Pneumonia - classification, symptoms.

 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