Definition of BFE: The ability of packaging materials to resist bacterial penetration, ie bacterial filtration efficiency.
The material was evaluated for performance by parameters of bacterial filtration efficiency. No material can block bacteria into the package 100%, so BFE can reach more than 95%, which is a good result. BFE also changes under different air pressure conditions.
Microbial aerosol test
The experimental methods are clearly defined in AAMI ST77 and ISO 11607. There is no clear requirement for the design of the cabin of an aerosol cabinet for testing aerosols. The aerosol cabinets used in different laboratories are not the same, but they work basically the same way. Under normal circumstances, the size of the aerosol cabinet is one cubic meter. The aerosol can be continuously injected into the micro-organized aerosol through the circulation device, and the specific pressure is maintained. The rigid container or the whole package of the sterile package is placed in the aerosol-filled The test was carried out in the cabin for a duration of 1 hour. At the end of the test, remove the rigid container or sterile package and open the package to check for microbial penetration of the sterile barrier system.
The AAMI ST77 standard has specific requirements for microbial aerosol experiments. The pressure of aerosols in the experiment is relatively fixed, but in the actual working environment of the hospital, the air pressure changes continuously with the air flow. To simulate this situation, observe In the case of air flow, the sterility of the rigid container will be affected. In 2006, Dr. Prof. Dunkelberg used microbial aerosols of up to 10^8 order for perfusion, and used dynamic pressure to simulate the actual situation of the hospital. Finally, it is checked whether there is microbial intrusion in the rigid container.
In 2015, I used dynamic air to check for good sterility in hard and non-woven packaging.
A) rigid container
It may be used thousands of times during its life cycle. There are nano-coats on the top and bottom, with gaskets, filter components and more. The rigid container consists of a top filter system, an internal instrument fixture, a base, and a handle. One of the rigid containers uses a valve system.
B) Non-woven packaging
Compare the antibacterial properties of non-woven fabrics of different weights, and select the appropriate weight of non-woven fabric for packaging according to the weight of the instrument tray.
1. Compare the bacteriostatic properties of the two sterile barrier systems under dynamic air pressure.
2. Also observe whether the rigid container will affect performance as the number of uses increases.
The change in air pressure is simulated according to the actual situation in the hospital. At the end of the experiment, the operation should be carried out gently to prevent excessive air pressure changes from affecting the results. It is worth noting that during the sterilization process, the sterilizing medium first enters the sterile barrier system and is discharged upon cooling.
At the same time, aseptic packaging capacity, temperature changes, pressure changes are taken into account, including temperature and pressure changes during storage. At the time of storage, the air pressure also changes. The opening and closing of the door and the movement of the personnel are all factors that affect the change of the air pressure. These changes are also experienced during the transfer. These changes are the challenges that the sterile barrier system needs to face.
Therefore, according to such complicated environmental changes, the experiment simulates the actual situation, and adopts a strain with a smaller diameter, which is closer to the actual situation of the hospital. All parameters and factors in the experiment were effectively observed and controlled.
At the time of the experiment, three different gas pressures were used, 1.0 PSI, 0.7 PSI and 0.4 PSI.
Different rigid containers were used in the experiment, including 4 different brands of new rigid containers, all from different hospitals. The selection criteria were:
1. The rigid container must be functional and ready for use;
2. The life of a rigid container must be within the life cycle.
For the non-woven fabric, three kinds of non-woven fabrics such as high gram weight and low gram weight are used.
At the beginning of the experiment, a polycarbonate filter was placed at the bottom of the tray. The rigid container occupied 1/4 of the volume; a soft non-woven packaging would also be placed.
After that, they were sent to the hospital for sterilization, and sterilized using a program at 132 ° C for 30 minutes. After sterilization, wait for 30-60 min for cooling. It was then shipped back to the laboratory and placed in an aerosol cabinet to test with different air pressures.
The pressure is 1.0 PSI for two cycles, the pressure is 0.7 PSI and 0.4 PSI for 3 cycles each, and each cycle contains 255 living bacteria. Compared to Dr. Prof. Dunkelberg's experiment, he used a total of 24 cycles, up to 10^8 orders of bacteria.
The test sterile barrier system was then taken out, and the internal contents were subjected to bacterial culture at 30 ° C for 24 hours to observe whether it was contaminated. As a result, 110 rigid containers, 87% of which were contaminated, 18% of which were heavily contaminated. Non-woven packaging, 161 pieces, three different weights of non-woven fabrics, were not found to be contaminated.
The test is then continued, with three groups of rigid containers in different life cycles.
The first group, the new hard container.
The second group, which has been used for 5 years, is a rigid container.
The third group used a rigid container for 5-9 years.
As the age of use increases, the bacteriostatic performance decreases and the degree of contamination increases. The new rigid container is up to 72% resistant to bacteria failure.
Non-woven packaging, no microbial intrusion, 87% of hard containers are contaminated, of which 72% of new rigid containers are contaminated.
According to AAMI ST77, rigid containers should be able to withstand aerosol experiments. According to the experimental results, it should be noted that rigid containers should be maintained, but in many cases they are still not guaranteed to be bacteriostatic. This is worth considering.
For non-woven fabrics, although the antibacterial performance is good, as a soft package, attention should be paid to the characteristics of the package being easily broken.