Diagnostic accuracy of GeneXpert MTB/RIF in musculoskeletal tuberculosis : high sensitivity in tissue samples of HIV-infected and HIV-uninfected patients

• Published in: South African medical journal Vol. 107; no. 10; pp. 854 - 858
• Main Authors: Dunn, R., Workman, L., Held, M., Zar, H.J., Laubscher, M.
• Format: Journal Article
• Language: English
• Published: South Africa Health and Medical Publishing Group (HMPG) 01-10-2017; Health & Medical Publishing Group; South African Medical Association
• Subjects: Diagnosis; Diseases; Extrapulmonary; GeneXpert; HIV patients; Risk factors; Sensitivity; Tuberculosis; Xpert MTB/RIF; South Africa
• ISSN: 0256-9574; 2078-5135
• DOI: 10.7196/SAMJ.2017.v107i10.11186

Background. GeneXpert MTB/RIF is useful for the diagnosis of pulmonary TB in adults, but there is limited evidence on its usefulness in extrapulmonary TB. Objectives. To investigate the diagnostic accuracy of GeneXpert MTB/RIF in HIV-infected and HIV-uninfected patients with suspected musculoskeletal TB. Methods. A prospective study of patients with suspected musculoskeletal (bone and joint) TB was undertaken. The diagnostic accuracy of GeneXpert MTB/RIF was compared with the reference standards of culture and histopathology. Results. A total of 206 biopsies from 201 patients (23% HIV-infected) were evaluated. The sensitivity and specificity of GeneXpert MTB/RIF was 92.3% (84/91) and 99.1% (114/115), respectively. GeneXpert MTB/RIF detected 8.8% more cases than culture (84/91 (92.3%) v. 76/91 (83.5%), respectively; p=0.069). GeneXpert MTB/RIF also detected all 4 multidrug-resistant TB cases and an additional 2 rifampicin-resistant cases in culture-negative samples. The sensitivity of GeneXpert MTB/RIF in HIV-infected patients was 96.9% (31/32) v. 89.6% (43/48) in HIV-uninfected patients (p=0.225). Conclusion. GeneXpert MTB/RIF is an accurate test for the detection of TB in tissue samples of HIV-infected and HIV-uninfected patients with suspected musculoskeletal TB. A positive GeneXpert MTB/RIF result should be regarded as microbiological confirmation of TB.