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Rapid detection of Mycobacterium tuberculosis and rifampin resistance by use of on-demand, near-patient technology.
- Source :
-
Journal of clinical microbiology [J Clin Microbiol] 2010 Jan; Vol. 48 (1), pp. 229-37. Date of Electronic Publication: 2009 Oct 28. - Publication Year :
- 2010
-
Abstract
- Current nucleic acid amplification methods to detect Mycobacterium tuberculosis are complex, labor-intensive, and technically challenging. We developed and performed the first analysis of the Cepheid Gene Xpert System's MTB/RIF assay, an integrated hands-free sputum-processing and real-time PCR system with rapid on-demand, near-patient technology, to simultaneously detect M. tuberculosis and rifampin resistance. Analytic tests of M. tuberculosis DNA demonstrated a limit of detection (LOD) of 4.5 genomes per reaction. Studies using sputum spiked with known numbers of M. tuberculosis CFU predicted a clinical LOD of 131 CFU/ml. Killing studies showed that the assay's buffer decreased M. tuberculosis viability by at least 8 logs, substantially reducing biohazards. Tests of 23 different commonly occurring rifampin resistance mutations demonstrated that all 23 (100%) would be identified as rifampin resistant. An analysis of 20 nontuberculosis mycobacteria species confirmed high assay specificity. A small clinical validation study of 107 clinical sputum samples from suspected tuberculosis cases in Vietnam detected 29/29 (100%) smear-positive culture-positive cases and 33/39 (84.6%) or 38/53 (71.7%) smear-negative culture-positive cases, as determined by growth on solid medium or on both solid and liquid media, respectively. M. tuberculosis was not detected in 25/25 (100%) of the culture-negative samples. A study of 64 smear-positive culture-positive sputa from retreatment tuberculosis cases in Uganda detected 63/64 (98.4%) culture-positive cases and 9/9 (100%) cases of rifampin resistance. Rifampin resistance was excluded in 54/55 (98.2%) susceptible cases. Specificity rose to 100% after correcting for a conventional susceptibility test error. In conclusion, this highly sensitive and simple-to-use system can detect M. tuberculosis directly from sputum in less than 2 h.
- Subjects :
- Adolescent
Adult
Aged
Female
Humans
Male
Middle Aged
Mycobacterium tuberculosis isolation & purification
Polymerase Chain Reaction methods
Sensitivity and Specificity
Sputum microbiology
Tuberculosis microbiology
Uganda
Vietnam
Young Adult
Antitubercular Agents pharmacology
Bacteriological Techniques methods
Drug Resistance, Bacterial
Mycobacterium tuberculosis drug effects
Point-of-Care Systems
Rifampin pharmacology
Tuberculosis diagnosis
Subjects
Details
- Language :
- English
- ISSN :
- 1098-660X
- Volume :
- 48
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Journal of clinical microbiology
- Publication Type :
- Academic Journal
- Accession number :
- 19864480
- Full Text :
- https://doi.org/10.1128/JCM.01463-09