Simulated-Use Testing of Bedpan and Urinal Washer Disinfectors: Evaluation of Clostrium Difﬁcile Spore Survival and Cleaning Efﬁcacy

Home , Bedpan, Urinal (health care)

Simulated-use testing of bedpan and urinal washer disinfectors: Evaluation of Clostrium difﬁcile spore survival and cleaning efﬁcacy

Michelle J. Alfa, PhD, FCCM,a,b,d Nancy Olson, BSc,b and Louise Buelow-Smith, RNc Winnipeg, Manitoba, Canada

Background: Reusable bedpans and urinals are frequently cleaned and decontaminated using washer-disinfectors (WDs) that may be located in the central processing department (CPD) or on the ward. The objective of this study was to determine how efficiently the WDs provided cleaning and to evaluate the ability of such WDs to kill Clostridium difficile spores. Methods: The cleaning efficacy of 2 bedpan/urinal WDs (1 in the ward [ward-WD] and 1 in the CPD [CPD-WD]) were evaluated using simulated-use testing that included an ultraviolet-visible marker (UVM) that is readily removed when exposed to liquid. In addition, a proprietary test object surgical instrument (TOSI) device was used to assess the efficacy of the WDs. Artificial test soil (ATS) and C difficile spore removal and killing also were evaluated. The removal of ;106 C difficile spores and subsequent killing of these spores was assessed using autoclaved stool and/or urine as the soil challenge. Results: Reusable stainless steel bedpans, plastic bedpans, and plastic urinals were assessed. Triplicate testing done on 3 separate days using TOSI devices, UVM, ATS, and stool and urine soils indicated that the ward-WD did not demonstrate adequate cleaning. It was determined that installation errors accounted for the inadequate cleaning. But the ward-WD did not adequately inactivate C difficile spores even when the installation problems were corrected and the manufacturer-adjusted maximal thermal conditions were used. The CPD-WD was able not only to adequately clean the test devices of organic soil, but also to completely inactivate the 6 logs of C difficile spores placed in sealed ampules inside the WD. Conclusion: The results of this study indicate that user testing of the efficacy of WDs is critical to ensure appropriate functionality. The currently accepted thermal decontamination parameters for all bedpan WDs (ie, 808C for 1 minute) are not adequate to eliminate C difficile spores from bedpans. (Am J Infect Control 2008;36:5-11.)

Automated washer-disinfectors (WDs) are com- Monitoring of temperature conditions and cycle print- monly used to clean and decontaminate bedpans and outs are routinely performed for such WDs to ensure urinals in health care facilities. To streamline this pro- that they are performing properly. In addition, WDs cess, some WDs are available as closed systems that that claim thermal disinfection are to be routinely facilitate disposal of waste as well as cleaning and de- monitored using appropriate biological indicators. contamination of the bedpans (and other types of The incidence of Clostridium difficile–associated waste containers) on the wards. This eliminates the diarrhea (CDAD) has been on the rise over the past need to send the used device to the central processing 10 years and is currently a major nosocomial problem department (CPD) for cleaning and disinfection. in health care facilities. Patients with CDAD have diarrhea, are on contact precautions, and frequently use From the Department of Medical Microbiology,a University of Mani- bedpans or commodes. The reprocessing of recepta- toba; St. Boniface General Hospital Research Centreb; and Central cles that contact fecal waste should ensure no residual Processingc and Microbiology Departments,d St. Boniface General C difficile spores. There are little published data on the Hospital, Winnipeg, Manitoba, Canada. efficacy of these ward WDs for the cleaning of medical Address correspondence to Michelle J. Alfa, PhD, FCCM, Microbiology devices such as bedpans and for the removal and/or Lab, St. Boniface General Hospital, 409 Tache Avenue, Winnipeg, MB R2H 2A6, Canada. E-mail: [email protected]. killing of C difficile spores. Furthermore, there are little published data on user testing for assessing the clean- 0196-6553/$34.00 ing functionality of WDs postinstallation. Copyright ª 2008 by the Association for Professionals in Infection Control and Epidemiology, Inc. The present study used a WD cleaning test device available to users, along with simulated-use testing, to doi:10.1016/j.ajic.2007.04.277 evaluate the efficacy of cleaning and microbial killing

5 6 Vol. 36 No. 1 Alfa, Olson, and Buelow-Smith of 2 types of WDs used in the reprocessing of bedpans Table 1. Sites inoculated on reusable test devices and urinals, 1 designed for use on the ward (ward-WD) Device Test soil Site inoculated and 1 designed for use in the CPD (CPD-WD). We assessed the ward-WD against the CPD-WD (the device Plastic bedpan ATS d Inside bedpan on bottom surface currently used for reprocessing bedpans and urinals) d Inside bedpan under front lip using a proprietary test object surgical instrument UVM d Inside bedpan on bottom surface d Inside bedpan under front lip (TOSI) device, artificial test soil (ATS), as well as sterile d Outside bedpan on underside surface feces and urine seeded with known concentrations of Sterile feces Inside bedpan under front lip C difficile spores. Stainless ATS d Outside bedpan on seat surface steel bedpan d Inside bedpan on bottom surface UVM d Outside bedpan on seat surface MATERIALS AND METHODS d Inside bedpan on bottom surface d Inside bedpan under the seat side lip Washer/disinfectors Sterile feces Inside bedpan under the seat side lip Plastic urinal ATS d Inside bottom CPD-WD. The CPD-WD evaluated was a STERIS Re- d Inside middle liance 444 single-chamber WD (STERIS Corp, Mentor, d Inside top UVM d Inside urinal near handle OH). The cleaning cycle used in the test was the ‘‘uten- Sterile urine d Inside urinal opposite handle sils’’ cycle, comprising a 2-minute prewash, a 2-minute wash at 668C (1508F), a 15-second rinse with hot tap water, a 1-minute thermal rinse at 828C (1808F), and a Test soils 10-second final rinse with treated (demineralized) water. This cleaning cycle was followed by a drying phase ATS. For simulated-use testing, we used ATS, which for 7 minutes at 1168C (2408F). This CPD-WD was de- mimics the worst-case organic load expected for flexi- signed for the reprocessing of many different medical ble endoscopes exposed to the human gastrointestinal devices, not just bedpans and urinals. tract. This soil has been studied extensively for evaluat- Ward-WD. This WD was designed specifically for lo- ing the cleaning of medical devices.1-6 The same lot of cation on wards to wash bedpans and urinals of various ATS was used for all of the experiments performed in shapes and sizes. It was located in a tertiary care health this study. The ATS was stored at 48C until use and care facility on a ward that had not yet opened. The de- was used within the 1-month expiration period. vice was set to the ‘‘standard’’ cycle for bedpans and to ATS was inoculated onto the internal and external the ‘‘urinal’’ cycle for urinals, in accordance with the surfaces of the devices to be tested. Bedpan inoculation manufacturer’s recommendation. The cycle parame- involved placing a 50-mL drop of ATS into the center of ters included a 14-second cold water wash, followed the square and using the edge of the sterile tip to spread by a 15-second warm water wash, and finally a 16- out the soil within the boundaries of a 2-cm2 area. For second warm water wash. The standard disinfection urinals, 10 mL of ATS was inoculated along the inner temperature was 808C (1768F) for 60 seconds. The cycle flat side (ie, opposite the handle). The soil was swirled used no detergent and had 2 cold water washes fol- around the bottom and along the entire length of the lowed by 3 warm water washes. In addition, a cus- inner side. Once inoculated, the devices were allowed tom-set (manufacturer-adjusted) cycle was evaluated to dry at room temperature for 1 hour before process- that used detergent, 4 cold water rinses, 4 warm water ing in the WD. rinses, and a disinfection temperature of 858C (1858F) After processing in the WD, the inoculated area was for 300 seconds. This WD is ISO-registered and li- harvested using a sterile swab moistened in sterile censed for sale in Canada, but no data are available reverse-osmosis water that was thoroughly rubbed for cleaning validation. over the entire inoculated area. Each test represented TOSI device. The TOSI testing device (Pereg GmbH, a separate inoculated area. The swab used to ‘‘harvest’’ Waldkraiburg, Germany) consists of a stainless steel any residual soil was then placed into a tube containing strip with red-colored soil dried on one surface. The de- either 1 mL of Bradford reagent (which turns blue in the vices used in this study were tested with and without presence of protein) or 1 mL of tetramethylbenzidine the clear plastic cover. Exposing the strip to water dur- (TMB) reagent (which turns green in the presence of ing the wash cycle will remove the red material to some blood). The swabs were immersed in the test reagent degree. A completely clean strip indicates a properly for 20 minutes at room temperature for the Bradford re- functioning WD. agent and for 30 minutes at room temperature for the Bedpans and urinals. All of the bedpans and urinals TMB reagent and then the absorbance was measured evaluated were reusable. The inoculation sites for the at 595 nm for protein or 650 nm for blood. The higher various bedpans and urinals are listed in Table 1. the absorbance value for the Bradford or TMB reagent, Alfa, Olson, and Buelow-Smith February 2008 7 the more protein or hemoglobin is present. Negative agar, MacConkey agar (split-plate) and FAB to confirm (not soiled and not cleaned) and positive controls (soiled that it was sterile. The C difficile spores were mixed but not cleaned) were included for all experiments. All with the sterile urine or sterile stool to provide a final tests were performed in triplicate on 3 separate days. concentration of about 1 3 107 cfu/mL. The devices Ultraviolet-visible marker. Ultraviolet-visible marker to be evaluated were inoculated as described previ- (UVM) lotion (GlitterBug; Brevis Corp, Salt Lake City, UT) ously and allowed to dry at room temperature over- is visible under UV light and is used to monitor compli- night before testing. In addition, 0.2 mL of the fecal ance with handwashing. It is nontoxic and readily re- suspension containing C difficile spores was placed in moved by washing with water. This lotion was applied a cryovial and sealed. The closed cryovial containing to ;2-cm2 surface areas using a sterile swab inside the C difficile spores was placed in the WD along with and outside the test devices and allowed to dry for the devices to evaluate the effect of heat of the cycle 1 hour. The inoculated devices were then exposed to on spore killing (ie, to assess the heat effect of the cycle the wash cycle to evaluate the efficacy of removal of independent of the wash-off effect of the cycle). the UVM. After processing in the WD, the inoculated Once the devices were removed from the WD, a sin- sites on the devices were harvested using a sterile gle Rodac plate containing CDMN agar was pressed flat swab. This swab was rubbed over the area inoculated. onto the circular marked area that had been inoculated This swab was then evaluated by exposing it to UV light and was held there for 5 seconds. The plates were incu- in a dark room. The presence of any detectable fluores- bated anaerobically in an anaerobic chamber contain- cence indicated inadequate cleaning. The amount of ing palladium catalyst and a gas mixture comprising fluorescence detected was scored as 31 (100% fluores- 5% H2, 10% CO2, and 85% N2. The colony counts of cence), 21 (66% fluorescence), 11 (33% fluorescence), C difficile were determined after 48 hours of incuba- 0.51 (10% fluorescence), or 0 (no fluorescence). Nega- tion. Only colonies that had appropriate colony mor- tive (not soiled, not cleaned) and positive (soiled but phology and Gram’s stain were counted. not cleaned) controls were included in all experiments. In addition, the suspension in the cryovials was seri- Efficacy of WDs in removing and/or killing C diffi- ally diluted, and viable counts were determined using cile spores. The test organism used was a patient- the spread-plate method on CDMN agar. The inoculated derived strain of C difficile (strain 765 from clinical CDMN agar was incubated anaerobically; after 48 stocks at the Microbiology Laboratory, St. Boniface hours of incubation, colony counts were determined General Hospital). Spores were prepared by inoculating as described previously. a 48-hour culture of the organism on blood agar plates and incubating these under anaerobic conditions for 7 RESULTS to 14 days. The surface growth was harvested and suspended in sterile reverse-osmosis water and assessed TOSI testing using malachite green stain to ensure that spore forma- The TOSI device was positioned in the ward-WD and tion had occurred. If adequate spore formation was the CPD-WD. Original and repeat testing indicated that identified, then the spore concentration was deter- the ward-WD did not completely remove the soil, mined by pelleting the spores by centrifugation and whereas CPD-WD did completely remove the soil. then alcohol-shocking the pellet by incubating it in These tests were performed with and without the pro- 95% alcohol for 20 minutes at room temperature, fol- tective plastic cover on the TOSI device, and similar re- lowed by determining the viable count using the spread sults were obtained in both cases. Additional testing plate method on C difficile moxalactam norfloxacin was performed by placing the TOSI device inside a bed- (CDMN) agar (Oxoid Ltd, Nepean, ON, Canada). The pan and a urinal. Again, the results indicated incom- spore preparation was stored at 48C until use. plete removal of soil by the ward-WD. The test soils used for these studies consisted of To evaluate the difficulty of soil removal, several stool and urine. The stool was a clinical sample ob- TOSI devices without the plastic protective cover tained from the diagnostic laboratory that was negative were held under running warm (458C) tap water. for C difficile toxin. The stool was autoclaved and sub- Within ;2 minutes, 99% of the visible soil was re- sequently inoculated onto CDMA, blood agar, chocolate moved, indicating that removing the soil from this de- agar, and fastidious anaerobe broth (FAB) to confirm its vice is not a difficult challenge. sterility. The urine was a clinical sample obtained from the diagnostic laboratory known to be culture-negative Testing of ATS-soiled devices for residual (ie, no organisms were detected using standard micro- protein and hemoglobin (blood) postcleaning biology methods when 0.001 mL of urine was inoculated onto blood agar medium). The urine was also The 2 types of bedpans and the urinal were inocu- autoclaved and subsequently inoculated onto blood lated with ATS as described in Materials and Methods, 8 Vol. 36 No. 1 Alfa, Olson, and Buelow-Smith

Fig 2. Residual UVM on bedpans or urinals postwashing and disinfection. The UVM lotion was inoculated onto bedpans (plastic or stainless steel) and urinals and allowed to dry for 1 hour before Fig 1. Residual protein and hemoglobin on processing through either the ward-WD or CPD- bedpans and urinals postcleaning. The bedpans WD. The stainless steel bedpan (SS-BP) had 4 sites (plastic and stainless steel) and urinals were on each of 3 bedpans tested (12 tests in total), the inoculated with ATS and dried for 1 hour as plastic bedpan (plastic-BP) had 3 sites on each of 3 described in Materials and Methods. After bedpans tested (9 tests in total), and the urinal had processing through the Ward-WD (clear bars) or 1 site on each urinal tested (3 tests in total). Positive CPD-WD (solid bars), the inoculated sites were controls were inoculated in the same manner, but sampled and assessed for the presence of residual these were not cleaned; negative controls consisted protein (A) and hemoglobin (B). The values listed are of the same surface area sites that were not the average of triplicate absorbance readings from all inoculated. Positive and negative controls (A) were sites tested per device. The corresponding negative included in each experiment. The average residual control value for each site was subtracted from the ﬂuorescent score was determined (B) for multiple absorbance value of the test site, and the average sites in bedpans and urinals on 3 separate days. absorbance value was used for graphics. visualized using UV light. This swab collection method and the soiled devices were processed through the was necessary because some sites could not be readily ward-WD and CPD-WD. The results of testing for resid- illuminated directly with UV light. The efﬁcacy of the 2 ual organic material (protein and hemoglobin [blood]) WDs in removing this water-soluble mark is summa- are shown in Figure 1. rized in Figure 2B.

UVM removal Cdifficilespore removal The stainless steel and plastic bedpans and plastic The stainless steel and plastic bedpans and plastic urinals were inoculated with UVM as described in Ma- urinal were soiled with feces (bedpans) or urine (urinal) terials and Methods. Figure 2A shows how the fluores- containing C difficile spores. After the complete clean- cence on swabs used to sample the devices was ing and decontamination cycle, the inoculated areas Alfa, Olson, and Buelow-Smith February 2008 9

Fig 4. Ability of ward-WD and CPD-WD to kill C. Fig 3. Residual viable C. difficile spores on bedpans difficile spores in test vials. Spores of C. difficile were or urinals postwashing and disinfection. Spores of C suspended in sterile feces to a final concentration of difficile were suspended in sterile feces (for bedpan 1.1 3 107 cfu/mL, 0.2 mL was inoculated inside a testing) or sterile urine (for urinal testing) to a final cryovial, and the cap was sealed. Viable counts were concentration of 1.1 3 107 cfu/mL (ie, 5 3 105 cfu/ done on the material after processing through the site inocubated). Plastic bedpans (plastic-BP), ward-WD or CPD-WD. The results represent the stainless steel bedpans (SS-BP), and urinals were average of 3 replicate experiments performed on 3 inoculated and dried as specified in Materials and different days. Methods. Rodac plates were used to sample the inoculated surfaces. The data represent the average of 3 replicate experiments done on 3 separate days. manufacturer then made additional adjustments, For the sake of graphing, plates with colonies that including increasing thermal disinfection to 858C were too numerous to count were graphed as having (1858F) for 300 seconds (5 minutes), installing a deter- 100 cfu/plate. gent dispenser, and changing the wash program from 2 cold rinses followed by 3 warm rinses to 4 cold rinses followed by 4 warm rinses. Repeat testing for the plas- were directly sampled using Rodac plates pressed onto tic bedpan with stool and C difficile spores resulted in the surface. For the purposes of graphing, the Rodac the bedpans being visibly clean but still having . 100 plates that had too many colonies to count were scored colonies/site when tested by Rodac plates. as having 100 cfu per plate. All testing was performed To further assess why C difficile spores survived the in triplicate (on 3 separate days); the results, presented heat decontamination cycle provided by the ward- in Figure 3, are the average viable counts. WD but not the CPD-WD, additional testing with stool To further evaluate the effect of the heat on killing C containing C difficile spores in sealed vials was per- difficile without the liquid wash-off effect, cryovials formed. The viable count results indicated that the containing the same stool soil seeded with C difficile spore count in the vial was 6.41 log10 cfu/mL, and after spores were placed in the WDs for the entire washing exposure to the ward-WD (with revised cycle parame- and drying cycle. The contents were subsequently eval- ters), the count was 6.07 log10 cfu/mL. To determine uated for residual viable organisms; the results are the role of drying (at 1168C for 7 minutes) on spore vi- shown in Figure 4. ability, vials of stool containing C difficile spores were When the data were shared with the manufacturer evaluated after exposure to only the thermal decon- of the ward-WD, the manufacturer sent a technical spe- tamination cycle (ie, no drying cycle) of the CPD-WD. cialist, who identified that there were installation prob- The inoculum of spores was 6.16 log10 cfu/mL in feces, lems with some of the sprayer arms in the unit. Further and after the wash cycle only, the viable count was 4.59 evaluation indicated that the hot and cold water feeds log10 cfu/mL. It should be noted that the CPD-WD also had been reversed. The feed lines were corrected, has a hot water rinse at 828C (1808F) for 1.25 minutes and the sprayer arms were properly adjusted. Once as well as a 668C (1508F) hot water rinse for 2 minutes the adjustments were made, the fecal C difficile spore before the thermal decontamination cycle. The ward- testing for the plastic bedpan was repeated. The repeat WD does not have these hot water rinses. testing did show improved cleaning of the TOSI device; Because there were surviving C difficile spores in the however, testing by Rodac plates revealed . 100 C dif- ward-WD, we further evaluated whether there could be ficile colonies per plate for all 3 replicate tests. The ‘‘cross-contamination’’ between bedpans. We did this 10 Vol. 36 No. 1 Alfa, Olson, and Buelow-Smith by processing one bedpan that had been inoculated to prevent staff exposure and ensure that the bedpans with spores in fecal material, followed by an uninocu- are not a source for nosocomial transmission of C diffi- lated bedpan, then testing the uninoculated bedpan us- cile between patients. Figures 3 and 4 indicate that the ing Rodac plates to determine whether it had acquired ward-WD did not provide decontamination of C difficile any spores. We detected no spores on the bedpans eval- spores to a level that would ensure that the bedpans uated in this manner (data not shown). were safe to handle and safe to use on a patient. This insufficient decontamination appears to be due to DISCUSSION too-low thermal conditions for the ward-WD at its standard settings. In contrast, the success of the CPD-WD Although the ISO has developed guidance docu- appears to result from a cumulative effect of the hot ments for WDs15 and others have evaluated flexible en- water rinses, thermal decontamination, and drying cy- doscope WDs7-9 and medical devices,10-13 this is one of cle. This raises infection control concerns regarding the the first published studies to compare the efficacy of use of such ward-WDs for bedpans, in which high bedpan and urinal cleaning efficacy of a ward-WD levels of C difficile spores are commonly encountered and a CPD-WD. The data demonstrate that for all of because CDAD is a common nosocomial infection in the tests undertaken, the ward-WD (as it was originally hospitalized patients. installed) did not provide the equivalent level of clean- Although the ATS, feces, urine, and C difficile spore ing (ie, removal or ATS, feces, urine, or UVM) or decon- testing used in this study are beyond the capability of tamination (ie, killing of C difficile spores) as shown by routine onsite user testing, UVM and the TOSI device the CPD-WD. Correction of improper installation im- can be used onsite to evaluate the cleaning efficacy proved the ward-WD cleaning function, but despite of WDs. This evaluation demonstrates that user assess- maximal possible adjustment to temperature/time pa- ment of WDs is important to ensure adequate perfor- rameters, the ward-WD was not able to provide C diffi- mance even for new equipment; for example, the use cile spore killing equivalent to that achieved by the of these tests at our site helped identify problems CPD-WD (Fig 4). Review of other manufacturer’s ward- that were ultimately determined to be installation er- WD cycles indicated that thermal decontamination at rors. Furthermore, our data demonstrate that the max- 808C for 1 minute was commonly used. Furthermore, imum temperature of 858C (1858F) in the ward-WD was these conditions are endorsed by ISO 1588315 for bed- inadequate to eliminate C difficile spores effectively. pan reprocessing. (Note that the manufacturer does not claim that the Multiple test soils, including ATS, UVM, TOSI devices, ward-WD can eliminate C difficile spores.) The cleaning and autoclaved feces and urine, were evaluated, and provided by the ward-WD was not sufficient to remove the same conclusions were reached. ATS has been the spores from the surface of the plastic bedpans. This used to evaluate cleaning of various medical devices1- is not a unique problem to this specific type of ward- 6 and is a relevant soil for simulated-use testing to de- WD; we are not aware of other ward-WDs that have determine how well organic material is removed from contamination cycles differing from that used in this the devices processed through the washers. This soil study. This is an important issue that should be taken is not overly difficult to remove, so although the resid- into consideration for the thermal conditions for uals from Figure 1 appear to be low for the ward-WD, bedpan washers recommended by national and inter- these should have been equivalent to the negative con- national guidance documents. The Ao value for reproc- trol if adequate washing had been achieved (as was ob- essing of bedpans currently recommended by ISO served for the CPD-WD). The presence of UVM after the guidance document 15883 (ie, Ao 5 60) is insufficient wash cycle further confirms the inadequacy of washing from an infection control perspective to ensure reliable by the ward-WD (Fig 2B). These 2 experimental ap- elimination of C difficile spores. Although ISO 1588315 proaches clearly document that cleaning was inade- recommends that the setting be approved by infection quate for the ward-WD. This lack of efficient cleaning control in the context of the type of pathogens ex- after the original installation appeared to have been pected, it is apparent that the existing ward-WDs may due (at least in part) to the sprayer arm problems iden- not be able to provide adequate conditions for killing tified by the technical specialist sent by the manufac- C difficile spores, because they cannot achieve the nec- turer to address our concerns with the device. essary thermal killing conditions. Testing of ward-WDs The disinfection capability of the 2 WDs was evalu- from 2 different manufacturers produced similar find- ated using C difficile spores as the microbial indicator. ings (data not shown). This is a relevant indicator, because the bedpans from Zuhlsdorf et al7 has documented that decreasing the patients who either carry C difficile or are ill with this reprocessing temperatures for endoscope WDs can al- organism would be processed through such WDs. It is low significantly more bacterial survival. Furthermore, critical to ensure that no spores remain after the cycle, they reported that evaluation of cleaning efficacy in Alfa, Olson, and Buelow-Smith February 2008 11 various endoscope WDs indicated variability. As more manual with automated cleaning methods. Am J Infect Control 2003; attention is focused on testing the cleaning efficacy of 31:193-207. 3. Alfa MJ, Olson N, DeGagne P, Jackson M. Survey of reprocessing WDs, it is becoming apparent that users need to incor- methods, residual viable bioburden and soil levels in patient-ready porate this type of testing as part of their ongoing quality ERCP scopes used in Canadian centers. Infect Contr Hosp Epidemiol assurance program. Although hospitals have tradition- 2002;23:198-206. ally monitored temperature and cycle parameters to 4. Alfa MJ, Jackson M. A new hydrogen peroxide–based medical device verify adequate functioning of WDs it is also useful to detergent with germicidal properties: comparison with enzymatic cleaners. Am J Infect Control 2001;29:1-10. monitor the cleaning efficacy of these units. This is a 5. Alfa MJ, DeGagne P, Olson N. Worst-case soiling levels for patient- valuable parameter to evaluate, because it provides a used flexible endoscopes before and after cleaning. Am J Infect Con- cost-effective means of reducing the risk of improperly trol 1999;27:392-401. cleaned and decontaminated bedpans and urinals, 6. Alfa MJ, DeGagne P, Olson N, Hizon R. Comparison of liquid which may pose a risk for nosocomial infection trans- chemical sterilization using peracetic acid to ethylene oxide sterilization for long narrow lumens. Am J Infect Control 1998;26: mission. This also reflects the recommendations by 14 469-77. Ransjo et al, although they used microbial markers 7. Zuhlsdorf B, Winkler A, Dietze B, Floss H, Martiny H. Gastroscope (Enterococcus faecalis and Bacillus subtilis spores) to processing in washer-disinfectors at three different temperatures. monitor cleaning and disinfecting. For users in health J Hosp Infect 2003;55:276-82. care settings, methods that require bacterial culture 8. Zuhlsdorf B, Martiny H. Intralaboratory reproductibility of the Ger- man test method of prEN ISO 15883-1 for determination of the clean- are often too difficult to implement. ing efficacy of washer-disinfectors for flexible endoscopes. J Hosp In conclusion, our data support the value of users Infect 2005;59:286-91. evaluating the cleaning efficacy of WDs used in their 9. Zuhlsdorf B, Emmrich M, Floss H, Martiny H. Cleaning efficacy of nine facility by either UVM or TOSI testing. WDs that do different cleaners in a washer-disinfector designed for flexible endo- not provide adequate cleaning as determine by these scopes. J Hosp Infect 2002;52:206-11. 10. Verjat D, Prognon P, Darbord JC. Fluorescence assay on traces of pro- tests should be taken out of service until they are fixed tein on reusable medical devices: cleaning efficacy. Int J Pharm 1999; or replaced. Furthermore, the data demonstrate that 179:267-71. thermal settings achieved by currently available 11. De Bruijn ACP, Orzechowski TJH, Wassenaar C. Validation of the nin- ward-WDs cannot effectively kill C difficile spores. hydrin swab test to monitor cleaning of medical instruments. Zentr This has significant infection control implications Steril 2001;9:235-47. 12. Fengler W, Pahlke H, Bisson S, Michels W. Are processed surgical in- that should be taken into consideration by interna- struments free of protein? Zentr Steril 2001;9:20-32. tional and national bodies when drafting guidelines 13. Kruger S. Testing the cleaning efficacy in decontamination equipment, for washers used to reprocess bedpans. Part 1. Zentr Steril 1997;5:333-44. 14. Ransjo U, Engstrom L, Hakansson P, Ledel T, Lindgren L, Lindqvist A, References et al. A test for cleaning and disinfection processes in a washer-disin- 1. Alfa MJ, Nemes R. Manual versus automated methods for cleaning re- fector. APMIS 2001;109:299-304. usable accessory devices used for minimally invasive surgical proce- 15. International Standards Association. ISO 15883-3, washer-disinfec- dures. J Hosp Infect 2004;58:50-8. tors: requirements and tests for washer-disinfectors employing ther- 2. Alfa MJ, Nemes R. Inadequacy of manual cleaning for reprocessing sin- mal disinfection for human waste containers. Geneva, Switzerland: gle-use, triple-lumen sphinctertomes: simulated-use testing comparing International Standards Association; 2006.