Infections of the Respiratory Tract

1. Infections of the Respiratory Tract Dr. Raid Jastania

2. Infections of the Respiratory Tract • Upper Respiratory Tract • Lower Respiratory Tract • Bacterial, Viral, Fungal, T.B, Parasitic • Most URT infections are viral • Most LRT infections are bacterial

3. Upper Respiratory Tract Infections • Common cold (Acute coryza) • Viral infection of URT • Organisms: • Rhinoviruses: Coronaviruses, Enteroviruses, Adenoviruses, Respiratory syncytial virus) • Influenza A and B • Croup (Parainfluenza 1,2,3)

4. Upper Respiratory Tract Infections • Tonsillitis (mostly bacterial) • Otitis media (mostly bacterial) • Epiglottitis • Laryngitis • Laryngotrachiobronchitis • Bronchitis • Bronchiolitis • Pneumonia

5. Pneumonia • Pneumonia is inflammation of the lung (lower respiratory tract) caused mainly by infection. • Pneumonia can be caused by Bacterial infection and less commonly by other organisms eg. Viruses, Fungi • The term Pneumonia is sometimes used to indicated inflammation of lungs due to other causes eg. Including interstitial lung disease (interstitial pneumonia)

6. Types of Pneumonia • Different ways of classification • Problematic, confusing • Classification is Based on • etiology, • anatomic site involved, • clinical presentation, • pathological type of inflammation

8. Types of Pneumonia • One of the classification divides pneumonia into: • Primary (community-acquired) • Secondary • Others

9. Types of Pneumonia • One of the classification divides pneumonia into: • Primary (community-acquired) • Typical pneumonia • Lobar pneumonia • Bronchopneumonia • Atypical pneumonia • Secondary • Aspiration pneumonia • Nosocomial (hospital-acquired) pneumonia • Pneumonia in immunosuppression • Others: • Chronic pneumonia • Necrotizing pneumonia/Supporative pneumonia/Lung Abscess

10. Risk of Pneumonia • Underlying disease • COPD • Heart failure • Diabetes • Immunodeficiency • Absent splenic function (sickle cell disease)

11. Primary, Community-Acquired PneumoniaTypical Pneumonia

12. Clinical Presentation • Fever, rigor, malaise, weakness, vomiting, loss of appetite, headache • Cough with sputum • Dyspnea • Chest pain, pleuritic pain • Sick, ill , distressed • High respiratory rate >30 / mint • In lobar pneumonia: localized area of dullness on percussion, increased tactile fremitus, bronchial breath sounds, and crepitation, pleural rub

13. Morphology • Common in lower lobes and right middle lobe • In Lobar pneumonia: there is a localized area of inflammation • Stages: • Congestion • Vascular congestion, edema, few neutrophils • Red hepatization • Fibrin, RBC, neutrophils in alveolar spaces • Gray hepatization • Fibrin, RBC lysis • Resolution

15. Bronchopneumonia • Inflammation of the bronchi and bronchioles with collapse of the distal airspaces • Multiple, patchy bilateral small infiltrates • Affect lower lobes usually

16. Outcome and complications • Resolution • Fibrosis • Abscess • Empyema • Dissemination of infection • Meningitis, arthritis, endocarditis

17. Investigations • CBC • Arterial blood gases • Radiological exam: chest x-ray • Sputum exam and culture • Nose and throat swabs • Blood culture • Serological tests

18. Pneumonia: Features of different organisms (community-acquired pneumonia) • Strep. Pneumoniae • commonest • Staph. Aureus • Common following viral infection • Risk of complications: abscess • Common in IV drug abusers • Legionella • Legionnaire’s disease, epidimics • Grow in water reservoir, humidifiers • People with heat disease, renal disease, immunosuppressed • Presentation with GIT symptoms, mental confusion • Hemophilus influenzae • Common in COPD, chronic bronchitis, bronchiectasis, cystic fibrosis • Klebsiella • Chronic alcoholics and malnourished persons

19. Primary, Community-Acquired PneumonaAtypical Pneumonia

20. Atypical Pneumonia • Viruses, Mycoplasma, Chlamydia • Fever and malaise precede the respiratory symptoms by few days • Severe headache, malaise, anorexia • No localized sings on chest exam, No consolidation on chest x-ray • Spleen may be enlarged • WBC normal, cultures negative • No improvement with Penicillin

21. Atypical Pneumonia (community-acquired) • Mycoplasma • Sporadic or epidemics • Viruses • Influenza, Parainfluenza, Adenovirus, respiratory syncytial virus, measles, chicken pox • Chlamydia

22. Atypical pneumonia • Morphology: • Patchy or involve whole lobe • Inflammation is confined to the alveolar walls • Widening of alveolar walls by edema, mononuclear cell infiltration (lymphocytes, plasma cells, macrophages)

24. Secondary Pneumonia

25. Secondary pneumonia • Aspiration pneumonia • Nosocomial (hospital-acquired) pneumonia • Pneumonia in immunosuppression

26. Secondary Pneumonia • Pre-existing disease of lung or factors increasing the risk of infection • Low virulence organisms: Hemophilus infleunzae, viruses, fungi • Anaerobic bacteria • Gram negative bacteria • Staph aureus • All the others in commuity-acquired

27. Aspiration Pneumonia • Aspiration of gastric contents • During surgery, anesthesia, surgery of tonsils, dental work • Infection following Aspiration of vomitus in coma, anesthesia, or sleep • Ineffective coughing (post operative) • Can result in severe hemorrhage in lungs • Chemical injury + infection (Anaerobic) • Destruction of lung parenchyma with cavitations

28. Nosocomial Pneumonia • Patients admitted to hospital • Organisms • Same as community acquired and • Gram-negative (Klebsiella, E.coli, Pseudomonas) • Staph. Aureus

29. Pneumonia in Immunosuppression • Congenital or acquired • AIDS, Immunosuppression • Humoral and Cellular immunity • Infection by • Pneumocystis carinii • Gram negative bacteria • The common bacteria • Opportunistic pathogens: CMV, Herpes, Aspergillus, TB, mycobacteria

30. Lung Abscess • Suppurative pneumonia • Necrotizing pneumonia • Cavity • Localized suppurative necrosis

31. Lung Abscess • Mechanisms: • Aspiration of infective material: teeth, tonils, coma, alcoholics • Aspiration of gastric conetnets • Complication of necrotizing pneumonia • Bronchial obstruction • Septic emboli • Hematogenous spread

32. Lung Abscess • Morphology • Cavity 1-2mm to 5-6 cm • Filled with pus, cellular debris • Surrounded by fibrosis and chronic inflammation • Aspiration tend to involve the right lung • May rupture in airways resulting in Air-fluid levels • May rupture in pleura resulting in pneumothorax and empyema