Physical and composition characteristics of clinical secretions compared with test soils used for validation of flexible endoscope cleaning.

AIM: To determine which simulated-use test soils met the worst-case organic levels and viscosity of clinical secretions, and had the best adhesive characteristics. METHODS: Levels of protein, carbohydrate and haemoglobin, and vibrational viscosity of clinical endoscope secretions were compared with test soils including ATS, ATS2015, Edinburgh, Edinburgh-M (modified), Miles, 10% serum and coagulated whole blood. ASTM D3359 was used for adhesion testing. Cleaning of a single-channel flexible intubation endoscope was tested after simulated use. RESULTS: The worst-case levels of protein, carbohydrate and haemoglobin, and viscosity of clinical material were 219,828µg/mL, 9296µg/mL, 9562µg/mL and 6cP, respectively. Whole blood, ATS2015 and Edinburgh-M were pipettable with viscosities of 3.4cP, 9.0cP and 11.9cP, respectively. ATS2015 and Edinburgh-M best matched the worst-case clinical parameters, but ATS had the best adhesion with 7% removal (36.7% for Edinburgh-M). Edinburgh-M and ATS2015 showed similar soiling and removal characteristics from the surface and lumen of a flexible intubation endoscope. CONCLUSIONS: Of the test soils evaluated, ATS2015 and Edinburgh-M were found to be good choices for the simulated use of endoscopes, as their composition and viscosity most closely matched worst-case clinical material.

Adenosine tri-phosphate (ATP)-based cleaning monitoring in health care: how rapidly does environmental ATP deteriorate?

BACKGROUND: Ensuring cleaning compliance of housekeeping staff is critical to ensure adequate application of surface disinfectants. Adenosine triphosphate (ATP) testing has been recommended as a way to monitor cleaning compliance; however, little is known about the stability of ATP on environmental surfaces. AIM: To assess the stability of ATP from various sources to determine if it is stable for sufficient time to be an effective means of assessing environmental cleaning and disinfection in health care. METHODS: Purified ATP, ATP derived from ATS-T (blood-based test soil) and ATP derived from 10(7) colony-forming units/site of micro-organisms (Pseudomonas aeruginosa, Enterococcus faecalis, Candida albicans) were evaluated in liquid suspension and dried on to surfaces to assess stability over 29 days. Cleaners and disinfectants were sprayed on to surface-dried material with no wiping to determine their effect on microbial viability and ATP stability. FINDINGS: Surface-dried P. aeruginosa, E. faecalis and C. albicans retained 65-96% of their original ATP level on Day 29, despite reduced or no viability. Surface-dried ATS-T had 100% and 3% of its original ATP on Days 4 and 29, respectively. Deterioration of the ATP signal was most pronounced for suspensions. Purified ATP was stable over 29 days in suspension or dried on to a surface. CONCLUSIONS: ATP residuals from organic material and micro-organisms (dead or alive) are stable when dried on to surfaces. In the absence of cleaning and disinfection, the relative light unit signal will not deteriorate rapidly, making ATP a good marker to monitor cleaning.

Intermediate-level disinfection with accelerated hydrogen peroxide prevents accumulation of bacteria in Versajet™ tubing during repeated daily debridement using simulated-use testing with an inoculated pork hock.

OBJECTIVE: This study assesses the feasibility of using the Versajet™ system (VJS) on an inoculated pork hock (PH) skin surface sequentially for 8 days with daily cleaning and intermediate-level disinfection (ILD). METHODS: Daily, PHs were inoculated with bacteria suspended in artificial test soil (ATS). An ILD protocol with accelerated hydrogen peroxide (AHP, OxivirTB(®)) was employed to clean and disinfect the VJS between debridements. RESULTS: PH skin contains 6.1-6.8×10(6)cfu/cm(2) bacteria. Bacterial counts in the handpiece and discharge hoses immediately after debridement of the PHs, and before cleaning, increased throughout the study period (5.19-6.43log10cfu/mL). Cleaning with the ILD protocol was reduced bacterial counts on the VJS by 6-log. Protein, a surrogate marker of organic contamination, was also reduced post-cleaning and ILD. Compared to a maximum post-debridement level of protein (57.9 µg/mL) obtained before ILD, VJS protein levels dropped to 9.8 (handpiece) and 13.8 µg/mL (discharge hose). CONCLUSIONS: Disinfection of the handpiece and discharge hose after debridement with AHP resulted in a 6-log reduction in bacterial count and 4.2 fold reduction in protein. An ILD protocol with an AHP may be a feasible method for serial skin surface debridements with the VJS for up to eight days.

Continuing performance feedback and use of the ultraviolet visible marker to assess cleaning compliance in the healthcare environment.

BACKGROUND: Environmental surfaces have long been suspected to be a reservoir that could contribute to the presence of micro-organisms in healthcare facilities. The objective of this study was to evaluate the effect of providing weekly feedback to the housekeeping staff in improving and sustaining cleaning compliance when using ultraviolet visible marker (UVM) as an audit tool. METHODS: The housekeeping staff selected 90% as the cleaning compliance target. The UVM was applied to the toilet seat, sink, soap dispenser and door knob surfaces within the patient's washrooms on consecutive weekdays. The study included three arms: staff in arm 1 received cleaning compliance feedback throughout the 24-week study period, arm 2 and arm 3 staff received feedback for weeks 13-24 and weeks 1-12, respectively. Feedback was also provided to housekeeping staff by posting graphs on the wards and in the housekeeping office. FINDINGS: A pre-study audit showed 66.9%, 66.5% and 66.4% cleaning compliance for arms 1, 2 and 3 respectively. While receiving weekly feedback, all three arms demonstrated significantly improved cleaning compliance (86.7%, 80.4% and 73.7% for arms 1, 2 and 3, respectively). The use of casual staff may have contributed to difficulty in achieving better cleaning compliance as arms 1, 2 and 3 had 16.1%, 26% and 40.3% of shifts filled by casual staff, respectively. CONCLUSIONS: The use of UVM as an audit tool combined with weekly feedback of results to housekeeping staff resulted in significant, sustained improvement in the overall level of cleaning compliance of housekeeping staff.

Cleaning efficacy of medical device washers in North American healthcare facilities.

The objective of this study was to determine the worst case levels of organic soil on surgical instruments and whether the commercially available TOSI((R)) provided a clinically relevant organic challenge to an instrument washer. Our data showed that protein and haemoglobin levels (374 and 111microg/cm(2), respectively) from the instruments evaluated correlated with those on a TOSI that had a visual score of 2-3 (267 and 60microg/cm(2), respectively). However, the regular TOSI (without the plastic cover) and the TOSI Lum-Chek do not present difficult cleaning challenges; therefore, a visual TOSI score of 1-5 after processing in an automated washer represents a serious cleaning problem. Our results showed that surgical instruments may have high post-cleaning levels of carbohydrate (up to 352microg/cm(2)) and endotoxin (up to 25 373EU/cm(2)), suggesting unrecognised issues with the quality of water used for the final rinse. The average carbohydrate and endotoxin levels post procedure and before cleaning were 138.9microg/cm(2) and 18.14EU/cm(2), respectively. The average protein and haemoglobin levels both showed >99% reduction in levels post cleaning. Our data support the need to monitor the water quality used in instrument washers. In addition, there is an urgent need for establishment of standardised criteria for rapid cleaning indicators for instrument washers to ensure that they provide a clinically relevant method for monitoring washers used in healthcare facilities.

Survival of enveloped and non-enveloped viruses on surfaces compared with other micro-organisms and impact of suboptimal disinfectant exposure.

Survival of enveloped and non-enveloped viruses was compared with that of bacteria, yeasts and mycobacteria when dried on the surface of polyvinyl chloride test carriers in the presence or absence of an organic matrix. The efficacy of glutaraldehyde and accelerated hydrogen peroxide (AHP) disinfectants was evaluated. Reovirus, a non-enveloped virus, persisted and had a RF of 2 after 30 days whereas Enterococcus faecalis had an RF of 4 over the same time period. The other test organisms (Sindbis virus, Pseudomonas aeruginosa, Mycobacterium chelonae and Candida albicans) had variable survivals but none survived as long as 30 days. Both glutaraldehyde and AHP were effective at manufactures' recommended dilutions for high-level disinfection. However, only 7% AHP eliminated a glutaraldehyde-resistant strain of M. chelonae. Breakthrough survival was detected at 0.1% glutaraldehyde and 0.05% AHP for all organisms tested. Our data emphasise the need for effective cleaning and disinfection in nosocomial settings to prevent pathogen transmission.

Manual methods are suboptimal compared with automated methods for cleaning of single-use biopsy forceps.

OBJECTIVE: Most reusable biopsy forceps and all of the currently available single-use biopsy forceps do not have a port that allows fluid flow down the inner tubular shaft of the device. Reusable biopsy forceps are widely used and reprocessed in healthcare facilities, and single-use biopsy forceps are reprocessed either in-house (eg, in Canada and Japan) or by third-party reprocessors (eg, in the United States). The objective of this study was to determine the cleaning efficacy of automated narrow-lumen sonic irrigation cleaning, sonication-only cleaning, and manual cleaning for biopsy forceps. DESIGN: A simulated-use study was performed by inoculating the inner channel of single-use biopsy forceps with artificial test soil containing both Enterococcus faecalis and Geobacillus stearothermophilus at concentrations of 10(6) colony-forming units per milliliter. The cleaning methods evaluated were manual cleaning, sonication-only cleaning, and "retroflush" cleaning by an automated narrow-lumen irrigator. Bioburden and organic soil reduction after washing was evaluated. Forceps used in biopsies of patients were also tested to determine the worst-case soiling levels. RESULTS: Only retroflush irrigation cleaning could effectively remove material from within the shaft portion of the biopsy forceps: it achieved an average reduction of more than 95% in levels of protein, hemoglobin, carbohydrate, and endotoxin. However, even this method of cleaning was not totally effective, as only a 2 log10 reduction in bioburden could be achieved, and there were low residual levels of hemoglobin and carbohydrate. CONCLUSION: The data from this evaluation indicate that manual and sonication-only cleaning methods for biopsy forceps were totally ineffective in removing material from within the biopsy forceps. Even the use of retroflush cleaning was not totally effective. These findings suggest that in-hospital reprocessing of biopsy forceps with currently available equipment and cleaning methods is suboptimal.

Manual versus automated methods for cleaning reusable accessory devices used for minimally invasive surgical procedures.

We undertook a simulated-use study using quantitative methods to evaluate the cleaning efficacy of ported and non-ported accessory devices used in minimally invasive surgery. We chose laparoscopic scissors and forceps to represent worst-case devices which were inoculated with artificial test soil containing 10(6) cfu/mL Enterococcus faecalis and Geobacillus stearothermophilus and allowed to dry for 1 h. Cleaning was performed manually, as well as by the automated SI-Auto Narrow lumen cleaner. Manual cleaning left two- to 50-fold more soil residuals (protein, haemoglobin and carbohydrate) inside the lumen of non-ported versus ported laparoscopic accessory devices. The SI-Auto Narrow lumen cleaner was more efficient than manual cleaning and achieved >99% reduction in soil parameters in both non-ported (using retro-flushing) and ported laparoscopic devices. Only the automated cleaning of ported devices achieved 10(3)-10(4)-fold reduction in bacterial numbers. Sonication alone (no flushing of inner channel) did not effectively remove soil or organisms from the inner channel. Our findings indicate that non-ported accessory devices cannot be as reliably cleaned as ported devices regardless of the cleaning method used. If non-ported accessory devices are reprocessed, they should be cleaned using retro-flushing in an automated narrow lumen cleaner.

The diagnosis of Clostridium difficile-associated diarrhea: comparison of Triage C. difficile panel, EIA for Tox A/B and cytotoxin assays.

This study prospectively compared; Triage(R) C. difficile test (TCT), TechLab C. difficile toxin A-B enzyme immuno-assay (EIA), and cell-culture cytotoxin test (CT). Of the 400 stools tested, 99 were positive by any test with 92, 41 and 58 detected by TCT, EIA and CT, respectively. Culture of discordant samples indicated that 52 contained C. difficile (42 toxigenic, 10 non-toxigenic), 10 contained Clostridium species and 2 had no detectable clostridium isolates. There were 21/42 toxigenic C. difficile isolates from 17 patients whose stools were negative when originally tested by CT. Review of available patient charts indicated that 12/14 did not previously or currently have C. difficile associated diarrhea, whereas 2 patients developed disease within a few days. Compared to CT as the gold standard, the sensitivity and specificity were; 93%, 89% and 66%, 99% for TCT and EIA respectively. The 8 stool samples with Toxin A(-) Toxin B(+) isolates were detected in 8, 4, and 6 samples by TCT, EIA and CT, respectively. In summary, TCT as a screening test allowed reliable reporting for 85% of stools on the day of receipt. For the 15% of stools requiring further testing we recommend the use of CT.

A new hydrogen peroxide--based medical-device detergent with germicidal properties: comparison with enzymatic cleaners.

BACKGROUND: The objective of this study was to evaluate the efficacy of the cleaning and bacterial killing ability of a new non-enzyme-based formulation (killing detergent solution [KDS]) compared with commercially available enzymatic detergents that included Metrizyme (Metrex Research Division of Sybron Canada Ltd. Morrisburg, Ontario) and Gzyme (Germiphene Corp, Brantford, Ontario). KDS is a hydrogen peroxide-based detergent formulation that combines cleaning efficacy with the ability to kill microorganisms. The KDS formulation helps ensure the protection of the health care worker from infectious risk during the soaking and cleaning stages of medical device reprocessing and reduces the bioburden on devices before sterilization/disinfection. METHODS: Test organisms that included Enterococcus faecalis, Salmonella choleraesuis, Staphylococcus aureus, and Pseudomonas aeruginosa were suspended in artificial test soil (ATS-B; patent submitted), inoculated at 10(6) colonyforming units per carrier and dried overnight before detergent exposure. The ATS-B mimics the blood, protein, carbohydrate, and endotoxin levels of patient-used medical devices. Plastic lumen carriers and a flexible colonoscope were used for surface and simulated-use testing, respectively. RESULTS: The results for the microbial challenge dried onto polyvinyl chloride (PVC) carriers demonstrated that the ability of KDS to remove protein, blood, carbohydrate, and endotoxin from surface test carriers was as effective as the enzyme detergents that were evaluated. Furthermore, KDS was able to effect approximately a 5-Log(10) reduction in microbial loads with a 3-minute exposure at room temperature, whereas none of the other detergents were as effective. In simulated-use testing of a soiled colonoscope, KDS was significantly better at ensuring microbial killing compared with Gzyme and Metrizyme and was equivalent to the enzymatic detergents in cleaning ability. CONCLUSIONS: In summary the KDS has excellent microbial-killing ability in 3-minute exposures at room temperature and cleans as well as the existing enzymatic detergent formulations that were tested.

Characterization of a toxin A-negative, toxin B-positive strain of Clostridium difficile responsible for a nosocomial outbreak of Clostridium difficile-associated diarrhea.

Clostridium difficile-associated diarrhea (CAD) is a very common nosocomial infection that contributes significantly to patient morbidity and mortality as well as to the cost of hospitalization. Previously, strains of toxin A-negative, toxin B-positive C. difficile were not thought to be associated with clinically significant disease. This study reports the characterization of a toxin A-negative, toxin B-positive strain of C. difficile that was responsible for a recently described nosocomial outbreak of CAD. Analysis of the seven patient isolates from the outbreak by pulsed-field gel electrophoresis indicated that this outbreak was due to transmission of a single strain of C. difficile. Our characterization of this strain (HSC98) has demonstrated that the toxin A gene lacks 1.8 kb from the carboxy repetitive oligopeptide (CROP) region but apparently has no other major deletions from other regions of the toxin A or toxin B gene. The remaining 1.3-kb fragment of the toxin A CROP region from strain HSC98 showed 98% sequence homology with strain 1470, previously reported by M. Weidmann in 1997 (GenBank accession number Y12616), suggesting that HSC98 is toxinotype VIII. The HSC98 strain infecting patients involved in this outbreak produced the full spectrum of clinical illness usually associated with C. difficile-associated disease. This pathogenic spectrum was manifest despite the inability of this strain to alter tight junctions as determined by using in vitro tissue culture testing, which suggested that no functional toxin A was produced by this strain.

Methodology of reprocessing reusable accessories.

Accessory devices used for gastrointestinal endoscopy are often complex and because they enter sterile body cavities, or contact blood because of invasive procedures, they should be sterile before being used for a patient procedure. The complexity of such reusable accessory devices is reviewed, and the critical aspects of cleaning, sterilization, and quality assurance are discussed. The effectiveness of adequate reprocessing between patient use is critical to prevent transmission of infectious diseases from one patient to another.

Etiology of genital ulcer disease in Dakar, Senegal, and comparison of PCR and serologic assays for detection of Haemophilus ducreyi.

We used PCR assays to determine the etiology of genital ulcers in patients presenting to a sexually transmitted disease clinic in Dakar, Senegal, and evaluated the ability of two PCR tests (groEL and recD) and two serological tests (adsorption enzyme immunoassay [EIA] and lipooligosaccharide [LOS] EIA) to detect current Haemophilus ducreyi infection. We found that in this population, H. ducreyi, T. pallidum, and herpes simplex virus HSV DNA were detected in 56, 15, and 13% of 39 genital ulcer specimens, respectively, and H. ducreyi DNA was detected in 60% (3 of 5) of samples from ulcerated bubos. Among 40 consecutive patients with genital ulcer disease and with sufficient sample for both PCR assays, the recD and groEL H. ducreyi PCR assays were 83% concordant, with the recD PCR assay detecting six (15%) additional positive specimens and the groEL assay detecting one (3%) additional positive specimen. Compared to PCR, the adsorption EIA and LOS EIA tests had sensitivities of 71 and 59% and specificities of 57 and 90%, respectively, for the diagnosis of current H. ducreyi infection. While these differences in specificity could be due either to previous infection with H. ducreyi or to the detection of cross-reacting antibodies, only 6% of patients from a nearby family planning clinic gave a positive reaction in both the adsorption EIA and LOS EIA assays, indicating that cross-reacting antibodies are not prevalent among clinic attendees in this city. Our studies indicate that the adsorption EIA detects both current and past infection, while the LOS EIA assay is more specific for current infection with H. ducreyi in this population.

Worst-case soiling levels for patient-used flexible endoscopes before and after cleaning.

BACKGROUND: The soiling levels of patient-used narrow-lumened flexible endoscopes were assessed for bronchoscopes, duodenoscopes, and colonoscopes. The effect of cleaning on the soil composition and concentration was evaluated. DESIGN: Suction channels from 10 each of bronchoscopes, duodenoscopes used for endoscopic retrograde cholangiopancreatography, and colonoscopes were assessed immediately after patient use for the levels of bilirubin, hemoglobin, protein, sodium ion, carbohydrate, endotoxin, and viable bacteria. Another 10 suction channels of each type of endoscope were evaluated for the same components after routine cleaning but before processing by high-level disinfection or sterilization for subsequent clinical use. RESULTS: Recognizing that only soluble components could be quantified, the worst-case soil levels in the suction channels (the average surface area of these channels was 45.6 cm(2), 149.8 cm,(2) and 192.0 cm(2) for bronchoscopes, duodenoscopes, and colonoscopes, respectively) were protein 115 microg/cm(2), sodium ion 7.4 micromol/cm(2), hemoglobin 85 microg/cm(2), bilirubin 299 nmol/cm(2), carbohydrate 29.1 microg/cm(2), endotoxin 9852 endotoxin units/cm(2), and bacteria 7.1 (log(10)) colony-forming units (CFU)/cm(2). Colonoscopes had 4 to 5 times greater soiling on average compared with the other endoscope types. Routine cleaning reduced the levels of bilirubin to below the limits of detection for all endoscopes evaluated (limits of detection were <1 nmol/mL). After cleaning, residual hemoglobin was detectable in bronchoscopes only. After cleaning, the levels of protein, endotoxin, and sodium ion all were reduced fivefold to tenfold for all types of endoscopes. Carbohydrate was reduced to lower than the limit of detection for all endoscopes after cleaning, except the duodenoscopes. The average load of viable bacteria was reduced from 3 log(10) to 5 log(10) CFU/cm(2) (which represents 5.9-9.5 log(10) CFU/endoscope channel) after patient use to approximately 2 log(10) CFU/cm(2) (which represents 3.2-5.3 log(10) CFU/endoscope channel) after cleaning. CONCLUSIONS: These data demonstrated that cleaning effectively reduced or eliminated many components of soil, but a substantial amount of viable bacteria and protein remained. Hemoglobin levels in before samples indicated that blood was not present in high concentrations in the suction channels of the majority of flexible endoscope samples. Soil that mimics the worst-case composition from patient-used endoscopes would be ideal for simulated-use studies for such medical devices.

E test versus agar dilution for antimicrobial susceptibility testing of viridans group streptococci.

Viridans group streptococci (VGS) are commonly isolated from the blood of hospitalized patients. The E test represents a convenient method for determining the MICs for VGS, but for this purpose it has not been well validated against reference methods. In this study, 180 unselected VGS isolates were identified to a species level, and the MICs of penicillin, cefuroxime, cefotaxime, and vancomycin were determined by both agar dilution and the E test. Available data regarding demographic and laboratory variables for each VGS bacteremic episode were collected, the significance of each VGS isolate was assessed, and the associations between and among laboratory and clinical variables were investigated. Among all VGS isolates, 68.3% (median of three runs) were found to be fully susceptible to penicillin by agar dilution. The E test and agar dilution showed average agreements (within +/-1 dilution) of 92.2% for penicillin, 95.7% for cefuroxime 91.3% for cefotaxime, and 86.7% for vancomycin. Agreements over serial E tests and serial agar dilutions were excellent for beta-lactam agents (intraclass correlation coefficients, >0.9) but less impressive for vancomycin. Very major error rates for the E test were

Comparison of liquid chemical sterilization with peracetic acid and ethylene oxide sterilization for long narrow lumens.

The aim of this study was to determine how well peracetic acid liquid chemical sterilization (LCPAS) killed test organisms in the presence of 10% fetal bovine serum and 0.65% salt challenge (RPMI-S) compared with a 100% ethylene oxide (ETO) sterilizer and an ETO hydrochlorofluorocarbon (ETO-HCFC) sterilization method with long (125 cm), narrow (3-mm internal diameter) flexible lumens as the test carrier. The inoculated lumens were dried overnight before processing. The test organisms included Mycobacterium chelonei, Enterococcus faecalis, and Bacillus subtilis. For all 3 organisms tested, the LCPAS process resulted in a 6 log10 reduction in bacterial load compared with a 2.5 log10 to 6 log10 reduction for the 100% ETO and ETO-HCFC sterilizers. Sterilization was achieved for 100%, 61%, and 67% of the lumen test carriers for the LCPAS, 100% ETO, and ETO-HCFC sterilizers, respectively. The data indicate that of the sterilization methods evaluated, LCPAS was the most effective for sterilizing narrow flexible lumens in the presence of residual inorganic and organic soil. This effectiveness was achieved through a combination of organism wash-off and peracetic acid sterilant killing of organisms. Salt was the major compounding factor for effective ETO gas sterilization, because carriers inoculated with organisms in 10% fetal bovine serum alone all were sterilized by both 100% ETO and ETO-HCFC sterilization methods. Our data support the critical need to ensure adequate precleaning of narrow flexible lumen endoscopes before any sterilization method.

Screening pregnant women for group B streptococcal colonization.

The recovery rates of group B streptococcus (GBS) from anorectal swabs (RS) and vaginal swabs (VS) that were enriched were compared to the routine method to determine the optimal procedure. Separate RS and VS were collected from women attending antenatal clinics. RS and VS were placed in 2 ml enrichment and selective broth. Swabs were inoculated onto colistin/nalidixic acid agar (CNA) upon arrival in the laboratory and onto 5% sheep blood agar (SBA) and CNA after 24 h enrichment. The routine method consisted of a VS sent in transport medium and inoculated in the laboratory onto SBA (no enrichment). The overall GBS colonization rate was 24% (64/264). Of the 64 GBS carriers, 77% were colonized in the vagina and 89% were colonized in the anorectum. The anorectum was the only site of colonization in 24% of the women, whereas the vagina was the only site of colonization in 11% of cases. Enrichment increased the detection of GBS from both RS (55 versus 42; P < 0.025) and from VS (49 versus 27; P < 0.001). Of the 64 cases, enriched RS detected 86%, enriched VS detected 77% and the standard VS detected only 41%. Enriched RS and enriched VS collectively detected 99% of cases. SBA was better than CNA for subculture of the enrichment broth because of a higher recovery rate (98-100% versus 80-82%; P < 0.01) and the fact that the hemolysis on SBA made it easier to differentiate GBS from enterococci. The data confirm that optimal screening of pregnant women for GBS should include a combined RS/VS swab placed in enrichment broth that is then subcultured onto SBA after 24 h incubation.