Infections of the Respiratory Tract

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Infections of the Respiratory Tract

• Dr. Raid Jastania

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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

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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)

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Upper Respiratory Tract Infections

• Tonsillitis (mostly bacterial)
• Otitis media (mostly bacterial)
• Epiglottitis
• Laryngitis
• Laryngotrachiobronchitis
• Bronchitis
• Bronchiolitis
• Pneumonia

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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)

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Types of Pneumonia

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

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Types of Pneumonia

• One of the classification divides pneumonia into
• Primary (community-acquired)
• Secondary
• Others

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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

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Risk of Pneumonia

• Underlying disease
• COPD
• Heart failure
• Diabetes
• Immunodeficiency
• Absent splenic function (sickle cell disease)

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Primary, Community-Acquired PneumoniaTypical
Pneumonia
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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 gt30 / mint
• In lobar pneumonia localized area of dullness on
  percussion, increased tactile fremitus, bronchial
  breath sounds, and crepitation, pleural rub

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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

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

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Outcome and complications

• Resolution
• Fibrosis
• Abscess
• Empyema
• Dissemination of infection
• Meningitis, arthritis, endocarditis

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Investigations

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

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• 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
• Legionnaires 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

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Primary, Community-Acquired PneumonaAtypical
Pneumonia
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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

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

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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)

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

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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

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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

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Nosocomial Pneumonia

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

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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

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Lung Abscess

• Suppurative pneumonia
• Necrotizing pneumonia
• Cavity
• Localized suppurative necrosis

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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

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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