2.1.5.2.1 Purpose
To test the disinfection effect of infrared sterilizer (hereinafter referred to as sterilizer dishwasher) on food (drinking) utensils, as a reference to evaluate its microbicidal performance in accordance with the design requirements.
2.1.5.2.2 Test equipment
(1) E. coli ( 8099 ) suspension.
(1) Poliovirus suspension.
(2) A sterile slide ( 10mm x 10mm) carrier (other carriers may be added or changed if necessary, depending on the object to be sterilized)
(4) Equipment required for viable bacterial culture enumeration (see 2.1.1.3).
(5) Virus inactivation test required test solution, medium and equipment (see 2.1.1.10 ).
(6) food (drinking) utensils (type and quantity according to the manufacturer's instruction manual, used to fill the sterilized dishwasher for full test)
(7) multi-point thermometer
2.1.5.2.3 cabinet temperature measurement
Temperature measurement of the multiple probes, respectively, placed in the sterilized dishwasher on the inside of each layer, the outside of the two points (large cabinets can be). Inside, in the middle, outside 3 points placed), placed food (drinking) utensils to the instructions specified in the maximum loading (full load). Close the door, turn on the power supply, according to the disinfection cupboard disinfection procedures. Every 3 minutes, record the temperature at each point. Test repeated 3 times, calculate the average temperature of each point at different times, and listed in the table.
2.1.5.2.4 E. coli killing test
(1) Prepare E. coli bacterial slices (the carrier is a slide) according to the method shown in 2.1.1.2.
(2) In a fully loaded sterilized dishwasher, place the dried E. coli slices in sterile petri dishes, 2 slices per dish, without overlapping. In the sterilized dishwasher in each layer of the inner and outer two points of a petri dish containing slices (large dishwasher can be in the inner, middle and outer each put a petri dish), open the lid of the petri dish.
(3) Close the door, turn on the power supply, according to the original design of the disinfection cabinet disinfection procedures. Disinfection is complete, open the door according to the time specified in the instructions, remove the dish. Transfer the slices into a test tube containing 5 ml of PBS and count the viable bacteria according to the method shown in 2.1.1.3.
(4) During the above sterilization test, leave the unsterilized slices at room temperature, and when the sterilization test is completed, take the slices for viable culture count as positive control. In addition, the same batch of medium and PBS culture, as a negative control.
(5) Repeat the test 3 times, and the average killing rate should be calculated and expressed according to 2.1.1.7.
(6) In each of the three tests, the number of bacteria recovered from the positive control reaches 5×105cfu/slice to 5×106cfu/slice, and there is no bacterial growth in the negative control; if the results of the positive and negative control groups are not in accordance with the above requirements, the test shall be invalidated and re-examined.
2.1.5.2.5 Poliovirus inactivation test
(1) Prepare poliovirus suspension according to the method shown in 2.1.1.10.3. If not required, use a slide as a carrier.
(2) With the sterilized dishwasher fully loaded, place the dried poliovirus-containing carriers in sterile petri dishes, 2 per dish, without overlapping. Place a dish containing poliovirus vector at each of the inner and outer points of each level of the sterilized cupboard (large cupboards can be placed in the inner, middle and outer dish), and open the lid of the dish.
(3) Close the cabinet door, turn on the power supply, according to the original procedure for disinfection. After sterilization, open the door and take out the petri dish according to the time specified in the instruction manual. Transfer the carrier into a test tube containing 1ml of cell maintenance solution. After shaking and washing, take a sample and test the infection titer of residual poliovirus according to the method shown in 2.1.1.10.4.
(3) For the positive control, 2 slices of unsterilized poliovirus-contaminated vector were placed outside a sterilized dishwasher at room temperature. After the test group was sterilized, the vector was immediately transferred into a test tube containing 1ml of cell maintenance solution. After shaking, samples were taken for the detection of residual poliovirus infection titers according to the method described in 2.1.1.10.4. The infection titer of poliovirus should be ≥105 TCID50.
(5) Negative control, complete medium without poliovirus was used as a negative control to observe that the medium was not contaminated and the cells grew well.
(6) The test was repeated 3 times.
(7) The inactivation index of each group was calculated according to the average virus infection titer (TCID50), and the inactivation index of the virus should reach 4 logarithmic values.
2.1.5.2.6 Evaluation requirements
The evaluation of the disinfection effect of the laboratory test of the disinfection cupboard should be based on the killing effect of microorganisms. When the measured results meet the following requirements can be judged as qualified:
(1) the lowest temperature point in the cabinet reached 120 ℃, and can last more than 15min.
(2) of E. coli, each test, the positive control group recovered bacteria up to 5 × 105cfu / piece ~ 5 × 106cfu / piece, the negative control of no bacterial growth, E. coli kill logarithmic value of the points are ≥ 3 for the disinfection of qualified.
(3) For poliovirus, each test, the medium is not contaminated, the cell growth is good. Poliovirus infection titer (TCID50) ≥105, inactivation logarithmic value of 4 logarithmic values. It can be judged as disinfection qualified.
2.1.5.2.7 Precautions
(1) There can be a considerable difference in the results between a full load and a non-full load in the sterilizing dishwasher, so the formal test must be carried out under full load conditions.
(2) different sizes of disinfection cabinets, cabinets equipped with infrared lamp power or installation of the number of branches, can affect the disinfection effect, so the design changes in this regard, should be re-measured.
(3) See 2.1.1.7 for E. coli inactivation test.
(4) See 2.1.1.10 for poliovirus inactivation test.
(5) See 2.1.1.7 for E. coli inactivation test.