GB/T 38502-2020 English PDF (GBT38502-2020)

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GB/T 38502-2020: Test method for bactericidal effect of disinfectant in laboratory
GB/T 38502-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 11.080
C 50
Test method for bactericidal effect of disinfectant in
laboratory
ISSUED ON: MARCH 06, 2020
IMPLEMENTED ON: OCTOBER 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Terms and definitions ... 4 
4 Basic requirements ... 5 
4.1 Laboratory and personnel requirements ... 5 
4.2 Requirements for disinfection test ... 5 
5 Test method for disinfection and bactericidal effect ... 7 
5.1 Preparation of bacterial suspension and bacterial slices ... 7 
5.2 Counting technology of viable bacteria culture ... 11 
5.3 Removal method of residual disinfectant (chemical factor) ... 14 
5.4 Neutralizer identification test ... 15 
5.5 Test for removing residual disinfectant by filter washing method ... 18 
5.6 Bacterial killing test ... 20 
5.7 Mycobacterial killing test ... 25 
5.8 Fungal killing test ... 27 
5.9 Test on factors affecting the bactericidal effect of disinfectants ... 30 
Appendix A (Normative) Laboratory and personnel requirements ... 34 
Appendix B (Normative) Reagent ... 36 
Test method for bactericidal effect of disinfectant in
laboratory
1 Scope
This standard specifies the terms and definitions, basic requirements, test methods for
bactericidal effect of disinfectant in laboratory.
This standard is applicable to the inspection and evaluation of the bactericidal effect of
various disinfectants in the laboratory.
2 Normative references
The following documents are essential to the application of this document. For the dated
documents, only the versions with the dates indicated are applicable to this document;
for the undated documents, only the latest version (including all the amendments) is
applicable to this standard.
GB 19489 Laboratories - General requirements for biosafety
3 Terms and definitions
The following terms and definitions apply to this document.
3.1
Disinfectant
Preparations, which are used to kill microorganisms on the transmission medium, to
achieve disinfection or sterilization requirements.
3.2
Neutralizer
In the microbial killing test, a reagent, which is used to eliminate the residual
disinfectant in the suspension of the test microorganism and the disinfectant and on
the surface of the microorganism, so that it loses the inhibitory and killing effect on
the microorganism.
3.3
b) For laboratory tests to evaluate disinfectants, the test concentration of the
disinfectant shall be the lowest use concentration of the disinfectant, which is
specified in the product specification, for a representative disinfection object.
Three different action times are set in the test. In principle, the first time is 0.5
times the shortest action time, which is specified in the manual; the second time
is the shortest action time; the third time is 1.5 times the shortest action time.
c) For multi-purpose disinfectants, when the microorganisms involved in the
disinfection objects are the same, if the concentration used is the same, THEN,
select the shortest action time, among various purposes. If the duration of action
is the same, select the lowest use concentration for each application. When the
low concentration and short action time AND the high concentration and long
action time coexist, the former shall prevail. When using high concentration and
short action time coexist with low use concentration and long action time, each
dose shall be tested.
d) Qualitative test of carrier shall be used for sterilization test. Stainless steel sheet
is used as carrier for sterilization of common medical devices. Glass sheet,
polytetrafluoroethylene sheet, etc., can be used for special purposes. The
sterilization test is carried out, according to the lowest use concentration (intensity)
and 0.5 times the shortest action time, which are specified in the product
specification. The carrier qualitative test shall be repeated 5 times. The total
number of samples shall be no less than 30. A specified number of negative
controls and positive controls shall be established for each test.
e) When conducting laboratory tests, the concentration of the organic interfering
substance - bovine serum albumin - is 3.0%, for the disinfectant, which is used
for unwashed or relatively dirty disinfection objects. The concentration of the
organic interfering substance - bovine serum albumin - is 0.3%, for the
disinfectant, which is used for cleaned or relatively clean disinfection objects. The
organic interfering substance may not be used, for the disinfectant, which is used
for the disinfection object that has been strictly cleaned or extremely clean.
4.2.2 Requirements for repeated tests
For the repeatability test, it shall not only increase the number of bacterial slices in the
same test, OR make several more samples, BUT shall be carried out in stages and in
batches. Necessary equipment and reagents shall be re-prepared or sterilized, to prevent
systematic errors.
4.2.3 Evaluation of results
Disinfection products, that meet all the following corresponding conditions, are judged
to be qualified in the disinfection effect test results:
a) The qualification test for the effect of removing residual disinfectant is qualified.
5.1.2.1 Preparation of bacterial propagule suspension
5.1.2.1.1 Open the strain tube, by aseptic operation. Use a capillary pipette, to add an
appropriate amount of nutrient broth medium. Blow and suck several times, to melt and
disperse the strain. Take a test tube, which contains 5.0 mL ~ 10.0 mL of nutrient broth
medium. Add dropwise a little strain suspension. Incubate it at 36 °C ± 1 °C for 18 h ~
24 h. Use the inoculation ring, to take the bacterial suspension of the first generation
culture. Streak to inoculate it on the nutrient agar medium plate. Incubate it at 36 °C ±
1 °C for 18 h ~ 24 h. OR take out a bacterial bead, from the strain storage tube. Inoculate
it on a plate. Incubate it at 36 °C ± 1 °C for 18 h ~ 24 h. Pick out the typical colonies in
the second generation culture above. Inoculate it on a nutrient agar slant. Incubate it at
36 °C ± 1 °C for 18 h ~ 24 h, which is the third generation of culture.
5.1.2.1.2 Take the fresh slant culture, which is obtained by cultivating the 3rd to 8th
generation of nutrient agar medium, for 18 h ~ 24 h. Use a 5.0 mL pipette, to draw 3.0
mL ~ 5.0 mL of dilution (usually TPS, acidified water uses normal saline). Add it into
the test tube. Repeat blowing and sucking, to wash the bacterial moss. Then, use a 5.0
mL pipette, to transfer the lotion to another sterile test tube. Use an electric mixer, to
mix it for 20 s. OR vibrate 80 times on the palm of hand, to suspend the bacteria evenly.
5.1.2.1.3 For the initially prepared bacterial suspension, first use the bacterial
concentration turbidimetric method, to roughly measure the bacterial concentration;
then use a diluent, to dilute it to the desired concentration.
5.1.2.1.4 The bacterial propagule suspension shall be stored in a refrigerator, at 4 °C for
future use. It shall be used in the same day of preparation. It is not allowed for overnight.
5.1.2.1.5 When contamination is suspected, it shall be identified, by methods such as
colony morphology, Gram staining, biochemical tests.
5.1.2.2 Preparation of bacterial spore suspension
5.1.2.2.1 Open the ...