Reliability of Amplicor Mycobacteria Kit for detection of Mycobacterium tuberculosis complex and Mycobacterium intracellulare: results of cooperative study among 331 laboratories in 2000

Amplicor Mycobacterium Kit (Roch Diagnostics: Japan) is the most widely used kit in Japan for the diagnosis of mycobacteria infections, especially those caused by Mycobacterium tuberculosis, Mycobacterium avium and Mycobacterium intracellulare. We evaluated the reliability of the kit in co-operation with 331 laboratories using the kit in routine examination. We distributed specially prepared 4 test samples to each laboratories. The negative sample was NALC-NaOH treated sputum which showed "negative" when tested by this kit and positive samples were NALC-NaOH treated sputum containing M. bovis or M. intracellurare. False-positive results were reported in 6 out of 331 laboratories (1.8%) and false-negative results were reported from 7 laboratories (2.1%). (The details were 1 out of 331 labs for TB-H sample, 5 out of 331 labs for TB-L sample and 1 out of 316 in MIN sample.) Statistical significance between MWP method and COBAS method was not significant. After receiving and evaluating the test results on the 4 samples, the follow up questionnaires were sent out to 22 laboratories which reported incorrect results and low optical density (O.D.) on positive control. Results of this questionnaire suggested that it was important to follow the package insert instructions and to follow the correct procedures for PCR assay. These results suggested that Amplicor Mycobacterium Kit is reliable for rapid diagnosis of Mycobacteria infections.