Sterilization Performance of Autoclave Units on Cannular Materials

Abstract

Autoclaves are devices that are used for sterilization of medical devices under high pressure and temperatures. As with all medical devices, the correct operation of autoclave units is vital for their performance and for successful sterilization. Thus, they should be tested to investigate their technical performance and biological effects within the studies of hospital quality control. Starting from setting the temperature and the pressure parameters up to taking out the materials from the autoclave after sterilization, all steps of the process need to be revised at these control stages. In this study, biological effects of sterilization were tested on microorganisms placed in cannular materials by using different temperatures and sterilization durations. As for the sterilization unit, a vertical type autoclave was used. The technical parameters of the autoclave during the sterilization process were measured by using a temperature–pressure data logger device. Bacillus subtilis var. niger strain was used to examine the biological performance of the sterilization unit. We performed different experiments by changing the temperature and the duration of the sterilization, and using several sizes of cannular materials. Experiments were made at 100°C, 95°C, 90°C, 85°C, 80°C, 75°C, 70°C and for 1 and 5 min. Additionally, two different cannula type sterile glass pipettes (1 and 10 ml) were used in experiments to compare the status of sterilization for different volumetric materials. Biological and technical results obtained for both test and control parameters were compared. The percent of bacteria reduction (Bacteria reduction% = (Test Number/Control Number) × 100) was calculated for biological tests. Technical tests resulted that the autoclave was not able to provide a stable output for temperatures from 70°C to 100°C, and for durations of 1 and 5 min. However, biological tests showed that the sterilization was achieved for the strain at all test conditions. It was observed that the autoclave provided technical requirements for sterilization even for short sterilization durations and low temperature, as such no microbial growth was observed. In short, the bacteria reduction percent was 100%. It was explained that the reason for biological sterilization at these low parameters is because the autoclave generated higher pressure and higher temperature than the set pressure and temperature values. Consequently, the results of the biological tests were supported by measuring the technical parameters of the autoclave.