HIV and STIs

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HIV Pathogenesis - Viral Villainy Unveiled

  • HIV (retrovirus) infects CD4+ T-cells, macrophages, dendritic cells.
  • Entry: gp120 binds CD4, then co-receptor (CCR5/CXCR4).
    • CCR5: Early infection, M-tropic strains.
    • CXCR4: Later infection, T-tropic strains, more cytopathic.
  • Key Viral Enzymes: Reverse Transcriptase, Integrase, Protease.
  • Replication Cycle:
  • Outcome: Progressive ↓CD4 cell count, immune deficiency (AIDS). HIV Life Cycle Diagram

⭐ HIV primarily utilizes the CCR5 co-receptor for entry in early infection (M-tropic), while CXCR4 usage (T-tropic) often emerges later and is associated with faster disease progression.

HIV Clinical & Diagnosis - Spotting The Enemy

  • Acute Retroviral Syndrome (ARS): Flu/mono-like illness, high viral load (2-4 wks post-exposure).
  • Clinical Latency: Asymptomatic, CD4 count gradually ↓.
  • AIDS: CD4 < 200/µL or AIDS-defining illness (e.g., PCP, Kaposi Sarcoma). WHO Stage 4.
  • Diagnosis:
    • Initial: 4th Gen (p24 Ag + HIV Ab) test. Window period: 2-6 weeks.
    • Confirmatory: HIV-1/HIV-2 differentiation assay or NAT.
    • NAT: Detects HIV RNA. Shortest window (1-4 weeks); for acute/neonatal Dx.

⭐ Most common opportunistic infection in HIV patients in India is Tuberculosis.

HIV Management - Fighting Back Smart

  • ART Initiation: Start immediately for all PLHIV, regardless of CD4 count. Goal: viral suppression.
    • Monitoring: VL at 6, 12 months, then annually if suppressed (<50 copies/mL). CD4 if advanced/unsuppressed.
  • PEP: ASAP (<2h ideal, max 72h) post-exposure; TDF + 3TC + DTG for 28 days.
  • PrEP: Daily TDF/FTC or TDF/3TC for high-risk individuals.
  • IRIS: Paradoxical worsening on ART; manage OI, continue ART.

⭐ Preferred first-line ART (NACO): Tenofovir (TDF) + Lamivudine (3TC) + Dolutegravir (DTG) as a fixed-dose combination.

Syphilis Spotlight - The Ancient Foe

  • Agent: Treponema pallidum.
  • Stages:
    • Primary: Painless chancre.
    • Secondary: Rash (palms/soles), condyloma lata. Condyloma Lata: Signs, Background, Cause, Treatment

      ⭐ Jarisch-Herxheimer Reaction: Post-Rx fever, chills, myalgia from treponemal lysis; self-limiting. Usually within 2-12h.

    • Latent: Asymptomatic (early/late).
    • Tertiary: Gummas, neurosyphilis, cardiovascular. Syphilis gumma on arm
  • Diagnosis: Screen: VDRL/RPR. Confirm: TPPA/FTA-ABS.
  • Treatment (Penicillin G):
    • Early (1°, 2°, Early Latent): Benzathine 2.4 MU IM x1.
    • Late Latent/Tertiary: Benzathine 2.4 MU IM weekly x3.
    • Neurosyphilis: Aqueous Crystalline 18-24 MU IV daily x10-14d.

Gonorrhea & Chlamydia - Dual Trouble Duo

  • Co-infection common. Dx: NAAT.
  • Dual Tx for co-infection.
FeatureGonorrhea (GC)Chlamydia (CT)
OrganismGram -ve diplococciObligate intracellular
SymptomsPurulent D/C, PID, DGIOften Asx, PID
Tx (Uncomp.)Ceftriaxone 500mg IM + Azithro 1g POAzithro 1g PO or Doxy 100mg BD x7d

⭐ Fitz-Hugh-Curtis: perihepatitis (RUQ pain, violin-string adhesions) with PID (GC/CT).

Other STIs - Rapid Roundup Reel

  • Trichomoniasis: T. vaginalis; frothy discharge, strawberry cervix. Metronidazole 2g PO single. Trichomoniasis "strawberry cervix" indication
  • HPV (Warts): HPV; condylomata acuminata. Podophyllin, Imiquimod.
  • HSV (Herpes): HSV; painful vesicles. Acyclovir.
  • Chancroid: H. ducreyi; painful ulcer. Azithromycin 1g PO single.
  • LGV: C. trachomatis L1-L3; adenopathy. Doxycycline.

    ⭐ LGV: C. trachomatis L1-L3; pathognomonic "groove sign".

  • Donovanosis: K. granulomatis; beefy-red ulcer, Donovan bodies. Azithromycin.

High‑Yield Points - ⚡ Biggest Takeaways

  • HIV primarily targets CD4+ T-lymphocytes; HAART is crucial for management.
  • Syphilis (Treponema pallidum) presents with a painless chancre; screen with VDRL/RPR, confirm with FTA-ABS/TPHA.
  • Gonorrhea (Neisseria gonorrhoeae) shows Gram-negative diplococci; causes urethritis and cervicitis.
  • Chlamydia (Chlamydia trachomatis) is often asymptomatic; can lead to PID and infertility.
  • Genital Herpes (mainly HSV-2) is characterized by painful vesicular lesions.
  • HPV serotypes 16 & 18 are linked to cervical cancer; 6 & 11 cause genital warts (condyloma acuminata).
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_____ syphilis can present with aortitis, particularly of the ascending thoracic aorta

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