Determination of the Effect of Superheat on Class 6 Indicators Report No 286/

Transcription

1 Determination of the Effect of Superheat on Class 6 Indicators Report No 286/ Testing conducted by BSI Product Services, Hertfordshire, Great Britain

2 1. PURPOSE This study is intended to determine the effect of superheated steam conditions on the STERIS Verify Class 6 indicators compared to a rapid read biological indicator and biological spore strip. The testing shall be conducted in a steam resistometer that is controlled by pressure and not temperature. 2. SCOPE This protocol will focus on the performance of the TST 121 C 15 minute Class 6 Indicator strip. It will demonstrate the effect of superheated steam conditions on the indicator strips when compared to a rapid read biological indicator and biological spore strip.. BACKGROUND.1 Related Material BS EN ISO 18472: Sterilization of health care products Biological and chemical indicators Test equipment..2 Definitions BI CI RRBI - Biological Indicator - Chemical Indicator - Rapid Read Biological Indicator. Product Description The 121 C 15 minute Class 6 Indicator is a chemical indicator whose performance exceeds that of biological indicator kill. It consists of a proprietary ink formulation that is calibrated and printed onto a plastic substrate, then laminated. Upon exposure to saturated steam at 121 C (250 F) for 15 minutes, the indicator ink changes from its start colour, yellow, to a blue/purple endpoint colour. The indicator conforms to Class 6 requirements of ANSI/AAMI/ISO : Necessary Equipment Calibrations / Verifications Prior to Testing Steam resistometer working at 121 C (250 F) capable of controlling by pressure, with jacket temperature controllable up to 140 C. 4. BASIS FOR TEST DESIGN It is the intent of this protocol to assess the performance of Class 6 chemical indicators, rapid-read biological indicators and conventional biological indicators in saturated steam and superheated steam conditions. All indicators will be tested in parallel hence the relative sensitivities of the three indicators can be compared at 121 C (250 F). A 121 C (250 F) Class 6 indicator has been chosen for this study due to practical issues with the creation of superheat; the ability to create superheated steam is enhanced at this lower temperature, and more accurate correlation with the biological indicators can be determined. 5. RESPONSIBILITIES All aspects of this study are to be performed by trained personnel. 2

3 6. RESOURCES REQUIRED Chemical Indicators STERIS 121 C 15 minute Class 6 Indicator Strips (Manufacturer: STERIS, Product Code: 242 or 202) Biological Indicators M Attest Rapid Read Biological Indicators (Manufacturer: M, Product Code: 1292) STERIS 10 6 Spordex Biological Indicator Strips (Manufacturer: STERIS, Product Code: NA07) Equipment and Supplies Steam resistometer complying with BS EN ISO 18472: 2006 and capable of control by pressure and with controllable jacket temperature Incubator working at C for Spordex Biological Indicator Strips STERIS Spordex NA114 Culture Media Attest rapid read incubator for 1292 biological indicators Linen huckaback towels Dry Heat Oven 7. METHODS 7.1 GENERAL Positive controls will be performed on both types of biological indicators for each lot used. Negative controls will be performed on the conventional BI culture media and unactivated RRBI s. 7.2 STANDARD SATURATED STEAM RESISTOMETER CYCLES Use of a 121 C 15 minute indicator allows the parallel testing of the Class 6 chemical indicators with the biological indicators. The indicators shall be tested in 2 minute increments, starting from 7 minutes up to 25 minutes at 121 C (250 F). Time increments outside of this window may be conducted if the all pass or all fail point of all indicators is not determined; equally, if the all pass or all fail point is determined, the time increment window may be reduced. 7. SUPERHEATED STEAM RESISTOMETER CYCLES The methods stated in section 7.1 are applicable to the superheated steam cycles. In order to obtain superheat, the temperature of the resistometers jacket shall be increased to a pressure corresponding to a temperature of a 140 C. Chemical and biological indicators shall be loosely wrapped in linen huckaback towels that have been dried in a dry heat oven at 140 C for at least 20 minutes. After wrapping the indicators loosely in the towels, the towel shall be placed in a dry heat oven operating at 140 C for 10 minutes. The temperature of the resistometer chamber shall be independently recorded using 0.2mm diameter T type thermocouples to determine the actual superheat generated. Superheat is measured as the temperature of the load thermocouple above that of the saturation pressure. Due to the transient nature of superheat, it will be unlikely to achieve the same level of superheat in each resistometer cycle, therefore it is the intention to obtain a range of superheat from 5 C to 20 C. The amount of superheat generated can then be correlated to the results. 7.4 RECORDING OF RESULTS Following exposure to the resistometer cycles, all results shall be recorded in the table of Annex B. The Class 6 Indicators shall be evaluated as per the manufacturer s instructions. The results will be recorded as number pass / number fail, for each cycle. The Biological Indicators shall be evaluated as per the manufacturer s instructions and the result recorded as the number showing no growth / growth for each cycle. The RRBI shall be evaluated both after 48 hours and also after 48 hours.

4 8. PROCEDURE 8.1 RESISTOMETER TESTING Insert the number of indicators indicated for each resistometer cycle in Annex A inside a suitable holder. Place inside steam resistometer chamber Process according to cycle parameters listed in Annex A Upon cycle completion, remove towel containing the BIs or CIs and allow the BIs to cool to a safe temperature if using. Interpret the results The Class 6 Indicator Strips shall be evaluated as per the manufacturer s instructions. The results will be recorded as number pass (P) / number fail (F), for each cycle The Biological Indicators shall be evaluated as per the manufacturer s instructions and the result recorded as number showing no growth (NG) / growth (G) for each cycle Repeat this procedure for a total of test cycles Continue this procedure for each exposure time and steam condition indicated in Annex A. Note The RRBIs shall be read for fluorescence after hours and after 48 hours for ph. 9 TEST RESULTS 9.1 SUMMARY OF TEST CYCLES CONDUCTED Test Matrix of Required Cycles and Number of Chemical and Biological Indicators for saturated and superheated steam resistometer cycles at 250 F (121 C) CI s / BI s Steam Type Sterilization Required Indicators per cycle No. of cycles 7-5 x M Rapid Read Biological Indicator 9-5 x M Rapid Read Biological Indicator 11-5 x M Rapid Read Biological Indicator Saturated 1-5 x M Rapid Read Biological Indicator 15-5 x M Rapid Read Biological Indicator 17-5 x STERIS Verify 250F 0 Class 6 Indicator Strips - 5 x M Rapid Read Biological Indicator CI s BI s 7-5 x M Rapid Read Biological Indicator 9-5 x M Rapid Read Biological Indicator 11-5 x M Rapid Read Biological Indicator Superheated 1-5 x M Rapid Read Biological Indicator 15-5 x M Rapid Read Biological Indicator 17-5 x M Rapid Read Biological Indicator 4

5 9.2 CHEMICAL INDICATOR TESTING SATURATED STEAM Saturated 7 mins Class 6 CI M RRBI Fluorescence M RRBI Spordex BI Strip ( hrs) Cycle 1.50/02 0/5 0/5 0/5 0/5 Cycle /02 0/5 0/5 0/5 0/5 Cycle 4.10/02 0/5 0/5 /2 0/5 Saturated 9 mins Class 6 CI M RRBI M RRBI Spordex BI Strip Fluorescence ( hrs) Cycle 1.15/02 0/5 0/5 /2 0/5 Cycle 2.0/02 0/5 0/5 1/4 0/5 Cycle.40/02 0/5 0/5 1/4 1/4 Saturated 11 mins Class 6 CI M RRBI M RRBI Spordex BI Strip Fluorescence ( hrs) Cycle /02 0/5 1/4 2/ /2 Cycle /02 0/5 5/0 4/1 4/1 Cycle 12.25/02 0/5 5/0 5/0 5/0 Saturated 1 mins Class 6 CI M RRBI M RRBI Spordex BI Strip Fluorescence ( hrs) Cycle /02 0/5 5/0 5/0 5/0 Cycle 2 2.0/02 0/5 5/0 5/0 5/0 Cycle 2.45/02 0/5 5/0 5/0 5/0 Saturated 15 mins Class 6 CI M RRBI M RRBI Spordex BI Strip Fluorescence ( hrs) Cycle /02 5/0 5/0 5/0 5/0 Cycle /02 5/0 5/0 5/0 5/0 Cycle 2.00/02 5/0 5/0 5/0 5/0 Saturated 17 mins Class 6 CI M RRBI M RRBI Spordex BI Strip Fluorescence ( hrs) Cycle 1 9.5/0 5/0 5/0 5/0 5/0 Cycle /0 5/0 5/0 5/0 5/0 Cycle 10.15/0 5/0 5/0 5/0 5/0 5

6 9. CHEMICAL INDICATOR TESTING SUPERHEATED STEAM Superheated 1 mins Class 6 CI M RRBI Fluorescence M RRBI Spordex BI Strip ( hrs) Cycle /25 0/5 2/ 5/0 /2 Cycle /25* 0/5 0/5 5/0 1/4 Cycle 17.20/26 0/5 1/4 4/1 0/5 *0 sec over-exposure Superheated 15 mins Class 6 CI M RRBI Fluorescence M RRBI Spordex BI Strip ( hrs) Cycle /25 0/5 2/ 5/0 0/5 Cycle /26 0/5 /2 5/0 1/4 Cycle 18.05/26 0/5 2/ 5/0 0/5 Superheated 17 mins Class 6 CI M RRBI Fluorescence M RRBI Spordex BI Strip ( hrs) Cycle /25 0/5 1/4 5/0 4/1 Cycle /25 0/5 0/5 5/0 2/ Cycle 18.25/26 0/5 2/ 5/0 /2 Superheated 19 mins Class 6 CI M RRBI Fluorescence M RRBI Spordex BI Strip ( hrs) Cycle /25 0/5 /2 5/0 /2 Cycle /26 0/5 /2 5/0 4/1 Cycle 19.05/26 0/5 4/1 5/0 2/ Superheated 21 mins Class 6 CI M RRBI Fluorescence M RRBI Spordex BI Strip ( hrs) Cycle /26 0/5 4/1 5/0 5/0 Cycle /26 0/5 5/0 5/0 5/0 Cycle 16.40/26 0/5 5/0 5/0 /2 Superheated 2 mins Class 6 CI M RRBI Fluorescence M RRBI Spordex BI Strip ( hrs) Cycle /25 0/5 5/0 5/0 5/0 Cycle /25 0/5 5/0 5/0 5/0 Cycle 19.40/25 0/5 5/0 5/0 5/0 6

7 9. CHEMICAL INDICATOR TESTING SUPERHEATED STEAM (CONTINUED) Superheated 25 mins Class 6 CI M RRBI Fluorescence M RRBI Spordex BI Strip ( hrs) Cycle /25 0/5 5/0 5/0 5/0 Cycle /26 0/5 5/0 5/0 5/0 Cycle 19.55/26 0/5 5/0 5/0 5/0 Superheated 27 mins Class 6 CI M RRBI Fluorescence M RRBI Spordex BI Strip ( hrs) Cycle /25 1/4 5/0 5/0 5/0 Cycle /25 0/5 5/0 5/0 5/0 Cycle 18.20/25 1/4 5/0 5/0 5/0 Superheated 29 mins Class 6 CI M RRBI Fluorescence M RRBI Spordex BI Strip ( hrs) Cycle /25 5/0 5/0 5/0 5/0 Cycle /25 5/0 5/0 5/0 5/0 Cycle 1.00/09 5/0 5/0 5/0 5/0 7

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