False-negative BD MGIT™ TBc Identification Test results in routine tuberculosis diagnosis: a New Zealand perspective

>We previously reported on a comparison of the AccuProbe(®) Gen-Probe(®) MTBC assay (AccuProbe) (BioMérieux, Marcy L'Etoile, France) with the Becton Dickinson (BD) MGIT™ TBc Identification (TBc) Test (BD, Franklin Lakes, NJ, USA) in our laboratory. In the period following the shift from the AccuProbe assay to the TBc test, we obtained six false-negative results. On sequencing the mpt64 gene, we found that these false-negative cases had mutations in the mpt64 gene due to deletion, insertion or substitution. Despite the occurrence of false-negative results, we found that the reduced cost and minimal technical expertise, combined with a new testing algorithm, still make this test the preferred option for rapidly identifying Mycobacterium tuberculosis complex in MGIT cultures in a low TB burden country such as New Zealand.