Sexually Transmitted Infections

Syphilis & Ulcers - Ulcerative Villains

• Syphilis (Treponema pallidum): Spirochete.
  • Primary: Painless, indurated chancre. Darkfield microscopy.
  • Secondary: Maculopapular rash (palms/soles), condyloma lata.
  • Latent: Asymptomatic, seropositive.
  • Tertiary: Gummas, neurosyphilis (tabes dorsalis), aortitis.
  • Congenital: Hutchinson's triad.
  • Dx: VDRL/RPR (screen/monitor); TPPA/FTA-ABS (confirm).
  • Rx: Benzathine Penicillin G 2.4 MU IM. ⚠️ Jarisch-Herxheimer.
• Other Genital Ulcers: 📌 Painful: Chancroid, Herpes.
  • Chancroid (H. ducreyi): Painful, soft ulcer; painful bubo. "School of fish".
  • Genital Herpes (HSV): Painful vesicles → ulcers. Multinucleated giant cells (Tzanck).
  • LGV (C. trachomatis L1-L3): Evanescent painless ulcer; painful lymphadenopathy ("groove sign").
  • Donovanosis (K. granulomatis): Painless, beefy-red, progressive ulcer. Donovan bodies.

⭐ Neurosyphilis can present with Argyll Robertson pupils (accommodate but don't react to light).

Gono & Chlamydia - Discharge Dilemmas

• Gonorrhea (N. gonorrhoeae):
  • Gram-negative diplococci (GNDC).
  • Men: Purulent urethral discharge, dysuria.
  • Women: Often asymptomatic; cervicitis, PID.
  • Complications: Disseminated Gonococcal Infection (DGI) (arthritis-dermatitis syndrome), ophthalmia neonatorum.
  • Dx: NAAT, Gram stain (PMNs + GNDC).
  • Rx: Ceftriaxone 500mg IM + Azithromycin 1g PO.
• Chlamydia (C. trachomatis D-K):
  • Obligate intracellular bacteria.
  • Men: Mucoid/watery discharge, dysuria; often asymptomatic.
  • Women: Often asymptomatic; cervicitis, PID.
  • Complications: Reactive Arthritis (Reiter's: "can't see, can't pee, can't climb a tree" 📌), infertility. Neonatal conjunctivitis/pneumonia.
  • Dx: NAAT (gold standard).
  • Rx: Azithromycin 1g PO or Doxycycline 100mg BID x 7 days.
• Key Points:
  • Co-infection is common; consider dual therapy.
  • NAAT is the preferred diagnostic test for both.

  ⭐ Chlamydia trachomatis is the most common bacterial STI globally. oka

Viral STIs - Viral Vagabonds

• Herpes Simplex Virus (HSV): Genital Herpes
  • Types: HSV-1 (often oral), HSV-2 (genital predominance).
  • Clinical: Painful vesicles → ulcers. Recurrent.
  • Diagnosis: Tzanck smear (multinucleated giant cells), PCR (gold standard).
  • Treatment: Acyclovir, Valacyclovir.
  • Latency: Sensory ganglia (📌 HSV-S-Sacral/Sensory).
• Human Papillomavirus (HPV):
  • Types:
    • Low-risk: 6, 11 (Condyloma acuminata/genital warts).
    • High-risk: 16, 18, 31, 33 (Cervical, anogenital, oropharyngeal cancers).
  • Diagnosis: Clinical (warts), Pap smear (koilocytes), HPV DNA.

  ⭐ Koilocytes (cells with perinuclear halo & wrinkled nucleus) are characteristic cytopathic effects of HPV seen on Pap smears.

  • Prevention: HPV Vaccine (e.g., Gardasil 9).
• Hepatitis B Virus (HBV):
  • Transmission: Sexual, blood, perinatal.
  • Sequelae: Chronic hepatitis, cirrhosis, Hepatocellular Carcinoma (HCC).
  • Key markers: HBsAg (infection), Anti-HBs (immunity).
• Molluscum Contagiosum Virus (MCV): (Poxvirus)
  • Clinical: Pearly, umbilicated papules.
  • Diagnosis: Clinical; Henderson-Paterson bodies (intracytoplasmic inclusions).
• HIV: (Covered in detail separately)
  • Targets CD4+ T-cells. Sexual transmission is a major route.

Other STIs & Syndromic Rx - Critters & Kits

• Protozoal & Ectoparasites ("Critters")

  • Trichomonas vaginalis (Protozoa): Frothy, yellow-green discharge. Strawberry cervix. Wet mount: motile flagellates. Rx: Metronidazole 2g PO single (or Tinidazole 2g). Treat partner.
  • Sarcoptes scabiei (Scabies): Intense pruritus (night), burrows. Rx: Permethrin 5% cream.
  • Phthirus pubis (Pediculosis): Pubic lice, nits. Rx: Permethrin 1% lotion.

• Syndromic Management (NACO "Kits")

  • Approach based on clinical syndromes, not etiology. Uses pre-packaged, color-coded kits.

  ⭐ NACO Kit 1 (Grey): Urethral Discharge, Cervicitis, Anorectal Discharge - Azithromycin 1g + Cefixime 400mg (all PO).

  • Other common kits:
    • Kit 2 (Green): Vaginal Discharge - Secnidazole 2g + Fluconazole 150mg (all PO).
    • Kit 3 (White): Non-herpetic GUD - Benzathine Penicillin 2.4MU IM + Azithromycin 1g PO.
    • Kit 6 (Red): PID - Cefixime + Doxycycline + Metronidazole (all PO; Doxy/Metro for 14 days).

High-Yield Points - ⚡ Biggest Takeaways

• Syphilis: Painless chancre (1°), condyloma lata (2°); screen with VDRL/RPR. Jarisch-Herxheimer reaction.
• Gonorrhea: Gram-negative diplococci, purulent discharge, arthritis (DGI). Treat with Ceftriaxone.
• Chlamydia: Most common bacterial STI, often asymptomatic. Azithromycin/Doxycycline. LGV by L-serovars.
• Genital Herpes (HSV-2): Painful vesicles, recurrences. Acyclovir. Tzanck: multinucleated giant cells.
• HPV: Condyloma acuminata (types 6, 11); cervical cancer link (types 16, 18). Vaccine available.
• Trichomoniasis: Motile protozoa, strawberry cervix, frothy discharge. Treat with Metronidazole.