Transcript COMMUNITY ACQUIRED PNEUMONIA…..AN OVERVIEW

COMMUNITY ACQUIRED
PNEUMONIA…..AN
OVERVIEW
DR E. A. ODEGHE
OUTLINE
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Introduction
Aetiology
Viral pneumonias
Pathology
Clinical features
Examination findings
Investigations
Treatment
Complications
Poor prognostic factors
Prevention
INTRODUCTION
• Definition: inflammation of the lung parenchyma, which is
characterized by consolidation of the affected part and a
filling of the alveolar air spaces with exudate, inflammatory
cells, and fibrin
• Community acquired or Health care associated.
• Lobar /Focal/ nonsegmental pneumonia
• Multifocal/lobular (bronchopneumonia)
• Interstitial (focal diffuse)
• Important cause of morbidity and mortality worldwide.
• Usually acquired through inhalation or aspiration of
pulmonary pathogenic organisms into a lung segment or lobe;
less common is the haematogenous route
AETIOLOGY
• Typical or atypical organisms
• Typical organisms- commonest organisms
are Strep. pneumoniae, H. influenzae, M.
catarrhalis…account for approximately
85% of CAP cases.
• Less common… S. aureus, E.coli, K.
pneumoniae, S. faecalis
AETIOLOGY… ATYPICAL
ORGANISMS
• Most common…Legionella species,
Mycoplasma pneumoniae, Chlamydophila
spp.
• Less common… viruses (influenza virus,
adenovirus, respiratory syncytial virus,
human parainfluenza virus, measles,
varicella zoster) mycobacteria, parasites
VIRAL PNEUMONIAS
• Can vary from a mild, self-limited illness to a
life-threatening disease.
• The commonest causes are influenza virus,
respiratory syncytial virus, adenovirus, and
parainfluenza virus. Less common are varicellazoster virus and measles virus.
• Routes include large-droplet spread over short
distances, hand contact with contaminated skin
and fomites with subsequent inoculation onto
the nasal mucosa or conjunctiva, and smallparticle aerosol spread
PATHOLOGY
• Pathogenesis of most viral pneumonias is not well
known.
• After contamination, viruses multiply in the epithelium
of the upper airway, destroy respiratory cilia, cause
disruption of the respiratory epithelium, clearing the
way for bacterial infection
• Severe pneumonias may result in extensive
consolidation of the lungs
• They also generally cause impairment of T cells,
macrophages, and neutrophil function and thus
increase risk of bacterial super-infection
CLINICAL SYMPTOMS
• Incubation period depends on the specific
virus.
• Symptoms: fever, chills, dry cough,
rhinitis/rhinorrhoea, myalgias, headache,
fatigue
• Travel history is important.
• With bacterial superinfection, symptoms
last longer, cough becomes productive of
sputum and the patients becomes more ill.
EXAMINATION FINDINGS
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Fever and/or chills
Cough
Tachypnoea and/or dyspnoea
Tachycardia or bradycardia
Wheezing/ Rhonchi
Crepitations
Dullness to percussion
Decreased breath sounds
Hypoxia
INVESTIGATIONS
• Full blood count: anaemia, leucocytosis (lymphocytosis or
neutrophilia)
• Sputum for microscopy, culture, sensitivity
• Chest x-ray
• Rapid antigen detection on nasal swabs by ELISA and
immunofluorescence
• Serologic tests
• Gene amplification by RT-PCR
• Blood culture
• Examination of bronchoalveolar lavage samples
• Viral culture of tissue from the respiratory tract, sputum,
and samples obtained by nasopharyngeal washing,
bronchoalveolar lavage
• Lung biopsy for histopathologic studies and viral culture
TREATMENT
• General measures – Oxygen, bed rest,
antipyretics, analgesics, fluids,
respiratory isolation
• Specific measures – mechanical
ventilation if respiratory failure is
present or impending, antibiotics (if
infiltrate is seen on the chest
radiograph)
ANTIVIRAL AGENTS
• Acyclovir for varicella or herpes
pneumonia
• Respiratory syncythial virus – ribavirin,
immunoglobulin only for severe disease
• Adenovirus – cidofovir
• Parainfluenza virus – ribavirin
• Influenza virus – Acyclovir, Oseltamivir,
Zanamir
COMPLICATIONS
• Complications of CAP include empyema,
cavitation, precipitation of myocardial
infarction or heart failure and
overwhelming pneumococcal sepsis in
asplenic/hyposplenic patients.
• Viral pneumonias…Secondary bacterial
infections, encephalitis, hepatitis
POOR PROGNOSTIC FACTORS
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Significant co-morbidity eg cardioresp disease
Increased respiratory rate
Hypotension
Fever
Anaemia
Hypoxia
Multilobar involvement
Immunosuppression eg asplenia/hyposlenia
Elderly patients
Virulent organisms.
PREVENTION
• INF…vaccination; zanamivir,
oseltamivir, amantadine
• RSV…RSV immunoglobulin,
Palivizumab
• Measles…intravenous Ig
• VZV… VZV Ig