USMLE Step I Microbiology > HIV > Flashcards

HIV Flashcards

(52 cards)

Study These Flashcards
1
Q

what kind of genome does HIV have?

A
  • diploid genome
    • 2 molecules of RNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are the 3 structural genes of HIV?

A
  • env (gp120 and gp41)
    • formed from cleavage of gp160 to form envelop glycoproteins
    • gp120–attachment to host CD4+ T cell
    • gp41–fusion and entry
  • gag (p24 and p17–capsid and matrix proteins, respectively)
  • pol–reverse transcriptase, aspartate protease, integrase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

HIV–mechanism

A
  • reverse transcriptase synthesizes dsDNA from genomic RNA
  • dsDNA integrates into host genome
  • virus binds CD4 as well as a coreceptor
    • either CCR5 on macrophages (early infection)
    • OR CXCR4 on T cells (late infection)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

HIV–homozygous CCR5 mutations

A
  • = immunity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

HIV–heterozygous CCR5 mutation

A
  • = slower course
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

HIV–tests for diagnosis and pros/cons

A
  • presumptive diagnosis made with ELISA
    • sensitive
    • high false + rate
    • low threshold
      • rule out test
    • results are then confirmed with Western blot assay
      • specific
      • low false + rate
      • high threshold
        • rule in test
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

HIV–viral load

A
  • viral load tests determine the amount of viral RNA in the plasma
    • high viral load associated with a poor prognosis
  • also use viral load to monitor effect of drug therapy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

AIDS–diagnosis

A
  • less than or equal to 200 CD4+ cells/mm3
    • normal is 500-1500 cells/mm3
  • HIV+ with AIDS defining condition (ie. Pneumocystis pneumonia) or CD4+ percentage <14%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what do ELISA/Western blot tests look for to diagnose HIV?

when may they give a false result?

A
  • ELISA/Western blot tests look for antibodies to viral proteins
  • often false - in first 1-2 months of HIV infection
  • often false + initially in babies born to infected mothers (anti-gp120 crosses placenta)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

explain the time course of untreated HIV infection

A
  • Four stages of untreated infection:
    • Flu like (acute)
    • Feeling fine (latent)
      • during latent phase, virus replicates in lymph nodes
    • Falling count
    • Final crises
  • Most patients who do not receive treatment eventually die of complications of HIV infection
  • Graph:
    • red line = CD4+ T cell count (cells/mm3)
    • blue line = HIV RNA copies/mL plasma
    • blue boxes on vertical CD4+ count axis indicate moderate immunocompromise (<400 CD4+ cells/mm3) and when AIDS defining illnesses emerge (<200 CD4+ cells/mm3)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

other diseases in HIV+ adults

A
  • as CD4+ cell count decreases, risks of reactivation of past infections (ie. TB, HSV, shingles), dissemination of bacterial infections and fungal infections (ie. coccidioidomycosis), and non-Hodgkin lymphomas increase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are common pathogens in an HIV+ patient when CD4+ cell count < 500/mm3?

A
  • Candida albicans
  • EBV
  • Bartonella henselae
  • HHV-B
  • Cryptosporidium spp.
  • HPV
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Candida albicans–presentation in HIV+ patients (CD4+ <500/mm3​)

A
  • oral thrush
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Candida albicans–findings in HIV+ patients (CD4+ <500/mm3​)

A
  • scrapable white plaque
  • pseudohyphae on microscopy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

EBV–presentation in HIV+ patients (CD4+ <500/mm3)

A
  • oral hairy leukoplakia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

EBV–findings in HIV+ patients (CD4+ <500/mm3​)

A
  • unscrapable white plawue on lateral tongue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Bartonella henselae–presentation in HIV+ patients (CD4+ <500/mm3​)

A
  • bacillary angiomatosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Bartonella henselae–findings in HIV+ patient (CD4+ <500/mm3​)

A
  • biopsy with neutrophilic inflammation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

HHV-8–presentation in HIV+ patient (CD4+ <500/mm3​)

A
  • Kaposi sarcoma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

HHV-8–findings in HIV+ patient (CD4+ <500/mm3​)

A
  • biopsy with lymphocytic inflammation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Cryptosporidium spp.–presentation in HIV+ patients (CD4+ <500/mm3​)

Study These Flashcards
A
  • chronic, watery diarrhea
22
Q

Cryptosporidium spp.–findings in HIV+ patients (CD4+ <500/mm3​)

Study These Flashcards
A
  • acid fast oocysts in stool
23
Q

HPV–presentation in HIV+ patients (CD4+ <500/mm3​)

Study These Flashcards
A
  • squamous cell carcinoma
    • commonly of anus (men who have sex with men) or cervix (women)
24
Q

what are common pathogens in an HIV+ adult with CD4+ cell count < 200/mm3?

Study These Flashcards
A
  • HIV
  • JC virus (reactivation)
  • pneumocystis jirovecii
25
HIV--presentation in HIV+ patient (CD4+ \<200/mm3​)
* dementia
26
JC virus (reactivation)--presentation in HIV+ patient (CD4+ \<200/mm3​)
* progressive multifocal leukoencephalopathy
27
JC virus (reactivation)--findings in HIV+ patient (CD4+ \<200/mm3​)
* nonenhancing areas of demyelination on MRI
28
*Pneumocystis jirovecii*--presentation in HIV+ patient (CD4+ \<200/mm3​)
* *Pneumocystis* pneumonia
29
*Pneumocystis jirovecii*--findings in HIV+ patient (CD4+ \<200/mm3​)
* "ground glass" opacities on CXR
30
what are common pathogens in HIV+ adults with CD4+ cell count \<100/mm3?
* *Aspergillus fumigatus* * *Cryptococcus neoformans* * *Candida albicans* * CMV * EBV * *Histoplasma capsulatus* * *Mycobacterium avium--intracellulare, Mycobacterium avium**​* complex * *Toxoplasma gondii*
31
*Aspergillus fumigatus--*presentation in HIV+ patient (CD4+ \<100/mm3)
* hemoptysis * pleuritic pain
32
*Aspergillus fumigatus*--findings in HIV+ patient (CD4+ \<100/mm3​)
* cavitation or infiltrates on chest imaging
33
*Cryptococcus neoformans*--presentation on HIV+ patient (CD4+ \<100/mm3​)
* meningitis
34
*Cryptococcus neoformans*--findings in HIV+ patient (CD4+ \<100/mm3​)
* encapsulated yeast on India ink stain or capsular antigen +
35
*Candida albicans*--presentation in HIV+ patient (CD4+ \<100/mm3​)
* esophagitis
36
*Candida albicans*--findings in HIV+ patient (CD4+ \<100/mm3​)
* white plaques on endoscopy * yeast and pseudohyphae on biopsy
37
CMV--presentation in HIV+ patients (CD4+ \<100/mm3​)
* retinitis * esophagitis * colitis * pneumonitis * encephalitis
38
CMV--findings in HIV+ patients (CD4+ \<100/mm3​)
* linear ulcers on endoscopy, cotton wool spots on fundoscopy * biopsy reveals cells with intranuclear (owl eye) inclusion bodies
39
EBV--presentation in HIV+ patient (CD4+ \<100/mm3​)
* B cell lymphoma * ie. non Hodgkin lymphoma, CNS lymphoma
40
EBV--findings in HIV+ patient (CD4+ \<100/mm3​)
* CNS lymphoma * ring enhancing, may be solitary (vs. *Toxoplasma*)
41
*Histoplasma capsulatum*--presentation in HIV+ patients (CD4+ \<100/mm3​)
* fever * weight loss * fatigue * cough * dyspnea * nausea * vomiting * diarrhea
42
*Histoplasma capsulatum*--findings in HIV+ patient (CD4+ \<100/mm3​)
* oval yeast cells within macrophages
43
*Mycobacterium avium-intracellulare, Mycobacterium avium* complex--presentation (CD4+ \<100/mm3​)
* nonspecific systemic symptoms * fever * night sweats * weight loss * focal lymphadenitis
44
*Toxoplasma gondii*--presentation in HIV+ patients (CD4+ \<100/mm3​)
* brain abscesses
45
*Toxoplasma gondii*--findings in HIV+ patients (CD4+ \<100/mm3​)
* multiple ring enhancing lesions on MRI
46
Prion diseases--mechanism, transmission
* prion dzs are caused by the conversion of a normal (pre-dominantly alpha helical) protein termed prion protein (PrPc) to a beta pleated form (PrPsc) * PrPsc is transmissible via CNS related tissue (iatrogenic CJD) or food contaminated by BSE-infected animal products (varian CJD) * PrPsc resists protease degradation and facilitates the conversion of still more PrPc to PrPsc
47
Prion diseases--what is it resistant to
* standard sterilizing procedures * including standard autoclaving
48
Prion diseases--what does accumulation of PrPsc result in?
* spongiform encephalopathy (A) and dementia * ataxia * death
49
what are 3 diseases that result from prions?
* Creutzfeldt-Jakob disease * Bovine spongiform encephalopathy * Kuru
50
Creutzfeldt-Jakob disease
* rapidly progressing dementia * typically sporadic (some familiar forms)
51
Bovine spongiform encephalopathy (BSE)
* also known as "mad cow disease"
52
Kuru
* acquired prion disease noted in tribal populations practicing human cannibalism
USMLE Step I Microbiology
flashcards
Decks in class (44)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions