respiratoryinfections.ppt

Respiratory Infections Respiratory tract defences Ventilatory flow Cough Mucociliary clearance mechanisms Mucosal immune system Upper respiratory tract infections Rhinitis Rhinovirus, coronavirus, influenza/parainfluenza Non-infective (allergic) rhinitis has similar symptoms (related to asthma) Sinusitis Otitis media Latter 2 have a risk of bacterial superinfection, mastoiditis, meningitis, brain abscess Laryngitis Most commonly upper respiratory viruses Diphtheria C. diphtheriae produces a cytotoxic exotoxin causing tissue necrosis at site of infection with associated acute inflammation. Membrane may narrow airway and/or slough off (asphyxiation) Acute epiglottitis H. influenza type B Another cause of acute severe airway compromise in childhood Pneumonia Infection of pulmonary parenchyma with consolidation Pneumonia Gr. “disease of the lungs” Infection involving the distal airspaces usually with inflammatory exudation (“localised oedema”). Fluid filled spaces lead to consolidation Classification of Pneumonia By clinical setting (e.g. community acquired pneumonia) By organism (mycoplasma, pneumococcal etc) By morphology (lobar pneumonia, bronchopneumonia) Pathological description of pneumonia Organisms Viruses – influenza, parainfluenza, measles, varicella-zoster, respiratory syncytial virus (RSV). Common, often self limiting but can be complicated Bacteria Chlamydia, mycoplasma Fungi Lobar Pneumonia Confluent consolidation involving a complete lung lobe Most often due to Streptococcus pneumoniae (pneumococcus) Can be seen with other organisms (Klebsiella, Legionella) Clinical Setting Usually community acquired Classically in otherwise healthy young adults Pathology A classical acute inflammatory response Exudation of fibrin-rich fluid Neutrophil infiltration Macrophage infiltration Resolution Immune system plays a part antibodies lead to opsonisation, phagocytosis of bacteria Macroscopic pathology Heavy lung Congestion Red hepatisation Grey hepatisation Res