Empiric Therapy Regimens

General principles/recommendations and empiric therapeutic regimens for osteomyelitis are provided below, as well as treatment based on contiguous spread of infection.^{[1, 2, 3, 4, 5, 6, 7]}

General principles/recommendations

Most cases of osteomyelitis in adults require a combination of medical and surgical therapy for successful eradication of infection.

If possible, antimicrobials should be withheld until percutaneous or surgical deep cultures have been obtained. Once cultures are obtained, a parenteral antimicrobial regimen is initiated to cover suspected pathogens. However, if the patient is acutely ill (with sepsis or concomitant soft-tissue infection), antibiotic therapy should not be delayed.

In hematogenous long-bone osteomyelitis, infection is usually monobacterial, whereas in contiguous infection, it is usually polymicrobial.

The most commonly encountered organisms in osteomyelitis are Staphylococcus aureus, coagulase-negative streptococci, aerobic gram-negative bacteria, and anaerobes including Finegoldia (formerly Peptostreptococcus) species.

Empiric therapy of osteomyelitis should provide antimicrobial activity against gram-negative organisms and methicillin-resistant S aureus (MRSA). Beta-lactams and vancomycin are commonly used as initial empiric therapy. Suggested empiric antibiotic regimens include vancomycin in combination with a third- or fourth-generation cephalosporin or piperacillin-tazobactam. Caution should be advised with concomitant use of vancomycin and piperacillin-tazobactam because of the increased risk of nephrotoxicity with this regimen.^[7]

Antibiotic therapy for hematogenous osteomyelitis should be pathogen-directed, based on the results of bone biopsy or blood cultures.

For osteomyelitis from contiguous spread of infection, wound culture is poorly correlated with bone biopsy culture for all organisms except MRSA.

The duration of therapy for acute osteomyelitis is 4-8 weeks.

The optimal duration of therapy for chronic osteomyelitis is uncertain, but treatment is usually administered for a minimum of 6 weeks.^[4]

Osteomyelitis from contiguous spread of infection

Recommended agents are as follows:

Piperacillin-tazobactam 3.375 g IV q6h or
Ampicillin-sulbactam 3 g IV q6h or
Ticarcillin-clavulanate 3.1 g IV q6h or
Cefepime 2 g IV q8-12h (consider adding metronidazole 500 mg q8h for empiric anaerobic coverage)

Patients with penicillin allergy and osteomyelitis from contiguous spread of infection:

(Clindamycin 600 mg IV/PO q6h or metronidazole 500 mg IV/PO q8h) plus (ciprofloxacin 750 mg PO or 400 mg IV q12h or levofloxacin 750 mg PO daily), or moxifloxacin 400 mg PO daily

If MRSA is suspected:

Add vancomycin 15 mg/kg IV q12h
If a contraindication exists to the use of vancomycin, an alternative anti-MRSA agent such as linezolid, daptomycin, or ceftaroline ^[6]may be used