Antimicrobial adhesion surface

Details Antimicrobial adhesion surface Antimicrobial adhesion surface

1999-12-09

2002-10-22

Dixon, Merrick (Department: 1774)

Stock material or miscellaneous articles

Web or sheet containing structurally defined element or...

Weight per unit area specified

C428S340000, C428S413000, C428S420000

Reexamination Certificate

active

06468649

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a composition and a method for inhibiting adherence and growth of microorganisms on surfaces of implantable medical devices. More particularly, the present invention provides a substrate with a hydrophilic coating that becomes lubricous when contacted with an aqueous fluid to inhibit adherence and multiplication of microorganisms on the coating.
BACKGROUND OF THE RELATED TECHNOLOGY
There are a number of medical devices that are used in an environment where microorganisms, for instance bacteria, may be present on the surface of the device to cause device-related infection or biofilm formation. A few common, but nonlimiting, examples of such devices include ureteral stents, central venous catheters and ureteral catheters.
Bacterial colonization of indwelling and implantable medical devices may often lead to serious and sometimes fatal infections. For instance, urethral catheterization contributes to a high incidence of nosocomial urinary tract infections. Many patients who have an indwelling catheter for more than five days often develop a bacterial colonization of the bladder. Such colonization can lead to bacteremia, including septicemia, in hospitalized patients. Furthermore, the colonization of bacteria on the surfaces of a catheter may also result in the need to remove and/or replace the implanted device and to subsequently treat secondary infective conditions.
One technique to reduce microbial colonization on indwelling medical devices, such as catheters, is to impregnate the medical device with one or more antimicrobial agents to inhibit the growth of bacterial and fungal organisms, such as staphylococci, other gram-positive bacteria, gram-negative bacilli and Candida. Various methods have previously been employed to coat or impregnate antibiotics onto the surfaces of medical devices. Classes of antibiotics used include tetracyclines, rifamycins, macrolides, penicillins, cephalosporins, other beta-lactam antibiotics (i.e. imipenem, aztreonam), aminoglycosides, chloramphenicol, sufonamides, glycopeptides, quinolones, fusidic acid, trimethoprim, metronidazole, clindamycin, mupirocin, polyenes, azoles and beta-lactam inhibitors (i.e. sulbactam). For example, one method to coat a medical device is to simply flush the surface of the device with a solution of antibiotics.
Medical devices have also been coated with oligodynamic metals, such as silver, for use as antibacterial agents. For instance, catheters with silver impregnated in a soluble collagen or polymer coating are known. After these silver-coated catheters are placed at an in vivo location, the coating slowly dissolves to release silver ions which have a bactericidal effect against some types of bacteria. Furthermore, other iontophoretic medical devices use an electrical current derived from dissimilar galvanic materials to drive oligodynamic metal ions into solution to kill bacteria.
Furthermore, salicylic acid or its salts, and other nonsteroidal anti-inflammatory drugs (“NSAIDS”) have been used to retard the adherence of bacteria onto surfaces of medical devices, thereby preventing colonization of bacteria. Such materials may be coated onto or be impregnated into the surface of a medical device.
The practices of coating or incorporating antibiotics, oligodynamic metals, salicylates, NSAIDS and the like onto the surface of medical devices do not often provide long term efficacy. While such coated or impregnated surfaces may provide somewhat effective protection initially against bacteria, the antibacterial effectiveness declines over time. During the in vivo use of the medical device, the antibacterial materials leach from the surface of the device into the surrounding environment. Over a period of time, the amount of antibacterial material present on the surface decreases to a point where the protection against bacteria is no longer effective. Furthermore, the in vivo release of antibiotics, oligodynamic metals, salicylates, NSAIDS and the like may result in adverse effects in some patients under certain conditions.
Accordingly, there is a need for a medical device that can remain in vivo for extended periods of time without losing its antimicrobial efficacy. There is also a need for a medical device, such as a catheter, an implant, or other indwelling device, which provides protection against bacterial and fungal organisms for extended periods of time without leaching substances into a patient.
SUMMARY OF THE INVENTION
The present invention provides medical devices, such as implantable devices, catheters, guidewires and the like, having a substrate or a portion of a substrate with a hydrophilic coating composition. The hydrophilic coating composition becomes disaffinitive to microbes upon contact with an aqueous fluid to limit in vivo colonization of microbes for extended periods of time to less than 10,000 cfu/mm
2
thereat.
In one aspect of the present invention, the hydrophilic coating composition includes a hydrophilic polymer selected from copolymers acrylic acid, methacrylic acid, isocrotonic acid and combinations thereof. The hydrophilic polymer has a molecular weight in the range from about 100,000 to about 15 million. One useful hydrophilic polymer is an acrylamide-acrylic acid copolymer.
In another aspect of the present invention, the hydrophilic coating compositions inhibits primary adherence to medical devices of spherical bacterial, rod-shaped bacterial, spiral bacteria, fungi and combinations thereof.
In another aspect of the present invention, a method to limit in vivo the primary adherence of microbes of implanted medical devices is provided. The method includes coating a medical device with the hydrophilic polymer of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is an implantable medical device with a hydrophilic coating composition or surface to limit or inhibit adhesion of microbes or microorganisms thereat. The hydrophilic surface becomes disaffinitive to microbes upon contact with an aqueous fluid to limit microbial adherence. By inhibiting or limiting microbial adhesion, the risk of infection associated with indwelling medical devices is reduced. The present invention also includes a method for limiting microbial adherence to the surfaces of medical devices.
As used herein the terms “microbe”, “microorganism” and their variants are used interchangeably and refer to unicellular or small multicellular organisms, including bacteria, fungi, protozoa and viruses. As used herein, the terms “bacteria” and “fungi” refer to all genuses and species of bacteria and fungi, including but not limited to all spherical, rod-shaped and spiral bacteria. Some nonlimiting examples of bacteria are staphylococci (i.e.
Staphylococcus epidermidis, Staphylococcus aureus
),
Enterrococcus faecalis, Pseudomonas aeruginosa, Escherichia coli
, other gram-positive bacteria and gram-negative bacilli. One example of a fungus is
Candida albicans.
Generally, microorganisms can exist in two distinct physical states. In a planktonic or floating state, microbial cells function as individuals. In an sessile or adherent state, the microbial cells attach to a surfaces (primary adherence) and multiply in quantity (colonization) on the surface of the medical device.
Many bacteria and fungi have surface polysaccharides. These surface polysaccharides generate a glycocalyx that surrounds the microbe and portions of the adhering surface. The glycocalyx consists of a mass of long polysaccharide fibers. This mass is often referred to as a extracellular slime or simply a slime. The production of surface polysaccharide or slime by an microorganism enables it to adhere to surfaces of insertable or implantable devices. The glycocalyx surrounds individual microorganisms or colonies of microorganisms offering protection against phagocytes and biocides while also providing a suitable environment for the transport of nutrients.
As the microorganisms multiple, a biofilm or a dense population of microorganisms is formed on a surface of a medical device. Groups

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