Hospital acquired pneumonia (Antimicrobial)
TAM (Treatments and Medicines) NHS Highland
What's new / Latest updates
06/04/26 (v3):
- Duration of therapy updated to "Review at 5 days and stop if clinically stable" (NICE guidance).
10/10/25 (v2.2):
- Added line - For suspected or known Legionnaires Disease, refer to specific guidance here.
See NICE Guideline 250 (updated 2 September 2025)
For pneumonia presenting more than 3 days into hospital admission, it is important to give broad-spectrum antibiotics which are active against Gram-negative organisms in the first instance. In more severe infection, consider cover for Legionella, Staph aureus, both MSSA and MRSA.
Use SIRS criteria for severity assessment. Send a sputum sample for microbiological testing and start antibiotic treatment as soon as possible after establishing a diagnosis of hospital-acquired pneumonia, and within 4 hours of clinical suspicion.
Give oral antibiotics first line if the severity of their condition does not require intravenous antibiotics. Review ongoing need for intravenous antibiotics at 48 hours and switch to oral using positive microbiology results (if available) or options for non-severe infection as per table below.
For glossary of terms see Glossary.
Drug details
Non severe
Co-trimoxazole (oral) 960mg twice daily (reduce dose to 480mg twice daily in renal impairment CrCl 30ml/min or less)
OR Doxycycline (oral) 100mg twice daily
Review at 5 days and stop if clinically stable
Severe
Note: infection with an atypical pathogen is uncommon. If suspected, discuss with Microbiology.
IV aztreonam 1 gram every 8 hours in level 1 and 2 care, 2 gram every 8 hours in level 3 care (ICU) PLUS IV vancomycin refer to NHS Highland vancomycin dosing guidelines
Review at 5 days and stop if clinically stable