Lung infections: Pneumonia

Question 1

Definition

Answer 1

Inflammatory condition affecting the terminal bronchioles and the area surrounding the alveoli most commonly secondary to bacterial infection (can be viral and fungal too)
- Can be seen as consolidation on X-ray

Question 2

What is idiopathic interstitial pneumonia

Answer 2

non-infective causes of pneumonia, such as:
- cryptogenic organising pneumonia which may occur as a complication of rheumatoid arthritis or amiodarone use.

Question 3

Community acquired pneumonia

Answer 3

Develops outside of hospital

Question 4

Hospital acquired pneumonia

Answer 4

Develops 48 hours after hospital admission

Question 5

Aspiration pneumonia

Answer 5

Develops as a result of aspiration of foreign material

Question 6

Typical causes of bacterial pneumonia

Answer 6

CAP =
Streptococcus pneumonia (50%) = high fever, rapid onset, vaccine available
Haemophilus influenzae (20%) = COPD patients
Staph aureus = CF or following influenza infection
HAP = (ALL ABOVE +)
Pseudomonas aeruginosa = CF or bronchiectasis
Klebsiella pneumoniae = alcoholics
Other =
Moraxella catarrhalis = immunocompromised or those with COPD

Question 7

Atypical pneumonia definition

Answer 7

An organism which cannot be cultured in the normal way or detected using gram stain. Don’t respond to penicillin’s + can be treated with macrolides (clarithromycin), fluoroquinolones (e.g. levofloxacin) or tetracyclines (doxycycline)

Question 8

Atypical causes of pneumonia

Answer 8

• Legionella pneumonia = infected water + air conditioning units. Can cause hyponatraemia by causing SIADH + lymphopenia + deranged LFTs
• Mycoplasma pneumoniae = commonly seen in younger adults and is milder + can cause rash = ERYTHEMA MULTIFORME = varying sized ‘target lesions’ formed by pink rings with pale centres. Also associated with autoimmune haemolytic anaemia. Can also cause neurological symptoms in young patients. Dry cough + x-ray changes
• Chlamydia pneumoniae = typically contracted from contact with infected bird
• Coxiella Burnetti = exposure to animals + their bodily fluids = FARMER + flu like symptoms
• Chlamydia psittaci = typically contracted from contact with infected bird

Question 9

Fungal causes of pneumonia

Answer 9

Pneumocystis jiroveci (PCP) = immunocompromised patients especially poorly controlled or new HIV with low CD4 count.
Presents subtly with dry cough without sputum, SOB on exertion + night sweats
Treatment = CO-TRIMOXAZOLE (Trimethoprim/ Sulfamethoxazole)

Question 10

Epidemiology

Answer 10

Extremes of age: young children and the elderly are particularly at risk
Immunocompromised = e.g. due to steroid use

Question 11

Risk factors

Answer 11

Preceding viral infection
IV drug abuse: Staphylococcus aureus
Respiratory conditions: Asthma, COPD, malignancy, CF

Question 12

Signs

Answer 12

Reduced breath sounds, bronchial breathing and coarse crepitation’s
Hypoxia
Tachycardia
Pyrexia
Confusion
Hypotension (SHOCK)
Reduced O2 sats

Question 13

Symptoms

Answer 13

Productive cough
- usually green or brown in colour
- red currant jelly sputum is classically seen in Klebsiella Pneumoniae
Pleuritic chest pain (SHARP chest pain worse on INSPIRATION)
Dyspnoea
Fever
Delirium
SOB
SEPSIS

Question 14

Characteristic chest signs BCD

Answer 14

Bronchial breath sounds = harsh breath sounds equally loud on inspiration + expiration. These are caused by consolidation of the lung tissue around the airway
Focal course crackles = These are air passing through sputum in the airway
Dullness on percussion = Due to lung tissue collapse +/or consolidation

Question 15

How may Atypical pneumoniae present

Answer 15

dry cough,
mild dyspnoea,
flu-like symptoms,
mild or no fever
* CXR may also be normal in atypical pneumonia *

Question 16

Severity Assessment

Answer 16

CURB-65
Confusion
Urea > 7
Resp Rate > 30/min
Blood pressure < 90 systolic or < 60 diastolic (mmHg)
65 +

Question 17

What does CURB65 predict?

Answer 17

MORTALITY
- Score 0/1: Consider treatment at home
- Score > 2: Consider hospital admission
- Score > 3: Consider intensive care assessment

Question 18

Investigations

Answer 18

Chest X-ray: Classic finding of consolidation
Bloods:
- FBC = neutrophilia
- U + E = dehydration, urea > 7
- CRP = raised in infection
ABG: If O2 sats are low or patient has pre-existing respiratory disease (COPD)

Question 19

Management CAP

Answer 19

FIRST LINE = Antibiotics: Amoxicillin
- Clarithromycin if CI
- ADD Clarithromycin if an atypical pathogen is suspected, usually a 5 day course
High severity = IV co-amoxiclav + clarithromycin are often used

Question 20

Management HAP

Answer 20

Low severity: oral co-amoxiclav
High severity: broad spectrum antibiotics e.g. IV TAZOCIN or CEFTRIAXONE
Suspected or confirmed MRSA: + VANCOMYCIN

Question 21

How does amoxicillin work?

Answer 21

Inhibition of peptidoglycan cross linking = disruption of gram +ve cell wall synthesis

Question 22

Complications

Answer 22

Acute respiratory distress syndrome
Sepsis: complicates severe CAP and may be fatal, particularly in immunocompromised patients
Lung abscess: may require prolonged antibiotic therapy and drainage; can occur due to Klebsiella or Streptococcus pneumonia
Pleural effusion: parapneumonic effusions can either be sterile or infected (empyema)

Question 23

Treatment Pneumocytitis Jiroveci

Answer 23

Mild: co-trimoxazole
If co-trimoxazole is CI atovaquone
Moderate: dapsone + trimethoprim