RESPIRATORY TRACT INFECTIONS (RTI)

1. RESPIRATORY TRACT INFECTIONS (RTI) Dr B V Navaneeth, Dept of Microbiology

2. Dr B V Navaneeth, Dept of Microbiology

3. OVERVIEW URTIs common most often seen in GP LRTIs < common but > likely cause serious illness & death Diagnosis & therapy presents challenge to both clinician & lab staff Preventive strategies available for several RIs Dr B V Navaneeth, Dept of Microbiology

4. GOALS General Principles of Pathogenesis of RTI Host Defenses in the URT, LRT Agents of Infection in URT, LRT Prevention and Treatment Dr B V Navaneeth, Dept of Microbiology

5. Dr B V Navaneeth, Dept of Microbiology

6. General Principles • Encounter • Entry • Spread • Multiplication • Evasion of Host Defenses • Damage • Transmission Dr B V Navaneeth, Dept of Microbiology

7. Pathogenesis – inhalation, aspiration, haemotogenous Nasal hairs & its mucus coverings - filters Epiglottis & cough reflexes Trachea & Bronchi – mucus lining & mucociliary escalator Antimicrobial factors in secretions – lysozyme, lactoferrin & secretary IgA, alveolar macrophages Dr B V Navaneeth, Dept of Microbiology

8. Respiratory Pathogens Influenza virus Adhere to mucosal epithelial cells by specific surface antigens Under go genetic reassortment – expression of novel adhesins S pneumoniae & H influenzae Capsule – resist phagocytosis IgA protease – disabling mucosal IgA Mycobacterium – resist phagocytosis Dr B V Navaneeth, Dept of Microbiology

9. Agents of Upper Respiratory Tract Infections • Common cold (rhinitis) • Many viruses; rhino, corona, adeno, influenza • Pharyngitis and laryngotracheitis • Streptococcus pyogenes • Corynebacteria diphtheriae • Many viruses • Epiglottitis • Haemophilus influenzae • Bronchitis • Bordetella pertussis • Many viruses Dr B V Navaneeth, Dept of Microbiology

10. Systemic Diseases that Begin in the URT • Measles • Mumps • Influenza • Meningitis • Sinusitis • Middle Ear Infection • Pneumonia Dr B V Navaneeth, Dept of Microbiology

11. Agents of Lower Respiratory Tract Infections Legionairre’s Disease; Legionella pneumophila Tuberculosis: Mycobacterium tuberculosis Pneumonia • Viruses • Influenza • Measles • Many others • Bacteria • Streptococcus pneumoniae • Mycoplasma pneumoniae • Staphylococcus aureus • Almost ANY other Fungi & Parasites Dr B V Navaneeth, Dept of Microbiology

12. Lab Diagnosis of LRTI Responsible pathogen not determined in as many as 50% of cases Sputum Expectorated Gastric aspirate (children) Induced Postural drainage / thoracic percussion/ aerosal induced Endotracheal / tracheostomy suction Bronchial washing / aspirate Bronchoscopy Bronchio-alveolar lavage (BAL) Protected bronchial brush samples Open lung biopsy Dr B V Navaneeth, Dept of Microbiology

13. Over view Obtaining a protected catheter bronchial brush during a bronchoscopy examination Dr B V Navaneeth, Dept of Microbiology

14. Lab Diagnosis of LRTI Direct exam Sputum / saliva Microscopy Gram stain / AFB Gomori methenamine-PCP DFA - Legionella Direct antigen test for viruses Culture BA / CA / MAC / LJ Identification tests AST Report & Interpretations Dr B V Navaneeth, Dept of Microbiology