Final Exam (1)

Section 19.3: Diseases of the Upper Respiratory Tract

1. Highlight Disease: Pharyngitis

  • Causative Agents: Streptococcus pyogenes (most common bacterial cause), viruses (e.g., adenoviruses), other bacteria (less common).

  • Modes of Transmission: Respiratory droplets, direct contact, fomites.

  • Virulence Factors:

    • M protein (anti-phagocytic properties).

    • Streptolysins (toxin production).

    • Hyaluronidase (spreading factor).

  • Diagnostic Techniques:

    • Rapid strep test (antigen detection).

    • Throat culture (confirmatory).

  • Prevention/Treatment:

    • Prevention: Good hygiene, avoiding close contact with infected individuals.

    • Treatment: Antibiotics like penicillin or amoxicillin for bacterial cases.

2. Most Dangerous Causes of Pharyngitis and Sequelae

  • Dangerous Causes:

    • Streptococcus pyogenes due to potential complications.

  • Possible Sequelae:

    • Rheumatic fever (cardiac damage).

    • Glomerulonephritis (kidney damage).

    • Scarlet fever (rash and systemic toxicity).

3. Features of Other Upper Respiratory Infections

  • Common Cold:

    • Causative Agents: Rhinoviruses, coronaviruses, RSV.

    • Mild, self-limiting.

  • Sinusitis:

    • Causative Agents: Bacteria (e.g., Haemophilus influenzae, Streptococcus pneumoniae), viruses, fungi.

    • Symptoms: Nasal congestion, headache, facial pain.

  • Acute Otitis Media:

    • Causative Agents: Streptococcus pneumoniae, Haemophilus influenzae, Candida auris (rare fungal cause).

4. Causative Agents of Otitis Media
Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and rare fungal causes like Candida auris.

Section 19.4: Diseases of the Lower Respiratory Tract

5. Highlight Disease: Community-Acquired Pneumonia (CAP)

  • Causative Agents:

    • Bacteria: Streptococcus pneumoniae (most common), Legionella pneumophila, Mycoplasma pneumoniae.

    • Viruses: Influenza, SARS-CoV-2 (COVID).

  • Modes of Transmission: Respiratory droplets, aerosols, environmental exposure (e.g., water for Legionella).

  • Virulence Factors:

    • Capsule (antiphagocytic in Strep pneumo).

    • Adhesins (attachment to host cells).

    • Exotoxins (e.g., pneumolysin in Strep pneumo).

  • Diagnostic Techniques:

    • Chest X-ray, sputum culture, PCR for specific pathogens.

  • Prevention/Treatment:

    • Vaccines (e.g., pneumococcal vaccine, influenza vaccine).

    • Antibiotics for bacterial causes (macrolides, beta-lactams).

    • Antiviral therapy for viral causes.

6. Features of Other Respiratory Diseases

  • HealthAssociated Pneumonia: Highercare- risk due to ventilation, multidrug-resistant pathogens.

  • Influenza: High fever, systemic symptoms, risk of secondary bacterial pneumonia.

  • RSV Disease: Common in infants, leads to bronchiolitis, pneumonia.

  • Tuberculosis (TB):

    • Causative Agent: Mycobacterium tuberculosis.

    • Symptoms: Chronic cough, weight loss, night sweats.

    • Diagnostics: Tuberculin skin test, IGRA blood test, sputum culture.

7. Antigenic Drift vs. Antigenic Shift

  • Antigenic Drift: Small, gradual mutations in influenza virus genes. Causes seasonal flu changes.

  • Antigenic Shift: Sudden, major genetic changes creating new virus subtypes. Can lead to pandemics.

8. MDR-TB and XDR-TB

  • Definitions:

    • MDR-TB: Resistant to isoniazid and rifampin.

    • XDR-TB: Resistant to isoniazid, rifampin, fluoroquinolones, and second-line drugs.

  • Problems:

    • Limited treatment options.

    • Prolonged and toxic treatments.

    • Higher mortality rates.