Overview
Human Papillomavirus (HPV):
- HPV 6 & 11: Cause benign laryngeal papillomas (true vocal cords) and condyloma acuminata (anogenital warts).
- High-Risk HPV (16, 18, 31, 33): Linked to cervical, vaginal, and penile cancers. They encode E6 (inhibits p53) and E7 (inhibits RB), leading to uncontrolled cell proliferation.
- Cervical Cancer Screening:
- Pap Smear: Start at 21 years. From 21–29: every 3 years. From 30+: every 3 years (Pap only) or every 5 years (Pap + HPV DNA test).
- HPV Vaccine (Gardasil 9): Covers 6, 11, 16, 18, 31, 33, 45, 52, 58.
Neisseria Species:
- Neisseria gonorrhoeae: Non-capsulated, facultative intracellular, antigenic pili (no vaccine). Causes septic arthritis, neonatal conjunctivitis (2–5 days old), and Fitz-Hugh-Curtis syndrome.
- Neisseria meningitidis: Capsulated (vaccine available). Causes meningitis in high-risk groups (e.g., dormitory residents).
- Thayer-Martin Agar: Selective medium containing vancomycin, colistin, nystatin, and trimethoprim.
Infectious Mononucleosis:
- Epstein-Barr Virus (EBV):
- Posterior cervical lymphadenopathy, splenomegaly, and atypical lymphocytes on smear.
- Latency in B cells; associated with nasopharyngeal carcinoma, Hodgkin’s lymphoma, and Burkitt’s lymphoma.
- Serology: Active infection → Viral Capsid Antigen (VCA); Latent infection → EBV Nuclear Antigen (EBNA).
- Cytomegalovirus (CMV):
- Causes mononucleosis with a negative Monospot test. Latency in monocytes.
- Complications in immunocompromised: retinitis (cotton-wool spots), esophagitis (linear ulcers), colitis, and interstitial pneumonia.
Other Pathogens:
- Chlamydia trachomatis:
- Neonatal conjunctivitis (5–14 days) → Treat with oral erythromycin.
- D–K serotypes → STIs; L1–L3 → Lymphogranuloma venereum.
- Treponema cruzi (Chagas Disease): Vector: Reduviid bug. Symptoms: Cardiomyopathy, megaesophagus, megacolon.
- Staphylococcus saprophyticus vs. epidermidis: Differentiated by novobiocin sensitivity (S. epidermidis = sensitive).
Miscellaneous:
- Hypothyroidism: Treat with T4 (Levothyroxine).
- Group D Streptococci: Enterococcus species (E. faecalis, E. faecium) are vancomycin-resistant. Non-enterococcus (Strep gallolyticus, formerly S. bovis) linked to colon cancer.
- Tetanus Toxin: Inhibits release of GABA and glycine, causing spastic paralysis.
- Pott’s Disease: Tuberculosis of the vertebral bodies.
Prophylaxis and Treatment:
- Pneumocystis jirovecii: TMP-SMX; alternatives: Dapsone or Atovaquone.
- CMV Retinitis: Treat with ganciclovir or valganciclovir.
- Gonococcal Neonatal Conjunctivitis: IM/IV ceftriaxone + topical erythromycin prophylaxis (can cause chemical conjunctivitis).