Novel Multiplex Real-Time PCR Diagnostic Assay for Identification and Differentiation of Mycobacterium tuberculosis, Mycobacterium canettii, and Mycobacterium tuberculosis Complex Strains

• Published in: Journal of Clinical Microbiology Vol. 49; no. 2; pp. 651 - 657
• Main Authors: Reddington, Kate, O'Grady, Justin, Dorai-Raj, Siobhan, Maher, Majella, van Soolingen, Dick, Barry, Thomas
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.02.2011
• Subjects: Bacterial Proteins - genetics; Bacteriological Techniques - methods; Bacteriology; Biological and medical sciences; DNA Primers - genetics; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; Fundamental and applied biological sciences. Psychology; Humans; Microbiology; Miscellaneous; Molecular Sequence Data; Mycobacteriology and Aerobic Actinomycetes; Mycobacterium - classification; Mycobacterium - genetics; Mycobacterium - isolation & purification; Mycobacterium canettii; Mycobacterium tuberculosis; Polymerase Chain Reaction - methods; Sensitivity and Specificity; Sequence Analysis, DNA; Time Factors; Tuberculosis - diagnosis; Tuberculosis - microbiology; Mycobacterium tuberculosis; Multiplex polymerase chain reaction; Mycobacteriales; Mycobacteriaceae; Bacteria; Actinomycetes; Identification; Real time; Species complex; Strain
• ISSN: 0095-1137; 1098-660X
• DOI: 10.1128/JCM.01426-10

Tuberculosis (TB) in humans is caused by members of the Mycobacterium tuberculosis complex (MTC). Rapid detection of the MTC is necessary for the timely initiation of antibiotic treatment, while differentiation between members of the complex may be important to guide the appropriate antibiotic treatment and provide epidemiological information. In this study, a multiplex real-time PCR diagnostics assay using novel molecular targets was designed to identify the MTC while simultaneously differentiating between M. tuberculosis and M. canettii. The lepA gene was targeted for the detection of members of the MTC, the wbbl1 gene was used for the differentiation of M. tuberculosis and M. canettii from the remainder of the complex, and a unique region of the M. canettii genome, a possible novel region of difference (RD), was targeted for the specific identification of M. canettii. The multiplex real-time PCR assay was tested using 125 bacterial strains (64 MTC isolates, 44 nontuberculosis mycobacteria [NTM], and 17 other bacteria). The assay was determined to be 100% specific for the mycobacteria tested. Limits of detection of 2.2, 2.17, and 0.73 cell equivalents were determined for M. tuberculosis/M. canettii, the MTC, and M. canettii, respectively, using probit regression analysis. Further validation of this diagnostics assay, using clinical samples, should demonstrate its potential for the rapid, accurate, and sensitive diagnosis of TB caused by M. tuberculosis, M. canettii, and the other members of the MTC.