STIs (Dr. Whittum-Hudson)

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  1. Chlamydia Trochomatis
    General Characteristics?
    • Obligate intracellular bacteria
    • No peptidoglycan wall
    • Not an energy parasite
    • 2 forms: Infectious elementary bodies (EBs), Non-infectious metabolically active reticularbodies (RBs)
  2. Chlamydia Trochomatis
    Virulence factors?
    • Endosome/lysosome fusion inhibited in host cells
    • Multiple inclusions formed from >1 infectious EB
    • Infection can become persistent under stressful conditions - stress proteins hsp6O, hsp10
    • INF-gamma
  3. Chlamydia Trochomatis
    • Serotypes D-K cause UG infectious
    • Persistent infections are possible
    • Chronic inflammation and tissue scarring (fibrosis)
    • Disease in men - urethritis, epididymitis, orchitis, reactive arthritis
    • Disease in women - cervicitis and salpingitis, urethral syndrome, chronic pelvic pain, reactive arthritis
    • Vaginal discharge, but usually asymptomatic
    • Lymphogranuloma venereum (caused by L1, L2, L3 serotypes, fever, rashes, nausea; no known treatment)
  4. Chlamydia Trochomatis
    Clinical ID?
    • "First catch urine" specimen
    • Multiplex to detect >1 STD pathogen
    • Pus from lesions (LGV only)
  5. Chlamydia Trochomatis
    • Tetracyclines and erythromycin
    • May use macrolides ("Z-pack")
    • Beta-lactams are not effective!
  6. Neisseria gonorrhoeae
    General characteristics?
    • Gram-, non-motile diplococci
    • Fastidious organism, growth inhibited by fatty acids
    • Grows best on CAP
    • Facultative
  7. Neisseria gonorrhoeae
    Virulence factors?
    • Pili (hair-like appendages) - phase variation, antigenic variation, piliE, CD46 is a receptor
    • Opa proteins - reversible phase variation
    • Lipooligosaccharide (LOS)
    • Outer membrane protein 1 (OMP1)
    • IgA protease
    • Transferrin receptor
  8. Neisseria gonorrhoeae
    • Bacteria adhere to mucosal surface
    • Non-sexual transmission is rare
    • Gonococci can invade epithelial cells
    • Granulocyte response ->> mucosal damage
    • Can migrate to fallopian tubes and ovaries, or prostate and epididymis
    • Disseminated gonococcal infection is rare, but can result in bacteremia and hematogenous spread
    • Gonococcal arthritis, dermatitis, and endocarditis (rare)
    • Disease in men - urethra infection, dysuria and purulent urethral discharge
    • Disease in women - endocervix infection, vaginal discharge, urinary frequency, dysuria, chronic pelvic pain
    • Infertility in 20% of women with gonococcal salpingitis
  9. Neisseria gonorrhoeae
    Clinical ID and Diagnosis?
    • Gram smears
    • Cultures from gonococcus from urethral exudates or urethral scrapings (men) or cervical swabs (women) are positive
    • Oxidase positive
    • NAAT
    • Multiplex for multiple STD pathogens
  10. Neisseria gonorrhoeae
    • Peicillin resistance
    • Possible co-infection with Chlamydia
    • No lasting protective immunity after infection!
  11. Treponema pallidum (Syphilis)
    General characteristics?
    • Obligate human pathogen
    • Gram- spirochete
    • Very motile
    • Difficult to culture
    • Metabolically crippled organism
    • Rapid death in environment, sensitive to antimicrobial
    • Direct sexual contact transmission
    • Transplacental transmissions may occur
    • Causes genital ulcers (chanchres)
    • More males are infected than females!
  12. Treponema pallidum (Syphilis)
    Virulence factors?
    • Hyaluronidase - invasion
    • Inhibition of complement attack
  13. Treponema pallidum (Syphilis)
    Disease of blood vessels and perivascular areas - quickly disseminates and spreads to perivascular lypmhatics and systemic circulation
  14. List the 5 types of Syphilis and give a description of each.
    • Primary Syphilis
    • Chancre develop within 3-4 weeks
    • Chancre is round, hard, reddish, and painless
    • Located on penis, external genitalia, anal area, or lips - women may have chancres on cervix or vagina
    • Primary lesions visualized via darkfield microscopy
    • Lesions heal within 4-6 weeks
    • Secondary Syphilis
    • Develop within 2-10 weeks after primary lesions have healed
    • Fever, sore throat, rash, skin lesions on palms, soles of feet and face
    • Secondary lesions are highly infectious
    • Latent Syphilis
    • No signs or symptoms
    • Seroreactive
    • Antimicrobial are effective at this stage and prevent progression towards tertiary syphilis
    • Tertiary Syphilis (rare)
    • Non-progressive localized granulomatous lesions of the skin, bone, and joints called gummas
    • Neurosyphilis
    • Cardiovascular syphilis
    • Presence of organisms in tertiary lesions are rare
    • Congenital Syphilis
    • Anti-treponemal IgM present in infant indicates infection
    • Fetus is susceptible at any time during gestation
    • Causes prematurity, low birth weight
    • Most babies are asymptomatic at birth for 3-8 weeks
  15. Treponema pallidum (Syphilis)
    Clinical ID and Diagnosis?
    • Darkfield microscopy - fluid from primary or secondary lesions
    • Fluorescent antibodies
    • Serologically diagnosed
    • Non-treponemal cardiolipin antigen
    • Treponema-specific tests
    • NAATs
  16. Treponema pallidum (Syphilis)
    • Penicilin - highly effective
    • "Z-pack" also used for 4 treatment regimen
  17. Hemophilus ducreyi (Chancroid)
    General characteristics?
    • Fastidious organism
    • Gram- rod
    • Painful genital ulcers with ragged edges
    • Can infect non-genital skin, mucosal surfaces and stratified squamous epithelium
    • Increases susceptibility to HIV
  18. Hemophilus ducreyi (Chancroid)
    • Antibody based
    • DNA probes
    • Multiplex PCRs
  19. Hemophilus ducreyi (Chancroid)
    • "Z-pack"
    • Ceftriaxone
    • Erythromycin
    • HIV co-infection may alter response to treatment
  20. Candida albicans (not typically an STD)
    General characteristics?
    • "Yeast infections"
    • Pseudohyphae
    • Normal inhabitant of mouth and vagina
  21. Candida albicans (not typically an STD)
    Virulence factors?
    • Adhesins - vaginal epithelial cells
    • Morphogenesis - phenotypic switching, tissue invasion
    • Proteases
    • Phospholipases
    • Biofilm formation
    • Binds to fibronectin, collagen and laminin
  22. Candida albicans (not typically an STD)
    • Result from direct mucosal contact with lesions
    • Increased frequency in AIDS patients
    • Factors that can contribute to infection: pregnancy, diabetes, oral contraceptives, antibiotics
  23. Candida albicans (not typically an STD)
    • Patches or gray-white pseudomembrane develop on vaginal mucosa
    • Yellow-white discharge
    • Hyphal forms seen in skin scrappings and vaginal exudate
  24. Candida albicans (not typically an STD)
    • Topical nystatin
    • Miconazole
  25. Trochomonas vaginalis
    General characteristics?
    • Flagellated protozoan - highly motile
    • No cyst form
    • Viable for up to 24 hours in urine, semen and water
    • Disease in men - prostate and urethral infection
    • Disease in women - vaginal infection
  26. Trochomonas vaginalis
    • Nonvenereal transmission is rare
    • Direct contact with T. vaginalis with squamous epithelium > destroys involved cells and induces PMN inflammatory response
    • Trichomonas can phagocytose bacteria, viruses, RBCs, PMNs and lactobacillus (disrupts normal flora)
    • Infected men - usually asypmtomatic
    • Infected women - dysuria, vaginal itching and burning, foamy yellowish-green discharge
  27. Trochomonas vaginalis
    • Microscopic examination
    • Colpitis - red spots (strawberry cervix)
  28. Trochomonas vaginalis
    • Oral metronidazole (Flagyl)
    • Treatment of partners desirable
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STIs (Dr. Whittum-Hudson)
2012-09-05 15:22:32

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