Usefulness of the GenoType MTBC Assay for Differentiating Species of the Mycobacterium tuberculosis Complex in Cultures Obtained from Clinical Specimens

Abstract

(17,23,24,25). Although the species are closely related genetically, they differ in host and geographic range, certain phenotypes, and pathogenicity. M. tuberculosis is the most significant pathogen for humans in Europe and America, whereas M. africanum is widely distributed among African patients (4, 15). Both subspecies of M. bovis are reported to infect humans, yet they have a broad host range, including wildlife and domestic livestock like bovines and goats (12,26). Of particular interest is the intrinsic resistance of M. bovis subsp. bovis against pyrazinamide, one of the first-line antituberculous drugs (11,17). The vaccine strain M. bovis BCG is more frequently used for bladder cancer immunotherapy and can be detected in human urine specimens from bladder cancer patients (2, 6). Thus, for those specimens, the isolation of M. tuberculosis complex is not necessarily an indication for antituberculous treatment. Therefore, rapid differentiation to the species and subspecies levels should be obtained not only for epidemiological purposes but also for adequate treatment of each patient.So far, rapid identification of the M. tuberculosis complex has been achieved by using AccuProbe gene probes (Gen-Probe, San Diego, Calif.), which target the 16S rRNA. However, species identification still relies on the determination of a series of phenotypic and growth characteristics and on biochemical tests, which all require sufficient growth, are time-consuming, and may not be performed in every laboratory (5, 25). Recently, the GenoType MTBC (Hain Lifescience GmbH, Nehren, Germany)-a new commercially available DNA strip assay for the rapid identification of the members of the M. tuberculosis complex-was evaluated by use of a well-characterized collection of M. tuberculosis complex isolates and was proven to be useful for species differentiation (20). Moreover, due to the inclusion of an M. tuberculosis complex-specific oligonucleotide, this test may replace the AccuProbe tests of cultures from clinical specimens as a method for identification of the M. tuberculosis complex, giving the additional information provided for the species involved.The aim of this work was to evaluate the performance of the GenoType MTBC with positive liquid cultures from clinical specimens received for mycobacterial culture in comparison to species identification by classical methods. Furthermore, the GenoType MTBC results were compared to results obtained by AccuProbe tests.Specimens. Two German microbiology laboratories were involved in this study: (i) the National Reference Center for Mycobacteria, Borstel, Germany, and (ii) the Department of Microbiology of the Laboratory Group, Heidelberg, Germany. All samples used in this study originated from human specimens and a few veterinary specimens sent to the laboratories for routine mycobacterial culture. Specimens (pulmonary and extrapulmonary) were processed according to national and international guidelines (5, 10) by using an N-acetyl-L-cysteineNaOH decontamination procedure, inoculated into B...

Standardization of a TaqMan-Based Real-Time PCR for the Detection of Mycobacterium tuberculosis-Complex in Human Sputum

“…[16][17][18][19][20][21][22][23][24] Currently, several assays are commercially available for the detection of the M. tuberculosis complex, including the Cobas Amplicor MTB PCR test (Roche Diagnostics, Basel, Switzerland), the RealArt Mycobact Diff Kit (Qiagen, Hamburg, Germany), 25 AMTD (Gen-Probe, Inc. San Diego, CA), 26 the Inno-LiPA line probe assay (Innogenetics, Ghent, Belgium), 27 the GenoType MTDRplus assay (Hain Lifescience, Nehren, Germany), 28 and the Xpert RIF/TB, GeneXpert, Cepheid, Canada). 8 These commercial assays are divided into two methods: conventional PCR followed by probe hybridization and real-time PCR.…”

Diagnosis of bovine tuberculosis: review of main techniques

“…Currently, there is only one commercially available diagnostics kit for the differentiation of the MTB, this assay distinct members of the MTB using highly conserved single nucleotide polymorphisms (SNP) in the gyrB gene (Richter et al, 2004). However, it is limited as it does not distinguish M. canettii and M. pinnipedii.…”

“…It is necessary to distinguish M. bovis from the other members of the M. tuberculosis complex (Richter et al, 2004) (Meikle et al, 2007). This underscores the need for more sensitive, accurate, and faster methods to assist in the control of this zoonosis such as molecular methods.…”

Rapid Identification of Mycobacterial Whole Cells in Solid and Liquid Culture Media by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry

“…The techniques based on DNA hybridization are sensitive, fast, and simple, but the available commercial assays (AccuProbe; Gen-Probe, San Diego, CA) are able to identify only four species and two complexes of mycobacteria (10). Techniques requiring amplification followed by a hybridization step on a solid support are more complete than probes, but commercially available kits are limited to 5 (GenoType MTBC; Hain Lifescience GmbH, Nehren, Germany), 16 (Inno-LiPa Mycobacteria v2; Innogenetics, Gent, Belgium), or 30 (GenoType Mycobacterium; Hain Lifescience GmbH, Germany) species (19,22,30). Systems based on sequencing or enzymatic restriction targeting the hsp65, 16S rRNA, sod, and rpoB genes allow good identification of all mycobacteria at the species level but remain limited to specialized laboratories (14,17,23,31,36,37).…”