Determination of antibiotic resistance and high-performance liquid chromatography profiles for Mycobacterium species

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.

Determination of antibiotic resistance and high-performance liquid chromatography profiles for Mycobacterium species

BACKGROUND

Incidence of mycobacterial infections has been increasing. However, diagnosis and treatment of mycobacterial infections can be difficult. The aim of this study was to investigate high-performance liquid chromatography (HPLC) analysis of the mycolic acids for rapid identification and dendrogram cluster analysis of mycobacterium species.

METHODS

Clinical specimens received for mycobacterial culture and antimicrobial susceptibility test were processed by standard laboratory protocols. Positive cultures were analyzed with HPLC method. Mycolic acid analysis with HPLC was used for diagnosis of tuberculosis and other mycobacterial infections. These reports were compared with Sherlock Library mycobacterial species, and the similarity index was analyzed. This value was formed by a software in multidimensional space that was the calculation of the average distance between the nearest library profile and unknown profile.

RESULTS

The ninety-two samples were identified as M. tuberculosis. (similarity index between 0.593 and 0.994). One of the other strains was identified as M. avium intracellulare (strain No. 82) (SI = 0.906); one of them was identified as M. interjectum (strain no. 89) (SI = 0.644). Total 94 samples were identified, and dendrogram was applied to these samples. Profile A (10.6%), profile B (59.6%), profile C (11.7%), profile D (3.2%), and other profiles as single different profiles were identified. Rates for each as 1% (89, 94, 1, 82, 26, 42, 32, 41, 100, 43, 47, 44, 40, 35).

CONCLUSION

High-performance liquid chromatography is a useful, rapid, reliable, and practical method for diagnosis of mycobacterium species.