MBBS Year
2nd Year
Subject
What Is Usually Asked
Pneumococcus, Klebsiella, atypical organisms, laboratory diagnosis
ReferenceAll Years (1st-Final)All UniversitiesPneumonia
Pneumonia: Notes, PPT and PYQs for MBBS
Pneumonia is an acute infection of the lung parenchyma in which the alveoli fill with inflammatory exudate, causing consolidation. It is examined in Microbiology, Pathology and Pharmacology in 2nd Year, Community Medicine in 3rd Year, and General Medicine and Paediatrics in Final Year.
SME-reviewed. Updated 2026.
Open in GeckoMed for PPT slides and notesQuick Summary: What You Need to Know for University Exams
- Pneumonia is classified by setting (community-acquired, hospital-acquired, ventilator-associated) and by anatomy (lobar, bronchopneumonia, interstitial).
- Streptococcus pneumoniae is the most common cause of community-acquired pneumonia (CAP).
- Lobar pneumonia passes through four stages: congestion, red hepatisation, grey hepatisation and resolution.
- Classic signs of consolidation: dull percussion, bronchial breath sounds and increased vocal resonance.
- Chest X-ray confirms consolidation; CURB-65 helps decide where to treat the patient.
- Treatment is empirical antibiotics based on severity and setting, adjusted to culture results.
- Pneumonia is a leading infectious cause of death in children under five; India's SAANS campaign targets childhood pneumonia.
Pneumonia Across MBBS Subjects
| MBBS Year | Subject | What Is Usually Asked |
|---|---|---|
| 2nd Year | Microbiology | Pneumococcus, Klebsiella, atypical organisms, laboratory diagnosis |
| 2nd Year | Pathology | Lobar versus bronchopneumonia, stages, complications |
| 2nd Year | Pharmacology | Beta-lactams, macrolides, fluoroquinolones |
| 3rd Year | Community Medicine | Acute respiratory infections in children, IMNCI, vaccines |
| Final Year | General Medicine | Clinical features, severity assessment, management |
| Final Year | Paediatrics | Childhood pneumonia, fast breathing, danger signs |
MBBS Year
2nd Year
Subject
What Is Usually Asked
Lobar versus bronchopneumonia, stages, complications
MBBS Year
2nd Year
Subject
What Is Usually Asked
Beta-lactams, macrolides, fluoroquinolones
MBBS Year
3rd Year
Subject
What Is Usually Asked
Acute respiratory infections in children, IMNCI, vaccines
MBBS Year
Final Year
Subject
What Is Usually Asked
Clinical features, severity assessment, management
MBBS Year
Final Year
Subject
What Is Usually Asked
Childhood pneumonia, fast breathing, danger signs
Definition and Classification
Definition: Pneumonia is an acute inflammation of the lung parenchyma, usually caused by infection, in which the alveoli are filled with exudate, leading to consolidation.
Classification
| Basis | Types |
|---|---|
| Setting | Community-acquired pneumonia (CAP); hospital-acquired pneumonia (HAP), developing 48 hours or more after admission; ventilator-associated pneumonia (VAP), developing 48 hours or more after intubation |
| Anatomy | Lobar pneumonia; bronchopneumonia (patchy, centred on bronchioles); interstitial pneumonia |
| Organism | Typical (bacterial) versus atypical (Mycoplasma, Chlamydophila, Legionella, viruses) |
| Host | Pneumonia in immunocompromised people; aspiration pneumonia |
Basis
Setting
Types
Community-acquired pneumonia (CAP); hospital-acquired pneumonia (HAP), developing 48 hours or more after admission; ventilator-associated pneumonia (VAP), developing 48 hours or more after intubation
Basis
Anatomy
Types
Lobar pneumonia; bronchopneumonia (patchy, centred on bronchioles); interstitial pneumonia
Basis
Organism
Types
Typical (bacterial) versus atypical (Mycoplasma, Chlamydophila, Legionella, viruses)
Basis
Host
Types
Pneumonia in immunocompromised people; aspiration pneumonia
Lobar Pneumonia Versus Bronchopneumonia
| Feature | Lobar Pneumonia | Bronchopneumonia |
|---|---|---|
| Distribution | Whole lobe or large part of a lobe | Patchy, often bilateral and basal |
| Usual cause | Streptococcus pneumoniae | Many organisms, including Staphylococcus and Haemophilus |
| Usual host | Otherwise healthy adults | Extremes of age, debilitated people |
| X-ray | Homogeneous lobar opacity with air bronchogram | Patchy opacities |
Feature
Distribution
Lobar Pneumonia
Whole lobe or large part of a lobe
Bronchopneumonia
Patchy, often bilateral and basal
Feature
Usual cause
Lobar Pneumonia
Streptococcus pneumoniae
Bronchopneumonia
Many organisms, including Staphylococcus and Haemophilus
Feature
Usual host
Lobar Pneumonia
Otherwise healthy adults
Bronchopneumonia
Extremes of age, debilitated people
Feature
X-ray
Lobar Pneumonia
Homogeneous lobar opacity with air bronchogram
Bronchopneumonia
Patchy opacities
Aetiology (Causes)
| Setting | Common Organisms |
|---|---|
| Community-acquired | Streptococcus pneumoniae (most common), Haemophilus influenzae, Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella, respiratory viruses |
| After influenza | Staphylococcus aureus |
| Alcohol use disorder, diabetes | Klebsiella pneumoniae (classically "red currant jelly" sputum) |
| COPD | Haemophilus influenzae, Moraxella catarrhalis |
| Hospital-acquired and ventilator-associated | Pseudomonas aeruginosa, MRSA, Enterobacteriaceae, Acinetobacter |
| Aspiration | Anaerobes and mixed oral flora |
| Immunocompromised, including HIV | Pneumocystis jirovecii, fungi, cytomegalovirus, Mycobacterium tuberculosis |
Setting
Community-acquired
Common Organisms
Streptococcus pneumoniae (most common), Haemophilus influenzae, Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella, respiratory viruses
Setting
After influenza
Common Organisms
Staphylococcus aureus
Setting
Alcohol use disorder, diabetes
Common Organisms
Klebsiella pneumoniae (classically "red currant jelly" sputum)
Setting
COPD
Common Organisms
Haemophilus influenzae, Moraxella catarrhalis
Setting
Hospital-acquired and ventilator-associated
Common Organisms
Pseudomonas aeruginosa, MRSA, Enterobacteriaceae, Acinetobacter
Setting
Aspiration
Common Organisms
Anaerobes and mixed oral flora
Setting
Immunocompromised, including HIV
Common Organisms
Pneumocystis jirovecii, fungi, cytomegalovirus, Mycobacterium tuberculosis
Risk factors: Extremes of age, smoking, alcohol use, COPD, diabetes, heart failure, immunosuppression, impaired swallowing or consciousness, malnutrition, and indoor air pollution from solid fuel use.
Pathophysiology
Flowchart
- Organisms reach the alveoli, usually by inhalation or aspiration
- Host defences (cough reflex, mucociliary clearance, alveolar macrophages) are overwhelmed
- Organisms multiply and trigger an inflammatory response
- Alveoli fill with fluid, neutrophils, red cells and fibrin
- Consolidated alveoli are perfused but not ventilated, causing ventilation-perfusion mismatch
- Hypoxaemia develops, with systemic inflammation (fever, raised white cell count)
(Examiner may ask you to draw the stages of lobar pneumonia.)
Stages of Lobar Pneumonia (Pathology)
| Stage | Gross Appearance | Microscopic Features |
|---|---|---|
| Congestion | Heavy, red, boggy lung | Vascular engorgement, alveolar fluid with few neutrophils and many bacteria |
| Red hepatisation | Red, firm, airless lobe with a liver-like consistency | Alveoli filled with neutrophils, red cells and fibrin |
| Grey hepatisation | Greyish-brown, dry surface | Disintegrating red cells with persistent fibrinosuppurative exudate |
| Resolution | Lung returns towards normal | Exudate is digested by enzymes, cleared by macrophages and coughed up |
Stage
Congestion
Gross Appearance
Heavy, red, boggy lung
Microscopic Features
Vascular engorgement, alveolar fluid with few neutrophils and many bacteria
Stage
Red hepatisation
Gross Appearance
Red, firm, airless lobe with a liver-like consistency
Microscopic Features
Alveoli filled with neutrophils, red cells and fibrin
Stage
Grey hepatisation
Gross Appearance
Greyish-brown, dry surface
Microscopic Features
Disintegrating red cells with persistent fibrinosuppurative exudate
Stage
Resolution
Gross Appearance
Lung returns towards normal
Microscopic Features
Exudate is digested by enzymes, cleared by macrophages and coughed up
Clinical Features
Symptoms:
- Fever with chills and rigors
- Cough, initially dry then productive; rusty sputum is classical in pneumococcal pneumonia
- Pleuritic chest pain
- Breathlessness
- Confusion, especially in elderly people
- Atypical pneumonia: gradual onset, headache, myalgia, dry cough, with chest signs often milder than X-ray findings
Signs of consolidation:
| Examination | Finding |
|---|---|
| Inspection | Tachypnoea, reduced movement on the affected side |
| Palpation | Increased tactile vocal fremitus |
| Percussion | Dull note |
| Auscultation | Bronchial breath sounds, increased vocal resonance, crackles, pleural rub |
Examination
Inspection
Finding
Tachypnoea, reduced movement on the affected side
Examination
Palpation
Finding
Increased tactile vocal fremitus
Examination
Percussion
Finding
Dull note
Examination
Auscultation
Finding
Bronchial breath sounds, increased vocal resonance, crackles, pleural rub
Childhood Pneumonia: Fast Breathing Thresholds (IMNCI)
| Age | Fast Breathing |
|---|---|
| Below 2 months | 60 breaths per minute or more |
| 2 to 12 months | 50 breaths per minute or more |
| 1 to 5 years | 40 breaths per minute or more |
Age
Below 2 months
Fast Breathing
60 breaths per minute or more
Age
2 to 12 months
Fast Breathing
50 breaths per minute or more
Age
1 to 5 years
Fast Breathing
40 breaths per minute or more
Chest indrawing and general danger signs (inability to drink or breastfeed, convulsions, lethargy, vomiting everything) indicate severe disease needing referral.
Diagnosis
| Investigation | Findings or Purpose |
|---|---|
| Chest X-ray | Consolidation with air bronchogram (lobar) or patchy opacities (bronchopneumonia); effusion, cavitation |
| Complete blood count | Neutrophilic leucocytosis in bacterial pneumonia |
| Sputum Gram stain and culture | Identifies the organism and antibiotic sensitivity |
| Blood cultures | Especially in moderate to severe pneumonia |
| Urinary antigen tests | Pneumococcus and Legionella |
| CRP and procalcitonin | Support bacterial infection and help monitor response |
| Pulse oximetry and arterial blood gas | Assess hypoxaemia and respiratory failure |
| Renal function and electrolytes | Severity assessment (urea) |
| PCR tests | Respiratory viruses and atypical organisms |
| Sputum for acid-fast bacilli or CBNAAT | To exclude tuberculosis, important in India |
Investigation
Chest X-ray
Findings or Purpose
Consolidation with air bronchogram (lobar) or patchy opacities (bronchopneumonia); effusion, cavitation
Investigation
Complete blood count
Findings or Purpose
Neutrophilic leucocytosis in bacterial pneumonia
Investigation
Sputum Gram stain and culture
Findings or Purpose
Identifies the organism and antibiotic sensitivity
Investigation
Blood cultures
Findings or Purpose
Especially in moderate to severe pneumonia
Investigation
Urinary antigen tests
Findings or Purpose
Pneumococcus and Legionella
Investigation
CRP and procalcitonin
Findings or Purpose
Support bacterial infection and help monitor response
Investigation
Pulse oximetry and arterial blood gas
Findings or Purpose
Assess hypoxaemia and respiratory failure
Investigation
Renal function and electrolytes
Findings or Purpose
Severity assessment (urea)
Investigation
PCR tests
Findings or Purpose
Respiratory viruses and atypical organisms
Investigation
Sputum for acid-fast bacilli or CBNAAT
Findings or Purpose
To exclude tuberculosis, important in India
CURB-65 Severity Score
One point for each of the following:
| Letter | Criterion |
|---|---|
| C | New confusion |
| U | Blood urea above 7 mmol/L |
| R | Respiratory rate of 30 per minute or more |
| B | Systolic blood pressure below 90 mmHg or diastolic 60 mmHg or less |
| 65 | Age 65 years or more |
Letter
C
Criterion
New confusion
Letter
U
Criterion
Blood urea above 7 mmol/L
Letter
R
Criterion
Respiratory rate of 30 per minute or more
Letter
B
Criterion
Systolic blood pressure below 90 mmHg or diastolic 60 mmHg or less
Letter
65
Criterion
Age 65 years or more
| Score | Suggested Care |
|---|---|
| 0 to 1 | Usually suitable for home treatment |
| 2 | Consider hospital admission |
| 3 or more | Severe pneumonia; hospital admission, consider intensive care at higher scores |
Score
0 to 1
Suggested Care
Usually suitable for home treatment
Score
2
Suggested Care
Consider hospital admission
Score
3 or more
Suggested Care
Severe pneumonia; hospital admission, consider intensive care at higher scores
Management
General Measures
- Oxygen to maintain adequate saturation
- Fluids and nutrition
- Antipyretics and analgesia for pleuritic pain
- Chest physiotherapy where appropriate
- Monitoring of vital signs, oxygen saturation and response
Antibiotic Principles (MBBS Level)
| Setting | Usual Empirical Approach |
|---|---|
| Mild CAP (outpatient) | Oral amoxicillin, or a macrolide or doxycycline, as per local guidelines |
| Moderate CAP (hospital) | A beta-lactam combined with a macrolide |
| Severe CAP | Intravenous beta-lactam with a macrolide; intensive care support as needed |
| Hospital-acquired or ventilator-associated | Broader cover for Pseudomonas and MRSA, guided by local resistance patterns |
| Aspiration | Cover for anaerobes |
| Pneumocystis pneumonia | Co-trimoxazole |
Setting
Mild CAP (outpatient)
Usual Empirical Approach
Oral amoxicillin, or a macrolide or doxycycline, as per local guidelines
Setting
Moderate CAP (hospital)
Usual Empirical Approach
A beta-lactam combined with a macrolide
Setting
Severe CAP
Usual Empirical Approach
Intravenous beta-lactam with a macrolide; intensive care support as needed
Setting
Hospital-acquired or ventilator-associated
Usual Empirical Approach
Broader cover for Pseudomonas and MRSA, guided by local resistance patterns
Setting
Aspiration
Usual Empirical Approach
Cover for anaerobes
Setting
Pneumocystis pneumonia
Usual Empirical Approach
Co-trimoxazole
- Antibiotics are narrowed or changed once culture results are available.
- In India, fluoroquinolones are used cautiously for CAP because they are active against tuberculosis and can mask or delay its diagnosis.
Revise antibiotic groups with the antibiotic classification chart and the antibiotic sensitivity chart.
Complications
Local:
- Parapneumonic pleural effusion
- Empyema
- Lung abscess (especially with Staphylococcus aureus, Klebsiella and anaerobes)
- Delayed resolution
Systemic:
- Sepsis and septic shock
- Acute respiratory distress syndrome (ARDS)
- Respiratory failure
- Bacteraemia with spread, such as meningitis or endocarditis
- Worsening of existing heart disease
Prevention (Community Medicine Angle)
| Measure | Key Points |
|---|---|
| Vaccination | Pneumococcal conjugate vaccine (PCV) and Haemophilus influenzae type b (in the pentavalent vaccine) are part of India's Universal Immunisation Programme; influenza and pneumococcal vaccines for high-risk adults |
| Nutrition | Exclusive breastfeeding for six months and adequate nutrition |
| Environment | Reducing indoor air pollution and overcrowding |
| Case management | Early recognition of fast breathing and danger signs, and prompt treatment |
| Awareness | India's SAANS (Social Awareness and Action to Neutralise Pneumonia Successfully) campaign targets childhood pneumonia |
Measure
Vaccination
Key Points
Pneumococcal conjugate vaccine (PCV) and Haemophilus influenzae type b (in the pentavalent vaccine) are part of India's Universal Immunisation Programme; influenza and pneumococcal vaccines for high-risk adults
Measure
Nutrition
Key Points
Exclusive breastfeeding for six months and adequate nutrition
Measure
Environment
Key Points
Reducing indoor air pollution and overcrowding
Measure
Case management
Key Points
Early recognition of fast breathing and danger signs, and prompt treatment
Measure
Awareness
Key Points
India's SAANS (Social Awareness and Action to Neutralise Pneumonia Successfully) campaign targets childhood pneumonia
See the national immunisation schedule for India.
Prognosis
Most patients with community-acquired pneumonia recover with appropriate antibiotics. Mortality is higher in elderly people, people with comorbidities, severe pneumonia (high CURB-65 score), hospital-acquired infection and resistant organisms.
Quick Viva Questions
Q: Which organism causes rusty sputum? A: Streptococcus pneumoniae.
Q: Which organism is associated with red currant jelly sputum? A: Klebsiella pneumoniae.
Q: What is an air bronchogram? A: Air-filled bronchi seen against surrounding consolidated alveoli on chest X-ray.
Q: How does pneumococcus appear on Gram stain? A: Gram-positive, lanceolate (flame-shaped) diplococci.
Q: Which drug is used for Pneumocystis pneumonia? A: Co-trimoxazole.
How Pneumonia Appears in MBBS University Exams
Typical question styles (not attributed to specific papers or years):
- "Classify pneumonia. Discuss the aetiology, clinical features, investigations and management of community-acquired pneumonia." (Long essay, General Medicine)
- "Describe the pathology of lobar pneumonia. Add a note on its complications." (Long essay, Pathology)
- "Differentiate lobar pneumonia from bronchopneumonia." (Short answer, Pathology)
- "Describe the laboratory diagnosis of pneumococcal infection." (Short note, Microbiology)
- "Write a short note on the management of pneumonia in children under five." (Short note, Paediatrics or Community Medicine)
Frequently Asked Questions
What is the most common cause of community-acquired pneumonia?
Streptococcus pneumoniae is the most common bacterial cause of community-acquired pneumonia.
What are the four stages of lobar pneumonia?
Congestion, red hepatisation, grey hepatisation and resolution.
Can I download the pneumonia PPT for my presentation?
Yes. Use the Download PPT button at the top of this page. The GeckoMed app also gives offline access to the slides and notes.
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