Duration of therapy for osteomyelitis in adults

In adults, the first 7 days of treatment should usually be administered intravenously. A longer duration of intravenous therapy is required for patients who have a concomitant infection that requires a longer course of intravenous therapy (eg Staphylococcus aureus bacteraemia, infective endocarditis, spinal epidural abscess). Conversely, initial intravenous therapy may not be required for adults with chronic osteomyelitis – seek expert advice.

The minimum duration of antibiotic therapy (intravenous + oral) for osteomyelitis is 6 weeks for all sites of infection; however, a longer duration of therapy may be required for adults with chronic osteomyelitis or vertebral osteomyelitis.

For patients with chronic osteomyelitis, seek expert advice.

For patients with vertebral osteomyelitis 12 weeks of antibiotic therapy (intravenous + oral) is generally used, although evidence suggests 6 weeks may be appropriateBernard 2015. Longer therapy may be required when there are undrained collections, or infection is caused by methicillin-resistant Staphylococcus aureus (MRSA) or a gram-negative organism – seek expert advicePark 2014Park 2013.

For patients with long-bone osteomyelitis, a total of 6 weeks of antibiotic therapy (intravenous + oral) is likely to successfully treat infection, as long as there is an early clinical response, and any abscesses or infective collections have been drained.

For patients with osteomyelitis complicating sacral pressure ulcers, continue antibiotic therapy until the infection has resolved, but not necessarily until the wound has healed. The optimal duration of antibiotic therapy has not been clearly defined, but 6 weeks of therapy (intravenous + oral) is sufficient in most casesWong 2019.

Occasionally, a shorter total duration of treatment (ie less than 6 weeks intravenous + oral) may be appropriate. For example:

• when all infected tissue has been removed (eg total amputation of infected tissue)
• when all infected and necrotic tissue has been debrided (eg diabetic foot osteomyelitis)
• osteomyelitis involving metacarpals and/or phalanges.

In adults with osteomyelitis, an improvement in symptoms generally occurs gradually over days to weeks, with most patients experiencing minimal symptoms by the end of treatment. Persistence of localised symptoms are not necessarily associated with treatment failure.

In adults who are stable but require prolonged intravenous therapy, ambulatory antimicrobial therapy may be appropriate.