Respiratory Tract Infections and Rhinitis

Respiratory Infections

• Rhinoviruses, coronavirus, and RSV (respiratory syncytial virus) cause winter onset respiratory infections.
• Influenza affects the back of the nose (pharyngeal area).
• Adenovirus causes severe inflammation, leading to pus in the conjunctiva and mimicking bacterial infection, and can cause laryngitis.

Rhinosinusitis

• Rhinosinusitis can be fungal in immunocompromised individuals, such as those with diabetes, and is very rare.
• Sinusitis is caused by fluid buildup in the area, allowing organisms to colonize and produce pus.
• Anatomical issues affecting drainage and allergies can contribute to chronic sinusitis.
• Drainage may be required in cases where the patient cannot manage their sinusitis, resulting in a thick, tenacious membrane.

Pharyngitis

• 90% of pharyngitis cases are caused by viruses.
• The remaining 10% are caused by Group A Streptococcus (GAS).

Laryngitis

• Laryngitis is caused by viruses, with occasional incursion of organisms into the larynx and trachea.
• Inflammation can occur when the mucociliary escalator is damaged, leading to the proliferation of organisms like staph, strep, Moraxella, and Haemophilus.

Haemophilus

• Haemophilus has different strains, including one with a polysaccharide capsule (group B polysaccharide).
• Invasive Haemophilus can cause meningitis, which is addressed by the influenza type B vaccine.

Epstein-Barr Virus

• Epstein-Barr virus causes glandular fever and infectious mononucleosis.
• The first growth is in the throat, and quick diagnosis is essential to prevent prolonged symptoms and chronic fatigue.

Streptococcal Disease

• Streptococcal disease is caused by invasive, gram-positive cocci, including S.pyogenes, which causes streptococcal pharyngitis (strep throat).
• S.pyogenes produces little pus due to cytotoxin, which breaks down inflammatory cells.
• A swab can be sent to the lab to grow the causative organism, and treatment may involve lancing and draining abscesses.

Rheumatic Fever

• Rheumatic fever is a post-infection complication caused by cell surface antigens similar to human cell surface antigens.
• The immune response to the invading pathogen results in antibodies that cross-react with host tissues, leading to autoimmune disease and tissue destruction.
• Symptoms may include heart murmurs, which can be evidenced by a whooshing or swooshing sound.

Scarlet Fever

• Scarlet fever follows infection with streptococcus, particularly virulent strains that encode exotoxins.
• The rash begins on the chest and spreads to the rest of the body after a 2-day incubation period.
• The pathogenesis of scarlet fever involves the production of streptolysins (toxins) that lyse red cells and white blood cells, leading to beta-haemolysis.