chlamydia, rickettsia, and friends

Which two groups of gram(-) bacteria are obligate intracellular parasites?
Chlamydia and Rickettsia
How are Chlamydia and Rickettsia different from virus?
Virus has either DNA or RNA. Bacteria have both DNA and RNA.
How is Chlamydia different from other gram(-) bacteria?
Does not have a peptidoglycan layer, does not have muramic acid.
Which two forms does Chlamydia exist in?
* Elementary Body: metabolically inert, infectious.
* Initial Body (Reticulate Body): in the host cell, from binary fission of elementary body. requires host’s ATP for RNA and protein synthesis
What is the leading cause of preventable blindness? What causes it? Treatment?
Trachoma (a chronic conjunctivitis).
Chlamydia trachomatis.
Oral azithromycin.
Which organs does Chlamydia trachomatis target?
Eyes, lungs, and genitals.
What is inclusion conjunctivitis?
Babies from Chlamydia trachomatis – infected mothers. Diagnose by IDing basophilic intracytoplasmic inclusion bodies (collection of initial bodies).
Which urethritis-causing bacteria can penicillin treat?
Neisseria gonorrhoeae. Chlamydia trachomatis doesn’t have cell wall. Penicillin targets transpeptidase.
Three species that cause urethritis?
Neisseria gonorrhoeae
Chlamydia trachomatis
Ureaplasma urealyticum
What is pain with sexual intercourse?
dyspareunia
Treatment of pelvic inflammatory disease caused by Chlamydia trachomatis?
ceftriaxone shot + 14 days of oral doxycycline
What syndrome? Inflammatory arthritis of large joints, in men 20 – 40 y.o. Linked to Chlamydia trachomatis. Coexist with uveitis, conjunctivitis, or urethritis.
Reiter’s syndrome
Which syndrome? Infection of liver capsule, right upper quadrant pain. Associated with chlamydial/gonococcal infection.
Fitz-Hugh-Curtis syndrome
What is psittacosis?
atypical pneumonia caused by Chlamydophila psittaci, transmitted from birds.
How is Rickettsia different from Chlamydia?
* R requires an arthropod vector (tick, louse, flea)
* R replicates freely in the cytoplasm, C inside endosomes
* R: endothelial cells, C: columnar epithelium
* R causes rashes, high fevers, bad headaches; C causes eye inflammation, pneumonia, STD
Diagnostic methods of Rickettsial infection
* Weil-Felix test (share antigen characteristics with Proteus vulgaris)
* IFA (indirect immunofluorescence test)
* CF (complement fixation test)
* ELISA (enzyme-linked immunosorbent assay)
Treatment of Rickettsial infection?
doxycycline and chloramphenicol
Which two Rickettsial species cause typhus?
epidemic typhus: Rickettsia prowazekii (lice)
endemic typhus: Rickettsisa typhi (flea)
Infection to one confers immunity to the other!
What is “Brill-Zinsser Disease”?
When Rickettsia prowazekii is not eradicated, the latent bacteria cause symptoms. Dx: IgG titer (not IgM)
What causes trench fever (ricketssial infection-like symptoms) ?
Bartonella quintana
What causes “cat-scratch disease”?
Bartonella henselae
Which Rickettsia species has endospores?
Coxiella burnetii. Not transmitted by arthropods. Causes pneumonia and Q fever; no rash.

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