Flashcards in Chlamydia, Rickettsia, And Friends Deck (63):
Where is C.trachomatis found?
What is the morphology of C.trachomatis?
Gram(-), but lacks peptidoglycan layer and muramic acid.
How is C.trachomatis transmitted?
1. Direct personal contact
2. Due to poor hygiene
What does C.trachomatis primarily affect?
What is the life cycle of C.trachomatis?
1. Elementary body: dense spherule that infects cells.
2. Initial (reticulate) body: after EB enters the cell, it transforms into an initial body.
What is the metabolism of C.trachomatis?
1. Larger and osmotically fragile
2. Can reproduce via binary fission
3. Requires ATP from the host
4. The initial body transforms back into EB, which leaves the cell to infect other cells
What is important to keep in mind about Chlamydia?
They are obligate intracellular parasites - steal ATP from host with ATP/ADP translocator.
What is the virulence of C.trachomatis?
1. Resistant to lysozyme (since their cell wall lacks muramic acid).
2. Prevents phagosome-lysosome function.
4. No pili
5. No exotoxin
What can serotypes A,B,C of C.trachomatis cause?
Trachoma: causes scarring of the inside of the eyelid, resulting in redirection of the eyelashes onto the corneal surface. This results in corneal scarring and blindness.
What do serotypes D through K of C.trachomatis cause?
1. Ophthalmia neonatorum - inclusion conjunctivitis.
2. Infant pneumonia
3. Urethritis, cervicitis, PID (women)
4. Non gonococcal urethritis, epididymitis and prostatitis (men)
What are the complications of chlamydial genital tract infections?
1. Sterility, ectopic pregnancy and chronic pain may occur after PID.
2. Reiter's syndrome: triad of conjunctivitis, urethritis, and arthritis.
3. Fitz-Hugh-Curtis syndrome - perihepatitis.
4. Serotypes L1, L2, L3 --> Lymphogranuloma venereum.
Where is C.trachomatis "cultured"?
Can NOT grow on artificial media. Classically be grown in chick yolk sacs. Also, it is cultured in certain cell lines (McCoy lines).
How can we identify C.trachomatis in inclusion conjunctivitis (ophthalmia neonatorum)?
Scrapings from the surface of the conjunctiva will show intracytoplasmic inclusion bodies within conjunctival epithelial cells.
The inclusion bodies contain glycogen, and thus stain with iodine or giemsa.
How can we identify C.trachomatis in urethritis?
Most commonly diagnosed by PCR of urethral swab or urine sample.
How can we identify C.trachomatis in Lymphogranuloma venereum?
1. Serologic tests
2. Frei test, which is rarely used, is similar to the PPD skin test for TB.
Where is Chlamydophila psittaci found?
Birds and poultry.
How is C.psittaci transmitted?
1. Bird feces dry out.
2. Fecal particles are inhaled, infecting the lungs.
What is the life cycle of Chlamydophila psittaci?
Similar to C.trachomatis.
What is the virulence of C.psittaci?
Same as the one of C.trachomatis.
What can C.psittaci cause?
Psittacosis: viral-like atypical pneumonia , with fevere and dry, non-productive cough (similar to Mycoplasma pneumonia).
How can we identify C.psittaci?
2. Intracytoplasmic inclusion bodies do not stain with iodine
Where is Chlamydophila pneumoniae found?
Humans - spread from human to human.
How is C.pneumoniae transmitted?
What is the life cycle of C.pneumoniae?
Similar to C.trachomatis.
What can C.pneumoniae cause?
Atypical pneumonia in young adults.
How can we identify C.pneumoniae?
The same way we do with C.psittaci.
Where is Rickettsia rickettsii found?
Dogs, rabbits, and wild rodents.
What can R.rickettsia cause?
Rocky Mountain spotted fever:
2. Conjunctival injection (redness)
3. Severe headache
4. Rash on wrists, ankles, soles and palms initially - becomes more generalized.
How can we identify R.rickettsii?
1. Clinical exam
2. Direct immunofluorescent exam of skin biopsy from rash site.
4. Weil-Felix reaction: Positive for OX-19 and OX-2.
Where is Rickettsia akari found?
How is R.akari transmitted?
Mites (which live on the house mice).
What can R.akari cause?
Rickettsial pox: vesicular rash similar to chicken pox - resolves over 2 weeks.
How can we identify R.akari?
Weil-Felix reaction negative.
Where is R.prowazekii found?
2. Flying squirrels
How is R.prowazekii transmitted?
Human body louse (pediculus corporis).
What can R.prowazekii cause?
1. Epidemic Louse-borne Typhus
2. Brill-Zinsser disease
What happens in epidemic Louse-borne typhus?
1. Abrupt onset of fever and headache.
2. Rash, which spares the palms, soles, and face.
4. Gangrene of hands or feet
What happens in Brill-Zinsser disease?
1. Reactivation of R.prowazekii
2. Mild symptoms
3. No rash
How can we identify R.prowazekii?
1. Weil-Felix reaction: positive OX-19.
Where is R.typhi normally found?
2. Small rodents
How is R.typhi transmitted?
Via rat flea (Xenopsylla cheopis).
What can R.typhi cause?
Endemic (or murine) typhus --> fever, headache, rash.
How can we identify R.typhi?
Weil-Felix reaction positive OX-19.
Where is R.tsutsugamushi found?
How is R.tsutsugamushi transmitted?
Mite larvae (chiggers).
What can R.tsutsugamushi cause?
1. Fever and heachache
2. Eschar (scab) at bite site
3. Followed by a rash
How can we identify R.tsutsugamushi?
Weil-Felix reaction positive OX-K.
Where is Bartonella quintana found?
How is B.quintana transmitted?
What is the metabolism of B.quintana?
Not an obligate intracellular parasite.
What can B.quintana cause?
1. Trenche fever
4. Bacillary angiomatosis
What happens in Trench fever?
Headache and back pain.
It lasts for 5 days and recurs at 5 days intervals.
How can we identify B.quintana?
Is Bartonella henselae an obligate intracellular parasite?
What can Bartonella henselae cause?
1. Cat-scratch disease
2. Bacillary angiomatosis
4. Endocarditis (culture-negative)
How can we identify B.henselae?
Where is Coxiella burnetii found?
How is C.burnetii transmitted?
EXCEPTION - NO arthropod vector is required.
Direct airborne transmission of endospore from cow hide or dried placenta, or via consumption of endospore-contaminated unpasteurized cow milk.
What is the metabolism of C.burnetii?
1. Can grow at a pH of 4.5 within phagolysosomes.
2. Has an endospore form.
What can C.burnetii cause?
1. Q fever
What happens in Q fever?
3. Viral-like pneumonia
4. NO RASH!!! This is the ONLY rickettsial disease without a skin rash!!
How can we identify C.burnetii?
1. Complement fixation test demonstrating a rise in antibody.