Comparison of laboratory methods for identifying members of the family Mycobacteriaceae.

BACKGROUND

The introduction of a method based on matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-ToF mass spectrometry) into the practice of laboratories significantly increased the identification of acid-resistant bacteria (ARB).

METHODS

Seventy-four nontuberculous mycobacteria (NTM) cultures identified by deoxyribonucleic acid (DNA) hybridization, polymerase chain reaction, Sanger sequencing, and MALDI-ToF mass spectrometry.

RESULTS

Analysis of the identification results obtained by the methods of DNA hybridization and Sanger sequencing showed a complete match only for 67.6% of samples of the total number of cultures included in the study. The partial match of the identification results was 68.9%. When comparing the results of the identification of 74 samples obtained by MALDI-ToF mass spectrometry to the results obtained by sequencing, full match of identification of Mycobacterium chimaera/Mycobacterium intracelullare, Mycobacterium porcinum/Mycobacterium peregrinum and Mycobacterium tuberculosis complex was found for 90.5% of the samples; the partial match of the results - for 4.1%.. DNA hybridization as a method for identifying NTM showed acceptable sensitivity and specificity; however, for mass spectrometry, a significantly higher sensitivity with comparable specificity was determined.

CONCLUSIONS

Mass spectrometry is an important element in the modern system of species identification of microorganisms. The optimization of sample preparation protocols and assessment of the impact on the identification of new techniques of cultivation of microorganisms can significantly improve the quality of identification of microorganisms from the ARB group. In this case, accurate species identification and the development of algorithms for its application will improve the diagnosis of diseases caused by ARB.