Community Acquired Pneumonia (CAP)


Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, Legionella spp, Staphylococcal aureus, Moraxella catarrhalis

Severe CAP

SIRS ≥ 2 or CURB65 score6: ≥3 or ≥ 2 with one additional feature

First Line

IV Amoxicillin 1g 8 hourly +  ORAL Clarithromycin1  500mg 12hourly


If previously treated: IV Co-amoxiclav 1.2g 8hourly + ORAL Clarithromycin500mg 12hourly

Stepping down to:

ORAL Amoxicillin 1g 8 hourly OR Co –amoxiclav 625mg 8 hourly (if treated previously)

 + ORAL Clarithromycin 500mg 12 hourly


Penicillin Allergy

IV Levofloxacin1,4  500mg 12 hourly (high oral bioavailability – consider switch to oral at 24 hours))

Stepping down to:

ORAL Levofloxacin1 500mg 12 hourly

Total Duration (IV/Oral): 7-10 days (Pneumococcal) to 21 days (confirmed Legionella)


Moderate CAP

CURB65 score6 =2

First Line

Oral Amoxicillin 500mg -1g 8hourly + Clarithromycin1 500mg 12 hourly


Penicillin Allergy or Alternative required

ORAL Doxycycline2 100mg 12hourly

Duration 7 Days


Low Severity CAP

CURB65 score6 = 0-1

First Line

ORAL Amoxicillin 500mg – 1g 8hrly


Penicillin Allergy or Alternative required

ORAL Clarithromycin1 500mg 12 hourly OR Doxycycline2 200mg stat then 100mg daily

Duration 7 days


CURB65 score

Score 1  for  each  of:                                 

  • Confusion new (AMT ≤8/10)
  • Urea > 7mmol/L
  • RR ≥ 30/min
  • BP SBP<90mmHg or DBP ≤60mmHg   
  • Age ≥65


Additional Adverse Prognostic features:

  • SpO2, <92% or PaO2 <8kPa on any FIO2,
  • Multi-lobar change on CXR

CURB 65 score may overestimate CAP severity in the elderly therefore correlate sepsis criteria.


Doses may need to be adjusted in renal impairment. Always check BNF for interactions. Seek advice if patient pregnant

Drug specific cautions:

  1. Check interactions in the BNF. Caution may prolong QT interval.
  2. Avoid Doxycycline and Co-trimoxazole if pregnant or breast feeding
  3. Gentamicin/Vancomycin refer to online calculators
  4. ALERT antibiotic needs ALERT form
  5. Monitor sodium
  6. See CURB65 definition
  7. Reference: The Renal Drug Handbook 4th Edition, 2014