Microbiological diagnosis of suspected vertebral osteomyelitis with a focus on the yield of percutaneous needle biopsy: a 10-year cohort study

This study aims to evaluate in patients hospitalized for vertebral osteomyelitis (VO) the effectiveness of bacteriological diagnosis and the yield of percutaneous needle biopsy (PNB) and to identify factors associated with the result of PNB. This retrospective, two-centre study was conducted between 2000 and 2009. Data on patients with VO were retrieved from the diagnosis database and confirmed by checking medical records. A total of 300 patients with VO were identified; 31 received antibiotics without bacteriological diagnosis, and 269 patients with spondylodiscitis imaging were included. Eighty-three (30.9%) and 18 (6.7%) infections were documented by blood cultures and by bacteriological samples other than PNB, respectively; 168 patients with no bacteriological diagnosis had PNB. Of these, 92 (54.8%) were positive and identified the pathogen and 76 (45.2%) were negative. The most common bacteria were Staphylococcus aureus (34.3%), Streptococcus spp. (20.6%) and coagulase-negative staphylococcus (14.8%). After multivariate analysis, the only factor associated with negative PNB was previous antibiotic intake (OR: 2.31 [1.07–5.00]). When VO was suspected on imaging, bacteriological investigation identified the microorganism in 209/300 (70%) of the cases. The yield of PNB was 54.8%. The only predictor of PNB negativity was previous antibiotic intake. Therefore, we believe that a second PNB should be done after a sufficient delay withdrawal of antibiotics if the first sample was negative. The study was retrospectively registered by the local ethics committee (N°E2019-61).