Multiplex Real-Time Polymerase Chain Reaction

Abstract

Case-control study for assessing a diagnostic test. The aim of this study was to analyze the diagnostic yield of a multiplex real-time polymerase chain reaction (PCR) assay in the differential diagnosis of tuberculous vertebral osteomyelitis (TVO) and brucellar vertebral osteomyelitis (BVO). Vertebral osteomyelitis (VO) is one of commonest osteoarticular complications of tuberculosis and brucellosis. However, the very similar clinical, radiologic, and histologic characteristics of these entities mean that diagnosis requires etiological confirmation, but conventional microbiologic methods have important limitations. Fifteen vertebral samples from patients with TVO or BVO and 9 from pyogenic and nontuberculous mycobacteria VO were studied by multiplex PCR and conventional microbiologic techniques. To identify Brucella DNA, we used a fragment of 207 bp from the conserved region of the gene coding for an immunogenic membrane protein of 31 kDa of B. abortus (BCSP31) and for Mycobacterium tuberculosis complex, a fragment of 164 bp from the intergenic region SenX3-RegX3. The histopathologic findings were inconclusive in 4 of 14 cases (28.6%) with TVO or BVO and cultures were positive in 11 of 15 cases (73.3%). Multiplex PCR correctly identified 14 of the 15 samples from patients with TVO and BVO and was negative in all the control samples. Thus, the overall sensitivity and specificity of the multiplex PCR were 93.3% and 90%, respectively, with an accuracy of 92% (95% CI, 81.4%-100%). These results suggest that multiplex real-time PCR is far more sensitive than conventional cultures, and this, together with its speed, makes this technique a very practical approach for the differential diagnosis between TVO and BVO.