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

AbstractPediatric extrapulmonary tuberculosis (EPTB) is a diagnostic challenge. A new immunochemistry based MPT64 antigen detection test has shown improved sensitivity compared to current laboratory tests. The aim of this study was to implement and validate the test performance in a resource limited African setting. Presumptive pediatric (0–18 y) EPTB patients were prospectively enrolled at Mbeya Zonal Referral Hospital, and followed to the end of treatment or until a final diagnosis was reached. Specimens from suspected sites of infection were subject to routine diagnostics, GeneXpert MTB/RIF assay and the MPT64 test. The performance of the tests was assessed using mycobacterial culture as well as a composite reference standard. 30 patients were categorized as TB cases, 31 as non-TB cases and 2 were uncategorized. In the TB group, the three most common infections were adenitis (30%), peritonitis (30%) and meningitis (20%). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of the MPT64 test was 92%, 88%, 87%, 92% and 90%, respectively. Mortality was equally high among TB/non-TB cases (23% vs 21%), and malnutrition was the main comorbidity among TB cases. The MPT64 test was implementable in the routine diagnostics in a low-resource setting and improved the diagnosis of pediatric EPTB.

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Utility of MPT64 antigen detection test for diagnosis of HIV coinfected extrapulmonary tuberculosis in Tanzania

10.1183/13993003.congress-2019.pa560 ◽

2019 ◽

Author(s):

Erlend Grønningen ◽

Lisbet Sviland ◽

Ester Ngadaya ◽

Marywinnie Nanyaro ◽

William Muller ◽

...

Keyword(s):

Extrapulmonary Tuberculosis ◽

Antigen Detection

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Immunochemistry-Based Diagnosis of Extrapulmonary Tuberculosis: A Strategy for Large-Scale Production of MPT64-Antibodies for Use in the MPT64 Antigen Detection Test

Antibodies ◽

10.3390/antib10030034 ◽

2021 ◽

Vol 10 (3) ◽

pp. 34

Author(s):

Ida Marie Hoel ◽

Iman A Mohammed Ali ◽

Sheeba Ishtiaq ◽

Lisbet Sviland ◽

Harald Wiker ◽

...

Keyword(s):

Large Volume ◽

Large Scale ◽

Polyclonal Antibodies ◽

Extrapulmonary Tuberculosis ◽

Antigen Detection ◽

Scale Production ◽

Volume Functional ◽

Large Scale Production ◽

Stable Performance ◽

Selection Of

Tuberculosis (TB) is a global health problem. The immunohistochemistry (IHC)-based MPT64 antigen detection test has shown promising results for diagnosing extrapulmonary TB in previous studies. However, the anti-MPT64 antibody currently used in the test is in limited supply, and reproduction of a functional antibody is a prerequisite for further large-scale use. Various antigen-adjuvant combinations and immunisation protocols were tested in mice and rabbits to generate monoclonal and polyclonal antibodies. Antibodies were screened in IHC, and the final new antibody was validated on clinical human specimens. We were not able to generate monoclonal antibodies that were functional in IHC, but we obtained multiple functional polyclonal antibodies through careful selection of antigen-adjuvant and comprehensive screening in IHC of both pre-immune sera and antisera. To overcome the limitation of batch-to-batch variability with polyclonal antibodies, the best performing individual polyclonal antibodies were pooled to one final large-volume new anti-MPT64 antibody. The sensitivity of the new antibody was in the same range as the reference antibody, while the specificity was somewhat reduced. Our results suggest that it possible to reproduce a large-volume functional polyclonal antibody with stable performance, thereby securing stable supplies and reproducibility of the MPT64 test, albeit further validation remains to be done.

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Tuberculosis: Diagnostic Challenges in Rural Africa

Praxis ◽

10.1024/1661-8157/a003355 ◽

2019 ◽

Vol 108 (15) ◽

pp. 991-996

Author(s):

Ngisi Masawa ◽

Farida Bani ◽

Robert Ndege

Keyword(s):

Extrapulmonary Tuberculosis ◽

X Ray ◽

Molecular Tests ◽

Rural Settings ◽

Chest X Ray ◽

Screening Questions ◽

Rural Africa ◽

Tb Diagnostics ◽

Strip Test ◽

Urine Strip

Abstract. Tuberculosis (TB) remains among the top 10 infectious diseases with highest mortality globally since the 1990s despite effective chemotherapy. Among 10 million patients that fell ill with tuberculosis in the year 2017, 36 % were undiagnosed or detected and not reported; the number goes as high as 55 % in Tanzania, showing that the diagnosis of TB is a big challenge in the developing countries. There have been great advancements in TB diagnostics with introduction of the molecular tests such as Xpert MTB/RIF, loop-mediated isothermal amplification, lipoarabinomannan urine strip test, and molecular line-probe assays. However, most of the hospitals in Tanzania still rely on the TB score chart in children, the WHO screening questions in adults, acid-fast bacilli and chest x-ray for the diagnosis of TB. Xpert MTB/RIF has been rolled-out but remains a challenge in settings where the samples for testing must be transported over many kilometers. Imaging by sonography – nowadays widely available even in rural settings of Tanzania – has been shown to be a useful tool in the diagnosis of extrapulmonary tuberculosis. Despite all the efforts and new diagnostics, 30–50 % of patients in high-burden TB countries are still empirically treated for tuberculosis. More efforts need to be placed if we are to reduce the death toll by 90 % until 2030.

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