Tuberculosis (TB) is a cause of ill health and death worldwide. Since 2010, the diagnostic process has strongly relied on GeneXpert assays on biological specimens. Xpert MTB/RIF is an automated nucleic acid amplification test (NAAT) for Mycobacterium tuberculosis and rifampicin resistance, endorsed by the World Health Organization and the US Food and Drug Administration. Xpert is used in many countries as the initial diagnostic test for tuberculosis. Nevertheless, the reliability of GeneXpert positive tests in patients with a history of TB is largely unknown, due to possible false-positive results (i.e., GeneXpert-positive but culture-negative patients). We present a case report of a patient with a history of pulmonary TB, who was GeneXpert positive but culture negative on bronchoalveolar lavage 22 months after completion of appropriate antitubercular therapy.
Learning points: GeneXpert assays have a pivotal role in the diagnosis of tuberculosis (TB), with overall good sensitivity and excellent specificity.Patients with a history of TB can be GeneXpert positive up to several years after the end of appropriate antitubercular treatment.Further studies are warranted to fully understand the role of GeneXpert assays in the diagnostic algorithms of patients with a history of TB.
Keywords: GeneXpert; TB; Tuberculosis; false positives; retested patients.
© EFIM 2020.