MPT64 antigen detection test improves routine diagnosis of extrapulmonary tuberculosis in a low-resource setting: A study from the tertiary care hospital in Zanzibar

PLoS One. 2018 May 9;13(5):e0196723. doi: 10.1371/journal.pone.0196723. eCollection 2018.

Abstract

Background: Extrapulmonary tuberculosis (EPTB) is a diagnostic challenge. An immunochemistry-based MPT64 antigen detection test (MPT64 test) has reported higher sensitivity in the diagnosis of EPTB compared with conventional methods. The objective of this study was to implement and evaluate the MPT64 test in routine diagnostics in a low-resource setting.

Methods: Patients with presumptive EPTB were prospectively enrolled at Mnazi Mmoja Hospital, Zanzibar, and followed to the end of treatment. Specimens collected were subjected to routine diagnostics, GeneXpert® MTB/RIF assay and the MPT64 test. The performance of the MPT64 test was assessed using a composite reference standard, defining the patients as tuberculosis (TB) cases or non-TB cases.

Results: Patients (n = 132) were classified as confirmed TB (n = 12), probable TB (n = 34), possible TB (n = 18), non-TB (n = 62) and uncategorized (n = 6) cases. Overall, in comparison to the composite reference standard for diagnosis, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of the MPT64 test was 69%, 95%, 94%, 75% and 82%, respectively. The MPT64 test performance was best in TB lymphadenitis cases (n = 67, sensitivity 79%, specificity 97%) and in paediatric TB (n = 41, sensitivity 100%, specificity 96%).

Conclusions: We show that the MPT64 test can be implemented in routine diagnostics in a low-resource setting and improves the diagnosis of EPTB, especially in TB lymphadenitis and in children.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Antigens, Bacterial / analysis*
  • Bacterial Proteins / analysis*
  • Biopsy, Fine-Needle
  • Child
  • Comorbidity
  • Developing Countries
  • Female
  • HIV Infections / epidemiology
  • Humans
  • Immunohistochemistry
  • Lymph Nodes / chemistry*
  • Male
  • Middle Aged
  • Mycobacterium tuberculosis / isolation & purification
  • Predictive Value of Tests
  • Prospective Studies
  • Sensitivity and Specificity
  • Surveys and Questionnaires
  • Tanzania / epidemiology
  • Tertiary Care Centers
  • Tuberculosis / diagnosis*
  • Tuberculosis / epidemiology
  • Tuberculosis / microbiology
  • Tuberculosis / pathology
  • Tuberculosis, Lymph Node / diagnosis
  • Tuberculosis, Lymph Node / epidemiology
  • Tuberculosis, Lymph Node / microbiology
  • Tuberculosis, Lymph Node / pathology
  • Young Adult

Substances

  • Antigens, Bacterial
  • Bacterial Proteins
  • MPB64 protein, Mycobacterium

Grants and funding

This work was partly supported by the Research Council of Norway through the Global Health and Vaccination Programme [project number 234457]. This project is part of the EDCTP2 programme supported by the European Union. The Department of International Collaboration (DIC), Haukeland University Hospital, Norway, provided logistic and financial support for relocation of the first author and her family in Zanzibar during the study period. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.