title: Comparison of the Xpert MTB/RIF Assay and Real-time PCR for the Detection of Mycobacterium tuberculosis.
abstract: BACKGROUND
  We compared the Xpert MTB/RIF assay with a real-time PCR assay using samples from culture-positive patients with TB. In addition, drug susceptibility test results were compared to evaluate the usefulness of these methods.
  
  
  METHODS
  Fifty-two clinical specimens were analyzed by standard smear-microscopy, mycobacterial growth indicator tube (MGIT) culture, solid culture, MGIT drug-susceptibility testing, TB real-time PCR, and the Xpert MTB/RIF assay.
  
  
  RESULTS
  Diagnostic sensitivity of AdvanSure TB/NTM real-time PCR was 80.0%. As shown from smear positive and negative specimens, sensitivities were 87.5% and 75.9%, respectively. The diagnostic sensitivity of Xpert MTB/RIF assay was 75.5%, and from smear positive and negative specimens, sensitivities were 93.8% and 65.5%, respectively. There were 10 cases with discrepant results between two methods. 2 cases were found resistant to rifampin, although Xpert MTB/RIF assay was able to detect rifampin resistance in only one specimen.
  
  
  CONCLUSIONS
  Xpert MTB/RIF assay is an easier method to conduct and while its ability to detect rifampin resistance simultaneously is a benefit, its sensitivity from smear negative-culture positive specimens was lower than Advansure TB/NTM real-time PCR. Further investigation to increase the sensitivity and detect other drug resistances by kit-based assays is required for the rapid and accurate diagnosis of tuberculosis.
authors.affiliation: Department of Laboratory Medicine, Graduate School of Medicine, Kyung Hee University, Seoul, Republic of Korea Seegene Medical Foundation, Graduate School, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Min Jin
authors.initials: MJ
authors.lastname: Kim
authors.affiliation: Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: You Sun
authors.initials: YS
authors.lastname: Nam
authors.affiliation: Department of Laboratory Medicine, School of Medicine, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Cho
authors.affiliation: Department of Laboratory Medicine, School of Medicine, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Tae Sung
authors.initials: TS
authors.lastname: Park
authors.affiliation: Department of Laboratory Medicine, School of Medicine, Kyung Hee University, Seoul, Republic of Korea leehejo@khmc.or.kr.
authors.forename: Hee Joo
authors.initials: HJ
authors.lastname: Lee
mesh_terms: D000995:Antitubercular Agents / Q000494:pharmacology; D001681:Biological Assay / Q000379:methods*; D024881:Drug Resistance, Bacterial / Q000187:drug effects; D006801:Humans; D008826:Microbial Sensitivity Tests; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification*; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012293:Rifampin / Q000494:pharmacology*; D012680:Sensitivity and Specificity
chemical_list: D000995:Antitubercular Agents; D012293:Rifampin
keywords: Mycobacterium tuberculosis; Real-Time Polymerase Chain Reaction; Smear-negative; Xpert