questions 16

Human Immunodeficiency Virus (HIV)

Topic updated on 11/24/17 9:49am

  • A 36-year-old woman is admitted to a hospital in India with a three-week history of fever, headache, and increasing drowsiness. Past medical history reveals she was diagnosed with pulmonary TB nine months ago. She is in the continuation phase of her anti-TB regimen. On exam, patient is pale and emaciated. There are coarse crackles in both lung fields. She is disoriented to time, person, and place but responds to commands. Kernig sign is positive. A complete blood count revealed a hematocrit of 30%, WBC of 12,500 cells/mm3, with 84% neutrophils. Urinalysis, basic metabolic profile, and liver function tests were within normal limits. Sputum for AAFB was negative. A HIV screen was positive and this was confirmed with a Western blot. CD4 count was 57 cells/μL. Fundoscopy was normal. Chest radiograph revealed bilateral opacities in both lung fields. CT scan of the brain was normal. CSF analysis revealed lymphocytes 64 cells/mm3, protein 84mg/dL and glucose 31 mg/dL. Gram and Ziehl-Neelsen stains were negative. CSF for India ink stain was positive for Cryptococcus neoformans.
  • Classification
    • (+) ssRNA retrovirus
      • HIV
  • CD4 < 400 cells/μL 
    • constitutional symptoms ("wasting syndrome")
      • weight loss
      • fever
      • night sweats
      • adenopathy
    • bacterial infections
      • M. tuberculosis
      • H. influenzae
      • S. pneumoniae
      • Salmonella
      • Nocardia may cause TB-like pulmonary cavitations 
    • oral thrush (Candida albicans)
    • tinea pedis
    • reactivation VZV
  • CD4 < 200 cells/μL 
    • PCP (Pnuemocystis jiroveci pneumonia)
    • Cryptococcus neoformans
    • Cryptosporidium
    • Coccidioidomycosis
    • reactivation HSV
    • Iospora
  • CD4 < 100 cells/μL
    • Toxoplasma gondii 
      • when patient presents with neurological findings
        • next best step is imaging of the head (CT or MRI)
      • if ring enhancing lesion is present
        •  the next best step is empiric treatment with pyrimethamine-sulfadiazine
      • if treatment fails, biopsy of lesion is necessary
    • Histoplasmosis
    • Candida albicans esophagitis
      • Candida is the most common cause of esophagitis in late HIV undefined
    • Kaposi Sarcoma
      • eruption of violaceous plaques Skin lesions of Kaposi Sarcoma
      • could be indicative of HIV
      • more common in men who have sex with men
  • CD4 < 50 cells/μL blood
    • M. avium-intracellulare  
    • CMV
      • retinitis and esophagitis
    • Cryptococcus neoformans
      • meningoencephalitis
  • HIV in the neonate (a ToRCHeS infection)
    • recurrent infections
      • oral thrush
      • interstitial pneumonia
    • chronic diarrhea
    • lymphopenia
  • HIV encephalitis
    • HIV crosses BBB via infected macrophages
    • results in inflammation in the brain
      • appearance of microglial nodules with multinucleated giant cells
    • occurs late in the course of HIV infection
  • AIDS dementia complex
    • mental status changes
    • depression
    • ataxia
    • seizures
    • urinary and bowel incontinence
  • Serous otitis media 
    • from obstructive lympadenopathy/lymphomas
  • Diagnosis of HIV
    • ELISA is the first step in diagnosis
      • high false-positive rate (high sensitivity and low specificity)
      • rules OUT the possibility of infection
    • HIV 1/2 differentiation assay 
      • best confirmatory test
      • returns result more quickly than a Western blot
    • Western blot is then used to confirm positive results
      • high false-negative rate (low sensitivity and high specificity)
      • rules IN the diagnosis of infection
    • Both tests detect antibodies to HIV proteins
      • antibodies take 3-6 weeks to develop
      • tests can be falsely negative in first 1-2 months of infection
      • tests can be falsely positive in babies born to infected mothers
        • anti-gp120 crosses placenrta
    • the presence of viral RNA or antigens (e.g. p24) can also be tested directly
  • Diagnosis of AIDS
    •  CD4+ ≤ 200 cell/ul (normal: 500-1500 cells/ul)
    • CD4+ percentage <14%
    • HIV positive with AIDS-associated infection
      • e.g., P. jiroveci pneumonia
  • Viral load tests
    • PCR used to monitor effects of therapy on viral load
    • high viral load associated with poor prognosis
  • Other causes of immune suppresion
    • cancer chemotherapy
    • organ transplant patients
    • congenital immuonodeficiencies
  • Over 25 HIV drugs exist in multiple categories
    • CCR5 inhibitors
    • fusion inhibitors
    • reverse transcriptase inhibitors
    • integrase inhibitors
    • protease inhibitors
  • Highly active antiretroviral therapy (HAART)
    • combines multiple drugs with multiple mechanisms of action to prevent resistance
      • e.g., tenofovir + emtricitabine + efavirenz or many other possible combinations
  • Pregnancy
    • use zidovudine (ZDV and AZT) to prevent mother-to-fetus transmission 
    • efavirenz and delavirdine are thought to be teratogenic 
    • HIV is an absolute contraindication to breastfeeding in the United States  
Prognosis, Prevention,  and Complications
  • Prognosis
    • has improved but depends on multiple factors
      • most important access to proper drug treatment
    • poor prognostic factors include
      • high viral RNA loads
      • CD4 count < 200 cells/μL 
  • Prevention 
    • no effective HIV vaccine available
      • for exposure: obtain HIV serology and immediately initiate three-drug antiretroviral therapy 
    • vaccination against secondary infection
      • pneumococcal vaccine is indicated in HIV-positive patients 
      • live vaccines are contraindicated in HIV-positive patients
        • MMR and Varicella can be given IF CD4 count is >200 cells/μL blood
    • secondary prevention involves prevention of opportunistic infection
      • CD4 count used to determine need for prophylaxis
        • < 200 cells/μL TMP-SMX for Pneumocystis pneumonia
        • < 100 cells/μL TMP-SMX for toxoplasmosis
        • < 50 cells/μL azithromycin for M. avium-intercellulare
  • Complications
    • may be due to HIV infection or side effects of HAART
      • dyslipidemia
      • glucose intolerance/diabetes mellitus
      • cardiovascular disease


Qbank (5 Questions)

(M3.ID.9) A 27-year-old G2P1 female is diagnosed with an HIV infection after undergoing routine prenatal blood work testing. Her estimated gestational age by first-trimester ultrasound is 12 weeks. Her CD4 count is 550 cells/mm^3 and her viral load is 26,000 copies/mL. She denies experiencing any symptoms of HIV infection. Which of the following highly active antiretroviral therapy (HAART) medications should be avoided in this patient? Topic Review Topic

1. Nelfinavir
2. Zidovudine
3. Lamivudine
4. Efavirenz
5. Ritonavir

(M2.ID.3) A 26-year-old HIV positive male presents to his primary care physician for routine care. The patient has not seen a healthcare provider in 2 years and at this visit his CD4 count is found to be 105 cells/mm^3. He has never had chicken pox. He plans to travel to Africa next month. Which of the following vaccines is indicated for this patient? Topic Review Topic

1. Pneumococcal polysaccharide vaccine
2. Varicella zoster virus vaccine
3. Live attenuated influenza vaccine
4. Live oral poliovirus vaccine
5. Yellow fever vaccine

(M2.ID.7) A 29-year-old woman presents to her obstetrician for her first prenatal visit. Screening tests reveal that she is HIV-positive, and her CD4 count is 550. What is the best course of action to prevent mother-to-child transmission? Topic Review Topic

1. No treatment
2. HAART for Mom during pregnancy if CD4 count falls below 500; Zidovudine for neonate for 6 wks postpartum
3. HAART for Mom during labor and delivery; Zidovudine for neonate for 6 wks postpartum
4. HAART for Mom during pregnancy; Zidovudine for neonate for 6 wks postpartum
5. HAART for Mom during pregnancy; no treatment for neonate after birth

(M2.ID.10) A 31-year-old male presents to the emergency department complaining of difficulty eating and pain with swallowing. He reports that the problem started yesterday, although he has been feeling weak for the past 8 months. Physical exam reveals a thin man in no acute distress and is otherwise unremarkable. Laboratory studies show a CD4+ count of 56 cells/microL. Which of the following is the most likely cause of this patient's dysphagia? Topic Review Topic

1. Acute HIV
2. Pneumocystis jiroveci (P. carinii)
3. Candida
4. HSV
5. CMV

(M2.ID.12) A 29-year-old male with HIV presents to his primary care physician with fevers, night sweats, weight loss, and a cough productive of yellow sputum for 2 months. The patient was found to have a negative PPD and treated with azithromycin in an urgent care clinic 1 month ago. The patient's chest radiograph is shown in Image A. An acid-fast stain of the patient's sputum is performed with the results shown in Image B. Which of the following infectious agents is most likely responsible for this patient's presentation? Topic Review Topic
FIGURES: A   B        

1. Streptococcus pneumoniae
2. Legionella pneumophilia
3. Mycobacterium tuberculosis
4. Nocardia asteroides
5. Actinomyces israelii

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