1、Designation: E 1837 96 (Reapproved 2002)Standard Test Method toDetermine Efficacy of Disinfection Processes for ReusableMedical Devices (Simulated Use Test)1This standard is issued under the fixed designation E 1837; the number immediately following the designation indicates the year oforiginal adop
2、tion or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONWhen special tests designed to register or validate a disinfection proc
3、ess currently are used, theprocedures, their statistical considerations (usually all negatives at a given time point), and thephysical problems of applying organisms to surfaces, such as sutures and unglazed porcelain carriers,may cause inaccurate and confusing results. Practical, in-use testing of
4、reprocessing techniques andconditions are needed. Exaggerated conditions for testing can be achieved with the use of actualinstruments contaminated with high numbers of organisms. The addition of serum as an organic loador hard water minerals as an inorganic load can be made to enhance worst-case co
5、nditions. When theseelements are coupled with the processing, as actually performed, the result is a structured test that isa simulated-use procedure. This test method is designed to incorporate several elements ofreprocessing, including cleaning, rinsing, and disinfection (including optional treatm
6、ent of the internalchannels of devices, such as endoscopes) with a terminal alcohol rinse rather than examining only theeffectiveness of the entire disinfection process. A simulated-use test to examine the effectiveness ofreprocessing procedures is valuable because several incidents of contamination
7、 of instruments in usehave been recorded with vegetative cells of bacteria, for example, Pseudomonas and the mycobacteria.When this procedure is performed with a representative mycobacterial culture, it is necessary to usea nonpathogenic strain such as Mycobacterium terrae (isolated from soil) that
8、can be manipulated onan open bench. This strain is used in tuberculocidal testing in Europe, and published informationshows comparable resistance to antimicrobials as that displayed by human tuberculosis strains ofMycobacterium tuberculosis. This organism can be handled easily and grows faster than
9、other teststrains, such as M. bovis. (1,2,3,4, and 5).2Because contamination of the surfaces of instruments has occurred from rinsing with tap water,bacteria-free water should be used for all rinsing during reprocessing in this test procedure when awater rinse step is part of the reprocessing direct
10、ions.1. Scope1.1 This test method is intended to describe a procedure fortesting the effectiveness of a disinfection process for reprocess-ing reusable medical devices when it is tested with a challengeof vegetative cells including mycobacteria. Disinfection nor-mally deals with testing activity aga
11、inst vegetative cells ofbacteria, viruses, and fungi. Since this test method is processoriented, the user may wish to examine a variety of testorganisms.1.2 This test method is designed to provide a reproducibleprocedure to verify the effectiveness of a previously validateddisinfectant or disinfecti
12、on procedure for reusable medicalinstruments and devices.1.3 This test method is not meant to define the effectivenessof or validation of the particular disinfection process used or itskinetics, but rather, it is devised to confirm the effectiveness ofthe disinfection process by simulating use situa
13、tions with aparticular test process using medical devices and instruments.Either manual or machine reprocessing can be tested.1This test method is under the jurisdiction of ASTM Committee E35 onPesticides and Alternative Control Agents and is the direct responsibility ofSubcommittee E35.15 on Antimi
14、crobial Agents.Current edition approved Oct. 10, 2002. Published March 2003. Originallyapproved in 1996. Last previous edition approved in 1996 as E 1837 96.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.1Copyright ASTM International, 100 Barr Harbor
15、Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.1.4 This test method is intended for use with reusablecleaned and previously sterilized or disinfected (high level)medical instruments and devices. Endoscopes are described inthis test method as a worst-case example for contaminatio
16、n andsampling. The selected sterilization or disinfection processes,or both, should have been validated previously, as well as theeffectiveness of rinsing for residual sterilant/disinfectant re-moval determined.1.5 An inoculum with high numbers of selected microor-ganisms is applied to both test and
17、 control, cleaned andsterilized, or disinfected medical instruments. Strains of mi-croorganisms with a recorded resistance to disinfectants areused to contaminate the instrument sites known or suspected tobe the most difficult to reprocess.1.6 It is impractical to test for recovery of survivors byim
18、mersion of some instruments, for example, endoscopes orsome laproscopic instruments, in growth medium because ofcomplexity, size, difficulty in long-term incubation, or deteri-ous effects resulting from incubation. Elution of organismsfrom the inoculated surfaces, therefore, may be performed toestim
19、ate the number of recoverable organisms. Immersion canbe used for smaller instruments.1.7 Control instruments are inoculated in the same manneras the test instruments and elution or immersion methods areperformed to determine the number of organisms recoverablefrom the instrument. For channeled devi
20、ces, such as endo-scopes testing, the number of organisms recoverable from theinstrument (inside and outside) will serve as the initial controlcount. It is expected that some fraction of the number oforganisms inoculated will be lost in the process of inoculation/drying.1.8 A testing procedure can b
21、e performed on a completereprocessing cycle or can be limited to just the cleaning ordisinfection portions of the cycle whether reprocessing is donein a machine or manually.1.9 After the test cycle has been completed, remaininginoculated bacteria will be recovered from test instrumentsusing the same
22、 elution procedures as for the control instru-ments.1.10 Efficacy of a disinfection cycle or reprocessing cycle,or any part thereof, may be determined by comparison of thenumber of microorganisms recovered from the control instru-ment (initial recoverable control count) to the recovery deter-mined f
23、or the test instruments.1.11 A knowledge of microbiological techniques is requiredto conduct these procedures.31.12 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate saf
24、ety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:E 1054 Practices for Evaluating Inactivators of Antimicro-bial Agents Used in Disinfectant, Sanitizer, Antiseptic, orPreserved Products43. Terminology3.1 Definit
25、ions:3.1.1 bioburden, nthe number and type of viable micro-organisms that can be recovered from surfaces using standardrecovery procedures.3.1.2 CFUcolony forming units.3.1.3 disinfectantany biocidal chemical that produces ma-terials free from vegetative microorganisms that may contami-nate them and
26、 potentially cause infection.3.1.3.1 DiscussionThe definitions included are the tradi-tional ones. The user may choose to conform to other criteriathat specify elimination of a certain number of test microor-ganisms. Other definitions describe the action as application ofa process resulting in elimi
27、nation of microorganisms. Whatevercriteria is selected, it should be stated before initiation of thetest procedure.3.1.3.2 DiscussionA series of three definitions devised bySpaulding (6, 8) separated the activity of germicides againstspores and mycobacteria and non-lipid viruses and are there-fore d
28、efined by activity against groups of microorganisms.These definitions are as follows:(1) High-level disinfectants must inactivate bacteria en-dospores, mycobacteria, non-lipid viruses, fungi, vegetativebacteria, and lipid viruses. If exposure time is extended longenough, this type of germicide can b
29、e used as a sterilant.(2) Medium-level disinfectants inactivate mycobacteria,vegetative bacteria, fungi including asexual spores, and lipidand non-lipid viruses.(3) Low-level disinfection inactivate vegetative bacteria,most fungi, and lipid viruses.3.1.4 disinfector, nany device or physical process
30、thatprovides a biocidal process that produces materials free fromvegetative microorganisms that may contaminate them andpotentially cause infection.3.1.5 inoculumthe number (usually expressed in colonyforming units, cfu) and type (genus and species) of viablemicroorganisms used to contaminate a give
31、n sample or object.Strain identification and the means used to identify the organ-ism should be indicated.3.2 Definitions of Terms Specific to This Standard:3.2.1 accessible site, na location on or in a reusablemedical instruments that can be contacted by bioburden anddisinfectants.3.2.2 reusable me
32、dical device, nany medical instrumentthat is claimed at manufacture to be usable after reprocessing.3.2.3 worst-case, nthe intentional exaggeration of one ormore parameters of test compared to normal condition.4. Summary of Test Method4.1 This test method is performed by contamination ofaccessible,
33、interior, and exterior surfaces of instruments ordevices intending to reach the sites identified as the leastac-cessible or most difficult to reach sites.3CDC-NIH Biosafety in Microbiological and Biomedical Laboratories, 3rd ed.,U.S. Department of Health and Human Services, Washington, DC, 1993.4Dis
34、continued. See 1999 Annual Book of ASTM Standards, Vol 11.05.E 1837 96 (2002)24.2 The number of microorganisms contaminating the testinstruments or devices prior to processing is determined bycontamination and elution of at least two control unprocessedunits (representing a large complex instrument)
35、. More controlunits of smaller instruments may be used. Contamination withan inoculum with high numbers of microorganisms to achieveat least 106cfu/instrument, recoverable is required.4.3 After inoculation, the test instrument(s) are processedaccording to the manufacturers instructions for use of th
36、ereprocessing cycle, the disinfectant, or disinfector. Either thedisinfectant, disinfector cycle alone, or the disinfectant (disin-fector) cycle plus any cleaning, rinsing, or other contributorysteps in the directions for use, may be tested.4.4 Following processing, the test instruments are sampledu
37、sing specified elution and culture techniques to determine thenumber of surviving bacteria in colony forming units (cfu).5. Significance and Use5.1 This test method is designed to demonstrate and docu-ment that reusable devices and medical instruments can bedisinfected using a specified technique.5.
38、2 This test method can be used to verify claims ofdisinfection of recesses, hinged sites, lumina, or other difficult-to-reprocess areas of reusable medical devices and instruments.5.3 This test method also can be used to document thecontribution of each element of the reprocessing cycle forreusable
39、medical devices and instruments.5.4 The number of surviving bacteria may be assessed usingswabbing and irrigation or total immersion.5.5 This test method may be used to produce quantitative orqualitative results.6. Apparatus6.1 Syringes, 10 to 50 mL, sterile.6.2 Sterile Cotton, dacron or other swabs
40、.6.3 Sterile Petri Dishes.6.4 Sterile Tubes, to hold 10 mL.6.5 Sterile Bottles, to hold 50 mL and sterile flasks to hold250 to 500 mL.6.6 Steam, or other type of sterilizer.6.7 Water Bath, to maintain temperatures from 20 to 50 62C.6.8 Incubator(s), to maintain 35 6 2C.6.9 Membrane Filters and Filte
41、r Supports, for membranefilters.6.10 Colony Counter.6.11 Disposable Plastic Pipettes, various sizes.6.12 Medical Devices or Instruments, cleaned in accordancewith the manufacturers direction and sterilized or disinfected(high level) prior to use.6.13 Devices or Apparatus Specified by the Instrument,
42、Disinfectant or Disinfector Manufacturer.6.14 Vortex Mixer or Sonicator, or Both.7. Reagents7.1 Media:7.1.1 Sterile buffered elution fluid containing 0.1 % TritonX-100 prepared in Type III or better ASTM water. Specificneutralizers for the test disinfectant may be added.7.1.2 Soybean-Casein Digest B
43、roth, USP, with and withoutappropriate neutralizers for the specific test disinfectant chemi-cal.7.1.3 Soybean-Casein Digest Agar, USP, with and withoutappropriate neutralizers in 10 to 50-mL tubes or bottlestempered to 50 6 10C.7.1.4 Middlebrook 7H9 Broth, with and without appropriateneutralizers i
44、n 10 to 50-mL tubes or 250 to 500-mL flask (formycobacteria).7.1.5 Middlebrook 7H11 Agar, with and without appropriateneutralizers in 10 to 500-mL tubes or bottles tempered to 50 61C (for Mycobacteria).7.1.6 Mycophil or Potato Dextrose Agar, with and withoutappropriate neutralizers in 10 to 500-mL t
45、ubes or bottlestempered to 50 6 1C (for fungi). Soybean-Casein DigestBroth or agar, or both, may be used for many fungi.7.1.7 Bacteria-Free Water (when a water rinse step is partof the reprocessing procedures).7.2 Test OrganismsSuspensions of selected test organ-isms, appropriate for test.NOTE 1Stra
46、ins such as those identified in AOAC disinfectant testprocedures or other publications or resistant environmental isolates thathave demonstrated resistance to antimicrobials should be selected.7.2.1 Bacterial cultures are incubated until they reach atleast 1 3 108cfu/mL. For most test strains, this
47、can beachieved with a 48-h suspension of bacterial vegetative cells oftest strains prepared in tubes or flasks of appropriate media andincubated at the appropriate optimal growth temperature,62C. Strains of mycobacteria are slow growing and must beincubated for longer times depending on the strain.
48、M. terrae isnormally countable using magnification and lateral lighting in21 days, although it may be counted as early as 14 days.7.2.2 Any test strain which is easy to identify, such asSerratia marcescens, Escherichia coli, Mycobacterium bovisor Mycobacterium terrae, Pseudomonas aeruginosa, or Sta-
49、phylococcus aureus, and has documented disinfectant resis-tance selected. Suspensions should be grown for sufficient timeto achieve a 108-cfu/mL level.7.3 Neutralizers (appropriate for test system)For neutral-izer selection and testing refer to Practice E 1054. Neutralizersmay be added to dilution fluids.8. Procedure8.1 Use pre-cleaned and pre-sterilized or pre-disinfectedinstruments or devices.8.2 Inoculation of Devices (Endoscopes or Other ReusableInstruments):8.2.1 The suspensions are used as grown for inoculation.The approximate count may be estimated spectroph
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