Pneumologie 2012; 66 - P399
DOI: 10.1055/s-0032-1302665

Evaluation of the new, easy to perform, IS6110 based molecular assay Speed-oligo® Direct MTB (Vircell, Spain) for the detection of M. tuberculosis and direct comparison to probeTec (BD, USA)

U Antonenka 1, S Hofmann-Thiel 1, A Esenalieva 2, L Turaev 3, K Mirazim 3, M Abdullaeva 4, H Hoffmann 1
  • 1IML Red GmbH, Synlab Bayern, Asklepios Fachklinken, WHO Supranationales Referenzlabor für Tuberkulose, Gauting
  • 2National Reference Laboratory of Tuberculosis, Bishkek, Republic of Kyrgyzstan
  • 3National Reference Laboratory of Tuberculosis, Tashkent, Republic of Uzbekistan National Institute of Tuberculosis
  • 4National Reference Laboratory of Tuberculosis, Machiton, Republic of Tajikistan, Dushanbe

Background: “Speed-oligo® direct mycobacterium tuberculosis” (SPO DMTB) from Vircell is a novel assay, based on multiplex PCR dipstick hybridisation detecting Mycobacterium spp. and Mycobacterium tuberculosis complex (MTBC) in respiratory specimens. The amplification targets are: IS6110 (MTBC-specific), 16S rRNA (Mycobacterium genus-specific), and human gene RNAsaP (amplification control). Several authors consider IS6110-PCR as the most sensitive assay for direct detection of tuberculous bacteria in clinical specimens. We compare the IS6110 based SPO DMTB assay with ProbeTecTM MTBC (Becton Dickinson), another assay using the same target.

Scope: Evaluation of the novel IS6110 based SPO DMTB assay and its head-to-head comparison with the commercial IS6110 ProbeTecTM MTBC for the detection of Mycobacterium tuberculosis in clinical specimens.

Results: Tests performances were evaluated using 121 NALC-decontaminated respiratory specimens (sputa and bronchial secret) including 18 TB culture-positive (c+) and smear-microscopy positive (ss+) samples, 50 c+/ss-, and 53 non-TB samples. The latter ones included 24 samples with non-tuberculous mycobacteria (NTM). Assays were performed according to manufacturer's instructions. Overall sensitivity values were 77.9% and 58.9% for ProbeTec and SPO DMTB, respectively. As for ss-samples SPO DMTB sensitivity was significantly lower (42.1%) then ProbeTec (72.0%). At the same time, specificity was higher for SPO DMTB (100.0%) than for ProbeTec (98.1%), due to one NTM falsely detected as MTBC. Of both assays, only SPO DMTB can detect NTM in clinical samples with a sensitivity of 93.0% and a specificity of 100% in our sample collection.

Conclusions: Direct comparison of SPO DMTB test to ProbeTecTM MTBC revealed that not all IS6110-based NAATs yield the same sensitivity. Although SPO DMTB is quicker to perform, needs less investment costs and has a higher specificity, its sensitivity is lower compared to ProbeTecTM MTBC, especially for smear microscopy negative samples.