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ehamm
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Organism
- Obligate intracellular bacteria
- No rigid cell wall
- trilaminar outer membrane, with LPS
- Lack peptidoglycan layer
- Only grow in eukaryote cells
- Ribosomes
- Lack genes for amino acid synthesis
- Ag in outer membrane proteins
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Replicative cycles
- Two forms
- Elementary bodies: infectious form, hardy, attaches to receoptors of plasma membranes, enters and converts to replicative body
- RB: active protein synthesis, expands by fusing with lipids of golgi -> forms inclusion body, compacts to form EB
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Forms
- Trachoma (A-c)
- Genital (b, d-k)
- LGV (l1-l3)
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Epidemiology
- Genital infection: spread by secretions, humans sole reservoir, more asymptomatic in men
- Eye infection: inclusion conjuctivitis (direct contact with infective cervical secretions); Trachoma ( chronic follicular conjunctivitis, usually contracted at birth, spread via direct contact or flies, repeated re-infections, blindness)
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Pathogenesis
- Tropism for epithelial cells of endocervix, upper genital tract, urethra, rectum and conujunctiva
- enter via endocytosis, inhibit phagosome-lysosome fusion
- Causes inflammation -> scarring
- immunity: no reliable against reinfection
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Manifestations
- Trachoma: chronic infection of eyelids; increased vascularization of corneal conjunctiva leads to scarring over 15-20 years; most common cause of infectious blindness; poor hygiene/sanitation; inversion of eyelashes
- Inclusion conjunctivitis: acute infection in infants and adults; acute, copious, purulent eye exudate; not associated with chronicity
- Genital: urethritis, epididymitis in mean and cervitis, salpingitis, and urethral syndrome in women; dysuria and discharge; can cause PID in 5-20% of women -> scarring, ectopic pregnancy
- LGV: MSM, HIV+ assoc; local and systemic venereal disease; multi system involvement; inguinal adenopathy, LGV proctitis
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Diagnosis
- Epithelial cells from site of infection
- Inclusion bodies
- Culture: cells stained with IF
- Non-culture: DFA, immunoassays, PCR; more sensitive, faster
- Tx: tetracycline, azithromycin for trachoma
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