Advertisement

Pitfalls of cleaning controls in ultrasonic washers

Published:October 02, 2015DOI:https://doi.org/10.1016/j.ajic.2015.08.020
      To the Editor:
      Many published data underline the need to clean critical medical devices properly, and Evangelista et al have recently confirmed some of the pitfalls of using automatic washing.
      • Evangelista S.S.
      • dos Santos S.G.
      • Stoianoff M.A.
      • de Oliveira A.C.
      Analysis of microbial load on surgical instruments after clinical use and following manual and automated cleaning.
      • Vassey M.
      • Budge C.
      • Poolman T.
      • Jones P.
      • Perrett D.
      • Nayuni N.
      • et al.
      A quantitative assessment of residual protein levels on dental instruments reprocessed by manual, ultrasonic and automated cleaning methods.
      In particular, ultrasonic washing is highly variable in terms of residual protein levels on dental instruments and leads to an approximately 21% reduction in the average microbial load of gastrointestinal surgical instruments.
      • Evangelista S.S.
      • dos Santos S.G.
      • Stoianoff M.A.
      • de Oliveira A.C.
      Analysis of microbial load on surgical instruments after clinical use and following manual and automated cleaning.
      • Vassey M.
      • Budge C.
      • Poolman T.
      • Jones P.
      • Perrett D.
      • Nayuni N.
      • et al.
      A quantitative assessment of residual protein levels on dental instruments reprocessed by manual, ultrasonic and automated cleaning methods.
      We agree with the crucial warning from Evangelista et al: “The use of cleaning equipment and solutions must be appropriate, and their inadequate manipulation by users might affect the quality of cleaning, the possibility of relapse, and adverse events related to the use of processed products.”
      • Evangelista S.S.
      • dos Santos S.G.
      • Stoianoff M.A.
      • de Oliveira A.C.
      Analysis of microbial load on surgical instruments after clinical use and following manual and automated cleaning.
      A subjective assessment of solution turbidity, the use of cleaning indicators, and the visual inspection of cleaned medical devices are the main means of checking the cleaning efficacy of validated automated washers indicated in the regulations for the decontamination of dental medical devices.

      Department of Health. Decontamination Health Technical Memorandum 01-05: decontamination in primary care dental practices. 2013 edition. Available from: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/170689/HTM_01-05_2013.pdf. Accessed August 2015.

      Department of Health. Choice framework for local policy and procedures 01-01 – management and decontamination of surgical instruments (medical devices) used in acute care. Part D: Washer-disinfectors. Available from: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/148522/CFPP_01-01C_Final.pdf. Accessed August 2015.

      We here describe our experience of verifying the efficacy of the ultrasonic washers (UWs) and washer-disinfectors (WDs) in our dental offices. We used the Browne STF Load Check Indicator (Albert Browne International Ltd, Leicester, UK), which is claimed to be equivalent to the cleaning efficacy soil test and appropriate for checking both types of equipment in accordance with ISO/TS 15883-05-2005.

      Available from: http/www.steris-healthcare.com/products/ipt/stf-load-check-indicator. (Accessed September 2015). and Browne's declaration dated 23/03/2011 (obtained the information demanded on July 2015).

      Although its detailed composition is unknown, the lipid and polysaccharide protein-containing red glue deposited on the polymer-structured thin film is not hazardous for dental workers or devices. Red glue product release in UWs is acceptable for subsequent medical device cleaning, whereas the aluminum particles released from damaged foil during the aluminum foil test (the reference test mainly used by UW manufacturers) are not.

      Department of Health. Choice framework for local policy and procedures 01-01 – management and decontamination of surgical instruments (medical devices) used in acute care. Part D: Washer-disinfectors. Available from: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/148522/CFPP_01-01C_Final.pdf. Accessed August 2015.

      We first confirmed that the STF works properly in a Miele G7881 automatic WD (93°C, 10-minute cycle using Neodisher; Miele & Cie, Gutersloh, Denmark),
      • Alfa M.J.
      • Olson N.
      Comparison of washing-disinfectors cleaning indicators: impact of temperature and cycle parameters.
      but to our knowledge, there is only 1 article evaluating cleaning indicators in UWs.

      Crutwell MA. Comparison of surgical instrument test soils published in ISO/TS 15883-5. New Zealand Sterile Services Association Journal - “Supplyline”. Central Service 2008; 16: 19-22.

      We therefore decided to use the STF to check the cleaning efficacy of a UW (Eurosonic 4D, 3,4L; Euronda, Montecchio Precalcino (VI) Italy), which works in sweep mode at the frequency of 32-35 kHz at a power of 100 W. After selecting a 10-minute cycle at 30°C to avoid the possible degradation of product components (mainly disinfectants and enzymes) and the precipitation of proteins on medical devices, the STF was inserted in its holder and placed vertically in the middle of the basket of the UW for all of the experiments.

      Department of Health. Decontamination Health Technical Memorandum 01-05: decontamination in primary care dental practices. 2013 edition. Available from: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/170689/HTM_01-05_2013.pdf. Accessed August 2015.

      Department of Health. Choice framework for local policy and procedures 01-01 – management and decontamination of surgical instruments (medical devices) used in acute care. Part D: Washer-disinfectors. Available from: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/148522/CFPP_01-01C_Final.pdf. Accessed August 2015.

      Available from: http/www.steris-healthcare.com/products/ipt/stf-load-check-indicator. (Accessed September 2015). and Browne's declaration dated 23/03/2011 (obtained the information demanded on July 2015).

      All of the chosen products used (Metrizyme Kerr, Orange, CA; Enzymax Earth Hu-Friedy, Mfg. Co., Tuttlingen, DE; ID 212 Strong Durr, Orochemie gmbH+ Co., KG, Kornwesthein, Denmark; and Z1 Ultra Zhermack SpA, Badia Polesine, Italy) were declared to be compatible with UWs and were freshly prepared by diluting them with purified water as instructed by the manufacturers (used concentration: Metrizyme [1%]; Enzymax Earth [0,8%]; ID212 Strong [2%]; Z1 Ultra [1%]). A first cycle was run to achieve a temperature of 30°C and remove gas bubbles from all of the solutions and purified water (used as a negative control).
      Under the same UW operating conditions, the STF gave the same results when using Enzymax Earth and Metrizyme: at the end of the cycles, there were no red residue on the film, and the presence of a red transparent liquid indicated complete red glue release by the enzymes and detergents in the products. However, ID 212 Strong and Z1 Ultra left unacceptable red residues (>2% of the soil) on the STF. The presence of a cloudy red solution (normally attributed to protein denaturation) indicated some drawbacks when the STF is used to check the cleaning efficacy of disinfectants based on quaternary ammonium compounds (QACs), whereas QAC solutions alone remain transparent. We think that the failure was caused by the strong alkaline pH (10-11) of ID 212 Strong and Z1 Ultra (Enzymax Earth and Metrizyme have an acid pH of 6-6.5) and increased adhesion of the red glue as a result of some of the product components. It is known that other cleaning indicators have more failures at 40°C than at 60°C in WDs,
      • Alfa M.J.
      • Olson N.
      Comparison of washing-disinfectors cleaning indicators: impact of temperature and cycle parameters.
      but in UWs, 60°C impairs QACs (see the stringent temperature ranges indicated in the manufacturer's instructions),

      Zhermack. Zeta 1 ultra. Available at: http://en.zhermack.com/Clinical/Hygiene/Instruments/C810000.kl. Accessed August 1, 2015.

      enzymes, and protein stability, therefore causing protein precipitation; in addition, at 60°C, occupational hazards caused by product evaporation cannot be excluded.

      Department of Health. Decontamination Health Technical Memorandum 01-05: decontamination in primary care dental practices. 2013 edition. Available from: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/170689/HTM_01-05_2013.pdf. Accessed August 2015.

      Our evidence suggests that care should be taken when using the STF in UWs (particularly in the presence of QAC disinfectants) and that the stability of the cleaning products (in relation to the number of UW cycles and loads),
      • Muqbil I.
      • Burke F.J.T.
      • Miller C.H.
      • Palenik C.J.
      Antimicrobial activity of ultrasonic cleaners Zhermack. Zeta 1 ultra.
      which is not indicated by the manufacturers, should be borne in mind. We therefore agree with Evangelista's warning concerning the absolute need for strict guidelines and well-designed protocols based on clear information from manufacturers, appropriate solutions and test soils, and properly operating UWs.

      References

        • Evangelista S.S.
        • dos Santos S.G.
        • Stoianoff M.A.
        • de Oliveira A.C.
        Analysis of microbial load on surgical instruments after clinical use and following manual and automated cleaning.
        Am J Infect Control. 2015; 43: 522-527
        • Vassey M.
        • Budge C.
        • Poolman T.
        • Jones P.
        • Perrett D.
        • Nayuni N.
        • et al.
        A quantitative assessment of residual protein levels on dental instruments reprocessed by manual, ultrasonic and automated cleaning methods.
        Braz Dent J. 2011; 210: E14
      1. Department of Health. Decontamination Health Technical Memorandum 01-05: decontamination in primary care dental practices. 2013 edition. Available from: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/170689/HTM_01-05_2013.pdf. Accessed August 2015.

      2. Department of Health. Choice framework for local policy and procedures 01-01 – management and decontamination of surgical instruments (medical devices) used in acute care. Part D: Washer-disinfectors. Available from: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/148522/CFPP_01-01C_Final.pdf. Accessed August 2015.

      3. Available from: http/www.steris-healthcare.com/products/ipt/stf-load-check-indicator. (Accessed September 2015). and Browne's declaration dated 23/03/2011 (obtained the information demanded on July 2015).

        • Alfa M.J.
        • Olson N.
        Comparison of washing-disinfectors cleaning indicators: impact of temperature and cycle parameters.
        Am J Infect Control. 2014; 42: e23-e26
      4. Crutwell MA. Comparison of surgical instrument test soils published in ISO/TS 15883-5. New Zealand Sterile Services Association Journal - “Supplyline”. Central Service 2008; 16: 19-22.

      5. Zhermack. Zeta 1 ultra. Available at: http://en.zhermack.com/Clinical/Hygiene/Instruments/C810000.kl. Accessed August 1, 2015.

      6. DÜRR DENTAL. Hygosonic. Available at: http://www.duerrdental.com/de/nc/produkte/hygiene/hygiene-geraete/instrumente/hygosonic/?sword_list%5B0%5D=hygosonic. Accessed August 1, 2015.

        • Muqbil I.
        • Burke F.J.T.
        • Miller C.H.
        • Palenik C.J.
        Antimicrobial activity of ultrasonic cleaners Zhermack. Zeta 1 ultra.
        J Hosp Infect. 2005; 60: 249-255