EP1733044A2

EP1733044A2 - Method and device for testing the bactericidal effect of substances

Info

Publication number: EP1733044A2
Application number: EP05714739A
Authority: EP
Inventors: Daniel Fäh; Caroline Amberg
Original assignee: EMPA Testmaterialien AG
Current assignee: EMPA Testmaterialien AG
Priority date: 2004-04-06
Filing date: 2005-04-06
Publication date: 2006-12-20
Also published as: JP2007531533A; US20090011457A1; BRPI0509639A; WO2005098019A3; WO2005098019A2; CH703678B1

Abstract

Disclosed is a method for testing the degree of microbial load of laundry following one washing cycle. Said method is characterized in that a defined number of living microorganisms are washed along with the laundry, the number of living microorganisms after completing the washing process is determined, and the effectiveness or the quality of the washing process is determined from the difference between the original number of living microorganisms and the number of microorganisms that are alive following the washing process. The inventive device for carrying out said method comprises, among other things, a receptacle (90) in which the microorganisms are enclosed in such a way that the washing liquid can penetrate into said receptacle (90) while the microorganisms cannot escape therefrom.

Description

Method and device for testing bactericidal activity of substances

The present invention relates to a method for testing bactericidal activity of substances and to a device for carrying out this method.

Methods of this type can be used to test the bactericidal activity of, for example, disinfectants, antiseptics, detergents, detergent components, etc. In Zbl. Bakt. Hyg., I. Abb. Orig. B176, 463-471 (1982) is a method of the type mentioned by Mr. Univ.-Prof. Dr. Walter Koller, Vienna. Germ carriers are used in this process. These are contaminated batiste lobes, which are enclosed between two membrane filters. This system acts as a perfusion chamber. Although the perfusion chamber allows water and the active ingredients dissolved in it to pass into the interior of the system, it prevents bacteria from escaping from the system. After the washing process has been completed, the living germs still present in the system are counted. This counting can only be carried out using means that are only available in laboratories set up for this purpose. The results of such examinations are only available in a day or two using the classic plate counting method, which is too long a period for practical purposes. Counting can be accelerated with the latest analysis devices, but the purchase of such devices requires large investments.

The invention has set itself the task of specifying a method and a device for performing this method, which make it possible to make statements about the microbial contamination level of textile laundry, or statements about the bacterial contamination level (= hygiene status) of textiles.

Bestätigungskopiθ to be able to wash clothes after a washing cycle in a washing machine if washing temperatures in the range of 30 to 60 ° C are used. The process and the equipment should also be designed so that semi-quantitative statements about the quality of the washing process can also be made. At the same time, the method and the device should be designed so that they can be handled in a simple manner. The procedure should also be designed so that the results of such an investigation are available as quickly as possible. The device for performing this method should be designed as a disposable product.

In the method of the type mentioned at the outset, the above-mentioned objects are achieved according to the invention as defined in the characterizing part of patent claim 1.

According to the invention, the above-mentioned objects are also achieved using a device which is defined in the characterizing part of patent claim 8.

Embodiments of the present invention are explained in more detail below with reference to the accompanying drawings. 1 shows a diagram of the present method,

2 shows the mode of action of some of the substances used in the present method, FIG. 3 shows, in a vertical section, a first embodiment of a monitor vessel, which is one of the components of a device for carrying out the present method,

4 shows a top view of the vessel or chamber from FIG. 3, FIG. 5 shows a perspective view of a second embodiment of the vessel in the operational state, FIG. 6 shows a vertical section and only schematically shows the vessel from FIG. 5, 7 perspective and schematic of the core of the device from FIG. 5, FIG. 8 in an exploded illustration the essential part of the second embodiment of the present device,

9 shows an exploded illustration of a third embodiment of the present device,

10 schematically shows a fourth embodiment of the present device,

11 is a perspective view of the lid of a fifth embodiment of the present

Facility,

12 in a vertical section the lower part of the fifth embodiment of the present device,

13 is a side view of a sixth embodiment of the present device,

14 in a vertical section the lower part of the embodiment of the present device shown in FIG. 13, FIG. 15 in a vertical section the cover of the embodiment of the present device shown in FIG. 13 and FIG. 16 in a view from below or inside the lid from FIG. 15.

1 shows a diagram of the sequence of the present method for testing the bactericidal action of substances 1. In this method, a predetermined or defined number of living microorganisms are exposed to the action of the substance to be tested for a certain period of time. The number of microorganisms still alive after the expiry of the exposure period mentioned is determined and the bactericidal activity of the tested substance is inferred from this number of microorganisms still alive. The living microorganisms, before being exposed to the substance to be tested, are placed in a liquid with which they form a suspension. This liquid is expediently a nutrient solution or a physiological saline solution. The substance to be tested is expediently in the form of a solution for the test process or a suspension. These are also called substance liquid 88 below.

A device for performing this method also includes, among other things, a vessel 85 (FIG. 1) in which the test method can be carried out. The substance liquid 88 is also located in this test vessel. If, for example, components of a washing process are to be tested, the washroom of a washing machine can represent the test vessel 85 and the wash liquor is the substance liquid 88. The present device also includes a container 90 (FIG. 1, 3 and 4), which serves to take up the test microorganisms, in particular a defined amount of microorganisms. Such a container 90 can also be called a monitor vessel.

The microorganism container or monitor vessel 90 comprises a hollow lower part 91 and an essentially flat upper part 92. In the example shown in FIGS. 3 and 4, these components 91 and .92 of the container 90 have a circular outline. The microorganisms float in a liquid 98, which is located in the interior of the lower part 91 of the container 90. As already mentioned, this liquid is expediently a physiological saline solution. The interior of the container 90, which serves to hold the test organisms 98, should have a volume of at least 1 ml.

The outside of the upper edge region of the lower container part 91 is provided with a thread 93. The cover 92 has a disk-shaped base body 89. A collar 94 which has the shape of a short cylinder jacket hangs from the edge part of this disk-shaped base body 89 of the container lid 92. The thread 93 is also embodied in the inner surface of this cylinder jacket 94, so that the cover 92 can be screwed onto the lower part 91. In the disk-shaped base body 89 of the Kels 92 are holes 95 through which the substance liquid can penetrate into the interior 98 of the container 90 during the interaction between the substance and the microorganisms.

The test microorganisms must remain enclosed inside 98 of the hollow lower part 91 of the container during the said interaction so that the results of the tests are not falsified. A semipermeable membrane 96 is assigned to the underside or inside of the plate-shaped base body 89 of the cover 92, which covers the entire underside of the plate-shaped base body 89 of the cover 92 and thus also the holes 95 in the plate-shaped base body 89 of the cover 92. The membrane 96 is designed such that the substance liquid can penetrate into the interior 98 of the monitor vessel 90 during the interaction and can interact with the microorganisms. However, the membrane 96 is also designed such that it is impermeable to the test microorganisms, so that the microorganisms cannot leave the container 90 through the holes 95 in the lid 92.

So that the test microorganisms cannot leave the cavity in the lower container part 91 through the gap between the lower part 91 and the lid 92 of the container 90, a sealing ring 97 is arranged in that corner part of the lid 92 where the collar 94 with the disk-shaped base body 89 of the lid 92 hits. Consequently, the sealing ring 97 can be squeezed between the disk-shaped base body 89 of the cover 92 and the upper edge of the wall of the lower part 91, as a result of which the said gap between the threaded parts 93 is considered sealed for the microorganisms.

However, it is also conceivable that there is an active inside the container 90

Unit there, which is designed as a perfusion chamber (not shown). This perfusion chamber comprises a carrier for the test microorganisms which are enclosed in the perfusion chamber. The perfusion ka mer also includes the aforementioned semipermeable and pore-containing membrane 96, which covers the test organisms attached to the support.

For example, the following germs can be used as test microorganisms in the present method:

- Escherichia coli,

- Candida glabrata,

- Enterococcus faecium, - Enterococcus faecalis,

- Staphylococcus epidermidis and

- Bacillus subtilis.

A defined amount of living microorganisms or of living test germs in pure culture, in the case shown in FIG. 1 it is a suspension which contains Enterococcus faecium in an amount of about 10 ⁸ germs, is placed in the container 90 and this container 90 is then closed. Microorganisms of only one type are enclosed in the perfusion chamber 99 of the monitor vessel 90. The monitor vessel 90 is brought into the test vessel 85 and the microorganisms enclosed in the monitor vessel 90 are exposed to the action of the substance liquid 88. During this interaction between the substance liquid 88 and the microorganisms 98, the test vessel 85 can be moved, for example shaken, the temperature inside the test vessel 85 can be changed so that its changes have a desired course, and the period of the interaction can expediently be changed ,

After the exposure time, tetrazolium salt is added to the microorganism suspension 98, which by the enzyme dehydrogenase in the test microorganisms corresponds to the number of those still living Microorganisms is reduced to a colored product, the formazan. The optical density caused by Formazan is then measured. From the result of this measurement, conclusions are drawn on the bactericidal activity of the tested substance and thus also on the number of those test microorganisms which have survived the exposure period of the tested substance 88.

The number of those microorganisms that were alive at the start of a test process is usually known because you have chosen or determined this number yourself. After the end of the test process, the number of microorganisms that survived the interaction is determined using the measurement method already mentioned. This detection is an indirect method, i.e. one measures the metabolic activity of those microorganisms that survived the test process. It is important that only the living microorganisms are detected, because only these can multiply later and because only these can pose a health risk

To carry out the measurement, the monitor vessel 90 is opened and the microorganism suspension 98 is removed from the monitor vessel 90. The microorganism suspension 98 is placed in a cuvette 86 (FIG. 1). It can be a cuvette 86 which can be used in a photometer (not shown) and which has a volume of 1.5 ml, for example. A liquid medium can be in the cuvette. This medium is a known nutrient solution for the microorganisms.

In a further step of this method, substances can be added to the suspension which are able to neutralize residues, for example of a detergent, in the microorganism suspension 98 or to remove them from the suspension 98. Such a substance can also be called an inactivating substance. For example, 200 μl of organ nisms 98 come from the monitor vessel 90 about 600 μl of liquid, this liquid consisting of the nutrient solution and the inactivating substance. The microorganisms 98 are kept in this liquid for a predetermined period of time, for example 1 hour, and at a predetermined temperature, for example 37 ° C.

After such a pretreatment of the suspension or after such an incubation period, that section of the present method can begin which leads to the actual assessment of the quality of the washing cycle in question. For this purpose, the tetrazolium salt is added to the suspension. Living microorganisms contain a bacterial enzyme, dehydrogenase. This enzyme is such that it contains the tetrazolium salt according to the number of microorganisms still alive, i.e. according to the activity of the living microorganisms in the suspension to a colored product, the formazan. FIG. 2 schematically shows the process in which the tetrazolium salt is reduced to a colored product, the formazan, in accordance with the number of microorganisms still living in the suspension 98. From the amount of formazan formed and thus also from the intensity of the resulting color, one can deduce the activity of the microorganisms and thus also the number of those microorganisms that have survived the interaction process.

In the next step of the present method, that optical density or intensity of that light is measured which is caused by the formazan. This measurement can be done with the help of a photometer. The optical density can be measured at a predetermined wavelength, for example 450 nm. From the result of this measurement, conclusions can be drawn about the number of microorganisms which before the test process has survived and therefore also on the bactericidal effect of the tested substance.

However, the measurement of the optical density can also be carried out in a more precise manner, due to the increase in the amount of Formazän during a certain period of time (not shown). The microorganisms present in the suspension are first incubated for a first period, for example of 30 minutes and at a specific temperature, for example of 37 °. This is followed by a first measurement of the optical density. The microorganisms present in the suspension are then incubated for a second and subsequent period, for example 30 minutes, and at a specific temperature, for example 37 °. This is followed by a second measurement of the optical density. In this way, the increase in the amount of formazan can be measured over a certain period of time (e.g. 30 minutes). The increase in optical density correlates directly with the bacterial activity or number of bacteria. From the difference between the results of these two measurements, conclusions can be drawn about the number of those microorganisms that have survived the interaction process and thus also about the bactericidal effect of the tested substance.

If it is a matter of testing washing components, the microbial load level of textile laundry after a washing cycle or φe hygiene effect of a washing process, ie the decrease in the number of bacteria during a washing process in a textile washing machine 85, is to be determined. For such tests, the container 90 is designed in such a way that it can be accommodated inside a washing machine 85 without being significantly damaged during the washing process. The container 90 is made of a material which is mechanically very stable, which can be machined, which is autoclavable (at least up to +121 ° C / 1 atm) and which is washing machine and tumble proof. The interior of the container should have a volume of at least 1 to 1.5 ml, which is used to hold the sample or test material.

A predetermined or defined amount of living test microorganisms 98 is filled into the monitor vessel 90, this monitor vessel 90 is brought together with the textile laundry into a washing machine 85 and subjected to a washing cycle. As a result, the test microorganisms 98 are exposed to the same influences of the washing process as the textile washing. The washing machine 85 can be, for example, a household machine or an industrial washing machine. After the washing cycle has ended, the number of microorganisms still living is determined in one of the measurement methods already described. From the difference between the defined initial amount of the living microorganisms introduced into the washing cycle and the amount of microorganisms still living after the washing cycle, the effect or quality of the washing process or of the detergents, detergent components or washing processes used in the washing process is inferred , The fewer microorganisms that are still alive after a washing cycle, the more effective the washing cycle, the lower the degree of microbial contamination of the textile laundry after a washing cycle and the greater the hygiene effect of the washing process.

A second embodiment of the present device is shown in FIGS. 5 to 8. It comprises a container 1, which is designed such that it has a hollow base body 2. This container base body 2 can have the shape of a cuboid, a cube, a sphere, etc., for example. In the case shown, the base body 2 of the container 1 is disc-like.

The hollow base body 2 of the container 1 of the first embodiment of the present device comprises an upper part 3 and a lower part 4, which also as Halves 3 and 4 of the container 1 can be designated. In this embodiment, the base body of each of the container halves 3 and 4 has the shape of a thick disk with a cylindrical circumferential surface 5. The base body of each of the container halves 3 and 4 also has two opposing disk-shaped and parallel large surfaces 6 and 7 , In each of the large areas 6 and 7 of the container halves 3 and 4 there is a recess 8 and 9 respectively. The depth of the recesses 8 and 9 in one of the container halves 3 and 4 is smaller than the thickness of the disk-shaped container half 3 and 4, respectively, in such a way that an intermediate wall 10 between the bottom of the recesses 8 and 9 in the respective container halves 3 and 4, respectively 4 is present.

In the circumferential area, the respective recesses 8 and 9 in one of the container halves 3 and 4 are delimited by an annular edge part 11. This edge part has an inner side surface 37. The intermediate wall 10 is in one piece with the edge part 11 of the pane 3 or 4 in question. Those sections 12 and 13 of the annular edge parts 11 of the hollow container halves 3 and 4 as described, which face each other, are provided with a thread known per se, so that the container halves 3 and 4 can be detachably connected to one another with the aid of this thread. This thread is advantageously designed so that one and a half turns are enough to open or close the housing 2.

Openings 14 are made in the intermediate wall 10 of the relevant pane 3 or 4, which connect the depressions 8 and 9 in the respective disk-shaped container half 3 or 4 with one another in terms of flow. In the illustrated case, these connection openings 14 are designed as slots in the intermediate wall 10, which run radially away from the center of the intermediate wall 10. In addition to these slots 14 or alternatively to this, connection openings 14 with a different shape of their contour can be made in the intermediate wall 10 be executed. The interior of the container 1 is defined by the inner recesses 9 which open towards one another in the halves 3 and 4 of the container. The aforementioned openings 14 connect the interior 9 of the container 1 with its surroundings, in particular with the depressions 8 lying on the outside of the container halves 3 and 4.

The interior 9 of the container 1 should have a volume of at least 1 to 1.5 ml, which is used to hold the sample material. In the interior 9 there is an active unit or a perfusion chamber 20 of the present device. This perfusion chamber 20 includes, among other things, a carrier 15 for the test microorganisms. This carrier 15 can be a piece of paper, for example. Or the carrier 15 can be designed as a lobule, which is made of a textile material, for example cotton. In the illustrated case, the carrier 15 has the shape of a disk, for example made of one of the materials mentioned, this disk having a circular edge. The diameter of this disk-shaped carrier 15 is dimensioned such that the edge portion of the same on the practically cylindrical. Inner wall 37 of the cavity 9 rests in the container 1. In this edge area 37 there is an O-ring 16 or 17 on each side of the carrier 15. The diameter of the cross section of these O-rings 16 and 17 is dimensioned such that the O-rings 16 and 17 between the carrier 15 for the test microorganisms and the bottom 35 of the inner recess 9 in the container halves 3 and 4, so that no liquid can flow between the cylindrical inner wall 37 of the container cavity 9 and the edge of the carrier 15.

The perfusion chamber 20 of the present invention also includes disks 21 and 22 (FIG. 3), which are made of a material that is normally used for so-called sterile filters. The pore size of these sterile filters can be, for example, 0.2-0.4 micrometers. Sterile filters usually exist from nitrocellulose and they are very brittle. That is why they are exposed to a high risk of damage in the event of mechanical loads which occur in the machine when vibrating. The disks 21 and 22 have practically the same diameter as the carrier 15, so that they can also find space in the interior 9 of the container 1. The filter disks 21 and 22 run practically parallel to one another and to the carrier 15 for the test microorganisms.

One of the filter disks 21 and 22 is assigned to one of the large-area sides of the carrier 15 for the test microorganisms. In the case shown in FIG. 6, the respective filter disk 21 or 22 lies between the bottom 35 of the inner recess 9 in the relevant container half 3 or 4 and the O-ring 16 or 17 assigned to it. In this case, there is one filter disk each 21 and 22 of the inside or the bottom 35 of the respective intermediate wall 10 of the container halves 3 and 4, respectively, and the respective filter disk 21 or 22 covers the openings 14 in the intermediate wall 10 from the inside 9 of the container 1. However, it is also conceivable that one of the filter disks 21 or 22 rests directly on one of the large areas of the carrier 15 for the test microorganisms, so that the O-rings 16 and 17 are located between the outside of the filter disk 21 or 22 and the bottom 35 of the relevant inner recess 9.

8 shows this first embodiment of the present device in an exploded illustration. As stated, this first embodiment of the present device is intended to be housed in a washing machine.

Fig. 9 shows a third embodiment of the present device. This embodiment of the present device can be used in those cases in which the wash liquor or another liquid can only flow through the present device. Inside, this third facility is practical table executed the same as the second version of this facility. Instead of the outer recesses or depressions 8 of the second embodiment, the respective container half 3 or 4 of the third embodiment is provided with a nozzle 24. The respective nozzle 24 is connected to the interior 9 of the respective container half 3 or 4 in terms of flow. A known nipple 25 can be screwed into the respective socket 24 with its threaded end. The opposite end part of the nipple 25 is designed to attach a hose through which the liquid can be introduced into the device according to FIG. 9 or can be carried out from it.

10 shows yet another possible embodiment of the present device. The perfusion chamber 30 of this device also includes the carrier 15 for the microorganisms already described. However, this carrier 15 is enclosed in a sheath 31, which is a further component of this perfusion chamber 30. The sleeve 31 has essentially the shape of a piece of tubing. This is made of a material from which dialysis tubing is normally made. In the present case, sections of such dialysis tubes 31 should have the largest possible pores. The maximum size of the pores in the tubes 31, which can consist, for example, of regenerated cellulose, is 50,000 Daltons. The exchange of liquid through such membranes is therefore much slower than with the sterile filters described above. If such membrane tubes 31 are used, the microorganisms can be brought onto the carrier 15 as powder or likewise distributed in a liquid.

The tube section 31 is sealed in its end regions in a manner that is bacteria-proof, namely at an appropriate distance from the carrier 15. This can be done, for example, with the aid of clips. Weldable dialysis tubes 31 made of PVDF are also available, but the pore size is the same. ben is 12,000 daltons. In addition, they are not as flexible and resilient as the cellulose membrane hoses 31. Furthermore, the end parts of the hose section 31, as shown in the illustrated case, can be closed by constricting the end parts of the hose section 31 with the aid of a suitable cord .32.

Since the material of the hose 31 has a relatively low strength, the hose piece 31 is arranged in an open housing 33 made of a stable material. This housing 33 can be designed as a can-like plastic vessel with large slots or holes. In the illustrated case, the housing 33 is designed as a jacket of a cylinder, the outer parts of this cylinder jacket being open so that the washing liquid can flow through the housing 33. This housing 33, together with the perfusion chamber 30 mentioned and arranged in this housing 33, is accommodated in a washing machine or similar. Because the bottom areas of the housing 33 are open, the washing liquid can flow through the housing and thereby reach the microorganisms on the carrier 15 in the casing 31. In order to prevent the perfusion chamber 30 from slipping out of the housing 33, the perfusion chamber 30 is held in the interior of the housing 33 with the aid of holding means 34 known per se. Those sections of the cord 32 already mentioned which protrude from the sheath 31 and whose ends are fastened on or in the wall of the housing 33 can serve as the holding means 34.

11, the cover 51 of a fifth embodiment of the present device 50 is shown in perspective. 12 shows in a vertical section the lower part 52 of this fourth embodiment of the present device 50. In the vertical section, both the base body of the cover 51 and the base body of the lower part 52 have a U-shaped cross section. The inside of the side wall of the cover 51 and the outside of the side wall of the Lower part 52 are provided with corresponding and already described thread halves, so that the cover 51 can be screwed onto the lower part 51. The cover 51 is provided with the openings 14 already described. In the case shown, a semipermeable, pore-containing membrane 53 rests on a carrier 54 and this arrangement is located in the interior of the cavity 55 in the lower part 52. The membrane 53 is permeable to water and detergents.

13 shows a fifth embodiment of the present device in a side view. This embodiment also has a cover 61 and a lower part 62. Essentially, both the cover 61 and the lower part 62 are of the same design as the cover 51 and the lower part 51 of the fourth embodiment of this device.

FIG. 14 shows in a vertical section the lower part 62 of the embodiment of the present device shown in FIG. 13. The inner wall 73 of this lower part 62 has the shape of the shell of a spherical cap. In the wall of such a lower part 62, slot-shaped openings 14 are made which extend from the central region 74 of the spherical cap bottom to the upper edge 75 of the lower part 62. A radially projecting collar 76 is formed on the outside of the lower part 62 approximately at the height of the spherical cap bottom 74.

15 and 16 show a further possibility of designing the cover 61.

11, the cover 61 is shown in a vertical section. 16 shows the cover 61 in a view from below or from the inside. In the bottom 66 of the

Lid 61 are perpendicular to the bottom surface 69 and parallel to each other bores 67 which are distributed over the surface of the bottom 66. These bores 67 extend between the large outer surface 68 and the bottom surface 69 of the cover 61. The bottom surface 69 is flat. Only in the edge area of the bottom surface 69 is an annular GE groove 70 executed, in which a seal 71 is located. This seal 71 can be designed as an O-ring. The diameter of the groove 70 is dimensioned such that the bottom of this groove 70 lies opposite the upper edge 75 of the lower part 62 when the cover 61 is screwed onto the lower part 62. Consequently, the sealing ring 71 is also opposite the upper edge of the lower part 62, so that the sealing ring 71 is squeezed between the upper edge of the lower part 62 and the bottom of the groove 70.

In the interior 73 of this container 60 there is an active unit or a perfusion chamber 80 of the present device. This perfusion chamber 80 also includes a disk 81, which is made of a material that is normally used for so-called sterile filters. The pore size of this sterile filter can be, for example, 0.2-0.4 micrometers. Sterile filters are usually made of nitrocellulose and are very brittle. They are exposed to a high risk of damage in the case of mechanical loads that occur in the machine when vibrating. Therefore, such washers 81 must be housed in one of the containers disclosed herein while performing the present method.

The disk 81 has practically the same diameter as the interior space in the bottom region of the cover 61, so that the disk 81 can be accommodated in the interior of the cover 61. Your edge area lies on the seal 71. After the cover 61 has been screwed onto the lower container part 62, the edge part of this disk 81 is pressed together in a sealing manner between the upper edge 75 of the lower container part 62 and the seal 71. The perfusion chamber 80 further includes a carrier for the test microorganisms. This carrier can be of the type described above. This carrier is attached to that side of the disk 81 which faces the interior 73 of the container 60 which is delimited in the form of a cap. The following test germs, which are also prescribed by European Standard No. 1276, are often used in laboratory washing tests: • Staphylococcus aureus,

• Escherichia coli, Pseudomonas aeruginosa and

Enterococcus hirae.

The following test germs are often used in laboratory washing tests, but are not required by European Standard No. 1276: • Enterococcus faecalis (Streptococcus faecalis),

Enterococcus faecium,

• Candida albicans and • Trichophyton mentagrophytes (dermatophyte).

In the present method, a defined amount of living microorganisms or of living test germs is placed on the carrier in pure culture. , The test nuclei to be used can float in a liquid or they can be in powder form. Drops of the liquid or predetermined amounts of the powder are placed on the carrier. The microorganisms can be fixed on the support before being introduced into the washing process. This can be done, for example, with the aid of a gel, e.g. Alginate gels are made. The bacteria are embedded in the gel in the piece of fabric so that they remain fixed on the carrier. Furthermore, the microorganisms can be preserved or stabilized on the carrier before being introduced into the washing process, for example dried by freeze-drying.

The carrier prepared in this way is sealed in the perfusion chamber so that it is bacteria-proof. Microorganisms of only one type are enclosed in the perfusion chamber. The perfusion chamber is so tight that the microorganisms nisms cannot escape from the perfusion chamber, but the washing liquid can nevertheless come into contact with the microorganisms. If the perfusion chamber is inside the container, the microorganisms are enclosed therein. The container is brought together with the textile laundry into a household washing machine and washed with the textile laundry. If the perfusion chamber 30 is designed as the tube piece described, this is first fastened in the housing 33, the housing 33 is then brought together with the textile laundry into a household washing machine and washed with the textile laundry.

After the washing process has ended, the carrier is removed from the perfusion chamber from the container and the number of microorganisms still living after the completion of the washing process is determined. The effect or quality of the washing process is inferred from the difference between the original quantity of living microorganisms and the microorganisms still living after the washing process.

When detecting after washing, it is important that only the cells that are still alive are detected, because only these can multiply later and because only these can pose a health risk. If a carrier for the microorganisms, for example a cloth rondelle, is used, this carrier is first removed from the cage or container and washed out in a physiological solution. The kill rate can be read directly after the washing process or washing cycle, for example using a color indicator. This detection can be carried out relatively easily. Or the kill rate can be measured based on ATP activity. An ATP determination is carried out by direct measurement of the liquid or by means of "swabs" in the luminometer. The number of microorganisms that have survived the washing process can, however, also be determined using so-called gene probes. Gene probes are produced by VIT-Vermicon, for example. The surviving microorganisms could also be measured using other methods such as impedance (from BioMerieux or from SyLab), optoelectric counting (from FOSS), solid phase cytometry (from ChemScan), ImmunoMagneticSeparation / IMS (from DYNAL).

In principle, it would also be possible to place and incubate aqueous samples on agar plates. With this method, however, the results are only available after 2-3 days. However, the results of such an evaluation method are precise. The personnel costs are high with this method.

The determination of the quality of the washing process is based on the ratio between the number of those microorganisms that were alive at the beginning of the washing process and the number of those microorganisms that were still alive at the end of the washing process. Such an evaluation can also be carried out on a computer using a suitable program.

Many manufacturers add bleaching and / or bactericidal substances to their detergents, which are said to effectively combat microorganisms. These manufacturers should at least know internally whether their additives really kill germs during washing or to what extent the germs are killed. The present method and the present facilities are intended to enable the effectiveness of the substances used in the detergent and thus the effectiveness of the washing process to be checked with internal control during operation in the simplest and fastest possible manner. This method and these facilities can be used by detergent, bleach, washing machine manufacturers and in Large laundries and in relevant research institutes are used. The targeted test laundry can, for example, also be the textile material that must not be washed at more than 60 ° C. These are, for example, color-sensitive fabrics, wool, silk, synthetic fibers, etc. Furthermore, this method and these devices are suitable for the microbiological assessment of new products such as machines, programs, detergents etc. and for the microbiological assessment of washing processes within the large laundry. With the help of the present devices, a possibly semi-quantitative statement about the germ killing rate in a washing cycle of a washing machine can be made within a few hours with a minimal amount of preparation. The facilities also allow a quick assessment of the actual washing process and the corresponding influencing factors such as temperature, time, detergents and mechanical stress. No samples need to be taken from the machine during the washing process.

Claims

claims

1. A method for testing the bactericidal action of substances, characterized in that a predetermined or defined number of living microorganisms is exposed to the action of a liquid contaminated with bacteria, which contains the substance with the bactericidal action that the number of after a microorganisms that are still living for a certain period of exposure and that the bactericidal activity of the tested substance is concluded from this.

2. The method according to claim 1, characterized in that a defined amount of living microorganisms is washed together with textile laundry, that the number of microorganisms still alive after the end of the washing process is determined and that from the difference between the original amount of living microorganisms and the amount of microorganisms that remain after the washing process, the effectiveness or quality of the washing process, in particular the bactericidal activity of the substance tested, is determined.

3. The method according to claim 2, characterized in that a defined amount of microorganisms is placed on a carrier, for example by drops or in the form of powder, that the microorganisms are fixed on the carrier before the introduction of the carrier into the washing process, for example with With the help of a gel and / or that the microorganisms are preserved before the carrier is introduced into the washing process, for example by freeze drying and that the number of microorganisms surviving the washing process can be determined by the so-called bioluminescence method or with the aid of so-called gene probes.

4. The method according to claim 1, characterized in that the living microorganisms are brought into a liquid with which they form a suspension, which liquid can be a nutrient solution that the substance to be tested in the form of a solution or a suspension in the test - Process can be introduced that tetrazolium salt is added to the solution or the suspension after the exposure time has elapsed, that the tetrazolium salt is reduced to a colored product, the formazan, by the enzyme dehydrogenase in the test microorganisms in accordance with the number of microorganisms still alive A measurement of the optical density caused by Formazan is carried out and that the result of this measurement is used to draw conclusions about the bactericidal activity of the tested substance and thus also about the number of test microorganisms which survived the exposure time of the tested substance.

5. The method according to claim 4, characterized in that due to the increase in the amount of formazan after an incubation period, conclusions are drawn about the number of microorganisms which have survived the exposure period of the tested substance, that the conclusions are drawn based on the measurement of optical density, that the microorganisms present in the suspension or in the nutrient solution are incubated for a first period of time, for example of 30 minutes, after which a first measurement of the optical density takes place, that the microorganisms present in the suspension or in the nutrient solution during a subsequent one , second period of time, for example of 30 minutes, that a second measurement of the optical density is carried out, and that the difference between the results of the measurements of the optical density is used to draw conclusions about the bactericidal action of the tested substance.

6. The method according to claim 4, characterized in that substances which can remove or neutralize detergent residues are added to the suspension before the tetrazolium salt is added to this suspension, that the microorganisms in this suspension for a predetermined period, for example of 1 hour , and are kept at a predetermined temperature, for example of 37 ° C, and that the tetrazolium salt is only added to the suspension after this incubation period.

7. Device for performing the method according to claim 1, characterized in that a container is provided in which the test microorganisms are included, that this container is designed so that the liquid can come into contact with the microorganisms in the container and that the microorganisms cannot escape from the container during the test process.

8. Device according to claim 7, characterized in that the container has a hollow base body, that the container is made of a material that is chemically and physically stable, that the base body of the container has at least one opening which the interior of the container connects with its surroundings that the opening can be covered by a wall made of a material, that a defined amount of microorganisms is attached to a carrier and that this carrier is located inside the container.

9. Device according to claim 7, characterized in that the container is substantially disc-shaped, that at least one opening is made in at least one of the large areas of the hollow disc-shaped base body of the container.

10. Device according to claim 8, characterized in that at least one opening is made in at least one large area of the hollow container base body, that a sterile filter is assigned to the inside of the respective large wall of the container and that the microorganisms are located between these two sterile filters, which are arranged practically parallel to each other.

11. Device according to claim 7, characterized in that it further comprises a photometer and a cuvette for receiving that suspension which has been removed from the container (90).