QuestionSBA
QuestionChoice
This forms a part of the CURB-65 score (Age > 65).
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b
Patient's age
QuestionChoice
This forms a part of the CURB-65 score (Urea greater than 7 mmol/L).
10015658
c
Urea and electrolytes
QuestionChoice
This scenario describes a community acquired pneumonia. The CURB-65 score is used to estimate mortality and thus helps inform choice of antibiotic and whether the patient can be managed in the community. LFTs are the only option which do not form a part of the CURB-65 score.
10015656
a
Liver function tests
QuestionChoice
Confusion is a component of the CURB-65 (AMTS less than/equal to 8).
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e
AMTS
QuestionChoice
This forms a part of the CURB-65 score (RR over or equal to 30 breaths per minute, SBP 90mmHg or less or DBP 60mmHg or less).
10015659
d
Basic observations
QuestionComment
This feels like a backward way of testing this knowledge
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Juicy Myotome
QuestionComment
"least helpful" fml
52684
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Contusion Migraine
QuestionComment
This would never be in the UKMLA 
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Ali Abdaal
QuestionComment
toooooooo easssssyyyyyy c'mon Quessyy need to up ur game
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TheSecretSayer
Concept
Chapter
# Summary

Pneumonia is a common infection of the lung parenchyma that involves the alveoli becoming consolidated with inflammatory cells and microorganisms. Key symptoms include fever, malaise, a productive cough and pleuritic chest pain. Investigations include a chest X-ray to detect consolidation, blood tests for inflammatory markers and blood and sputum cultures to look for an underlying cause. Management involves oxygen if hypoxic, IV fluids if required and antibiotics targeted to the causative organism. 

# Definition

Pneumonia is an inflammatory condition of the lung parenchyma caused by infection. Alveoli become filled with inflammatory cells and microorganisms, leading to consolidation of the lung tissue. This impairs gas exchange and can lead to hypoxia.

# Epidemiology

Community-acquired pneumonia has an incidence of 5-10 per 1000 adults in the UK per year. Approximately 22-42% of these cases require admission to hospital. Mortality estimates range from 5 to 14%, with half of these being in people aged over 84 years. 

# Aetiology

The commonest cause of pneumonia is Streptococcus pneumonia, which is usually community-acquired, followed by Haemophilus influenzae and Moraxella catarrhalis. These are referred to as typical pneumonias (as they tend to present with the classic symptoms listed below).

Atypical pneumonias have a variety of atypical features, e.g. a more insidious onset, extra-pulmonary symptoms such as headache and varying appearances on chest imaging. These include Mycoplasma pneumoniae, Legionella pneumophila and Chylmydophila psittaci. 

Hospital-acquired pneumonias are defined as pneumonia that started 48 hours or longer after admission. Gram negative organisms such as Pseudomonas aeruginosa, as well as Staphylococcus aureus are more common in these environments.

Aspiration pneumonias are covered in a separate chapter. 

**Specific features of some of these microbiological causes are as follows:**

**Staphylococcal pneumonia**

- A bilateral cavitating bronchopneumonia due to staphylococcal aureus, a gram-positive cocci found in clusters.
- Commoner in intravenous drug users, elderly patients, or as a superadded bacterial infection in those with influenza.

**Klebsiella pneumonia**

- Usually a cavitating pneumonia affecting the upper lobes presenting with red-currant sputum.
- It is caused by a gram-negative anaerobic rod.
- Increased risk in the immunocompromised, elderly and in alcohol excess.

**Mycoplasma pneumonia**

- Presents with flu-like symptoms of arthralgia, myalgia, dry cough and headache.
- Primarily affects younger patients.
- Associated with an autoimmune haemolytic anaemia caused by cold agglutinins.
- May lead to erythema multiforme, Stevens-Johnson syndrome, Guillain-Barre syndrome and meningoencephalitis.

**Legionella pneumonia**

- Fever, myalgia and malaise followed by dyspnoea and a dry cough are typical presenting features.
- Caused by a gram-negative coccobacillus.
- Occurs in those exposed to contaminated water e.g. in humidifiers or cooling systems.
- Typically causes hyponatraemia and deranged liver function tests. 

**Chlamydophila psittaci pneumonia**

- An intracellular bacteria acquired from contact with infected birds such as parrots.
- Features include lethargy, arthralgia, headache, anorexia, dry cough and fever.

# Classification

Community-acquired pneumonias are classified using the CURB-65 score to determine severity and guide management.

One point is awarded for each of the following:

- Confusion 

- Urea > 7mmol/L

- Respiratory rate > 30 breaths/min

- Blood pressure < 90 systolic and/or < 60mmHg diastolic

- 65 years or older

This can be used to estimate 30 day mortality from pneumonia:

- CURB-65 0 - **0.7%** 

- CURB-65 1 - **3.2%** 

- CURB-65 2 - **13%** 

- CURB-65 3 - **17%** 

- CURB-65 4 - **41.5%** 

- CURB-65 5 - **57%** 

A CURB-65 score of 0-1 requires home treatment, 2 should consider hospital admission, 3-5 admit to hospital and consider ITU referral.

# Symptoms

- Fever
- Malaise
- Rigors
- Cough
- Purulent sputum
- Pleuritic chest pain
- Haemoptysis

# Signs

- Tachypnoea
- Tachycardia
- Hypotension
- Cyanosis
- Pyrexia
- Dullness to percussion over the consolidated area
- Increased vocal resonance/ tactile vocal fremitus over the consolidated area
- Bronchial breathing over the consolidated area
- Pleural rub may be heard due to inflammation of the adjacent pleura

# Differential Diagnosis

- **Bronchiectasis** - chronic productive cough with copious sputum, may be triggered by a severe lower respiratory tract infection or another condition (e.g. cystic fibrosis)
- **Tuberculosis** - suspect in patients with risk factors (e.g. TB contact, from endemic area, no fixed abode), haemoptysis and weight loss more common
- **Lung cancer** - may lead to pneumonia e.g. by obstructing a bronchus with downstream infection, important to consider especially in patients with a history of smoking, weight loss, chronic cough and haemoptysis
- **Bronchitis** - infection of the bronchi rather than the lower respiratory tract, usually viral and self-resolving 

# Investigations

**Bedside:**

- Sputum for microscopy, culture and sensitivity
- Consider arterial blood gas if hypoxaemic 
- Urinary legionella and pneumococcal antigens
- ECG to look for complications e.g. atrial fibrillation

**Bloods:**

- Blood cultures if febrile
- FBC and CRP for inflammatory markers
- U&Es to look for an AKI
- LFTs may be deranged e.g. in Legionella, baseline important when giving antibiotics
- Mycoplasma serology if atypical pneumonia suspected
- HIV testing should be offered to all patients with recurrent pneumonia (and all patients in a high prevalence area such as London)

**Imaging:**

- Chest X-ray: may show lobar consolidation or bilateral consolidation in atypical infections, parapneumonic effusions may also be seen.
- CT chest may be indicated in some cases (e.g. suspected underlying malignancy, suspicious findings on X-ray)

[lightgallery]


# Management

**Conservative:**

- Oxygen if low saturations
- IV fluids if dehydrated
- Analgesia for myalgia or chest pain
- Escalate for respiratory support (e.g. continuous positive airway pressure or intubation and ventilation) if patients are severely unwell - consider escalation status and patient wishes

**Medical:**

- Oral antibiotics for patients managed in the community (e.g. amoxicillin 500mg three times a day for 5 days)
- IV antibiotics for those admitted with more severe pneumonia (e.g. co-amoxiclav and clarithromycin)
- Different regimens are indicated for those with penicillin allergies and local guidelines should be consulted
- Antibiotics should be tailored to antimicrobial sensitivities when these are resulted

Patients with pneumonia should be followed up with a repeat chest X-ray after 6 to 8 weeks to screen for an underlying lung cancer (as this may be masked on initial imaging by infective changes).

# Complications

- Parapneumonic effusion
- Empyema
- Lung abscess
- Sepsis

# NICE Guidelines

[NICE - Pneumonia in adults](https://www.nice.org.uk/guidance/cg191)

[NICE CKS - Chest Infections](https://cks.nice.org.uk/topics/chest-infections-adult/)

# References

[Radiopaedia - Lobar Pneumonia](https://radiopaedia.org/articles/lobar-pneumonia)
1985
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A right sided basal pneumonia seen on chest x-ray.
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Types of Pneumonia
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In estimating the mortality of a patient with suspected community-acquired pneumonia, liver function tests are less relevant compared to other parameters included in the CURB-65 scoring system.
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Cancer
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Ear, nose and throat
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Respiratory
A 75-year-old male comes to the emergency department with a productive cough, fever, and confusion.

Given the likely diagnosis, which of the following is the least helpful in estimating mortality?
a