Experimental selection of a test strain to evaluate the tuberculocidal efficacy of high-level disinfection of endoscopes. Part 1

The one of the priority tasks of disinfectology is the justified choice of test-microorganisms for evaluating the efficacy of disinfectants. Mycobacterium terrae DSM 43227 is the test-strain for assessing the tuberculocidal efficacy of disinfectants for disinfection of endoscopes, including high-level disinfection (HLD). However, it has been determined that M. terrae DSM 43227 were sensitive to the effect of heating during the drying stage with disinfection and washing machines (DWM) of HLD of endoscopes. This necessitated the search of isolate of mycobacterial for a promising as a test-strain with resistant to disinfectants and heat-resistant. At the first step of the study, the isolates of M. abscessus Ь?3, M. fortuitum Ь?2 иКM. avium Ь?2, which have the highest resistance to disinfectants among the studied clinical isolates of fast- and slow-growing NTMBs (n?=?14) were selected in comparison with test-strains (M. terrae DSM 43227; Mycobacterium B5; M. tuberculosis H37Rv) according to Guideline P 4.2.3676-20. At the second step, the sensitivity of selected isolates of NTMB and test-strains of mycobacterial to heating was studied. It has been established that M. fortuitum is a promising microorganism as test-strains of mycobacteria for assessing the efficiency of disinfectants for HLD of endoscopes with DWM. Because M. fortuitum has target resistance to the temperature factor (resistance to heating up to 60?ЎC for 1 hour), is resistant to chemical disinfectants and gives growth of visible colonies on nutrient media on average on 3Р4 days of cultivation (which allows reducing the time for the study 5Р7 times, from 21 days when using as a test-strain M. terrae DSM 43227 to 3Р4 days when using M. fortuitum). In addition, the comparative assessment of resistance of clinical isolates of NTMB to disinfectants has revealed resistance of NTMB to tuberculocidal modes of application of disinfectants, which requires in-depth study, determination of clinical and epidemiological significance and search for approaches to ensure biological safety of susceptible population to infection with mycobacteriosis pathogens. Keywords: high-level disinfection, flexible endoscopes, disinfectants, disinfection and washing machines, test-strain.