Analysis of misidentified strains using a Mycobacterium abscessus complex genotype identification kit.

Accurate subspecies identification and determination of macrolide resistance status are crucial for the treatment of Mycobacterium abscessus complex (MABC) infections. In recent years, a kit that uses DNA chromatography to differentiate the three MABC subspecies and detect macrolide-induced resistance has become available in Japan. Using this kit, testing strains isolated from patients with MABC infection resulted in one false-positive and one false-negative result. A detailed analysis of these strains revealed that the discrepancies were due to the presence or absence of specific target genes included in the kit. Because MABC has a high level of genetic diversity, interpreting the test results obtained using this kit requires the consideration of such genetically exceptional strains.