[Duration of antibiotic therapy in bone infection and biological or radiological data]

Modalities of bone infection therapeutic follow-up are controversial, notably for biological and radiological parameters. We have proposed six weeks of antibiotic therapy for all patients presenting with bone infection, since July 2005. Therefore, biological and radiological exams performed during the treatment were not taken into account when determining the duration of antibiotherapy. This protocol allows determining the usefulness of these biological and radiological parameters.

Methods: All patients presenting with bone infection, from July 2005 to July 2008, were included. Inflammatory biological parameters such as C-reactive protein (CRP) and sedimentation rate were analyzed, and values were considered as normal when less than 10 mg/L and less than 15 mm respectively. All available CT- and MR imaging were analyzed by the same referent radiologist.

Results: Eighty-seven patients presenting with bone infection received antibiotic therapy for a mean [SD] 42 ± 0.3 days. Cure was reported in 82 patients (94%) with a mean follow-up after antibiotic therapy of 36 ± 9 months, five patients relapsed. CRP was available in 66 cases by the end of antibiotic therapy, it was normal in 40/64 of patients with favorable outcome (62%) and in one case of unfavorable outcome. The sedimentation rate was available in 22 cases, and normal in seven cases of favorable outcome (32%). By the end of antibiotic therapy, CT-scan showed active bone infection for 15/23 of patients with favorable outcome (65%), while MR imaging suggested the same diagnosis in 8/14 cases (57%).

Conclusion: Biological parameters and radiological findings are inadequate to determine the duration of antibiotic therapy in bone infection.