AU703790B2

AU703790B2 - A process for cleaning and disinfecting sensitive medical instruments

Info

Publication number: AU703790B2
Application number: AU14453/97A
Authority: AU
Inventors: Klaus-Peter Bansemir; Holger Biering; Rudolf Glasmacher; Hubert Schwidden
Original assignee: Henkel Ecolab GmbH and Co KG
Current assignee: Ecolab GmbH and Co oHG
Priority date: 1996-02-05
Filing date: 1997-01-27
Publication date: 1999-04-01
Anticipated expiration: 2017-01-27
Also published as: BR9707348A; AU1445397A; NZ326367A; CA2245726A1; JP2000506516A; EP0888134A1; DE19603977A1; WO1997028829A1

Description

Il I I )i hr A Process for Cleaning and Disinfecting Sensitive Medical Instruments This invention relates to a process for cleaning and disinfecting sensitive medical instruments, more particularly endoscopes, and to formulations for carrying out the process Endoscopes, especially flexible glass fibre endoscopes. are used in medical diagnosis and therapy and in surgical operations. Glass fibre endoscopes in particular are extremely complicated precision instruments which comprise moving parts and which are made of a number of materials. They are extremely difficult to i; clean and disinfect for a number of reasons. Thus, not only the outer surfaces of the instrument, but also the narrow internal bores have to be cleaned and disinfected. In machine-based treatment processes, the instruments are normally cleaned first and then disinfected. The technique of thermal disinfection preferably used for medical jquipment and instruments cannot be applied to endoscopes ri because these instruments are partly made of temperature-sensitive materials So far as thermochemical processes are concerned, it is important to remember that.

although glass fibre endoscopes can be completely immersed in cleaning and disinfecting baths, they are only capable of withstanding temperatures of at most Another factor to be borne in mind is that many of the metal parts present are susceptible to corrosion and that the elements connecting the individual parts of the instruments together can be attacked by the cleaning and disinfecting baths In addition, parts consisting of rubber-like materials can be made to swell and become tacky. Finally, the cleaning and disinfection of endoscopes should be able to be carried out quickly to ensure that the instruments are re-available for treating patients in the shortest possible time.

Preferred treatment processes are machine-based processes because they are standardised and, if necessary, can be checked.

European patent application EP-A 0 268 227 describes a two-stage cleaning process in which the instrument surfaces to be treated are successively contacted i. with a cleaning solution which is heated to 55-65 C, kept at that temperature for 1 to 15 minutes and then removed and which contains at least one low-foaming nonionic surfactant, at least one proteolytic enzyme, at least one complexing agent and, optionally, other typical ingredients of cleaning formulations and has a pH value of 6 to 8 and with a disinfecting solution which is heated to 55-65 C, kept at that temperature for 1 to 15 minutes and then removed and which contains at least one aldehyde from the group consisting of formaldehyde and aliphatic dialdehydes containing 2 to 8 carbon atoms and at least one complexing agent and has a pH value in the range from 6 to 8. The endoscope is then rinsed at least twice with water having a pH value of 6 to 8, the water being heated to 55-65 C in the fir'al rinse cycle, and dried with a sterilised hot air at 55 to /1

I

t It I i 1 1, it I I Luropean pateit application EP-A 0 342 499 dt",;iltr 1 two ti) for cleaning and disinfecting endoscopes in which the endoscopes are contacted with a cleaning/disinfecting solution with a pH value of 6 to 8 which contains at least one low-foaming nonionic surfactant, at least one proteolytic enzyme, at least one complexing agent and at least one aldehyde from the group consisting of formaldehyde and aliphatic dialdehydes containing 2 to 8 carbon atoms, the solution being heated to 55 to 65"C, kept at that temperature for 1 to 15 minutes and then removed. The surfaces to be treated are then rinsed twice with water, the water being heated to 55-65'C at least in the final rinse cycle, and dried with S sterilised hot air at 40 to It is known from Europaan patent application EP-A 0 156 275 that amine compounds obtained by reacting compounds corresponding to the formula

R'NHCH:CH

2

CHNH

2 in which R' is a linear alkyl group containing 12 to 14 carbon atoms, with compounds corresponding to the formula R OCOCH 2 CH CHNH:COOH, in which R' is an alkyl group containing 1 to 4 carbon atoms or a hydrogen atom, in a molar ratio of 1. 1 to 1 2 at temperatures of to 175"C can be used as antimicrobial agents These reaction products are also known by the name of Glucoprotamin German patent application DE-A-40 07 758 describes an aqueous surfactantcontaining cleaning and disinfecting concentrate which contains the amine compounds mentioned in European patent application EP-A 0 156 275 in combination with selected quaternary ammonium compounds as antimicrobial agents. This German patent application also describes a process for the spray cleaning and disinfection of items of medical equipment in automatic machines which comprises the steps of a) spraying on an aqueous disinfecting cleaning solution prepared by diluting the described concentrate at elevated temperature and, if desired, b) spraying on an aqueous optionally surfactant-containing rinse-aid solution and, if desired. c) drying, preferably with hot air EP-A-343 605 describes a liquid, aldehyde-free tuberculocidal disinfectant so which contains N,N-bis-(3-aminopropyl)-lauryl amine as its active component European patent application EP-A 620 013 describes a disinfectant for communal toilet systems and similar facilities which is manually applied It contains salts of amines corresponding to the formula NR[(CH,),NH] or NRH[(CH2)b-NH 2 in which R is a linear or branched alkyl or alkenyl group Scontaining 6 to 22 carbon atoms, n and m have values of 4 to 12 and p has a value of 2 to 12. On account of their corrosive effect on metals, such as steel, and plastics, the disinfectants are applied at low temperatures of up to 50 C.

European patent application EP-A-0 551 975 describes a disinfectant concentrate and a disinfectant based on amine and alcohol and its use. the alcohol component comprising at least one aromatic alcohol and the amine component coimprising at least one secondaly and/ur tt;tialy alkylamine fiti fi rm hydroxy groups. The ready-to-use solution has a pH value of 7 to 12. The disinfectant is used in particular as a bactericide and, more especially, as a mycobactericide, fungicide or virucide. European patent application EP-A-0 612 170 also describes an amine- and alcohol-containing disinfectant in which the alcohol component comprises at least one sparingly water-miscible glycol ether while the amine component comprises at least one secondary and/or tertiary alkylamine free from hydroxy groups.

Comparative investigations into the fully automated cold-chemical and Sthermochemical disinfection of endoscopes under practical conditions have shown that, at the present time, neither cold-chemical nor thermochemical processes provide entirely satisfactory cleaning and disinfecting results (cf. Hyg. Med. 1994 19, 75 to 93).

The disinfectants and disinfecting processes described in the documents cited Sabove are attended by a number of disadvantages. Thus, amine-based disinfectants, for example, tend to attack and destroy metals and plastics at relatively high temperatures above 50C. so that it was unlikely that they could be used in machine-based processes for cleaning and disinfecting sensitive medical instruments, such as endoscopes for example (cf. EP-A-0 620 013).

In addition, efforts are being made to replace the aldehydes used by other compounds because users are complaining that the maximum workplace concentrations are in danger of being exceeded and that personnel handling the cleaning machines can be affected by the aldehydes. In addition, aldehydes lead to the fixing of protein-containing soils where they have not been completely removed S in a preliminary cleaning step.

It is known that quaternary ammonium compounds, although having a good disinfecting effect, are absorbed onto surfaces and can cause tackiness.

The problem addressed by the present invention was to provide a process for cleaning and disinfecting sensitive medical instruments, more particularly endoscopes. which would enable these instruments to be reliably cleaned and disinfected in a short time by a combination of thermal treatment, ie at temperatures above 50"C. and chemical treatment. In addition, the process would not result in any damage to the treated instruments, even in the long term. The process would be designed in such a way that it could be carried out in an automatic rinsing machine The present invention relates to a process for cleaning and disinfecting sensitive medical instruments, more especially endoscopes, with aqueous cleaning and disinfecting solutions, in which a) the surfaces of the medical instruments to be treated are contacted with an aqueous disinfecting solution which has a temperature of 55 to 65 C. is kept at that temperature for 1 to 15 minutes and is then removed, the disinrfecting solutil) containing at least one disinfectant from the group of alkyl propylenediamines corresponding to general formula I 1

-N

NH

2 S2

R

(I)

in which R' is an alkyl or alkenyl group containing 8 to 18 carbon atoms and R' is hydrogen, an alkyl group containing 1 to 4 carbon atoms or an aminoalkyl group containing 2 to 4 carbon atoms, and the products known as Glucoprotamin obtainable from alkyl propylenediamine corresponding to formula II.

3 R'N N H

H

ill) in which R is a linear alkyl group containing 12 to 14 carbon atoms, by reaction with compounds corresponding to formula Ill 0 0 4 R"O

OH

NH

2 (I II) in which R 4 is hydrogen or an alkyl group containing 1 to 4 carbon atoms, in a molar ratio of 1:1 to 1:2 at temperatures of 60 to 175-C. and salts thereof and having a pH Svalue of 4 to 8.

b) the instruments are contacted with an aqueous cleaning solution before or at the same time as their treatment with the disinfecting solution and c) the instruments are rinsed with water and then dried in known manner The disinfecting solution used in step a) preferably has a pH value below 7 and, more particularly. in the range from 4.5 to 6 The process according to the invention the ad, antage that the medical instruments are not corroded and that pisingly, the amines develop an adequate antimicrobial effect without in any Aw troubling personnel. Another surprising effect is that the disinfecting soluuon pd also has a distinct cleaning Seffect of its own which contributes tuLwrds th ,ination of any residues still present on the surfaces.

Examples of the amines present in the disinfecting solution used in step a) are Glucoprotamin, N,N-bis-(3-aminopropyl)-laurylamine, N-dodecyl-1.3propanediamine or a mixture thereof, Glh zcjotarnin being particularly preferred.

SThe amine used in accordance with ie nv r'ion is preferably present in the

I

VVi I I 1 1 1 l 1 disinfecting solution of step a) in quantities of 0.01% by weight to 0.20% by weight and more preferably in quantities of 0.02% by weight to 0.15% by weight The disinfecting solution is preferably prepared by diluting a corresponding concentrate with water in a ratio of 1:30 to 1:200.

The disinfectant solution may contain surfactants, complexing agents, solvents, corrosion inhibitors, dyes and fragrances and optionally other antimicrobial agents and pH regulators as further components.

Nonionic surfactants and amphoteric surfactants are preferably used as surfactants in the process according to the invention, low-foaming surfactants being 1 particularly advantageous.

Nonionic surfactants in particular are used as the low-foaming surfactants.

Alkylene oxide adducts above all have proved to be particularly suitable, being obtained by addition of 3 to 30 moles of ethylene oxide (EO) and/or propylene oxide (PO) to fatty alcohols, long-chain oxoalcohols, fatty acids. fatty amines and alkylphenols containing 8 to 18 carbon atoms, the terminal hydroxyl groups of these polyglycol ether derivatives optionally being etherified, esterified or acetalised.

Particularly suitable nonionic surfactants are adducts of 3 to 15 moles of ethylene oxide with saturated and unsaturated fatty alcohols containing 8 to 18 carbon atoms, adducts of 3 to 5 moles of ethylene oxide and 3 to 6 moles of propylene oxide with saturated and unsaturated fatty alcohols containing 8 to 18 carbon atoms, these mixed alkylene oxide adducts being obtainable both by random polymerisation and by block polymerisation processes. and ether derivatives of the above-mentioned fatty alcohol alkylene glycol ethers in which the terminal hydroxyl groups are etherified with a linear or branched, saturated aliphatic alcohol preferably containing 4 to 8 carbon atoms. Of particular significance in this regard are the polyethylene glycol ethers corresponding to formula IV R' (3O, 'R

(IV)

in which R is a linear or branched alkyl or alkenyl group containing 8 to 18 carbon atoms, R" is a saturated or branched alkyl group containing 4 to 8 carbon atoms and n is a number of 7 to 12, polyethylene glycol ethers corresponding to formula IV, in which R 5 stands for a mixture of alkyl and/or alkenyl groups containing 12 to 18 carbon atoms emanating from a hydrogenated or non-hydrogenated tallow fatty alcohol and R 6 is an n-butyl group while n is a number of 9 to 10, being preferred Amphoteric surfactants may be used as further surfactants. Suitable amphoteric surfactants include derivatives of tertiary aliphatic amines and quaternary aliphatic ammonium compounds, of which the aliphatic radicals may be linear or branched and one of which may carry a carboxy, sulfo, phosphono. sulfato or phosphato group. Examples of such amphoteric surfactants are N.N-dimethyl-N- 0 I I I I 1 1 1 I tetradecyl glycine. N,N-dimethyl-N hexadecyl glycine. NN dim thyl N octade:cyl glycine, 3-(N,N-dimethyl-N-dodecylammonium)-1-propane sulfonate.

Examples of complexing agents are alkali metal salts of nitrilotriacetic acid, ethylenediamine tetraacetic acid, 1-hydroxyethane-1,1-diphosphonic acid, aminotris-(methylene phosphonic acid), ethylenediamine-tetrakis-(methylene phosphonic acid), phosphonobutane tricarboxylic acid, tartaric acid, citric acid, gluconic acid and mixtures of the above, sodium gluconate being particularly preferred.

Preferred organic solvents are those from the group of alcohols containing 1 to 4 carbon atoms, glycols containing 2 to 4 carbon atoms and the diglycols and Sdiglycol ethers derived therefrom. These solvents are preferably used in the concentrates in a quantity of 1% by weight to 25% by weight and more preferably in a quantity of 10% by weight to 20% by weight. The corresponding in-use solutions may be prepared from the concentrates in the required concentrations In one preferred embodiment, the disinfectant concentrate contains from 0 by weight to 30% by weight and, more particularly. 2% by weight to 15% by weight of antimicrobial agents, 0,5% by weight to 15% by weight and. more particularly, 1% by weight to 10% by weight of surfactants, 1% by weight to 25% by weight and, more particularly. 10% by weight to 20% by weight of organic solvents, up to by weight and, more particularly, 0.5 to 6% by weight of complexing agents and optionally other typical additives and water.

The concentrate is preferably adjusted to a pH value of 4 to 6 with acid, base or an acid/base mixture.

Before or at the same time as their treatment with the disinfecting solution, the instruments are contacted with a cleaning solution. If the instruments are contacted with the cleaning solution before their treatment with the disinfectant and if the cleaning solution is removed before the disinfecting solution is added, the process according to the invention represents a two-stage cleaning and disinfecting process similar to that described, for example, in European patent application EP-A-0 268 227. If the instruments are treated with the cleaning solution and the disinfecting solution at one and the same time. the cleaning solution and the disinfecting solution may be introduced into the cleaning apparatus in the forrr of a mixture or separately, preferably one after the other, before being brought into contact with the instruments. In this case, the process according to the invention is carried out as a single-stage process similar to that described, for example, in European patent application EP-A-0 342 499.

In principle, the cleaning step of the cleaning and disinfecting process according to the invention may be carried out using any cleaning solutions of the type normally used for cleaning sensitive medical instruments providing they do not affect the advantages of the amine-containing active substances used for disinfection. In a preferred embodiment, neither the disinfecting solution nor the I V l''l i l cleaning solution contains any quaternary amrmontiumr compounds or any other active substances which could adversely affect the outcome of the process accordinq to the invention The cleaning solution used in step b) pttufrably contain;ll at t lrat o I low foaming nonionic surfactant and at least one proteolytic enzyme and, optionally.

other typical constituents of cleaning solutions, for example complexing agents It has proved to be particularly advantageous to use a cleaning solution which contains 0.1 to 1.0g/L of low-foaming surfactant, 0.03 to 0.3AU'L (AU Anson Units) of proteolytic enzyme and 0.03 to 0.3g/L of complexing agent.

Suitable surfactants, complexing agents and solvents for the cleaning solutions are the same as those mentioned for the disinfecting solution In order to obtain good cleaning results under the in-use conditions, the surfactants are Spreferably present in the cleaning solution used in quantities of 0 01% by weight to 0.08% by weight and more preferably in quantities of 0.02% by weight to 0.05% by weight. A corresponding concentrate preferably contains 2 to 15% by weight and, more preferably, 4 to 10% by weight of surfactants.

Suitable proteolytic enzymes for the cleaning solution used in step b) are. in particular, proteases obtained from bacterial strains, for example the enzymes obtained from Bacillus subtilis, Bacillus licheniformis and Streptomyces griseus.

Corresponding commercial preparations are either in the form of solutions of the enzyme in a mixture of water or an organic solvent, for example propane-1 2-diol.

or in the form of solid granules.

The cleaning concentrate may additionally contain enzyme stabilisers, for example triethanolamine, morpholine, a-pyrrolidone, ethylene glycol. propylene glycol, glycerol, water-soluble calcium salts or mixtures of these compounds.

Glycerol and/or propylene glycol are preferably used as the enzyme stabiliser.

The pH value of the cleaning solution is preferably in the same range as that of the disinfecting solution, ie. between 4 and 8, preferably below 7 and more preferably between 4.5 and Water with a hardness of 3 to 8 d is preferably used in the practical application of the process according to the invention. This applies both to the preparation of the cleaning and disinfecting solution and to the rinse cycles. The Shardness values mentioned are best established by passing tap water at least partly over a cation exchanger which removes the hardness-forming cations from the water. This cation exchange results in a shift in the pH value into the mildly alkaline range The cleaning solution and the disinfecting solution are preferably prepared from concentrates which have proved to be of advantage in economic terms. Corresponding concentrates may be formulated in such a way that they give

""A

I, ,7) solutions with a pH value in the required range after dilution with the tap w;ter treated in the cation exchanger The instruments treated with the cleaning solution and the disinfecting solution are then rinsed with water and dried in known manner The instiunllltiits am bhst innsed at least twice with water, which should be heated to fi5 at erast in :Ith final rinse cycle, and then dried. In the case of two stage prores', a rinse cycle may also be included between the cleaning step and the disinfecting step The drying step is preferably carried out with sterilised hot air at around 40 to and preferably at 55 to 60'C. The endoscopes are preferably dried with air which is sterilised before heating by suction through a microfilter The process according to the invention may be carried out. for example, in commercial apparatus for disinfecting laboratory equipment and medical instruments, automatic rinsing machines of the type commonly used for cleaning and disinfecting medical instruments, particularly endoscopes, being preferred.

The cleaning solution is preferably prepared from a storable concentrate. In one preferred embodiment, an aqueous cleaning concentrate for preparing the cleaning solution used in step b) contains to 10% by weight of low-foaming surfactant, 7.1 to 77AU/L of proteolytic enzyme.

1 to 5% by weight of complexing agent.

to 50% by weight of enzyme stabiliser, 1 to 5% by weight of solubiliser and 0.05 to 0.5% by weight of preservative.

The concentrate is adjusted to a pH value of 4 to 6 with acid, base or an acid/base mixture.

Suitable solubilisers for the aqueous cleaning concentrate are for example, sodium cumene sulfonate. sodium toluene sulfonate, sodium xylene sulfonate, urea, polyethylene glycols and methyl acetamide. Sodium cumene sulfonate is preferably used as the solubiliser.

Examples Concentrates having the following composition (pbw parts by weight) were prepared by mechanically mixing the following components Cleaning concentrate: 8pbw n-butyl ether of an adduct of 9.5 moles of ethylene oxide with 1 mole of hydrogenated tallow fatty alcohol (Dehypon LT 104, a product of Henkel KGaA, Dusseldorf) 1pbw proteolytic enzyme (Alcalase a product of Novo Industri A/S.

Bagsvaerd, Denmark: 6pbw glycerol 50pbw 1.2-propylene glycol 1111 1 I I 'JI I I "oi i I 2pbw citric acid 3pbw sodium cumene sulfonate 0 1pbw p-hydroxybenzoic acid methyl ester ad 100pbw water The mixture was adjusted to pH 5 with 37'1/ by weight NaOH solution Disinfectant concentrate 7pbw reaction product of .:-NHCHlCH CH NH, and

CH

3 OCOCHCH: CHNH2COOH (Glucoprotamin, a product of Henkel KGaA, Dusseldorf) 4pbw C fatty alcohol x 4 EO 5 PO (Dehypon LS 45. a product of Henkel KGaA, Dusseldorf) 4pbw C2--14 fatty alcohol x 5 EO 4 PO (Dehypon LS 54. a product of Henkel KGaA, Dusseldorf) 1pbw sodium nitrilotriacetate 0.5pbw aminotnmethylene phosphonic acid 1pbw citric acid 1.2-propylene glycol ad 100pbw water The endoscopes were cleaned and disinfected in a closable stainless steel vessel (diameter about 60cm; height about 65cm) which was provided with a heating system and with pipes for the introduction and removal of the cleaning and disinfecting solution, the water used in the rinse cycles and hot air required for drying the instruments. The apparatus was provided with a circulation pump by which the particular liquid present could be pumped through the bores of the fibre Sendoscopes The tests were carried out with a commercial gastroscope.

Water adjusted to a hardness of 5 d by passage over a cation exchanger was used to prepare the cleaning and disinfecting solution.

A ready-to-use cleaning and disinfecting solution was prepared by diluting corresponding quantities of cleaning concentrate and disinfectant concentrate The cleaning solution contained 0.40g of surfactant/l and 0 05g of enzyme/I in the in-use solution.

The disinfectant solution contained 0.84g of Glucoprotarminl in the in-use solution.

The air used for drying was taken in throu l a microfilter and. before introduction into the stainless vessel, was passed through a heating zone in which it was heated to 60 C.

For cleaning, the endoscope was placed in a wire basket and then introduced into the stainless steel container. The bores of the endoscope were connected to S the circulation pump. In the individual steps of the process. liquid was delivered to 0 1 1 1, 0 1 I the stainless steel container in such a quantity that the endoscope wvas completely covered During the individual process steps, the liquid present was continuously circulated through the bores of the endoscope.

The cleaner was introduced in a concentration of at 30 C The cleaning solution was pumped through the endoscope bores and heated to 45 C. After reaching that temperature, it was flushed through the endoscope for another 2 minutes. At the same time, the endoscope was externally cleaned with the cleaning solution.

Thereafter a) the cleaning solution was pumped off and discarded and the instrument was filled with fresh water to which disinfectant (1 2 had been added (test 1 b) the disinfectant was added to the cleaning solution (1 (test 2) The solutions used in the disinfecting step for tests 1 and 2 was heated to C The solutions were contacted with the gastroscope both internally and externally over a period of 5 minutes The solutions were pumped off and the endoscope was internally and externally rinsed twice with cold water The stainless steel vessel was then refilled with water which, on this occasion, was heated to 60 C and then removed Finally. filtered hot air was introduced for minutes to dry the endoscope.

To test the disinfecting effect achieved in the process according to the invention, the bores of the endoscope were separately contaminated with germ suspensions containing the following germs a) ca. 10" germs/mL Staphylococcus aureus b) ca. 10" germs/mL Pseudomonas aetuginosa c) ca. 10' germs/mL Enterococcus faecium To simulate practical conditions, the germ suspensions contained an addition of 20% by weight of defibrinated sheep's blood.

For contamination, the bores of the endoscope were filled with the germ suspensions. After standing for a short time, the germ suspensions were drained off again. One hour after contamination, the endoscope was cleaned and disinfected in accordance with the invention 0 5L of a solution containing by weight of Tween 80, 0.3% by weight of lecithin. 0 1' by weight of histidine. 0 1 by weight of tryptone and 0.05% by weight of sodium chloride was then drawn through the bores of the endoscope. Samples of 1mL of this solution were transferred to agar plates which were then incubated for at least 48 hours at 37 C or 72 hours at 35 C and then examined for any germ growth present In every case, the process according to the invention achieved the required sterility.

In further tests carried out under the process conditions described above, it was shown that the process according to the invention can also be successfully used against contamination by viruses, especially enteroviruses. such as polio and papova viruses, and other heat-resistant viruses.

Claims

1. A process for cleaning and disinfecting sensitive medical instruments, more especially endoscopes, with aqueous cleaning and disinfecting solutions, in which a) the surfaces of the medical instruments to be treated are contacted with an aqueous disinfecting solution which has a temperature of 55 to 65 C, is kept at that temperature for 1 to 15 minutes and is then removed, the disinfecting solution containing at least one disinfectant from the group of alkyl propylenediamines corresponding to general :ormula I: 1 RtN\ 'NH, S2 R 0 (I) in which R 1 is an alkyl or alkenyl group containing 8 to 18 carbon atoms and R' is hydrogen, an alkyl group containing 1 to 4 carbon atoms or an aminoalkyl group containing 2 to 4 carbon atoms, and the products known as Glucoprotamin obtainable from alkyl propylenediamine corresponding to formula II: 9 3 .N H 2 RN' N14 H in which R 3 is a linear alkyl group containing 12 to 14 carbon atoms, by reactio S. with compounds cr'responding to formula Ill: 0 01 R4' I OH in which R 4 is hydrogen or an alkyl group containing 1 to 4 carbon atoms, in a molar ratio of 1:1 to 1:2 at temperatures of 60 to 175"C, and salts thereof and having a pH value of 4 to 8, b) the instruments are contacted with an aqueous cleaning solution before or at the same time as their treatment with the disinfecting solution and c) the instruments are rinsed with water and then dried in known manner.

2. A process as claimed in claim 1, characterised in that the disinfecting solution has a pH value below 7.

3. A process as claimed in claim 2, characterised in that the disinfecting solution has a pH value between 4.5 and t, I

4. A process as claimed in any one of claims 1 to 3, characterised in that Glucoprotamin, N,N-bis-(3-aminopropyl)-laurylaminf N-dodecyl-1,3- propanediamine or a mixture thereof is used as the disinfi A process as claimed in any one of claims 1 to 5. characterised in that Glucoprotamin is used as the disinfectant.

6. A process as claimed in any one of claims 1 to 5, characterised in that the disinfectant concentrate contains from 0.5% by weight to 30% by weight of antimicrobial agents. 0.5% by weight to 15% by weight of surfactants, 1% by weight to 25% by weight of organic solvents, up to 10% by weight of complexing agents ii. and optionally other typical additives and water

7. A process as claimed in claim 6, characterised in that the disinfectant concentrate contains from 2% by weight to 15% by weight of antimicrobial agents.

8. A process as claimed in claim 6 o, claim 7, characterised in that the disinfectant concentrate contains from 1% by weight to 10% by weijht of surfactants.

9. A process as claimed in any one of claims 6 to 8, characterised in that the disinfectant concentrate contains from 10% by weight to 20% by weight of organic solvents. A process as claimed in any one of claims 6 to 9, characterised in that :A the disinfectant concentrate contains from 0.5 to 6% by weight of complexing agents. S* 11. A process as claimed in any one of claims 1 to 10, characterised in that S the aqueous cleaning solution contains 0.1 to 1.Og/L of low-foaming surfactant, 0.03 to 0.3AU/L (AU Anson Units) of proteolytic enzyme and 0.03 to 0.3g/L of complexing agent.

12. A process as claimed in any one of claims 1 to 11, characterised in that, before treatment with the disinfectant, the instruments are contacted with the cleaning solution and the cleaning solution is removed before addition of the 3i disinfecting solution.

13. A process as claimed in any on of claims 1 to 12. characterised in that the instruments are cortacted with the cleaning solution and the disinfecting solution at one and the same time.

14. A process as claimed in claim 13, characterised in that the cleaning solution and the disinfecting solution are successively introduced into the cleaning apparatus. K4 Ji j 14 A process for cleaning and disinfecting sensitive medical instruments, substantially as hereinbefore described with reference to any one of the examples. Dated 20 August 1998 HENKEL-ECOLAB GMBH Co. OHG Patent Attorneys for the Applicant/Nominated Person SPRUSON&FERGUSON *a *a S. S. e a S I 'K\