Construction of Composite Correlation Index Matrix and Analysis of Cultural Properties of Representatives of Mycobacterium abscessus Complex Isolated from Patients with Cystic Fibrosis.

BACKGROUND: Microbiological diagnosis of mycobacteriosis is often difficult, as it is necessary to differentiate between transient colonization and active infection. METHODS: We studied the cultural properties of Mycobacterium abscessus complex (MABSc) strains obtained from cystic fibrosis patients, and also analyzed composite correlation index (CCI) values in patients with repeated MABSc inoculation and their correlation with the presence of clinical and radiological manifestations of mycobacteriosis. RESULTS: As a result, MABSc more often grew in S-form colonies in patients without clinical manifestations of chronic infection, while R-form colonies were characteristic of patients with chronic infection and clinical symptoms. At the same time, in patients examined once, no growth of colonies in the R-form was recorded, and all strains produced growth in the form of either S-colonies or in the S- and R-forms simultaneously. Statistically significant results were obtained for the relationship of the CCI with the clinical and radiological picture. In addition, a heterogeneous MABSc population with low CCI score values correlated with the development of mycobacteriosis in patients. In patients with high CCI score values (homogeneity of isolated strains), on the contrary, there were no radiological or clinical signs of the disease. CONCLUSION: These data make it possible to build a strategy for monitoring patients depending on changes in CCI score values. The use of CCI matrix to evaluate microorganisms' identification results is a potentially new method that expands the use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

Identification of the Optimal Cultivation Period Required to Isolate Representatives of Mycobacterium abscessus Complex Isolated from Patients with Cystic Fibrosis.

BACKGROUND: In patients with cystic fibrosis (CF), representatives of the fast-growing Mycobacterium abscessus complex (MABSc) are often distinguished, but the culture of the material taken from such patients increases the growth time. We analyzed the terms of cultivation of MABSc representatives on dense nutrient media and also evaluated the productivity of a modified nutrient medium based on agar for the isolation of Burkholderia cepacia complex (BCC). METHODS: Sixty-four strains of MABSc isolated from patients with CF and suspected tuberculosis were analyzed. The material from the patients was cultured on a universal chromogenic medium, 5% blood agar, yolk-salt agar, selective medium for isolation of BCC, and Löwenstein-Jensen medium. The cultures were incubated for 5 days (37°C, aerobic conditions), after for 23 days (28°C, aerobic conditions). The productivity of the developed nutrient medium was evaluated by the number of cells that gave visible growth after culturing 0.1 mL of a bacterial suspension of 103 CFU/mL. RESULTS: 76.8% of the strains grew in a 2-week period, and 23.2% of the strains were obtained at a later date from 18 to 28 days (average: 21.23 days). The modified medium with a concentration of 240 mg of iron (III) polymaltose hydroxide proved to be the most optimal for the isolation of MABSc. CONCLUSION: When using a chromogenic medium for culture material from patients with CF, it is necessary to extend incubation up to 28 days to increase the probability of MABSc isolation. The modified BCC medium showed a good selectivity result but required further investigation.

Proteomic analysis of nontuberculous bacteria protein spectra as the element of subtyping of strains.

Background: For the present, matrix-assisted laser desorption/ionization-time-of-flight (MALDI-ToF) mass spectrometry is the fastest and the most correct method for species identification of microorganisms. Apart from species-level identification, it allows to use a variety of approaches for the analysis and comparison of protein spectra of microorganisms of the same species, which are isolated from a patient at various disease states, that can be used in routine microbiological practice in laboratories fitted with mass analyzers. Methods: Two strains of Mycobacterium fortuitum and two strains of Mycobacterium peregrinum were isolated from sputum samples, which were obtained from patients with different clinical aspects of mycobacteriosis, whereat were reinoculated on the universal chromogenic culture medium "UriSelect 4." Further, the MALDI-ToF mass spectrometry method was used, aiming to obtain protein profiles, which were analyzed using the FlexAnalysis 3.0 software package. Results of the statistical proteomic comparison of mass spectra were visualized using MALDI Biotyper 3.0 Offline Classification software. Results: Presented clinical examples demonstrate that strains of the same species, which are isolated from the same patient at different times of infection, change their cultural properties. Dynamic changes in cultural properties are reflected in changes in protein profiles by comparison spectra of isolates at different stages of colonization, which is reflected in the correlation with the clinical condition of the patient. Conclusion: Thus, the mentioned examples of proteomic analysis, using MALDI-ToF mass spectrometry, demonstrate the possibility of subtyping of strains, that are isolated on a universal chromogenic culture medium, in case of detection in the culture signs of population's heterogeneity, based on cultural properties.