Overview
HPV-Related Conditions:
- Laryngeal Papilloma: Caused by HPV 6 and 11, affecting stratified squamous epithelium of true vocal cords. Transmission is vertical (mother to fetus). Histology shows finger-like warty lesions.
- Cytological Hallmark: Koilocytes with a perinuclear halo.
- Condyloma Acuminata: HPV 6 and 11.
- High-Risk HPV (16, 18, 31, 33): Causes cervical, vaginal, and penile cancers. The mechanism involves E6 protein (inhibits p53) and E7 protein (inhibits RB).
Cervical Cancer:
- Most common type is squamous cell carcinoma.
- Screening: Pap smear starts at 21 years (every 3 years). From 30 years, combine with HPV DNA for 5-year intervals.
- Vaccine: Gardasil 9 (protects against HPV 6, 11, 16, 18, 31, 33, 45, 52, and 58).
Neisseria Species:
- Gonorrhea: Facultative intracellular, no capsule, pili with antigenic variation (no vaccine). Key syndromes include Fitz-Hugh-Curtis syndrome and neonatal conjunctivitis (treatment: IM/IV ceftriaxone).
- Meningitidis: Capsulated, vaccine available for serogroups A, C, W, Y, and B. Common in dorm-living college students.
- Virulence Factors: IgA protease and polysaccharide capsule (meningitidis).
Chlamydia trachomatis:
- Neonatal conjunctivitis (serotypes D-K). Treatment: Oral erythromycin.
- Key Differentiation: Chemical conjunctivitis (≤24 hours), gonococcal (2–5 days), chlamydial (5–14 days).
Other Key Pathogens:
- Treponema cruzi: Chagas disease, transmitted by the reduviid bug (kissing bug).
- Epstein-Barr Virus (EBV): Causes infectious mononucleosis (posterior cervical lymphadenopathy, atypical lymphocytes). Associated with Hodgkin’s lymphoma, Burkitt’s lymphoma, and nasopharyngeal carcinoma.
- Cytomegalovirus (CMV): Causes retinitis, esophagitis (linear ulcers), colitis, and interstitial pneumonia in immunocompromised patients. Hallmark: Owl’s eye inclusions.
Selective Culture Media:
- Thayer-Martin (VPN) media for Neisseria (contains vancomycin, polymyxin, nystatin, trimethoprim).
Step 1 Clinical Tips:
- Hypothyroidism: Treat with recombinant T4 (Levothyroxine).
- Tetanus: Caused by Clostridium tetani (toxin inhibits GABA and glycine, causing spastic paralysis).
- Pott’s Disease: Tubercular spondylitis (TB of vertebral bodies).
- UTI: E. coli is most common in sexually active females. Staph saprophyticus is associated with no-nobisitin resistance.
- Pneumocystis Pneumonia (PCP): Treated with TMP-SMX; alternatives include dapsone or atovaquone for sulfa-allergic patients