What is the diagnosis and treatment of Osteomyelitis (infection of the bone)?

From the Guidelines

Osteomyelitis requires prompt treatment with antibiotics and often surgical intervention, with a minimum 8-week course of therapy recommended, and surgical debridement and drainage of associated soft-tissue abscesses as the mainstay of therapy. The optimal route of administration of antibiotic therapy has not been established, but parenteral, oral, or initial parenteral therapy followed by oral therapy may be used depending on individual patient circumstances 1. Antibiotics available for parenteral administration include IV vancomycin and daptomycin 6 mg/kg/dose IV once daily, while some antibiotic options with parenteral and oral routes of administration include TMP-SMX, linezolid, and clindamycin 1.

Some key points to consider in the treatment of osteomyelitis include:

• The anatomic site of infection, the local vascular supply, the extent of both soft tissue and bone destruction, the presence of any systemic signs of infection, and the patient’s preferences for treatment 1
• The choice of an antimicrobial agent for treating osteomyelitis should optimally be based on the results of a bone culture, especially because of the need for long-duration therapy 1
• If empiric therapy is necessary, the regimen should usually cover S. aureus as it is the most common pathogen, but the patient’s history or culture results may suggest a need for broader coverage 1
• Surgical debridement is often necessary to remove infected and necrotic bone tissue, especially in chronic cases, and factors such as the patient's medical stability, the presence of bone necrosis or exposed joint, and the patient's preference for treatment should be considered when deciding between medical and surgical treatment 1

Imaging studies, such as MRI with gadolinium, are essential for diagnosis and monitoring treatment response, and erythrocyte sedimentation rate (ESR) and/or C-reactive protein (CRP) level may be helpful to guide response to therapy 1. A definite diagnosis of bone infection usually requires positive results on both histological and microbiological examinations of an aseptically obtained bone sample, but this is usually required only when the diagnosis is in doubt or determining the causative pathogen’s antibiotic susceptibility is crucial 1.

In terms of specific treatment recommendations, vancomycin 15-20 mg/kg IV every 12 hours or daptomycin 6-8 mg/kg IV daily are commonly used as initial empiric antibiotic therapy, and treatment duration is generally 4-6 weeks of parenteral antibiotics, though some cases may be transitioned to oral antibiotics with good bioavailability after initial IV therapy 1.

From the FDA Drug Label

Treatment of endocarditis and osteomyelitis may require a longer duration of therapy In severe staphylococcal infections, therapy with oxacillin should be continued for at least 14 days. Therapy should be continued for at least 48 hours after the patient has become afebrile, asymptomatic, and cultures are negative.

The recommended duration of therapy for osteomyelitis with oxacillin is at least 14 days and should be continued for at least 48 hours after the patient has become afebrile, asymptomatic, and cultures are negative. However, the exact duration may vary depending on the clinical and bacteriological response of the patient 2.

The treatment of endocarditis and osteomyelitis may require a longer duration of therapy. In severe staphylococcal infections, therapy with nafcillin should be continued for at least 14 days

Similarly, for nafcillin, the treatment of osteomyelitis may require a longer duration of therapy, with a minimum of 14 days for severe staphylococcal infections 3.

From the Research

Osteomyelitis Treatment

• Osteomyelitis is a difficult to treat infection of the bone, which requires a combined medical and surgical approach and often persists intermittently for years, with relapses and failures 4.
• The optimal type, route of administration, and duration of antibiotic treatment remain controversial, and the emergence of multi-drug resistant organisms poses major therapeutic challenges 4.

Antibiotic Treatment Options

• Daptomycin may be a tolerable and effective alternative to vancomycin for the treatment of osteomyelitis, with significantly fewer patients treated with daptomycin having a recurrence of their infection 5.
• Rifampicin, levofloxacin, and linezolid have been shown to reduce intracellular CFU numbers significantly in acute osteomyelitis models, but their effectiveness in chronic models is limited 6.
• Oral antibiotic therapy has been found to be as effective as intravenous treatment in bacterial osteomyelitis, with full recovery observed in 55.6% of cases, and no significant difference in outcomes between oral and intravenous treatment groups 7.

Specific Antibiotic Regimens

• For Staph aureus osteomyelitis, several oral antibiotics are effective, including methicillin, ciprofloxacin, clindamycin, doxycycline, trimethoprim/sulfamethoxazole, linezolid, and rifampin 8.
• The choice of antibiotic regimen should be based on the specific microbiological etiology and susceptibility patterns, as well as the patient's clinical characteristics and treatment history 4, 7.