Abstract:

Objective: Preliminary investigation of the killing effect of low-temperature plasma technology on different Mycobacterium tuberculosis in vitro experiments, aiming to provide a new technical method for killing common Mycobacterium tuberculosis. Methods: Mycobacterium tuberculosis H37Rv strain, extensive drug-resistant Mycobacterium tuberculosis (XDR-MTB) and multidrug-resistant Mycobacterium tuberculosis (MDR-MTB) mycobacterial fluids were inoculated on the culture medium, configured as a 0.5 mycobacterial suspensions within 3 weeks of incubation, and then multiply diluted to the test mycobacterial suspensions, and 2.0 ml of mycobacterial suspension samples were taken into sterile test tubes, the suspensions were ablated for 0, 3, 6, 9, 12 and 15 s by PLACOAG mode of low-temperature plasma surgery system, and then cultured in incubators. After 21 days, the number of the mean survival count, log10 reduction, and killing efficiency of each group at each treatment time point were calculated. Results: (1) The log10 reduction of H37Rv (F=20.313, P=0.003), XDR-MTB (F=13.956, P=0.006), and MDR-MTB (F=20.355, P=0.006) were statistically different at different treatment times. There was a statistically significant difference in the log10 reduction of three bacterial groups at 9 seconds (F=61.603, P=0.004), with XDR-MTB was the lowest (0.50±0.00), followed by H37Rv (1.14±0.12), and MDR-MTB was the highest (1.23±0.00), and the log10 reduction of the three groups reached the maximum value at 15 seconds, which were MDR-MTB (1.71±0.00), H37Rv (1.83±0.00), XDR-MTB (1.35±0.21). (2) The killing efficiency of H37Rv (F=10.458, P=0.012), XDR-MTB (F=10.945, P=0.011), and MDR-MTB (F=9.424, P=0.015) were statistically different at different treatment times. There was a statistically significant difference in the killing efficiency of three bacterial groups at 9 seconds (F=287.890, P<0.001), with XDR-MTB was the lowest ((68.25±0.00) %), followed by H37Rv ((92.59±2.10) %), and MDR-MTB was the highest ((94.12±0.00) %), and the killing efficiency of the three groups reached the maximum value at 15 seconds, which were MDR-MTB (100.00±0.00) %, H37Rv (96.26±1.05) %, XDR-MTB (99.35±5.16) %. Conclusion: In this study, in vitro experiments confirmed that low-temperature plasma technique has a rapid and significant killing effect on three Mycobacterium tuberculosis species, and that the killing effect varies and requires individualized strategy.

Key words: Mycobacterium tuberculosis, Sterilization, In vitro, Investigative techniques