Intravenous agents commonly used in the treatment of staphylococcal osteomyelitis include nafcillin, vancomycin and cefazolin. Although effective, they must be given in multiple doses, which may make ambulatory care problematic. While the third-generation cephalosporin ceftriaxone may not be as effective against Staphylococcus aureus as other agents, its long half-life allows for once-daily administration, which would be advantageous in at-home therapy. Guglielmo and colleagues evaluated the use of ceftriaxone for home therapy in adults with S. aureus osteomyelitis.
The study included 31 patients who ranged in age from 27 to 75 years; for at-home therapy, 22 received ceftriaxone, in a dosage of 2 g daily, and nine received cefazolin or vancomycin. All of the patients were initially treated with one to two weeks of intravenous nafcillin, vancomycin or cefazolin before discharge from the hospital. Antimicrobial therapy was given for a mean duration of 49 ± 7 days. Follow-up was continued at least six months in each patient. Excluded from the study were patients with infection caused by methicillin-resistant organisms.
Clinical cure was defined as resolution of all signs and symptoms of infection with microbiologic confirmation that the infection had been eradicated. An indeterminate outcome was defined as resolution of signs and symptoms of infection with a need for continued antimicrobial suppression. Treatment failure was defined as continued inflammation with signs of primary or secondary infection that required further surgical debridement or antibiotic therapy.
Sites of infection in the 22 patients who received ceftriaxone during home-care therapy included the sternum, knee, spine, humerus, foot, maxilla and a bone flap. Of the 22 patients who received ceftriaxone, 17 (77 percent) were cured of the infection. Two patients had indeterminate outcomes and, in both cases, infected hardware could not be removed and patients were maintained on oral antibiotics. Treatment failure occurred in three patients, but each of these patients had necrotic bone that could not be surgically excised. No adverse events were associated with the use of ceftriaxone.
Of the nine patients who received home-care therapy with vancomycin or cefazolin, seven were cured, one had an indeterminate outcome and one had a treatment failure. This latter patient had infection of the spine and hardware that could not be removed.
The authors note that the minimal inhibitory concentration for ceftriaxone is more than that for cefazolin (2 versus 0.5 μg per mL). Despite this difference, they conclude that ceftriaxone is effective in the treatment of S. aureus osteomyelitis. This agent offers the convenience of dosing once daily compared with three times daily for cefazolin and at least twice daily for vancomycin. The authors note the importance of bone debridement and removal of hardware, if possible, as critical to ensuring a good outcome.