title: The Xpert® MTB/RIF assay in routine diagnosis of pulmonary tuberculosis: A multicentre study in Lithuania.
abstract: BACKGROUND
  Drug-resistant tuberculosis (TB) is an important public health problem in Lithuania with MDR rates in new cases reaching 11% in 2012. Currently available diagnostic tools are not fully adequate for an accurate and rapid result for diagnosis of TB and MDR-TB.
  
  
  OBJECTIVE
  To evaluate the performance of Xpert(®) MTB/RIF assay for an early diagnosis of TB and detection of rifampicin (RIF) resistance in routine settings in Lithuania.
  
  
  METHODS
  A total of 833 individual respiratory samples obtained from patients previously treated for TB and MDR-TB contacts were tested using the Xpert MTB/RIF assay. Performance characteristics of the assay for TB and RIF resistance detection were calculated using culture and phenotypical DST results as a gold standard.
  
  
  RESULTS
  The overall sensitivity and specificity of the Xpert MTB/RIF assay for TB detection were 93.7% and 91.7%, respectively with the sensitivity for smear-negative specimens reaching 82.5%. Resistance to RIF was detected in 81 (20.7%) primary specimens with no false negative results; there were 4/225 (1.8%) false-positives among strains sensitive to rifampicin. Overall sensitivity and specificity of the molecular assay for detection of RIF resistance calculated against phenotypic DST results were 100% and 98.2%, respectively.
  
  
  CONCLUSIONS
  Our results demonstrate very good performance of the Xpert MTB/RIF assay for the detection of TB and RIF resistance on primary respiratory specimens. It provides strong evidence that implementation of the assay for routine laboratory diagnosis in high drug-resistance settings may improve and facilitate TB diagnosis.
authors.affiliation: Vilnius University Hospital Santariskiu Klinikos, Infectious Diseases and TB Hospital, P. Sirvio str. 5, 10214 Vilnius, Lithuania; Vilnius University, Department of Physiology, Biochemistry and Laboratory Medicine, Faculty of Medicine, M. K. Ciurlionio str. 21, 03101 Vilnius, Lithuania. Electronic address: edita.pimkina@yahoo.com.
authors.forename: Edita
authors.initials: E
authors.lastname: Pimkina
authors.affiliation: Vilnius University, Clinic of Infectious and Chest Diseases, Dermatovenereology and Allergology, Birutes str. 1/20, 08117 Vilnius, Lithuania; Vilnius University Hospital Santariskiu Klinikos, Centre of Pulmonology and Allergology, Santariskiu str. 2, 08661 Vilnius, Lithuania. Electronic address: rolandas.zablockis@santa.lt.
authors.forename: Rolandas
authors.initials: R
authors.lastname: Zablockis
authors.affiliation: Imperial College London, Du Cane Road, London W12 0NN, United Kingdom. Electronic address: v.nikolayevskyy@imperial.ac.uk.
authors.forename: Vladyslav
authors.initials: V
authors.lastname: Nikolayevskyy
authors.affiliation: Vilnius University, Clinic of Infectious and Chest Diseases, Dermatovenereology and Allergology, Birutes str. 1/20, 08117 Vilnius, Lithuania; Vilnius University Hospital Santariskiu Klinikos, Centre of Pulmonology and Allergology, Santariskiu str. 2, 08661 Vilnius, Lithuania. Electronic address: edvardas.danila@santa.lt.
authors.forename: Edvardas
authors.initials: E
authors.lastname: Danila
authors.affiliation: Vilnius University Hospital Santariskiu Klinikos, Infectious Diseases and TB Hospital, P. Sirvio str. 5, 10214 Vilnius, Lithuania. Electronic address: edita.david@takas.lt.
authors.forename: Edita
authors.initials: E
authors.lastname: Davidaviciene
mesh_terms: D000328:Adult; D000904:Antibiotics, Antitubercular / Q000494:pharmacology / Q000627:therapeutic use; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests / Q000379:methods; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D019095:Point-of-Care Systems; D016133:Polymerase Chain Reaction / Q000379:methods; D012189:Retrospective Studies; D012293:Rifampin / Q000494:pharmacology / Q000627:therapeutic use; D013183:Sputum / Q000382:microbiology; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis* / Q000188:drug therapy; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000188:drug therapy
chemical_list: D000904:Antibiotics, Antitubercular; D012293:Rifampin
keywords: Drug susceptibility testing; Mycobacterium tuberculosis; Nucleic acid amplification test; Xpert MTB/RIF assay