Lecture Notes - Respiratory Tract Infections: Pathways, Common Cold, Influenza, Pneumonia, and Tuberculosis

A set of practice flashcards covering entry routes for pathogens, common respiratory infections (common cold, influenza), pneumonia classifications and management, and tuberculosis pathophysiology and treatment from the notes.

What are the three routes/pathways for pathogens to enter the body?

Respiratory (airways), gastrointestinal tract (oral/fecal), and skin contact.

Which route is the easiest and most frequent route for pathogens to enter the body?

The respiratory route, because breathing cannot be stopped and air-borne pathogens readily enter the lungs.

What is the most frequent disease in the body due to the respiratory entry route?

Upper respiratory tract infections, with the common cold being the most frequent.

What causes the common cold?

Rhinoviruses (over 100 strains); vaccination against all strains is impractical.

How is the common cold primarily spread?

By droplets and personal contact.

What are the main influenza viruses and their key surface proteins?

Influenza A and B; hemagglutinin (H) for attachment and neuraminidase (N) for release; H and N variants; antigenic shift and drift; M2 protein as a conserved target.

What is the difference between major antigenic shift and minor antigenic drift in influenza?

Shift = major genetic change that can cause pandemics; drift = minor antigenic changes that cause epidemics.

What is the concept behind universal influenza vaccination?

Targets conserved viral components (e.g., M2 or core proteins) to provide cross-strain protection; still under development.

How did COVID-19 differ in terms of population immunity and frequency compared to influenza after vaccination?

COVID caused widespread chaos when immunity was low; after vaccination, it is less frequent than influenza.

What is pneumonia?

Inflammation of the alveoli, usually bacterial, classified by anatomy (lobar vs bronchopneumonia) and etiology (bacterial, viral, etc.).

How is pneumonia classified anatomically?

Lobar pneumonia (involves an entire lobe) and bronchopneumonia (patchy involvement in multiple lobes).

How is pneumonia classified etiologically?

Bacterial pneumonia (most common), viral pneumonia, or other causes; difference between community-acquired and hospital-acquired.

What is the most common cause of community-acquired pneumonia?

Streptococcus pneumoniae.

What is the typical causal pattern for hospital-acquired pneumonia?

Often caused by gram-negative organisms; treatment requires selecting antibiotics effective against Gram-negative bacteria.

What are common clinical features of pneumonia?

Cough, sputum (purulent or rusty), dyspnea, fever (pyrexia); systemic illness; pleural rub may be present.

What is consolidation in pneumonia?

Alveoli are filled with inflammatory exudate (protein-rich), leading to impaired air exchange and specific signs on exam or imaging.

What are two major complications of pneumonia?

Lung abscess (necrosis with cavitation) and empyema (pus in the pleural cavity).

What causes tuberculosis and how is it transmitted?

Mycobacterium tuberculosis; airborne transmission, especially in crowded settings.

What are primary and post-primary TB?

Primary TB is the initial infection with small granulomas (Ghon complex); post-primary TB is reactivation with larger granulomas, cavitation, and possible dissemination.

What is the Ghon complex?

A primary TB granuloma in the upper lung that may calcify upon healing.

What factors predispose to reactivation of TB?

Diabetes, malnutrition, immune suppression; compromised immunity allows bacilli to reactivate.

What is the standard TB treatment approach?

Multi-drug combination therapy (3–4 antibiotics) for 6–9 months; strict adherence to prevent drug resistance.