Download respiratory tract infections (rti)

RESPIRATORY TRACT INFECTIONS (RTI)

Dr B V Navaneeth, Dept of Microbiology

Dr B V Navaneeth, Dept of Microbiology

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

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

Dr B V Navaneeth, Dept of Microbiology

General Principles   

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Encounter Entry Spread Multiplication Evasion of Host Defenses Damage Transmission Dr B V Navaneeth, Dept of Microbiology

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

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

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

Systemic Diseases that Begin in the URT 

Measles

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Mumps

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Influenza

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Meningitis

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Sinusitis

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Middle Ear Infection

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Pneumonia

Dr B V Navaneeth, Dept of Microbiology

Agents of Lower Respiratory Tract Infections Legionairre’s Disease; Legionella pneumophila Tuberculosis: Mycobacterium tuberculosis Pneumonia

Bacteria Streptococcus pneumoniae Mycoplasma pneumoniae Staphylococcus aureus Almost ANY other

Viruses Influenza Measles Many others

Fungi & Parasites Dr B V Navaneeth, Dept of Microbiology

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 Bronchoscopy

Bronchial washing / aspirate

Bronchio-alveolar lavage (BAL) Protected bronchial brush samples Open lung biopsy Dr B V Navaneeth, Dept of Microbiology

Over view

Obtaining a protected catheter bronchial brush during a bronchoscopy examination

Dr B V Navaneeth, Dept of Microbiology

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