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Flashcards in STIs Deck (7)
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1

What viral family does HIV belong to? What features characterize this family?

- HIV is an RNA virus belonging to the retrovirus family
- ssRNA (linear)
- enveloped
- has reverse transcriptase
- (HIV contains 2 copies of its ssRNA genome)

2

What are the three genes coded for by HIV's RNA genome? Which proteins arise from each?

- gag, pol, and env
- gag: p24 (capsid protein; the antigen)
- pol: reverse transcriptase, aspartate protease, and integrase
- env: gp120 (binds to CCR5 receptor on CD4+ T-cells), gp41 (promotes fusion and entry)

3

What is "acute HIV syndrome" and how do patients present?

- this is the initial infection with HIV and occurs in about 2/3 of those infected
- it is the dissemination of the virus into lymphoid organs, resulting in generalized lymphadenopathy, fever, pharyngitis, maculopapular rash, splenomegaly
- the viral load peaks at this time (it returns to this elevated peak in end-stage AIDS)
- (notice the resemblance to EBV's mononucleosis)

4

How do screen for HIV? How do we confirm the diagnosis?

- screen with ELISA: (sensitive; rule out) if negative, patient is HIV negative; if positive, must confirm
- confirm with Western blot: (specific; rule in) if negative, patient is HIV negative (false positive ELISA); if positive, patient is HIV positive

5

When does an HIV person develop AIDS? What are some AIDS-defining conditions with a CD4+ count less than 200? What about less than 100? Less than 50? Which malignancies are associated with AIDS?

- AIDS is when an HIV patient has a CD4+ T-cell count that drops below 200 cells/mm cubed (or if they have an AIDS-defining condition)
- less than 200: Pneumocystis jirovecii (pneumonia), Cryptosporidium (GI infection), JC virus reactivation (causes encephalopathy)
- less than 100: Histoplasma (systemic), C. albicans (esophageal thrush), Toxoplasmosis
- less than 50: Mycobacterium-avium complex (TB-like disease), Cryptococcus neoformans (meningitis), CMV
- malignancies: Kaposi sarcoma, SCC (anal or cervical), non-Hodgkin lymphoma

6

What are the major STIs in order of incidence?

- chlamydia (by far MC)
- gonorrhea
- HCV
- syphilis (especially in MSM)
- HIV (especially in MSM)
- lymphogranuloma venereum (LGV)
- congenital syphilis

7

What bacteria make up the normal flora of the vagina? What is the normal pH of the vagina? What are the three common infections of the vagina and how is the pH changed in each? What findings do we see for each?

- normal flora: Lactobacilli; maintains the pH at 3.8-4.5
- bacterial vaginosis (Gardnerella vaginalis): pH is mildly less acidic (5-6); thin, watery, discharge with fishy odor (particularly after sex); no inflammation; clue cells on histo
- trichomoniasis (Trichomonas vaginalis): pH is less acidic (6-7); foul-smelling, green discharge; inflammation with itching and burning ("strawberry cervix"); motile trophozoites on wet mount
- candidiasis: pH is normal; thick, white, cottage-cheese discharge; inflammation; pseudohypae