Recommended treatment of microbiologically documented pneumonia and aspiration pneumonia (local specialist advice should also be sought*)
| Pathogen | Preferred | Alternative |
| S pneumoniae | Amoxicillin 500 mg –1.0 g† tds orally or benzylpenicillin 1.2 g qds IV | Clarithromycin 500 mg bd orally or cefuroxine 0.75–1.5 g tds IV or cefotaxime 1–2 g tds IV or ceftriaxone 2 g od IV |
| M pneumoniaeC pneumoniae | Clarithromycin 500 mg bd orally or IV | Doxycycline 200 mg loading dose then 100 mg od orally or fluoroquinolone‡ orally or IV |
| C psittaciC burnetii | Doxycycline 200 mg loading dose then 100 mg od orally | Clarithromycin 500 mg bd orally or 500 mg bd IV |
| Legionella spp | Fluoroquinolone orally or IVठ| Clarithromycin 500 mg bd orally or IV (or, if necessary, azithromycin in countries where this antibiotic is used for managing pneumonia) |
| H influenzae | Non-β-lactamase-producing: amoxicillin 500 mg tds orally or IVβ-lactamase-producing: co-amoxiclav 625 mg tds orally or 1.2 g tds IV | Cefuroxime 750 mg –1.5 g tds IV or cefotaxime 1–2 g tds IV or ceftriaxone 2 g od IV or fluoroquinolone‡ orally or IV |
| Gram-negative enteric bacilli | Cefuroxime 1.5 g tds or cefotaxime 1–2 g tds IV or ceftriaxone 1–2 g bd IV | Fluoroquinolone‡ IV or imipenem 500 mg qds IV or meropenem 0.5–1.0 g tds IV |
| P aeruginosa | Ceftazidime 2 g tds IV plus gentamicin or tobramycin (dose monitoring) | Ciprofloxacin 400 mg bd IV or piperacillin 4 g tds IV, plus gentamicin or tobramycin (dose monitoring) |
| S aureus | Non-MRSA: flucloxacillin 1–2 g qds IV ± rifampicin 600 mg od or bd orally/IV | MRSA: vancomycin 1 g bd IV (dose monitoring) or linezolid 600 mg bd IV or teicoplanin 400 mg bd IV ± rifampicin 600 mg od or bd orally/IV |
| Aspiration pneumonia | Co-amoxiclav 1.2 g tds IV | Seek local microbiology advice |
bd, twice daily; IV, intravenous; od, once daily; tds, three times daily.
*Treatment can be modified once the results of sensitivity testing are available.
†A higher dose of 1.0 g tds is recommended for infections documented to be caused by less susceptible strains (minimum inhibitory concentration >1.0 mg/l).
‡Currently UK licensed and available suitable fluoroquinolones include ciprofloxacin, ofloxacin and levofloxacin. Moxifloxacin can be used for patients who cannot be treated or have failed treatment with other antibacterials.
§Specifically for legionella pneumonia, the large majority of published experience regarding the efficacy of fluoroquinolones is only with levofloxacin. For high severity or life-threatening legionella pneumonia, combination therapy including the preferred and an alternative antibiotic can be considered for the first few days (see text for further details). Rifampicin is not recommended on its own but could be considered as the second additional antibiotic.