Pneumonia
Introduction
Pneumonia is an infection of the lung tissue. The alveoli become filled with micro-organisms, fluid and inflammatory cells causing impaired gaseous exchange and consolidation on Chest X-ray.
Pneumonia has many potential causes. Both viral and bacterial. Below are the most common causes.
Strep pneumoniae (commonest), H. influenza (more common in older, COPD, Chronic lung conditions), Staph aureus (post influenza, IVDU)
Atypical Bacteria – Mycoplasma pneumoniae (younger), C. pneumoniae, Legionella spp (commoner in smokers, outbreaks due to contaminated water)
Viruses – COVID 19, Influenza, RSV,
Hospital Acquired – E.coli, Klebsiella pneumoniae, Enterobacter spp, Pseudomonas, S. aureus, MRSA
Aspiration Pneumonia – Usual bacteria & Gut flora (anaerobes, enteric gram -ves)
Treatment for pneumonia varies and depends on
Community Acquired versus Hospital Acquired (in patient > 48 hrs/recently discharged) versus Aspiration
How unwell the patient is. (CURB 65)
Risk Factors e.g. immunosuppression, Asthma/COPD, Alcoholism, Chronic conditions, risk of aspiration
Clinical Features
Symptoms
Systemic
Chills, fevers, rigors, anorexia, lethargy
Chest
Cough, change in colour or sputum if chronic cough, dyspnoea, pleuritic chest pain
Signs
Signs of sepsis
fever, tachycardia, hypotension, hypoxia, tachypnoea
Chest Signs
Focal Decreased air entry, crackles, bronchial breath sounds, dullness to percussion, increased focal resonance
Complications
Respiratory Complications
Pleural effusion, empyema, Cavitation, Abscess Formation
Systemic Complications
Bacteraemia, Septic Shock + Multiorgan Failure, Respiratory Failure
Differential Diagnosis
Respiratory
LRTI - bacterial or viral
Bronchiectasis
Bronchitis
Asthma/COPD exacerbation
PE
TB
Malignancy
ARDS
Cardiac
CCF
Angina
ACS
Pericarditis
Myocarditis
Infective Endocarditis
Biliary Pathology
Cholecystitis
Choledocholithiasis
Clinical Investigation
CURB65 Score
CURB 65 grades severity of pneumonia and likely mortality rates
5 criteria. 1 point each. Score 0-5
1 = 1% Mortality (mild pneumonia) 2 = 8%, 3 =20%, 4 = 40%, 5 = 60%
C Confusion
U Urea > 7
R RR > 30
B BP. Systolic <90mmHg or Diastolic < 60mmHg
65 Age > 65 years
Management and Disposition
Initial Resuscitation
***PPE and appropriate isolation if ? COVID
Resuscitation as required. ABC approach
Oxygen as required to keep sats > 94%, or > 88% in COPD
Assess for volume depletion and IV fluids as required.
May require vasopressors if septic and non responsive to fluid challenge
Symptomatic Treatment
Analgesia as required
Encourage rest, fluids and not to smoke
Nebulised bronchodilators e.g. salbutamol, if associated bronchospasm
Specific Treatment
Antibiotics as per local guidelines. Below is an example of SJH guidelines
Mild CAP
Amoxicillin 500mg TDS PO x 5/7
Mod/Severe CAP (includes atypical cover)
Co-Amoxyclav 1.2 g TDS IV + Clarithromycin 500mg BD PO/IV
Hospital Acquired Pneumonia (HAP)
Piperacillin-Tazobactam 4.5g QDS IV +/- IV Amikacin +/- IV Vancomycin (if hx of MRSA)
Disposition
Mild Cases (Curb 0 -1) can be managed in the community with PO antibiotics
Moderate (Curb 2) and Severe (Curb 3-5) need to be managed in the hospital setting with IV antibiotics and supportive care +/- ventilatory and organ support in the ICU setting if appropriate
References
1. NICE Guidance. Pneumonia in adults. Quality Standard [QS110] Jan 2016
2. File TM et al. Epidemiology, pathogenesis and microbiology of community-acquired pneumonia in adults. Uptodate.com
3. Putland M, Cameron P et al. Chapter 6.3 Community Acquired Pneumonia. The Textbook of Adult Emergency Medicine 4th Edition
4. British Thoracic Society community acquired pneumonia guideline. Oct 2009
5. SJH Prescriber Capsule. Empiric Antimicrobial Guidelines.
This blog was written by Dr Deirdre Glynn and was last updated in October 2020