Infections of the Respiratory Tract Dr. Raid Jastania

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

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)

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

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)

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

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

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

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

Primary, Community-Acquired Pneumonia Typical Pneumonia

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

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

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

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

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

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

Primary, Community-Acquired Pneumona Atypical Pneumonia

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

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

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)

Secondary Pneumonia

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

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

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

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

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

Lung Abscess Suppurative pneumonia Necrotizing pneumonia Cavity Localized suppurative necrosis

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

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