Product Comparison:

Enzymatic Cleaners and its Protein Decomposing Properties

 

Martin Pfeifer, Waldkraiburg, Federal Republic of Germany

 

 

 

Summary

Enzymatic Cleaners are enjoying growing importance in the Central Sterile Supply Departments (CSSD) mainly for the reprocessing of Medical Devices consisting of materials which may react sensitive against alkaline cleaners. However a comparison study showed that the cleaning efficiency of enzymatic cleaners may vary significantly from product to product. When comparing five enzymatic cleaners in a simple to perform standardized test which considers only the chemical efficacy of the cleaner severe performance differences were detected.

 

Key words:             Cleaning efficiency; Dipping experiment; Enzymatic cleaner; Fibrin; Test

soil;

 

 

Introduction

There exist a variety of alternatives for the reprocessing of Medical Devices and they are mainly for the important cleaning step. Manual cleaning and rinsing procedures in wash-basins, ultrasonic cleaning and cleaning in fully automated washer-disinfectors or combinations of these options are also in use. The cleaning efficiency with all protocols  depends on a number of parameters. However there will be different degrees of interaction of each parameter with the methodology chosen. 

In contrast to the already existing mechanical equipment the cleaning chemistry is considered frequently as an “easy to exchange” parameter. The consequence is clear: Environmental factors, cost reduction programs or even marketing strategies may have an impact on the decision making to substitute the cleaner or the basic technology of a cleaner. As a result of this change of mind enzymatic cleaners and so called neutral cleaners replaced the traditional alkaline cleaners in a growing number of CSSD’s. Among enzymatic cleaners major performance differences exist from product to product and from manufacturer to manufacturer which are caused by the demanding chemical formulations.

 

 

Materials and methods

The efficiency of the reprocessing of a medical instrument in a washer-disinfector is  always a result of the combination of the chemical and mechanical capabilities of the system used. In order to evaluate this, only the chemical performance of the five different enzymatic cleaners evaluated in this study. All tests were conducted in a basin using a dipping experiment without any mechanical influences. The tests were done at common temperatures and with chemical concentrations as typically recommended by the manufacturers.

The cleaning efficiency of the five different enzymatic cleaners was measured with TOSI (manufactured by Pereg GmbH, Waldkraiburg, Germany) , a simple device for the monitoring of the cleaning efficiency of washer disinfectors. The heart of TOSI is a standardized test soil which is placed at an amount of 20mg on a small stainless steel plate. The test soil consists of 95% water soluble components and 5% water insoluble fibrin fibres and correlates with coagulated human blood. This means that pure water should already be able to remove 95% of this test soil, as water soluble components will become dissolved over a certain period of time even without any chemical additives and/or mechanical support. This statement will be confirmed in a blind test using pure water, while the efficiency of an enzymatic cleaner should result in a complete dissolution of the test soil including the water insoluble fibrin fibres.

 

 

Test conditions

-         Concentration of cleaner:                     0.5% (v/v) in 500 ml solution

-         Water quality:                                     demineralised water

-         Temperature:                                45°C

-         Dipping time of test object:            10, 15, 20, 25 and 30 min

At the end of each test cycle the test objects have been taken out of the solution and were allowed to dry prior to visual inspection.

 

 

Results

A side of the blind test using demineralised water at 45°C five commercially available enzyme cleaners were compared under test conditions as described above. The five cleaners were coded A, B, C, D and E.

 

Already after 10 minutes all (red) water soluble components were completely removed from the surface of the test objects while the (white) fibrin fibres remain unsolved. The extended  30 minutes exposure time at 45°C did not have any impact on the test result and the fibrin fibres remained on the surface of the stainless steel plate.

 

All three products were unable to dissolve the fibrin layer on the test objects. No difference was detected between shorter and longer exposure times. The test results indicate poor or even no cleaning but at least insufficient cleaning capabilities of these enzyme cleaners.

 

This cleaner showed some capabilities to dissolve the fibrin layer. Efficiency correlated with time, i.e. test results after 20 minutes were better than after 10 minutes, and results after 30 minutes showed less residuals on the test object than after 20 minutes. However significant dissolution was not observed until 20 minutes exposure time and even 30 minutes exposure time did not result in complete dissolution.

 

This cleaner proofed its capabilities to dissolve fibrin fibres. Already a 10 minutes exposure time showed some dissolution which became clearly visible after 15 minutes. After 20 minutes about 50% of the fibrin portion was dissolved, after 25 minutes only a small portion  and after 30 minutes only traces did remain on the test objects which were completely removed after additional 5 minutes in retests conducted.

 

 

Discussion

The tests conducted in this dipping experiment showed significant differences in the cleaning capabilities of five commercially available enzymatic cleaners. 3 of them did not show any visible capability to dissolve water insoluble blood components such as fibrin fibres. One cleaner showed at least some minor attack to fibrin fibres but only 1 out of 5 cleaners proofed satisfactory cleaning capabilities.

 

 

Note of the Publisher:

All five enzymatic cleaners were sent for evaluation from an interested CSSD to the publisher. Storage and transport conditions were therefore temporarily out of the control of the manufacturer and the tester. It is known that improper storage may result in a degradation of the enzymatic activity. Therefore it is mandatory to store enzymatic cleaners under conditions as specified by the manufacturer. Enzymatic cleaners should never be used after expiry date even when stored properly. In case of any doubts concerning proper storage the existing enzyme activity should be reconfirmed or the cleaner should not be used any longer.