title: False-positive rifampicin resistance on Xpert® MTB/RIF: case report and clinical implications.
abstract: The World Health Organization had endorsed Xpert® MTB/RIF (Xpert) as the initial diagnostic for multidrug-resistant tuberculosis (TB) or TB suspects co-infected with the human immunodeficiency virus. We investigated an unexpected case of rifampicin (RMP) resistance on Xpert using  repeat Xpert, smear microscopy, MTBDRplus assay, culture, drug susceptibility testing, spoligotyping and rpoB gene sequencing. A false-positive result was most likely, given the wild type rpoB gene sequence and exclusion of both mixed infection and mixture of drug-susceptible  and drug-resistant populations. When decentralising Xpert, test performance characteristics need to be understood by health care workers and methods of confirmation of RMP resistance need to be accessible.
authors.affiliation: Department of Epidemiology, University of North Carolina, Chapel Hill, North Carolina 27599, USA. vanrie@email.unc.edu
authors.forename: A
authors.initials: A
authors.lastname: Van Rie
authors.forename: K
authors.initials: K
authors.lastname: Mellet
authors.forename: M-A
authors.initials: MA
authors.lastname: John
authors.forename: L
authors.initials: L
authors.lastname: Scott
authors.forename: L
authors.initials: L
authors.lastname: Page-Shipp
authors.forename: H
authors.initials: H
authors.lastname: Dansey
authors.forename: T
authors.initials: T
authors.lastname: Victor
authors.forename: R
authors.initials: R
authors.lastname: Warren
mesh_terms: D000904:Antibiotics, Antitubercular / Q000627:therapeutic use; D004269:DNA, Bacterial / Q000032:analysis; D003937:Diagnosis, Differential; D005189:False Positive Reactions; D006678:HIV; D015658:HIV Infections / Q000150:complications; D006801:Humans; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D012293:Rifampin / Q000627:therapeutic use*; D013183:Sputum / Q000382:microbiology*; D018088:Tuberculosis, Multidrug-Resistant / Q000150:complications / Q000175:diagnosis* / Q000188:drug therapy; D014397:Tuberculosis, Pulmonary / Q000150:complications / Q000175:diagnosis* / Q000188:drug therapy
chemical_list: D000904:Antibiotics, Antitubercular; D004269:DNA, Bacterial; D012293:Rifampin