Image-guided percutaneous disc sampling: impact of antecedent antibiotics on yield

AIM: To evaluate the effect of antecedent antimicrobial therapy on diagnostic yield from percutaneous image-guided disc-space sampling. MATERIALS AND METHODS: A retrospective review of the electronic health records of all patients who underwent image-guided percutaneous sampling procedures for suspected discitis/osteomyelitis over a 5-year period was performed. One hundred and twenty-four patients were identified. Demographics, medical history, and culture results were recorded as well as duration of presenting symptoms and whether antecedent antibiotic therapy had been administered. RESULTS: Of the 124 patients identified who underwent image-guided percutaneous discspace sampling, 73 had received antecedent antibiotic treatment compared with 51 who had not. The overall positive culture rate for the present study population was 24% (n = 30). The positive culture rate from patients previously on antibiotics was 21% (n = 15) compared with 29% (n = 15) for patients who had not received prior antibiotic treatment, which is not statistically significant (p = 0.26). Eighty-six percent (n = 63) of patients who had antecedent antibiotics received treatment for 4 or more days prior to their procedure, whereas 14% (n = 10) received treatment for 1-3 days prior to their procedure. The difference in culture positivity rate between these two groups was not statistically significant (p = 0.43). Culture results necessitated a change in antibiotic therapy in a third of the patients who had received antecedent antibiotic therapy. CONCLUSION: Antecedent antibiotic therapy, regardless of duration, did not result in significantly diminished diagnostic yield from percutaneous sampling for suspected discitis/osteomyelitis. The present results suggest that percutaneous biopsy may nonetheless yield positive diagnostic information despite prior antimicrobial therapy. If the diagnostic information may impact choice of therapeutic regimen, percutaneous biopsy should still be considered in cases where there is a history of prior antimicrobial therapy. (C) 2015 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.