WO2000015288A1

WO2000015288A1 - Antimicrobial urinary catheter

Info

Publication number: WO2000015288A1
Application number: PCT/US1999/021579
Authority: WO
Inventors: Don E. Heskett
Original assignee: Kdf Fluid Treatment, Inc.
Priority date: 1998-09-17
Filing date: 1999-09-17
Publication date: 2000-03-23
Also published as: AU5928299A

Abstract

An antimicrobial urinary catheter (10) is disclosed in which metal rings (24) of copper, and zinc are spaced long the length of the catheter which is to be positioned in the urethra of the patient to prevent migration, and growth of infectious microbes in the urinary tract.

Description

ANTIMICROBIAL URINARY CATHETER

BACKGROUND AND SUMMARY OF INVENTION The present invention relates to urinary catheters and, more particularly, to a urinary catheter and method of forming such catheter to prevent microbial migration and growth along its length when the catheter has been placed in the urinary tract of the patient.

When urinary catheters are placed in patients for considerable periods of time, there is a tendency for the patient to develop urinary tract and/or bladder infections. It is believed that such infections are the result of the migration of undesirable microbes, such as bacteria, reversely through the urethra and to the bladder. Normally, urine is sterile and bacteria-free and, in the absence of such catheter, functions to flush the urethra when the urine is discharged on a regular, normal basis so that any bacteria which may tend to enter the urethra will be removed before it can grow or migrate to the bladder. However, when a urinary catheter is installed, the urine which would otherwise flush the urethra will instead be diverted to pass through the fluid passage in the catheter. Yet, the tissue in the urethra outside of the catheter remains moist with the body's physiological fluids and thereby provides a pathway for the growth and reverse migration of undesirable bacteria which would have otherwise been flushed during normal urine discharges in the absence of the catheter.

It is a principal purpose of the present invention to provide a urinary catheter which is antimicrobial in nature to prevent the growth and reverse migration of undesirable microbes, such as bacteria, which might result in urinary tract and/or bladder infections where the urinary catheter has been placed in the urinary tract of the patient for some considerable periods of time. It is known that pure copper zinc alloys, e.g. brass, are capable of inactivating microbial proteins to provide an action to control and kill bacteria, fungi and algae in aqueous systems. For example, it is known that if water is treated by passing it through a bed of copper zinc alloy particles, a substantial reduction of microbial activity is enjoyed. See U.S. Patent No. 5,599,454 of Heskett.

It is a purpose of the present invention to position metals of copper and zinc alloy in a urinary catheter in a manner so as to create a barrier in the urinary tract of the patient which will reduce or postpone the motility for migration or growth of certain microbes, such as bacteria, which might otherwise give rise to urinary tract and/or bladder infections. Another purpose of the present invention is to achieve these results while utilizing more solid and readily managed forms of these metals, rather than the finely divided particulates discussed in the aforementioned patent. Still another purpose of the present invention, is to provide a method of forming a urinary catheter which is simple and effective to achieve the aforementioned purposes.

In one principal aspect of the present invention, a urinary catheter comprises an elongate, flexible stretchable tube having an exterior surface which has an external diameter which permits insertion of the tube through the urethra of a person with an end of the tube in the bladder of the person, a fluid flow passage through the interior of the tube, and an opening adjacent the end of the tube communicating with the passage for discharging urine from the bladder through the passage. An area of metal adjacent the exterior surface of the tube is positioned longitudinally along the tube in spaced relationship to the opening by a distance so that the area of metal will be positioned in the urethra when the opening is positioned in the bladder of the person, and the area of metal inhibits the migration and growth of microbes along the tube and toward the bladder. In another principal aspect of the present invention, an inflatable balloon is located adjacent the end of the tube between the opening and the area of metal for retaining the opening in the bladder and the area of metal in the urethra.

In still another principal aspect of the present invention, the metal in the area of metal comprises copper and zinc, and is preferably an alloy thereof.

In still another principal aspect of the present invention, the weight ratio of copper to zinc is between about 9:1 and 1:9, and preferably is about 1:1.

In still another principal aspect of the present invention, the area of metal comprises at least one metal ring encircling said tube.

In still another principal aspect of the present invention, the exterior surface of the tube is larger in diameter than the maximum diameter of the ring.

In still another principal aspect of the present invention, the exterior of the ring is crowned.

In still another principal aspect of the present invention, a method of forming a urinary catheter comprises providing an elongate flexible catheter tube which is of an external diameter which is capable of being inserted into the urethra of a person with an end of the tube in the bladder of the person, and depositing at least one area of metal adjacent the exterior surface of the tube and in spaced relationship to the end of the tube which is to be positioned in the bladder by a distance so that the area of metal will be positioned in the urethra when the end of the tube is positioned in the bladder.

In still another principal aspect of the method of present invention, the area of metal comprises at least one ring of metal, and the ring is positioned on the tube by stretching the tube to reduce its diameter, positioning the ring over the tube in substantially the spaced relationship to the end of the tube, and relaxing the tube to expand the tube into the ring to hold the ring in position in the aforementioned relationship.

In still another principal aspect of the method of the present invention, after the ring is positioned over the tube the tube is relaxed by an amount sufficient for its exterior surface to expand to a diameter which is larger than the diameter of the exterior surface of the ring.

In still another principal aspect of the method of the present invention, the weight ratio of copper to zinc is between about 9:1 and 1:9, and preferably is about 1:1.

These and other objects, features and advantages of the present invention will be more clearly understood through a consideration of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWING

In the course of this description, reference will frequently be made to the attached drawing in which:

FIG. 1 is a broken, plan view of an antimicrobial urinary catheter constructed in accordance with a preferred embodiment of the present invention;

FIG. 2 is a perspective, enlarged view of one of the antimicrobial metal rings of the invention, substantially as seen in FIG. 1,

FIG. 3 is a broken, enlarged view of a section of the catheter substantially as shown in FIG. 1, and showing one bactericidal ring positioned thereon; and

FIG. 4 is a cross-sectioned elevation view of the catheter, as viewed substantially along line 4-4 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT With particular reference to the drawing, a urinary catheter typically comprises an elongate flexible tube 10 formed of a suitable polymer which is resistant to physiological attack. The lead end 12 of the tube 10 of such catheters typically includes an opening 14 which communicates with a passage 16 which extends longitudinally through the tube 10 to conduct urine from the opening 14 through the catheter tube to a suitable collection bag (not shown) . The tube 10 has an external surface which is of a diameter and nature to permit the tube 10 to be slidably installed through the urethra of the patient, and so that the lead end 12 with its opening 14 is positioned in the bladder of the patient to continuously drain urine as it collects in the bladder from the bladder through the opening and passage 16.

As is also conventional in urinary catheters, an inflatable balloon 18 is positioned adjacent the lead end 12. A small passage 20 extends preferably through the wall of tube 10, as seen in FIGS. 3 and 4, to communicate the balloon 18 with the exterior of the patient's body to permit a fluid to be introduced through the passage 20 to the balloon 18 to inflate the balloon once the catheter lead end 12 has been positioned in the bladder. When the balloon 18 which is also positioned in the bladder is inflated, it holds the catheter against inadvertent removal from the bladder and urethra.

As previously discussed, when catheters of the kind just described have been installed for some period of time, there is some tendency for the urinary tract, i.e. the bladder and/or urethra, to become infected. It is believed that this tendency for infection is the result of the growth and migration of undesirable microbes, such as bacteria, reversely through the urethra to the bladder about the outer exterior surface 22 of the tube 10 and the inner tissue wall of the urethra through the physiological fluids which are present in that space while the catheter is in place. This migration and growth would normally be prevented in the absence of the catheter by the normal flushing of the urethra which occurs periodically in the exercise of normal bodily functions. However, where a catheter has been placed, this flushing does not occur because the urine which would otherwise normally flush the urethra wall does not contact that wall because it is diverted through the fluid passage 16 in catheter, rather than around the catheter between its outer surface 22 and the wall of the urethra. Accordingly, there is a possibility that undesirable microbial growth and migration may occur through this space in the physiological fluids that are normally present there, and this can result in infections of the urethra and bladder.

In the present invention, this undesirable microbial growth and migration is precluded by providing areas of metal at the outer surface 22 of the catheter tube 10. In the preferred form of the invention, these areas of metal take the form of one or more rings 24 which are spaced longitudinally along the length of the catheter tube 10, as best seen in FIG. 1. These rings 24 are spaced away from the opening 14 and inflatable balloon 18, the latter of which are positioned so as to be in the patient's bladder when the catheter has been installed. The rings 24 are positioned relative to the balloon so that the rings 24 will be located in the patient's urethra when the opening 14 and balloon 18 are in the bladder.

The rings 24 are preferably formed of copper and zinc due to the excellent antimicrobicidal properties of those metals, and they are preferably an alloy of brass. The weight ratio of copper to brass may range between about 1:9 to about 9:1, and is preferably about 1:1. The rings 24 are preferably positioned on the catheter tube 10 by stretching the tube so that its diameter is reduced, as shown in dot and dash at 10' in FIG. 1, slipping the rings 24 over the reduced diameter stretched tube 10' to the positions in which they are to be located, and then relaxing the tube so that it expands to its normal larger diameter, thereby trapping the rings at their desired location. The rings 24 are preferably slightly crowned at 26 to facilitate their slidable insertion into and removal from the urethra with the catheter, and the maximum diameter at the crown 26 of the rings is preferably slightly less than the maximum diameter of the outer surface 22 of the tube to minimize direct contact of the metal with the wall of the urethra. Thus, it will be seen that the rings 24 effectively provide microbial barriers to the mobility and growth of infectious microbes up the urethra to the bladder of the patient, thus substantially minimizing the possibility of urinary tract infections in the patient.

The following tests demonstrate the efficacy of the present invention.

Flat bands of metal alloy of brass formed of copper and zinc in approximately a 1:1 ratio to each other and measuring 300 x 10 x 2 mm were sanitized by immersion into a 70% ethanol solution. The bands were allowed to dry completely in a sterile plastic petri plate before use. To form the test blocks a sanitized band was placed on a sterile petri plate between two 200 mm wide sterile agar sections of Difco Motility Test Medium (10 g. Bacto Tryptose, 5 g. sodium chloride and 5 g. Bacto Agar) which were cut from poured plates of motility medium. Each band was placed approximately 1 mm below the motility medium surface, leaving a "well" over the band and between the exposed edges of the motility medium sections adjacent the band of 1 mm depth and 2 mm width. The section of motility medium on each side of the band in each block was approximately 50 millimeters wide. A sterile saline buffer solution similar to physiological saline was pipetted onto the surface of each of the bands to a height of approximately 1 mm to fill each well. A petrolatum seal was placed on the end of each band to prevent the saline from running out of the ends of the "well".

Microorganisms used to determine motility inhibition were reconstituted from lyophilized cultures and grown on tripticase soy broth prior to use. The following pure cultures (Microbiologies, St. Cloud, MN) traceable to American Type Culture Collection stock microorganisms were used in the test: Proteus mirabilis (ATCC7002) Morganella morganii (ATCC25830) Serratia marcescens (ATCC8100) Providencia stuartii (ΑTCC33672) Candida albicans (ATCC 10231) Escherichia coli (ATCC 4157) Staphylococcus aureus (ATCC33862)

In addition, a culture of Pseudomonas aeruginosa isolated from a fresh water source was also used in this test.

Eight blocks of motility medium with the band was used, one for each of these eight respective cultures. One drop (approximately 0.05 ml) of a log culture of the microorganism was placed on the surface of the motility medium section on one side of band, with the band and saline well bisecting the middle of each block. The petri plates containing the inoculated motility medium blocks with the bands were incubated at 35° C for 24 and 48 hours. For each of the eight microorganisms tested, one motility block without a band, i.e. eight more blocks, was inoculated and incubated under identical conditions to serve as a positive motility control. One uninoculated block was also incubated as a negative control.

The motility blocks were observed at 24 and 48 hours. Growth and motility was observed to occur on all microorganisms on the positive control blocks without the bands and at the inoculation end section of each test block. No growth was observed in the negative control block.

No growth and/or motility of the test microorganisms across the bands was observed on any of the eight test blocks with the bands at 24 or 48 hours of incubation.

It will be understood that although the term "microbe" as employed herein has been described with reference to bacteria, the term is not intended to be limited to only bacteria, but may also include other microscopic organisms such as fungi, etc. It also will be understood that the preferred embodiment of the present invention which has been described is merely illustrative of the principles of the invention. Numerous modifications may be made by those skilled in the art without departing from the true spirit and scope of the invention.

Claims

I CLAIM ;

1. A urinary catheter, comprising: an elongate, flexible stretchable tube having an exterior surface which has an external diameter which permits insertion of the tube through the urethra of a person with an end of the tube in the bladder of the person; a fluid flow passage through the interior of said tube, an opening adjacent said end communicating with said passage for discharging urine from the bladder through the passage; and an area of metal adjacent said exterior surface, said metal being positioned longitudinally along said tube in in spaced relationship to said opening by a distance so that said area of metal will be positioned in the urethra when said opening is positioned in the bladder of the person, said area of metal inhibiting the migration and growth of microbes along said tube and toward the bladder.

2. The catheter of claim 1, including an inflatable balloon adjacent said end of said tube between said opening and said area of metal for retaining said opening in the bladder and the area of metal in the urethra.

3. The catheter of claim 2, wherein the metal in the area of metal comprises copper and zinc.

4. The catheter of claim 3, wherein said copper and zinc is an alloy.

5. The catheter of claim 3, wherein the weight ratio of copper to zinc is between about 9:1 and 1:9.

6. The catheter of claim 5, wherein said ratio is about 1:1.

7. The catheter of claim 2, wherein said area of metal comprises at least one metal ring encircling said tube.

8. The catheter of claim 7, wherein said ring comprises copper and zinc.

9. The catheter of claim 7, wherein the exterior surface of said tube is larger in diameter than the maximum diameter of said ring.

10. The catheter of claim 7, wherein the exterior of said ring is crowned.

11. The catheter of claim 1, wherein the metal in the area of metal comprises copper and zinc.

12. The catheter of claim 11, wherein said copper and zinc is an alloy.

13. The catheter of claim 11, wherein the weight ratio of copper to zinc is between about 9:1 and 1:9.

14. The catheter of claim 13, wherein said ratio is about 1:1.

15. The catheter of claim 1, wherein said area of metal comprises at least one metal ring encircling said tube.

16. The catheter of claim 15, wherein said ring comprises copper and zinc.

17. The catheter of claim 15, wherein the exterior surface of said tube is larger in diameter than the maximum diameter of said ring.

18. The catheter of claim 15, wherein the exterior of said ring is crowned.

19. A method of forming a urinary catheter, comprising: providing an elongate flexible catheter tube which is of an external diameter which is capable of being inserted into the urethra of a person with an end of the tube in the bladder of the person; and depositing at least one area of metal adjacent the exterior surface of the tube and in spaced relationship to the end of the tube which is to be positioned in the bladder by a distance so that the area of metal will be positioned in the urethra when the end of the tube is positioned in the bladder.

20. The method of claim 19, wherein the area of metal comprises at least one ring of metal, and the ring is positioned on the tube by stretching the tube to reduce its diameter, positioning the ring over the tube in substantially said spaced relationship to the end of the tube, and relaxing the tube to expand the tube into the ring to hold the ring in position in said spaced relationship.

21. The method of claim 20, wherein said tube is relaxed by an amount sufficient for its exterior surface to expand to a diameter which is larger than the diameter of the exterior surface of the ring.

22. The method of claim 20, wherein said metal comprises copper and zinc.

23. The method of claim 22, wherein said metal is an alloy.

24. The method of claim 22, wherein the weight ratio of copper to zinc is between about 9:1 and 1:9.

25. The method of claim 24, wherein said ratio is about 1:1.

ΓÇö26. A method of inhibiting the growth of microbes in a liquid comprising contacting the liquid which contains the microbes with a solid surface area of a metal comprising copper and zinc.

27. The method of claim 26, wherein said solid surface area is continuous and of substantial size.

28. The catheter of claim 26, wherein the metal comprises copper and zinc.

29. The catheter of claim 28, wherein said copper and zinc is an alloy.

30. The catheter of claim 28, wherein the weight ratio of copper to zinc is between about 9:1 and 1:9.

31. The catheter of claim 30, wherein said ratio is about 1:1. ΓÇö