Evaluation of the MeltPro Myco Assay for the Identification of Non-Tuberculous Mycobacteria

Abstract

Purpose: The purpose of this study was to evaluate a new commercial kit for Mycobacterium species identification and compare its results with that of the commonly used GenoType Mycobacterium CM assay. In addition, we were committed to identifying the main frequent species of nontuberculous mycobacteria (NTM) in Fujian. Methods: A total of 261 clinical strains, collected at the Center for Disease Control and Prevention of Fujian Province, China, were preliminarily identified as NTM based on p-nitrobenzoic acid (PNB) growth test. The genomic DNA of all 261 strains was extracted and subjected to species identification using MeltPro Myco assay and GenoType Mycobacterium CM assay. The results of the latter were used as a control to calculate the positive agreement, negative agreement, agreement and the total agreement of the former. For samples with inconsistent detection results, sequencing was performed for verification. Results: Compared to GenoType Mycobacterium CM assay, the total agreement of MeltPro Myco assay was 96.55% (252/261 strains). Both the positive and negative agreement of MeltPro Myco assay in identifying M. intracellulare, M. abscessus, M. kansasii, M. fortuitum, M. avium, M. gordonae, M. scrofulaceum, and mixed infections were higher than 99.00%, but the positive agreement of M. chelonae was relatively low at only 33.33%. In Fujian, the predominant strain of NTM was M. intracellulare (64.36%, 130/202 strains), followed by M. abscessus (19.31%, 39/202 strains), M. kansasii (4.46%, 9/202 strains), and M. fortuitum (3.96%, 8/202 strains). Conclusion: The reliability of MeltPro Myco assay for identifying mycobacterium species was strongly demonstrated in this study, which greatly supports its usage for the clinical identification of mycobacteria. The present study also showed that the distribution of mycobacteria in Fujian, China, was significantly different from that in other regions and provided important data for future epidemiological study of NTM.