To the question of improving methods for assessing the effectiveness of high-level disinfection of endoscopes

Introduction. The test-strain Mycobacterium terrae DSM 43227 is used to determine the required exposure time at the sporicidal concentration of disinfectant and temperature (up to plus 60?°C) for high-level disinfection (HLD) of endoscopes with disinfection and washing machines (DWM). Ame: to study the viability of the test-strain M. terrae DSM 43227 when testing the effectiveness of disinfectants for HLD of endoscopes with DWM. Materials and methods. Sterile endoscopes (OLIMPUS GIF P10 gastroscope (n?=?4)) were contaminated with DSM 43227 suspension (109 CFU) and donors’ blood as organic debris. Preliminary and final cleaned were carried out, then control of effectiveness was. Further – HLD with DWM with and without the addition of disinfectant. The washouts from endoscopes were taken according to MU 3.1.3798-22 for control of HLD and inoculated with 0.1 mL of Levenstein-Jensen medium. The effectiveness of HLD with the addition of disinfectant must be 100?%, according to Guideline R 4.2.3676-20. The study of the effect of high temperatures in the ranges from plus (30?±?1)?°C to plus (70?±?1)?°C on the test-strain was carried out using the algorithm (RU 139587 from 11.12.2023). Results. After HLD in DWM, the CFU growth of the test strain was not detected in the programs: with and without the disinfectant, which contradicted the expected results. Additional studies were conducted to clarify the reasons for the absence of CFU growth in washouts from endoscopes treated with DWM without addition of the disinfectant. Preliminary and final cleaning was excluded from the full cycle of processing of endoscope. Only HLD in DWM with and without addition of disinfectant were performed – no growth of CFU of DSM 43227 was detected again. Sensitivity of test strain to temperature plus (60?±?1)?°C after 30 min of exposure was detected. Conclusion. The revealed sensitivity of M. terrae DSM 4322 to the effect of a temperature of 60?°C casts doubt on the legitimacy of the use of the test-microorganism in the method of testing HLD of endoscopes with DWM and is the basis for finding new approaches and improving methods for assessing the effectiveness of disinfectants for HLD of endoscopes with DWM.