A case of pleural Mycobacterium tuberculosis infection with reversion of Quantiferon Gold Plus results from positive to negative

TL;DR

A case of active pleural tuberculosis was diagnosed despite negative results from modern tests like Quantiferon Gold Plus and Xpert PCR.

Contribution

This case highlights the reversion of IGRA results during the progression from latent to active pleural TB.

Findings

The patient had a positive QFG-Plus result in 2018 but a negative result during active infection in 2022.

Xpert MTB/RIF Ultra PCR and routine cultures were negative, but acid-fast bacilli were identified in pleural tissue cultures.

Declining T-cell response to TB antigens may explain the loss of host control over latent MTB.

Abstract

Introduction.Mycobacterium tuberculosis (MTB) infections continue to have a high mortality and morbidity burden globally. Interferon-gamma release assays such as Quantiferon Gold Plus (QFG-Plus) aid in diagnosis of latent TB but diagnosis of pleural TB remains challenging. We present a case of active pleural MTB infection with reversion from positive to negative of IGRA result as well as negative Xpert MTB/RIF Ultra PCR result from tissues obtained from pleural biopsy.

Case summary. A 52-year-old otherwise healthy male presented in August 2022 with a 2 week history of pleuritic chest pain associated with modest elevation in inflammatory markers. The patient had had a positive QFG-Plus result in 2018, however QFG-Plus during this admission was negative. Computed-tomography pulmonary angiogram and needle thoracocentesis showed an exudative left pleural effusion with predominant lymphocytes. The patient’s symptoms failed to resolve with empiric antimicrobial therapy for community-acquired pneumonia. Broncho-alveolar lavage as well as biopsies of pleural tissues via video-assisted thoracoscopic surgery from the left lower lobe yielded negative results on routine microbiological culture as well as Xpert Ultra PCR. Growth of acid-fast bacilli was noted from mycobacterial cultures of pleural tissues which was identified as MTB.

Conclusion. Despite significant technological advances, microbiological diagnosis of MTB infections remains challenging. We document QFG-Plus reversion during development from latent to active pleural TB. Decline in the ability of CD4+ and CD8+ T cells to produce interferon gamma in response to TB antigens (ESAT-6 and CFP-10) was likely associated with loss of host control of latent MTB. This case serves as a reminder that despite exhaustive testing with state-of-art diagnostic platforms, MTB infections can still elude discovery.

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