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Chlamydia, Rickettsia, & Friends
n/a
10
Medical
Graduate
05/25/2011

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Term
Chlamydia trachomatis
reservoir
morphology
transmission
life cycle
virulence
clinical
diagnostics
Definition
humans
gram-neg, but lacks peptidoglycan layer and muramic acid

direct person contact
primarily affects the eyes, genitals, lungs
Poor hygiene

1. elementary body (EB): infects *endosome*
2. initial (reticulate) body: after EB enters cell, it transforms into IB
-larger, fragile
-can reproduce via binary fission
-requires host ATP
-IB transforms back into EB, which leaves to infect other cells
*Chlaymdia are obligate intracellular parasites - steal ATP from host with ATP/ADP translocator

Resistant to lysozyme (CW lacks muramic acid)
prevents phagosome-lysosome fusion
non-motile
no pili
no exotoxins

Serotypes A,B,C:
Trachoma, scarring of inner eyelid, corneal scarring & blindness
D-K:
Inclusion conjunctivitis (opthalmia neonatorum)
Infant pneumonia
Urethritis, cervicitis and PID in women
Nongonococcal urethritis, epididymitis, prostatitis in men
Complications of infxn:
sterility, ectopic rpegnancy, chronic pain due to PID
Reiter's syndrome: conjunctivitis, urethritis, arthritis
Perihepatitis
L1, L2, L3:
*lymphogranuloma venereum*

Can't be grown on artificial media - use yolk sacs
Inclusion conjunctivitis: scrapings will show intracytoplasmic inclusion bodies; stain with iodine or Giemsa
Gram stain of genital secretions WON'T show gram-neg intracellular diplococci (that would be N. gonorrhoae)
PCR, immunofluorescence, serology
Term
Chlamydia psitacci
reservoir
transmission
life cycle
virulence
clinical
diagnostics
Definition
birds & poultry

bird feces dry out, fecal particles are inhaled, infecting the lungs

similar to C. trachomatis - EB infects, IB reproduces using host ATP

same virulence - lysozyme-resistant, no phago-lyso fusion, non-motile, no pili or exotoxins

Psittacosis: viral-like atypical pneumo, fever and dry, non-productive cough (similar to a Mycoplasma pneumo)

Serology
Intracytoplasmic inclusion bodies don't stain with iodine
Term
Chlamydophila pneumoniae
reservoir
transmission
metabolism
clinical
diagnostics
Definition
human to human

respiratory route

life cycle similar to C. trachomatis

atypical pneumonia: viral-like atypical pneumo in young adults

Serology: elevated titers of Ab with complement fixation
Intracytoplasmic inclusion bodies don't stain with iodine
Term
Rickettsia generalities
Definition
arthropod vector (except Q fever)
obligate intracellular parasites - use host ATP
grow in cytoplasm (Chlamydia replicates in endosome)
non-motile, no exotoxins
damages endothelial cells lining BV
culture: chick yolk sac, can't be grown on artificial media (except Bartonella)
Serology
Weil-Felix rxn
Term
Rickettsia rickettsii
reservoir
transmission
clinical
diagnostics
Definition
dogs, rabbits, wild rodents

wood or dog tick

NOT a platelet disorder - a BV disorder caused by bacteria in the vasculature
Rocky Mountain Spotted Fever: fever, conjunctival infxn, severe headache, rash on wrists, ankles, soles and palms initially, more generalized latere (petechiae is caused by endothelial invasion, proliferation, rupture)

PE, immunofluorescent of skin biopsy, serology
Weil-Felix: + OX-19, + OX-2
Term
Rickettsia prowazekii
reservoir
transmission
clinical
diagnostics
Definition
humans, flying squirrels

human body louse

Epidemic Louse-borne Typhus: abrupt fever & headache, *rash which spares the palms/soles/face,* delirium, stupor, gangrene of hands or feet
Brill-Zinsser Disease: reactivation of R. prowazekii, mild symptoms, no rash

Weil-Felix: + OX-19
Serology
Term
Rickettsia typhi
reservoir
transmission
clinical
diagnostics
Definition
rats, small rodents

rat flea

Endemic (Murine) Typhus: fever, headache, rash

Weil-Felix: + OX-19
Term
Bartonella henselae
Metabolism
clinical
diagnostics
Definition
Not an obligate intracellular parasite

Cat-scratch disease

Serology
Term
Coxiella burnetii
reservoir
transmission
clinical
diagnostics
Definition
cattle, sheep, goats

exception: no arthropod vector required
direct airborne transmission of endospore from cow hide or dried placenta, or consumption of contaminated unpasteurized cow milk

Exception: can grow with phagolysosomes
Has an endospore form

Q fever: fever, headache, viral-like pneumonia; *only rickettsial disease w/o a skin rash*
Complications: hepatitis, endocarditis

complement fixation test demonstrating rise in Ab
Term
Ehrlichia ss
reservoir
transmission
clinical
diagnostics
Definition
Dogs

ticks

Human Ehrlichiosis: similar to Rocky Mountain spotted fever, but rash is rare

rise in acute and convaslescent Ab titers
characteristic ehrlichial inclusion bodies sometimes seen in leukocytes on blood smear
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