Background: Two false-positive tuberculosis (TB) cases in Yamagata Prefecture, Japan, 2016.
Objective: To report the effectiveness of comparative genomics of Mycobacterium tuberculosis for identification of cross-contamination cases.
Design: Case report of laboratory cross-contamination.
Results: Beginning with detection of an identical genotype in two M. tuberculosis strains using variable number of tandem repeat typing, we suspected M. tuberculosis cross-contamination of specimens collected in a mycobacteriology laboratory based on epidemiological investigations. This suspicion was confirmed using comparative genomics of the two M. tuberculosis strains and a strain from an epidemiologically unrelated specimen from the same batch as the two strains in the mycobacteriology laboratory. All strains had an identical genomic sequence with no single nucleotide variants.
Conclusion: Comparative genomics, which offers the highest discrimination power, is a potent tool for identifying laboratory cross-contamination using epidemiological investigations.