
duck
What does serovar D of Chlamydia psittaci infect?
turkey
Which serovar of Chlamydia psittaci is associated wit zoonotic disease in humans?
serovar A - as well as C and D in workers in poultry processing plants
What is the primary route of transmission of Chlamydia psittaci?
Large numbers of EB are passed in the feces of infected birds so the primary route of transmission is via the respiratory tract by inhalation of dust contaminated by feces
How long can Chlamydia psittaci remain infective in the environment?
for several months
What clinical signs are associated with a Chlamydia psittaci infection?
inappetence, depression, nasal and eye discharges, and death
What lesions are associated with a Chlamydia psittaci infection?
enlarged spleen and liver, inflammation of air sacs, fibrinous pericarditis, severe enteritis
How do you control Chlamydia psittaci?
quarantie all imported birds
What is the treatment for a Chlamydia psittaci infection?
Chloramphenicol or tetracycline in the feed for 45 days although they are not effective in eliminating the infection in all cases
What other species can Chlamydia psittaci cause disease in?
ruminants
What does Chlamydia abortus cause in sheep?
enzootic abortion
How is Chlamydia abortus transmitted?
fecal-oral: most commonly from infected female to pregnant female
What clinical signs are associated with Chlamydia abortus infection in sheep?
abortions occur in the last trimester - subsequent fertility is not usually impaired
Once a ewe aborts, is she cured from Chlamydia abortus?
no - she is protected from abortion in the future but remains infecgted ad subsequent lambs to her are often infected
What lesions are associated with Chlamydia abortus infections in sheep?
placentitis and necrosis of the placenta
What causes follicular conjunctivitis and polyarthritis in lambs?
could be Chlamydia abortus, psittaci, or pecorum
How do lambs get follicular conjunctivitis?
it is transmitted by face flies and direct contact
What lesions are associated with polyarthritis in calves?
high mortality, enlarged joints, lameness, fever, and conjunctivitis
What does Chlamydia felis cause?
feline pneumonitis or chlamydiosis
Chlamydia felis causes less than 5% of feline respiratory infections, however, it is a major cause of conjunctivitis in _______.
kittens
How is Chlamydia felis transmitted?
with direct contact with infected ocular and nasal discharges and air droplet infection
How long can recovered cats carry Chlamydia felis?
for at least 2 months
What clinical signs are associated with Chlamydia felis?
mild disease with conjunctivitis and rhinitis - a serous to mucopurulent discharge may start in one eye and spread to the other eye, if pneumonia develops, cats have fever, depression, and anorexia
Is there a vaccine for Chlamydia felis?
yes
What does Chlamydia suis cause?
conjunctivitis, arthritis, abortion, pneumonia
What ‘other’ syndromes are caused by Chlamydia species?
canine pneumonitis. Equine polyarthritis, and pneumonitis
From the public health standpoint, what is the most important reservoir of Chlamydial infections in humans?
turkeys
What has been incrimiated as the cause of several human abortions in people?
the enzootic ovine abortion agent
What immunity measures are important against chlamydial infections?
interactions with phagocytes, antibody response, and cell mediated immunity
How are Chlamydial infections diagnosed?
exfoliative cytology, isolation of the organism, serology
What are some methods of isolating Chlamydia?
cell culture, chick embryo, and lab animal inoculations
Are vaccines against chlamydial infections affective?
their protection is questionable
What is used for treatment of chlamydial infections?
tetracyclines - they only suppress growth and multiplication but do not eliminate the infection
