title: Case report of a false positive result of the Xpert®MTB/RIF assay for rifampicin resistance in Mycobacterium tuberculosis complex.
abstract: In the present case, we report a false positive result for the detection of rifampicin (RIF) resistance by the Xpert®MTB/RIF assay, version G4.Miliary Mycobacterium tuberculosis infection (miliary TB) was suspected in a 50-year old Angolan woman. Imaging of the thorax and abdomen displayed diffuse lesions. The Xpert®MTB/RIF assay conducted on the broncho-alveolar lavage (BAL) fluid was positive for TB and positive for RIF resistance. Confirmatory molecular tests and the phenotypic drug susceptibility determination supported the diagnosis of TB but not RIF resistance. The patient was treated successfully with a conventional therapeutic scheme. Because, the Xpert®MTB/RIF assay allows the simultaneous detection of TB and RIF resistance, the World Health Organisation (WHO) recommends its use as initial diagnostic test, over microscopy, culture and phenotypic drug susceptibility testing. Even though specificity of the Xpert®MTB/RIF assay version G4 is high, false positive test results remain possible and have to be considered for the interpretation of the RIF resistance detection by Xpert®MTB/RIF assay.
authors.affiliation: a Department of Laboratory Medicine , University Hospitals Leuven , Belgium.
authors.forename: Jolien
authors.initials: J
authors.lastname: Claessens
authors.affiliation: b National Reference Centre of Tuberculosis and Mycobacteria, Communicable and Infectious Diseases , Scientific Institute of Public Health , Brussels , Belgium.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Mathys
authors.affiliation: c Department of Internal Medicine , University Hospitals Leuven , Belgium.
authors.forename: Inge
authors.initials: I
authors.lastname: Derdelinckx
authors.affiliation: a Department of Laboratory Medicine , University Hospitals Leuven , Belgium.
authors.forename: Veroniek
authors.initials: V
authors.lastname: Saegeman
mesh_terms: D000810:Angola / Q000208:ethnology; D000904:Antibiotics, Antitubercular / Q000627:therapeutic use*; D003951:Diagnostic Errors; D024881:Drug Resistance, Bacterial; D054242:Emigrants and Immigrants; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008875:Middle Aged; D012293:Rifampin / Q000627:therapeutic use*; D014376:Tuberculosis / Q000175:diagnosis* / Q000188:drug therapy; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis* / Q000188:drug therapy
chemical_list: D000904:Antibiotics, Antitubercular; D012293:Rifampin
keywords: Mycobacterium tuberculosis; Rifampicin; Specificity; Xpert® MTB/RIF