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
