Immunocytochemical detection of Mycobacterium Tuberculosiscomplex specific antigen, MPT64, improves diagnosis of tuberculous lymphadenitis and tuberculous pleuritis

Abstract

BackgroundA rapid, sensitive and accurate laboratory diagnosis is of prime importance in suspected extrapulmonary tuberculosis (EPTB) cases. However, traditional techniques for the detection of acid-fast bacilli have limitations. The aim of the study was to evaluate the diagnostic value of immunocytochemical staining for detection of Mycobacterium tuberculosis complex specific antigen, MPT64, in aspirates from pleural effusions and lymph nodes, the most common presentations of EPTB.MethodA cross-sectional study was conducted by including patients at Tikur Anbessa Specialized Hospital and the United Vision Medical Services from December 2011 to June 2012. Lymph node aspirates and pleural fluid samples were collected and analyzed from a total of 51 cases (26 tuberculous (TB) pleuritis and 25 TB lymphadenitis) and 67 non-TB controls. Each specimen was subjected to Ziehl-Neelsen (ZN) staining, culture on Lowenstein– Jensen (LJ) medium, cytological examination, Polymerase Chain Reaction (PCR) using IS1081gene sequence as a primer and immunocytochemistry (ICC) with polyclonal anti-MPT64 antibody. All patients were screened for HIV.ResultICC was positive in 38 of 51 cases and in the 7 of 67 controls giving an overall sensitivity and specificity of 74.5% and 89.5%, respectively. Using IS1081-PCR as a reference method, the sensitivity and specificity, positive and negative predictive value of ICC was 88.1%, 89.5%, 82.2% and 93.2%, respectively. The case detection rate increased from 13.7% by ZN stain to 19.6% by LJ culture, to 66.7% by cytology and 74.5% by ICC.ConclusionImmunocytochemistry with anti-MPT64 antigen improved detection of TB in pleural effusion and lymph node aspirates. Further studies using monoclonal antibodies on samples from other sites of EPTB is recommended to validate this relatively simple diagnostic method for EPTB.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-014-0585-1) contains supplementary material, which is available to authorized users.

Diagnosis of extrapulmonary tuberculosis using the MPT64 antigen detection test in a high-income low tuberculosis prevalence setting

“…Thus, the MPT64 test may strengthen the TB diagnosis in a pathology laboratory in the absence of culture confirmation. The MPT64 test performance was lower in the present study compared to previous studies [28][29][30]35]. Against a CRS, the overall sensitivity was 32% (95% CI 17-51) for the MPT64 test, compared to 67-100% in previous studies [28][29][30]35].…”

“…All previous studies were conducted in high TB burden settings, in which a higher pre-test probability of TB combined with potentially more advanced stage of TB disease at the time of diagnosis, may lead to higher test sensitivity. Still, also when using culture as a reference standard, the overall MPT64 test sensitivity was lower (19, compared to previous studies (75-100%) [26,28,30,35,37]. This could partly be explained by different procedures for culture used across the studies.…”

“…An immunochemistry-based test for detection of the mycobacterial secreted protein MPT64 (MPT64 test) from biopsies, fine-needle aspirates (FNAs) and fluid samples has shown high sensitivity for diagnosing EPTB in previous studies compared to culture and a TB specific nested-PCR [26][27][28][29][30][31]. The MPT64 test is robust and fast, and can differentiate between NTM and TB disease, as the MPT64 protein is specific for Mycobacterium tuberculosis complex (MTBC) species, and not found in NTM [32][33][34].…”

Diagnostic Value of Pleural Effusion Mononuclear Cells Count and Adenosine Deaminase for Tuberculous Pleurisy Patients in China: A Case-Control Study

“…As a common extrapulmonary TB, Tuberculous pleurisy (TBP) accounts for 25% of TB cases in China (2)(3)(4). The diagnosis of TBP is difficult (5,6), with the thoracoscopic pleural pathology as the gold standard method (7). However, thoracoscopic pleural biopsy is an invasive operation with the issues of considerable risks and cost.…”

Analysis of Plasma Cytokine and Chemokine Profiles in Patients with and without Tuberculosis by Liquid Array-Based Multiplexed Immunoassays

“…tuberculosis organisms are detectable in pleural effusions, even in those from TP patients. The gold standard for diagnosing TP involves the examination of pleural biopsies, which is effective, but still highlights the need to identify more convenient and novel diagnostic biomarkers [ 14 – 16 ].…”