The role of Xpert MTB/RIF in diagnosing pulmonary tuberculosis in post-mortem tissues.

Alberto L García-Basteiro,Lucília Lovane,Cristina Rodríguez,Cesaltina Lorenzoni,Carla Carrilho,Jaume Ordi,Esperança Ussene,Inacio Mandomando,Dércio Chitsungo,Mamudo R Ismail,Andrea Vergara,Miguel J Martínez,Elisa López-Varela,Clara Menéndez,Paola Castillo,Quique Bassat

doi:10.1038/srep20703

Abstract

The extent to which the Xpert MTB/RIF (Gene Xpert) contributes to tuberculosis (TB) diagnosis in samples other than sputum and cerebrospinal fluid remains uncertain. We aimed to assess the role of Xpert MTB/RIF for detecting M. tuberculosis in post-mortem tissues. We conducted a study among 30 complete diagnostic autopsies (CDA) performed at the Maputo Central Hospital (Mozambique). Lung tissues were screened for TB in all cases. In addition other tissues were tested when compatible lesions were identified in the histological exam. We used in-house real time PCR and LAMP assays to confirm the presence of M. tuberculosis DNA. The diagnosis of tuberculosis at death was established based on microbiological and histopathological results. Eight out of 30 cases (26.7%) were diagnosed of tuberculosis. Xpert had a sensitivity to detect TB in lung tissue of 87.5% (95% CI 47.3–99.7) and a specificity of 95.7% (95% CI: 78.1–99.9). In-house DNA amplification methods and Xpert showed 93.6% concordance for lung tissue and 100% concordance for brain and liver tissues. The final cause of death was attributable to tuberculosis in four cases. Xpert MTB/RIF may represent a valuable, easy-to perform technique for post-mortem TB diagnosis.

Highlights

Mozambique is one of the 22 TB high burden countries facing many challenges to achieve successful control[1,12], showing high incidence rates, especially among HIV-infected patients[13,14]
A first macroscopic evaluation of the whole organ was conducted and multiple sections of the organ were performed in order to sample lesions or areas with suspected lesions
To our knowledge this is the first study comparing the diagnostic accuracy of Xpert MTB/RIF with conventional real time PCR for TB diagnosis in tissue samples from autopsy cases of unknown cause of death

Summary

Introduction

Mozambique is one of the 22 TB high burden countries facing many challenges to achieve successful control[1,12], showing high incidence rates, especially among HIV-infected patients[13,14]. The case detection rate has been estimated at 37%, very low certainty exists on mortality estimates[1]. In Mozambique as well as other high TB burden countries, a rapid, easy to perform and reliable technique that helps to establish TB diagnosis at death, could have a significant impact on the accuracy of global TB mortality statistics, and on health planning. The objective of this study was to explore the utility of the Xpert assay for TB diagnosis in postmortem tissues in a high TB/HIV prevalence area

Objectives

Methods

Results

Conclusion