title: Performance evaluation of Xpert MTB/RIF in a moderate tuberculosis incidence compared with TaqMan MTB and TRCRapid M.TB.
abstract: Xpert MTB/RIF is an automated nucleic acid amplification test (NAT) that can detect the presence of Mycobacterium tuberculosis complex (MTC) in clinical specimens as well as rifampicin (RIF) resistance resulting from rpoB mutation. Despite its high sensitivity and specificity for diagnosing tuberculosis (TB) with or without RIF resistance, the clinical performance of the test is variable. In this study, we evaluated the performance of Xpert MTB/RIF in a setting of moderate TB burden and high medical resources. A total of 427 sputum specimens were obtained from 237 suspected TB cases. Of these, 159 were identified as active TB, while the other 78 were non-TB diseases. The overall sensitivity and specificity of MTC detection by Xpert MTB/RIF using culture results as a reference were 86.8% [95% confidence interval (CI): 81.8%-90.6%] and 96.8% (95% CI: 93.1%-98.5%), respectively. Among MTC-positive culture specimens, Xpert MTB/RIF positivity was 95.2% (95% CI: 91.2%-97.5%) in smear-positive and 44.7% (95% CI 30.1-60.3) in smear-negative specimens. Xpert MTB/RIF was similar to other NATs (TaqMan MTB and TRCRapid M.TB) in terms of performance. Xpert MTB/RIF detected 25 RIF-resistant isolates as compared to 22 with the mycobacterial growth indicator tube antimicrobial susceptibility testing system, yielding a sensitivity of 100% (95% CI: 85.1%-100%) and specificity of 98.3% (95% CI: 95.1%-99.4%). These results indicate that although sensitivity in smear-negative/culture-positive specimens was relatively low, Xpert MTB/RIF is a useful diagnostic tool for detecting TB and RIF resistance even in settings of moderate TB burden.
authors.affiliation: Clinical Research Center, Kinki-Chuo Chest Medical Center, National Hospital Organization, Japan.
authors.forename: Kazunari
authors.initials: K
authors.lastname: Tsuyuguchi
authors.affiliation: Center for Pulmonary Diseases, Tokyo National Hospital, National Hospital Organization, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Nagai
authors.affiliation: Department of Respiratory Medicine, Higashi Nagoya National Hospital, National Hospital Organization, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Ogawa
authors.affiliation: Osaka Prefectural Medical Center for Respiratory and Allergic Diseases, Osaka Prefectural Hospital Organization, Japan.
authors.forename: Tomoshige
authors.initials: T
authors.lastname: Matsumoto
authors.affiliation: Fukujuji Hospital, Japan Anti-Tuberculosis Association, Japan.
authors.forename: Kozo
authors.initials: K
authors.lastname: Morimoto
authors.affiliation: Department of Mycobacterium Reference and Research, Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Takaki
authors.affiliation: Department of Mycobacterium Reference and Research, Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, Japan; Department of Basic Mycobacteriology, Graduate School of Biomedical Sciences, Nagasaki University, Japan. Electronic address: mitarai@jata.or.jp.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Mitarai
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000904:Antibiotics, Antitubercular / Q000494:pharmacology*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000302:isolation & purification*; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D011446:Prospective Studies; D012372:ROC Curve; D012293:Rifampin / Q000494:pharmacology*; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D018709:Statistics, Nonparametric; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis*; D055815:Young Adult
chemical_list: D000904:Antibiotics, Antitubercular; D012293:Rifampin
keywords: MDR; TB; Xpert MTB/RIF