PNEUMONIA :
Pneumonia is an infection in one or both lungs
Pneumonia causes inflammation in the alveoli
The alveoli are filled with fluid or pus, making it difficult to breath.
DEFINITION :
Inflammation and consolidation of lung tissue due to an infectious agent
Consolidation: ‘ inflammatory induration of a normally aerated lung due to the presence of cellular exudative in alveoli.’
How does pneumonia develop .. ??
Most of the time, the body filters organisms
This keeps the lungs from becoming infected
But organisms sometimes enter the lungs and cause infections
This is more likely to occur when :
The immune system is weak
An organism is very strong
The body fails to filter the organism
Factors that influence pneumonia :
Cigarette smoking
Upper respiratory tract infections
Alcohols
Corticosteroid therapy
Old age
Recent influenza infection
Pre-existing disease
Reduced host defenses against bacteria :
Reduced immune defenses: e.G., Corticosteroid treatment, diabetes, malignancy
Reduced cough reflex: e.G., Post-operative
Disordered mucociliary clearance: e.G., Anaesthetic agents
Bulbar or vocal cord palsy (nerve impulses to your voice box are disrupted
Aspiration of nasopharyngeal or gastric secretions :
Immobility or reduced conscious level
Vomiting, dysphagia, achalasia, or severe reflux
Nasogastric intubation
Bacteria introduced into the lower respiratory tract
Endotracheal intubation/tracheostomy
Infected ventilators/nebulisers/bronchoscopes
Dental or sinus infection
Bacteraemia
Abdominal sepsis
Intravenous cannula infection
Infected emboli
How does pneumonia develop..??
1. pathology
i) congestion: Presence of proteinaceous exudate and often of bacteria in the alveoli
Ii) red hepatization: Presence of erythrocytes in the cellular intra-alveolar exudate
Neutrophils are also present
Bacteria are occasionally seen in cultures of alveolar specimens collection
Gray hepatization :
No new erythrocytes are extravasating, and those already present have been lysed and degraded
A neutrophil is the predominant cell
Fibrin deposition is abundant
Bacteria have disappeared
Corresponds with successful containment of the infection and improvement in gas exchange
Types of pneumonia :
i) anatomical classification :
Bronchopneumonia affects the lungs in patches around bronchi
Lobar pneumonia is an infection that only involves a single lobe, or section of a lung
Interstitial pneumonia involves the areas in between the alveoli
Clinical CLASSIFICATION :
Community-acquired – typical/atypical/aspiration
Pneumonia in elderly
Nosocomial – hap, vap, hcap
Pneumonia in an immunocompromised host
Community-acquired pneumonia (CAP)
Definition :
An infection of the pulmonary parenchyma
Associated with symptoms of a/c infection
Presence of a/c infiltrates on car or auscultatory findings consistent with pneumonia
In a patient not hospitalized or residing in LTC facility for > 14 days prior
Hospital-acquired pneumonia – hap
Hap is defined as pneumonia that occurs 48 hours or more after admission, which was not incubating at the time of admission
Ventilator-associated pneumonia – vap
Vap refers to pneumonia that arises more than 48-72 hours after endotracheal intubation
Health care-associated pneumonia hcap
Hcap includes any patient
Who was hospitalized in an acute care hospital for 2 or more days within 90 days of the infection
Resided in a nursing home or long term care facility
Received recent antibiotic therapy, chemotherapy or wound care within past 30 days of the current infection
Attended a hospital or hemodialysis clinic
Atypical pneumonia –
Clinically – Subacute onset, fever less common or intense, minimal sputum
Microbiologically – Sputum does not reveal a predominant microbial etiology on routine smears such as gram’s stain and zinc stain or culture
Radiologically – Patchy infiltrates or interstitial pattern
Hemogram – Peripheral leucocytosis are less common or intense
Causes – Mycobacterium pneumoniae, Chlamydophila pneumoniae, Legionell pneumoniae
Aspiration pneumonia
An overt episode of aspiration or bronchial obstruction by a foreign body
Seen in – alcoholism, nocturnal esophageal reflux, a prolonged session in the dental chair, epilepsy
Usually anaerobes
Elderly
Infection has a more gradual onset, with less fever and cough
Often with decline in mental status or confusion and generalized weakness
Often with less readily elicited signs of consolidation
Microbiology :
Etiology – bacterial, viral, mycobacterial, fungal, parasitic
Microbiological diagnosis – 40 – 71% (streptococcus pneumonae most common)
Viruses – 10 – 35%
In india –
Streptococci pneumonia – 35.3 %
Staphylococcus aureus – 23.5%
Klebsella pneumonia – 20.5%
Haemophilus influenzae – 8.8%
Mycoplasma pneumoniae
Legionella pneumophila
General symptoms
High grade fever
Cough- productive
Pleuritic chest pain
Breathlessness
Additional symptoms
Sharp or stabbing chest pain
Headache
Excessive sweating and clammy skin
Loss of appetite and fatigue
Confusion, especially in older people
Investigations :
Sputum : gram staining, afb, giemsa or methenamine silver stain, koh mount, culture
X ray – homogenous opacity with air bronchogram
Lobar pneumonia – peripheral airspace consolidation pneumonia
Without prominent involvement of the bronchial tree
Lobar pneumonia :
Peripheral airspace consolidation pneumonia
Without prominent involvement of the bronchial tree
Broncho pneumonia :
Centrilobular and peribronchiolar opacity pneumonia
Tends to be multi focal
Patchy in distribution rather than localized to any one lung region
Interstitial pneumonia :
Peribroncho-vascular infiltrate
Mycoplasma, viral
