Aspiration Pneumonia (Antimicrobial)

TAM (Treatments and Medicines) NHS Highland
NHS Highland

ASPIRATION PNEUMONITIS is a chemical insult to the lung tissue from aspiration of gastric acid.  Antibiotic treatment is only required if a secondary bacterial infection develops later in the lungs. 

See British Thoracic Society Clinical Statement on Aspiration Pneumonia published in 2022 for further information on pathogenesis, prevention, diagnosis, management and palliative care. 

Selected good practice points:

  • Characterised by microaspiration (maybe silent) from oropharynx or GI reflux, often accompanied by swallowing difficulties.
  • Good oral hygiene (twice daily brushing of teeth, gingiva, tongue and soft palate) with soft brush and fluoride toothpaste appears to reduce the rate of aspiration pneumonia.
  • Clinical history taking should include questions about conscious level, swallowing efficiency, recent choking episodes and risk factors for aspiration pneumonia.
  • Reduced immune function in older patients may result in absence of fever or raised inflammatory markers
  • Send sputum if productive cough – state “aspiration pneumonia” on Microbiology request form
  • Prescribe antibiotics via the oral route unless the patient is nil by mouth. With the exception of levofloxacin, all antibiotics recommended in this guideline are available as oral liquid formulations.  Metronidazole tablets can be crushed for enteral tube administration which avoids the need for a break in enteral feeding.

Antibiotic duration is 5 days. 

If poor response at 72 hours, consider alternative/non-infective diagnosis, assess for complications (pleural effusion, lung abscess, empyema) or consider second line therapy (seek advice from Microbiology).

For all severity presentations

Antibiotic therapy may improve symptoms of aspiration pneumonia (fever, cough, purulent secretions) in some patients at the end of life.  Review response within 48 hours and in accordance with the treatment goals agreed with the patient and carers.

For glossary of terms see Glossary.

Drug details

Mild to moderate (IV route only if nil by mouth)

Oral/IV amoxicillin 1g three times daily

5 days – see duration note above

Mild to moderate if penicillin allergy (IV route only if nil by mouth)

Oral/IV co-trimoxazole 960mg twice daily OR clarithromycin 500mg twice daily (check for drug interactions with clarithromycin)

5 days – see duration note above

Severe aspiration pneumonia (septic shock, intubation)

Oral/IV co-trimoxazole 960mg twice daily (IV only if nil by mouth)

5 days – see duration note above

Severe aspiration pneumonia if co-trimoxazole unsuitable or recent course

Oral/IV levofloxacin 500mg twice daily (see BNF warnings and MHRA Drug Safety Alert (updated 22 January 2024))

5 days – see duration note above

For all severity presentations - if at increased risk of anaerobic infection (significant dental or periodontal disease, putrid sputum production, suspected lung abscess or empyema)

ADD metronidazole 500mg (IV) / 400mg (oral) three times daily (IV route only if nil by mouth)

5 days - see duration note above

Editorial Information

Last reviewed: 22/08/2024

Next review date: 22/08/2027

Author(s): Antimicrobial Management Team.

Version: 3

Approved By: TAM Subgroup of ADTC

Reviewer name(s): Alison Macdonald, Area Antimicrobial Pharmacist.

Document Id: AMT156