Diagnostic accuracy and effectiveness of the Xpert MTB/RIF assay for the diagnosis of HIV-associated lymph node tuberculosis

• Published in: European journal of clinical microbiology & infectious diseases Vol. 32; no. 11; pp. 1409 - 1415
• Main Authors: Van Rie, A., Page-Shipp, L., Mellet, K., Scott, L., Mkhwnazi, M., Jong, E., Omar, T., Beylis, N., Stevens, W., Sanne, I., Menezes, C. N.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.11.2013; Springer; Springer Nature B.V
• Subjects: Accuracy; Adolescent; Adult; Aged; Bacterial diseases; Bacteriological Techniques - methods; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; CD4 antigen; Cellular biology; Drug resistance; Female; Granulomas; HIV; HIV Infections - complications; Human bacterial diseases; Human immunodeficiency virus; Human viral diseases; Humans; Immune system; Immunodeficiencies; Immunodeficiencies. Immunoglobulinopathies; Immunopathology; Infectious diseases; Internal Medicine; Lymphatic system; Male; Medical Microbiology; Medical sciences; Microscopy; Middle Aged; Molecular Diagnostic Techniques - methods; Patients; Sensitivity and Specificity; Software; Time Factors; Tuberculosis; Tuberculosis and atypical mycobacterial infections; Tuberculosis, Lymph Node - diagnosis; Viral diseases; Viral diseases of the lymphoid tissue and the blood. Aids; Young Adult; United States > US; South Africa; Johannesburg South Africa; Tuberculosis; Human Immunodeficiency Virus; Fine Needle Aspiration; Extrapulmonary Tuberculosis; Smear Microscopy; Immunopathology; Lymph node; Microbiology; Retroviridae; AIDS; Mycobacterial infection; Immune deficiency; Lentivirus; Infection; Virus; Accuracy; Viral disease; Bacteriosis; Diagnosis; Human immunodeficiency virus
• ISSN: 0934-9723; 1435-4373
• DOI: 10.1007/s10096-013-1890-0

Xpert MTB/RIF (Xpert) is recommended for human immunodeficiency virus (HIV)-associated pulmonary tuberculosis but not extrapulmonary tuberculosis. We assessed the performance of Xpert for HIV-associated lymph node tuberculosis (LNTB), the most common type of extrapulmonary tuberculosis. Among HIV-infected adults suspected of LNTB presenting for fine needle aspirate (FNA) at a South African hospital, we assessed the diagnostic accuracy of Xpert using either FNA culture or a composite of microscopy, culture, and cytology as the reference standard, and evaluated the impact of different diagnostics on patient management. Among 344 adults with valid FNA culture and Xpert results, 84 (24 %) were positive on microscopy, 149 (43 %) on culture, 152 (53 %) on Xpert, and 181 (57 %) had a cytology result suggestive of tuberculosis. Using liquid culture as the reference standard, the specificity of a single Xpert was suboptimal (88.2 %) but the sensitivity was high [93.3 %, 95 % confidence interval (CI) 87.6–96.6] and increased with decreasing CD4 count (from 87.0 % for CD4 >250 to 98.6 % for CD4 <100 cells/mm 3 ). Using a composite reference standard reduced the sensitivity to 79.2 % but increased the specificity to 98.6 %. All Xpert-positive patients initiated treatment within one day, compared to 70 % of culture-positive but Xpert-negative and 13 % of culture- and Xpert-negative but cytology-positive patients. Xpert is accurate and effective and could be endorsed as the initial diagnostic for HIV-associated LNTB.