8 The invention relates to the development of a specialized sterilization 9 indicator thnt yields post sterilization evidence of attainment of certQin sterilizationll 10 parameters by: (1) the change of a chemical indicator to give immediate visual I
11 ¦ indication of achievement of the desired temperature, and (2) biological verificationl 12 of the destruction of the spores conta;ned therein by the subsequent incubation of ¦
13 these indicator organisms. The specification of the chemical indicator, or melt pellet¦
14 in the sealed glass vial is such that the change takes place after achieving the desired 15 sterilization temperature, i.e. 250 F (121 C), 270 F (132 C), or 285 F (141 C), for a 16 defined period of time, thereby providing visual evidence of achieving sterilization 17 temperature. The biological indicator ampule contains a growth promoting culture 18 medium with a pH indicator or a vital dye selected for the indicator organism and 19 spores of known heat resistance. Change of the pH indicator present in the culture 20 medium and turbidity of the media following incubation are evidence for non-sterility, 21 whereas no color change and lack of turbidity after incubation are evidence for sterility.
22 Three novel applications of this invention are as follows:
23 1. There are, at present, two generally known means for monitoring the 24 ¦ efficacy of a solution sterilization cycle, neither of which is easily carried out. The 26 1I first and most difficult would be seeding a solution to be sterilized with a known 26 l~ amount of spores, sterili~ing the container of solution, recovery and concentration of 27 ¦¦ the spores, and determination of the viability of the spores by various microbiological 28 ¦¦ means.
29 ¦~ 2. The second generally known method would be to fill a solution flask with 30 1 culture medium, seed the media with spores of a known resistance, sterilize the 31 1 container of medium and incubate the -solution flask to determine viability of the 32 ¦ spores following the sterilizati~n cycleO This method has ~he disadvantages of requiring
2 ~:
~ 170~2 1 immediate use of the culture medium to preclude the growth of adventitious¦
2 microorganisms and is costly due to the large quanti~ies of culture medium which~
3 ¦ must be used for such tests. Storage of this type of test container al~o presents al
4 1 I problem in incubation due to their bulk.
I This invention is applicable to monitoring steriliz~tion of solutions by 6 placement of the indicators directly in one or more of the containers of solution being 7 sterilized. Usually one or more of the indicators is employed to monitor a solution~
8 sterilization cycle. It provides a compact and easy-to-use sterilization indicator which j 9 can be evaluated at the point of use, thereby eliminating~ the involved procedures and 10 speeialized equipment required in the commonly used methods described abo~e.
11 3. There is presently no acceptable method for evaluating the efficacy of 12 a washer-sterilizer cycle, due to the filling of the sterilizer ~vith water, or water 13 sprays, during a portion o~ the washer-sterilizer cycle. Such action does destroy the 14 integrity of the packaging commonly used in spore strip type indicators, thus making~
15 them susceptible to post sterilization adventitious contamination and false sterilization 16 test results. The system disclosed herein allows the retention of the stability of the 17 biological and chemical indicator until the sterilization cycle is completed. Placement 18 ¦ of this combined indicator may be accomplished by various means of anchorage, i.e., 19 ¦ tape, clips, or implantation in goods.
20 ¦ Other prior art applications may also be applicable to such a combined and 21 biological system. Such applications might be placement in challenge packs or within 22 other portions of a sterilizer load or such indicators may be used in the evaluation of 23 a dry heat sterilization means.
25 l ' REFERENCE TO P~IOR ART
26 ¦ 1 United States Patent No. 2,854,384 shows a glass ampule conaining two 27 ~ compartments separated by an aperture partition. The aperture is closed by a meltable 28 plug. One compartment contains spores and ~e other contains a culture media.
29 During sterilizdtion, the plug melts and falls into the culture media allowing the spores 30 ¦ to enter the culture media for incubation.
31 Unitefl States Patent No. 3,440,144 discloses an apparatus for testing 32 sterilization including a bag containing a glass ampule with culture medium therein and i 3 ~1'7~ S~
1 a spore strip in the bag. After sterilization, the operator can breal~ the glass ampule~
2 allowing the culture medium to join the spores for incubation.
3 ¦ United States Patent No. 3,661,717 shows a unitary indieator much like the 4 ! preceding indicator.
United States Patent NoO 2,99g,306 shows a spore strip of a common variety.
6 None of the forementioned patents combine both an immediate visual 7 indicator and the confirming biological sterilization indicator.
9 OBJECTS OF T~IE INVENTION
It is ~n object of the present invention to provide an improved sterilization 11 indicator.
12 Another object of the invention is to provide a sterilization indicator that 13 is simple and efficient to use.
14 Another object of the invention is to provide a self-contained indicator system, which is capable of being evaluated and incubated at the point of use, thus 16 1 eliminating procedures requiring a laboratory and microbiologist.
17 Another object of the invention is to provide a sterilization indicator wherein 18 a chemical indicator is isolated from culture media in a sealed glass ampul~. The 19 chemical indicator changes when the ambient media has reached a predetermined temperature level and the media containing spores can be subsequently incubated,21 thereby giving proof positive of the success of the sterilization cycle.
2~ With the above and other objectives in view, the present invention consists 23 of the combination and arrangement of parts hereinafter more fully described, 24 ¦ I illustrated in the acccompanying drawing and more particularly pointed out in the ~5 l l appended claims, it being understood that changes may be made in the form, size, 26 ~ proportions and minor details of construction without departing from the spirit or 27 1 saerificing any of the advantages of the invention.
28 Construction of the indicator is not limited to the chemical indicator being 29 ~ located within the sealed ampule nor within the culture medium. Similar results may 30 1 also be realized by placement of the chemical indicator externally, either separated 31 or attached to the container of culture medium.
170~
2 Figure 1 is a side view of the sterilization ind;cator according to th 3 invention.
4 Figure 2 is a view of the sterilization indicator in a container of solutior to be sterilized.
6 Figure 3 is an enlarged view of the inner vial of the sterilization indicato 7 showing the meltable pellet therein.
8 Figure 4 ;s a view of another embodiment of the invention.
9 Figure 5 is a view of yet another embodiment of the invention.
Figure 6 is a view of another embodiment of the invention.
11 ¦ Figure 7 is a view of another embodiment of the invention. I
12~
14 Now, with more particular reference to the drawings and ~igure 2, th~
invention of the sterilizing indicator is supported in the container 10 which contain~
16 a solution 11 to be sterilized. The combination chemical and biological indicator 12 1q is suspended in the solution 11 by means of a cord 19 supported on the closed end 2C
18 of the combination chemical and biological indicator 12 and attached to the cap 17 19 of the container.
The chemical and biological indicator 12 is made up of an ampule 14, which 21 may be made of glass, sealed with an incubation medium 13 therein, which is a suitable 22 broth that may contain an indicator. E~amples of indicators are pH indicators such 23 as phenol red or brom cresol purple or vital dyes, such as triphenyl tetrazolium chloride.
24 The inner tube 15 is hollow and contains a melt pellet 16. The melt pellet 25 11 16 is loosely rec~eived on the inside of the tube. The melt pellet 16 is adapted to meltl 26 ~ at a predetermined temperature, for example, 250 F, 270 F, or 285 ~ or at some¦
27 I suitable temperature. The broth, or incubation medium, 13 will also contain spores ol 28 a predetermined variety, such as B. stearothermophilus or some other suitable spores.¦
29 The melt pellet 16 may be isolated ~ince it may contain chemical materials that might~
30 be inhibitory to the spores or cidal to the bacterial growth and, therefore, interfere¦
32 with the accuracy of the tests if they were not sealed up in the inner tube 15.
s q 1 ~ 5 ~, When the con~ainel l~ of solution to be ster~ ed is pl~ced in a ste~m 2 sterilizer or suitable thermal controlled chamber and brought up to temperature, and 3 ~ when the central part of the solution reaches a temperature at which the pellet lB
4 will melt, the pellet will melt and this will be visible from outside the container. If!
the melt pellet has not melted, the op~erator is immediately notified that the cycle¦
6 1 was not successful and can resterili~e the solution. Then, when the combination 7 ~ chemical and biological indicator 12 is removed from the container 10 and incubated, 8 if the spores are viable, the vital dye will visually turn color ~nd turbid. If a pH
9 1 indicator is used, viable spores will also cause the solution to change color. If at the 10 1 end of the incubation time, the spores are not viable, no change in clarity, no change 11 ¦ in vital dye or color change will occur and a successful cycle is proven.
12 ¦ The biological test indicator could be used in a washer-sterilizer or other 13 apparatus when it is desirable to get a preliminary indication of the success of a 14 sterilizing cycle. If the pellet is melted, the operator knows immediately that the 15 challenge part of the load has reached sterili~ing temperature and can incubate the 16 indicator to verify the success of the cycle. If the pellet is not melted, the load 17 ¦ can immediately be resterilized.
18 I In the embodiment of the invention shown in Figure 4, we show a biological 1~ I indicator 112, which may be suspended in a solution, such as the solution 11 in Figure 20 ¦ 2. The chemical indicator 112 is made up of an ampule 114, which may be made of 21 I glass, sealed at 120 with an incubation medium 113 therein. This incubation medium 22 ¦~ may be a suitable broth that may contain an indicator. The indicator may be a pH
23 1 indicator, triphenyl tetrazolium chloride or other suitable indicator. The melt pellet 24 jl 116 is adapted to melt at a predetermined temperature, for example, 150 F., 270 F., 25 11 or 285 F. indicating that sueh temperature h~ been reached. The broth or incubation 26 j medium 113 will contain spores of a suitable variety.
27 I Referring to the embodiment of Figure 5, this embodiment of the biological 28 ~ chemical indicator 212 has an upper closed end 220 and contains a broth or incubation 29 medium 213 and a melt pellet 216 is supported inside the container 214.
Referring to the embodiment of the invention of Figure 6, the chemical ~1 biological indicator 312 shows a container 314 contalning a broth 313 and having al 32 suitable temperature indicating material 316 thereinO This could be a filter paper with i O l S 2 1 a temperature sensitive material painted onto it or it could be a material that melts 2 at the predetermined temperature. The ~enclosure 317 separates the material 316 from~
3 the broth 313.
4 In the embodiment of the invention shown in Figure 7, we show the chemical¦
and biological indicator 412 containing the incubation medium 413 inside of the outer~
6 ~ container 414. The container 416 is af Eixed to the outside surface of the container ¦
7 414 and the temperature indicator 417 is housed in the container 416. When the ~
8 temperature surrounding the container 414 reaches a predetermined temperature, thel 9 indicator material 417 wiU so in~licate.
The foregoing specification sets forth the invention in its preferred, practical~
11 forms but the structure shown is capable of modification within a range of equivalents¦
12 without departing from the invention which is to be understood is broadly novel as is¦
13 commensurate with the appended claims.
l8 2a~
31 l