Biomedical subjects

B Zühlsdorf

Publications and source records attributed to B Zühlsdorf.

7 recordsLinked to original sources

PubMed2006

Evaluation of the effectiveness of an enzymatic cleaner and glutaraldehyde-based disinfectant for chemothermal processing of flexible endoscopes in washer-disinfectors in accordance with prEN ISO 15 883.

BACKGROUND AND STUDY AIMS: This study evaluated the effectiveness of the cleaning process, the disinfection process, and a combination of the two in accordance with the new international standard, prEN ISO 15 883. MATERIALS AND METHODS: The cleaning process consisted of a 1-min prerinse at 20 degrees C, followed by a 5-min cleaning step at 45 degrees C (with an enzymatic cleaner, 0.5 %), followed by a 1-min interim rinse from 45 degrees C to 55 degrees C. The disinfection process consisted of a 1-min prerinse at 20 degrees C, followed by a 5-min disinfection step at 55 degrees C (with a glutaraldehyde-based disinfectant, 1 %), followed by two final rinses of 1 min each at 55 degrees C. Transparent test pieces were contaminated with a mixture of blood and ENTEROCOCCUS FAECIUM, and were assessed for visible cleanliness and microbial load. RESULTS: Cleaning alone, disinfection alone, and the combination of the two always led to visible cleanliness of all test pieces. The cleaning process revealed a mean reduction factor of > or = 4.6 (n = 6); the disinfection process revealed a mean reduction factor of > or = 9.0 (n = 6), and the combination of the two was found to reduce the test organism in the WD440 by 9.0 +/- 0.2 log (10) steps (n = 12) and in the AdaptaScope by 9.3 +/- 0.4 log (10) steps (n = 5). CONCLUSIONS: Overall, the entire process was found to be very effective and compatible for reprocessing flexible endoscopes in washer-disinfectors. No visible residual blood was found, despite the use of glutaraldehyde in the disinfection phase. These findings once again emphasize the importance of effective cleaning for the overall results when reprocessing flexible endoscopes.

Disinfectants↗

PubMed2005

Intralaboratory reproducibility of the German test method of prEN ISO 15883-1 for determination of the cleaning efficacy of washer-disinfectors for flexible endoscopes.

In Europe, the evaluation of processing flexible endoscopes in washer-disinfectors (WDs) is performed in accordance with prEN ISO 15883-1, which includes determination of cleaning efficacy. Recent data suggest that large differences are found between cleaning processes when the prEN ISO 15883-1 German test model is applied. Therefore, we analysed 12 separate cleaning processes, and each was assessed by determining the means of three experiments. Transparent test tubes used as test pieces (length 2m, lumen 2mm) were contaminated with a mixture of blood and Enterococcus faecium. The WD used was set to perform the cleaning process alone, which consists of three stages (pre-rinse, cleaning, intermediate rinse). Instead of a cleaning agent, demineralized water was used in all three stages of the cleaning process. The mean bacterial load was 10(11.3)cfu/mL (N=12) in the suspensions of test organism, 10(9.1)cfu/mL (N=12) in the test soils and 10(5.8)cfu/mL (N=12) in the controls (recovery). Mean log(10) reduction factors (RF) for each process, i.e. the difference in microbial loads between the control and the processed tubes, were calculated. The 12 cleaning processes with demineralized water led to a mean RF of 2.2 (range: 1.6-3.2) and excellent visible cleanliness of the test pieces. We found that the prEN ISO 15883-1 German test method leads to reproducible and valid results, and is suitable for determining the cleaning efficacy in WDs.

Colony Count, Microbial↗

PubMed2005

Suitability of the German test method for cleaning efficacy in washer-disinfectors for flexible endoscopes according to prEN ISO 15883.

In Europe, the evaluation of processing flexible endoscopes in washer-disinfectors (WDs) is performed in compliance with prEN ISO 15883-1 which includes determination of the efficacy of the cleaning process. Recent data suggest that cleaning processes show large differences when the prEN ISO 15883-1 German test model is applied. Hence, we analysed a total of 72 experiments in order to evaluate the test method. Transparent test tubes as test pieces (length 2 m, lumen 2 mm) were contaminated with a mixture of blood and Enterococcus faecium. Three set-ups were used: WD 425 with soft water, WD 425 with hard water and WD 440 with demineralized water. WDs were set to perform the cleaning stage of the programme alone. Seven cleaning agents were used according to the manufacturers' instructions (21 cleaning processes); in addition, three cleaning processes were carried out without a cleaning agent (i.e. with water alone). Each cleaning process was assessed by means of three experiments. Suspensions of test organism had 9.2x10(10) colony-forming units (cfu)/mL E. faecium (mean of 24 processes). Controls (recovery) contained 1.0x10(6) cfu/mL E. faecium (mean of 71 experiments). Mean log(10) reduction factors (RFs) for each process, i.e. the difference in microbial loads on the control and the processed tubes, were calculated. Cleaning processes led to RFs of 0-4.1, but no process led to residual bacterial loads below the limit of detection (1.8l gcfu/mL). Standard deviations for a cleaning process were small (< or =0.6 in 79% of the processes) indicating adequate reproducibility. The test model led to reproducible results and revealed large differences between the individual processes. If a cleaning process is intended to result in a bioburden reduction (i.e. RF> or =4), the control must carry a minimum bioburden of 6.5x10(5) cfu/mL. This was achieved in 58% of the processes. However, controls with a bioburden <6.5x10(5) cfu/mL never yielded a residual bacterial load below the limit of detection. We found that the prEN ISO 15883-1 German test method is suitable to determine the cleaning efficacy in WDs and leads to reproducible and valid results.

Decontamination↗

PubMed2004

The importance of cleaning for the overall results of processing endoscopes.

Reprocessing comprises three steps: cleaning, disinfection and-if required-sterilisation. While the extents of disinfection and of sterilisation are quantitatively defined, there are only imprecise (qualitative) definitions of cleaning. There are two main reasons for accurate cleaning. First organic and inorganic materials that remain on inner and outer surfaces will interfere with the efficacy of the disinfectants. In case of endoscopes this will lead to channel blockages; they remain undisinfected. Second the bioburden found on endoscopes after use can be very high. Data available demonstrate that a bacterial burden of up to 10(9)cfu/endoscope channel can be expected. Therefore it is necessary to perform a thorough cleaning. Studies using endoscopes showed a reduction in microbial counts by a factor of approximately 10(4) by cleaning (manual and mechanical). Therefore in 2001 the German Society of Hospital Hygiene (DGKH) specified its requirements and recommendations for determining cleaning efficacy separately from those for disinfection. Cleaning and disinfecting can be done manually or mechanically, but it seems impossible to validate manual processes. However our studies in two different washer-disinfectors (WD) showed differences in cleaning efficacy. The tested cleaning processes showed different efficacies. Not all cleaning processes showed better results than water alone with regard to visible cleanliness and to a microbiological reduction E. faecium. Our results show that the evaluation of cleanliness exclusively by visible inspection is not sufficient, particular for the lumens of endoscopes. The results also show that a cleaning process may be very effective also in reducing micro-organisms present.

Colony Count, Microbial↗

PubMed2004

Efficacy of 10 different cleaning processes in a washer-disinfector for flexible endoscopes.

Successful cleaning of medical devices, such as flexible endocopes, has been recognized to be of major importance for effective processing. Washer-disinfectors (WD) are considered to be an important step in this direction. The cleaning process in WD, however, has only been partially assessed regarding its effectiveness, and therefore to study this in more detail, tests were carried out, according prEN ISO 15883, using transparent teflon tubes as test pieces (length 2 m). For each experiment three test pieces were contaminated with the 'German test soil' containing Enterococcus faecium in blood, two for the test and one as a control (no automatic cleaning). Automatic cleaning was performed with a Wassenburg WD 440. Ten cleaning agents were used. In addition the process was carried out with water alone. After automated cleaning, test pieces were assessed visually (four categories, range: very poor to excellent visible cleanliness) and microbiologically [log(10) reduction factor (RF)]. Each experiment was repeated three times. Using the WD water gave excellent visible cleanliness with a mean RF of 1.1+/-0.6. The same excellent visible cleanliness was obtained with seven cleaning processes: deconex 23 Neutrazym, Helimatic Cleaner enzymatic, Korsolex-Endo-Cleaner, Labomat E, neodisher mediclean, Thermosept ER, and Thermoton NR. Worse visible cleanliness was found with three cleaning processes: Olympus ETD Cleaner and neodisher FE led to adequate visible cleanliness, and the cleaning process with neodisher medizym led to poor visible cleanliness. Six cleaning processes reduced the test organism by RF>or=3, i.e. the reduction was significantly higher than after cleaning with water alone. No significant difference between use of water alone and the cleaning process was found with three cleaning processes: Olympus ETD Cleaner, neodisher mediclean, and Thermosept ER (range RF: 0.8-1.8; P > 0.05). The cleaning process with neodisher medizym yielded a significantly lower mean RF (P = 0.039) in comparison with water treatment alone. Both visible cleanliness and mean RF, varied indicating that the choice of cleaning process had a major impact on the overall result.

Decontamination↗

PubMed2003

Gastroscope processing in washer-disinfectors at three different temperatures.

Endoscopes are processed chemo-thermally at approximately 56 degrees C in washer-disinfectors in Germany. In this study we investigated the processing of gastroscopes by an endoscope washer-disinfector at different temperatures. A total of 87 gastroscopes were tested hygienically and microbiologically before manual cleaning (after patient use), as well as after manual cleaning and after endoscope washer-disinfector processing at running temperatures of 43, 51 and 56 degrees C. In all tests the suction/biopsy channels of the gastroscopes were flushed with 50 mL sterile solution throughout their full length, from the proximal to the distal ends. The rinse solutions were plated on to various culture media. Also, in order to detect low bacterial counts, 3x10 mL rinse solution was membrane filtrated. The German guideline level for total bacterial counts, applicable since 2002, was exceeded at all temperatures tested (159 cfu/mL at 43 degrees C, <60 cfu/mL at 51 degrees C, and 8 cfu/mL at 56 degrees C). A temperature increase from 43 to 51 degrees C resulted in a highly significant reduction of the residual contamination by aerobic bacteria (P<0.001, Mann-Whitney U Test), Gram-negative bacilli (P<0.001), and pseudomonads (P=0.002). A further temperature increase from 51 to 56 degrees C resulted in a further highly significant drop in residual contamination by aerobic bacteria (P=0.021) and pseudomonads (P=0.036). The aim of the user-minimizing material damage to endoscopes or prolonging their product life-cannot be achieved through lowering the processing temperature without putting patients at risk. In order to ensure adequate processing, endoscope washer-disinfectors should meet the requirements of current draft standards.

Decontamination↗

PubMed2002

Cleaning efficacy of nine different cleaners in a washer-disinfector designed for flexible endoscopes.

Studies on processing endoscopes usually involve the combined cleaning and disinfecting activity. We compared nine cleaning agents designed for automatic processing for cleaning efficacy alone using soft and hard water as controls in 12 different processes in a washer-disinfector. Experiments were performed according to the German Endoscopy Working Group recommendations using transparent Teflon tubes (internal diameter 2mm, length 2m) as test pieces. For each test three pieces contaminated with a blood/test soil containing Enterococcus faecium were used; two for the test and one as a control; each test was repeated three times. Tests were run according to the manufacturer's instructions. Test pieces were assessed visually and microbiologically [log(10) reduction factors (RF) vs. untreated controls]. Soft water alone gave poor visible cleanliness and an RF of 0.3 (SD 0.2), while hard water produced adequate visible cleanliness and an RF of 1.2 (SD 1.0). Five processes gave better visible cleanliness than soft water, but only three were better than hard water. Six processes were worse than soft water and five worse than hard water. Nine processes gave a better microbiological reduction factor than soft water, but the difference was only statistically significant in three. Only one process yielded a significantly higher RF than hard water; three were significantly worse. None of the cleaning processes reached the RF of 4 specified in the US regulations. This study confirms the variability of cleaning processes to dissolve blood residues and reduce the bioburden. We do not recommend abandoning cleaning agents, but suggest that further research is needed to clarify the relationships between washer-disinfectors, cleaning agents, and cleaning performance.

Colony Count, Microbial↗