RELD OF THE INVENTION

This invention relates generally to the formation of an antimicrobial composition that is highly effective against microbial infestation of acute and chronic wounds. The antimicrobial ge is related to the water-based soiution in composition, but has a higher viscosit because of added viscosity enhancing or gelling agents,

BACKGROUND OF THE INVENTION

The primary function of non-compromised, intact skin is to control the various microbes that reside on the skin surface, thus preventing underlying tissue from being colonized by potentially pathogenic species. When a wound occurs, subcutaneous tissue is exposed, leading to a moist, nutritious environment for microbial colonization and proliferation. Wound colonization is often polymicrobial, involving organisms that are potentially pathogenic, if Infection occurs, particularly for chronic wounds, the wound may fail to heal. The consequences of this occurrence are traumatic for the patient, with greatly increased medical expenses.

Chronic wounds include pressure ulcers, diabetic foot ulcers, and venous leg ulcers. These wounds are difficult to heal and contribute to persistent individual health problems as well as markedly increasing health care costs. It is believed that bacteria colonizing chronic wounds exist as highly persistent biofilm communities (G.A. James, et ai., Wound Repair Regen., 16(1), 37-44, 2008). Biofllm formation appears to be an important contributing factor in delayed wound healing.

it does not appear that the bacteria present on the surface of chronic wounds are present as pianktonic ceils or even simple primary attachment modes. Rather, such

colonization is believed to be by biofilm formation, often of mixed microbial species within a matrix of extracellular hydroprtilic polysaccharides. Bacteria living In a biofilm have significantly different properties from planktonic bacteria, as the protected environment of the polymer coating allows them to cooperate and interact, A biofilm has the ability to neutralize host defenses and commandeer host systems, and possesses a vast array of defenses and virulence factors. One feature of this environment is increased resistance to detergents and antibiotics, as the dense extracellular matrix and the outer layer of cells protect the interior of the community. While biofilms are commonly present on chronic wounds, they are iess prominent on acute wounds. Clinically, there is a significant difference in the healing behavior between chronic wounds and acute wounds, with the latter being more facile. Suppression of the biofi!m bioburden using multiple simultaneous strategies including debridement, anii-biofilm agents, specific biocides, antibiotics and advanced technologies does enhance wound healing.

Wounds are an ideal environment for the formation of biofilm communities because of their susceptibility to contamination and the availability of substrate and nutrients for biofilm attachment. Chronic wound infections share two important attributes with other biofilm diseases: persistent infection that is not cleared by the host immune system, and resistance to systemic and topical antimicrobial agents. In the absence of a biocidal wound cleanser solution, frequent debridement is often a clinically effective treatment to help heal chronic wounds.

Biofilms reportedly cause an estimated 1 million nosocomial infections each year in the United States. Both aerobic and anaerobic bacteria have been found. Some studies have isolated the most common microorganism {Staphylococcus epidermidis) that triggers biofilm infections, while many other organisms have been isolated, Common bacteria found in biofilms include Gram positive Enterococcus f calis, Staphylococcus aureus, Micrococcus sop, and beta-h&moiytlc Streptococcus ($. pyogenes, S. agaiactiae) as weii as Gram-negative bacteria of Escherichia co!i, Klebsiella pneumoniae _. , Proteus mirabiiis, Pseudomonas aeruginosa,

Acinetobact&r bawnanmi and Sienoirophomonas maitophilia.

In addition to biofilms In chronic wounds, biofilms are involved i approximately 80% of ail chronic human infections and 65% of ail hospital-acquired infections. Biofilms are responsible for otitis media, the most common acute ear infection. Biofilms are also Involved in bacterial endocarditis, an infection of the inner surface of the heart and its valves. Biofilms are also found in patients with cystic fibrosis, a chronic disorder resulting in Increased susceptibility to serious lung Infections. Additionally, biofilms are also reported to be involved with Legionnaire's disease, an acute respiratory infection resulting in Legionnella biofilms, a ubiquitous aquatic organism that can be present in air and water heating/cooling and distribution systems. Biofilms are also involved with periodontal disease, dental plaque, transplant infections, infections of indwelling medical devices (e.g. , catheter, prostheses), contaminated clinical surfaces and reusable instruments.

For healing of acute and chronic wounds colonized by microorganisms, proper cleaning is essential. Most commercial wound cleansers are based predominantly upon surfactant cleaning and are designed to soften and remove necrotic tissue and debris. These aqueous solutions have used a surfactant with or without a preservative, with or without a buffer, and with or without a chelating agent.

U.S. Patent Publication No. 2004/0059008 describes a disinfectant composition comprising 1~(2-ethylhexyl)gi ceroi ether (octoxyglycerin, Sensiva® SC 50) and one or mor aromatic alcohols, such as ary!oxyafkanois, oligoalkanol aryl ethers or aryialkanois. The composition is said to be useful for controlling mycobacteria. No studies were performed on Mycobacterium biofilms.

U.S. Patent 8,106,854 discusses a liquid that has germicidal and biofl!m cleansing properties, comprising an anti-infective, an antiseptic agent, and an anti-biofllm agent, a water purifying agent, a sanitizer and a bactericide, wherein the bactericide includes chiorhexidlne in a concentration of 10.0 % to 23.0 % of the disinfectant concentration.

U.S. Patent 6,143,244 discusses compositions for cleaning and disinfecting contact tenses wherein a polymeric biguanide is used in combination with bis(biguanides) as

disinfectants, which will reduce microbial bioburden by two log orders in four hours and preferably by one log order in one hour. The examples utilize 0.8 ppm (0.00008 wt %) poiy hexamet yiene biguanide) and 2 ppm (0.0002 wt %) of aiexidine. This low concentration of biguanide is used in a regimen procedure according to FDA Chemical Disinfection Efficacy Test-July, 1985, Contact Lens Solution Draft Guidelines, utilizing bacteria in colony forming units and does not evaluate the efficacy against bacterial biofilms,

U.S. Patent 8,846,846 and U.S. Patent Application Number 2010/0305211 discuss a combination of a biguanide and a branched monoatkyl alcohol, namely octoxyglycerin,

(Sensiva® SC 50, glycerol 1-(2-eihylhexyl ether), or 1-{2-ei yfhexyi)glycerin), for use as a gentle-acting skin disinfectant. Additional Ingredients, particularly quaternary ammonium compounds, and particularly benzaikonium chloride, are shown to be effective against bacteria in colony forming units. This patent and application do not discuss the use of a biguanide and a branched monoalky! glycol In eliminating a bacterial bioflim.

Octoxyglycerin Is sold under the trade name Sensiva© SC 50 (Schulke & Mayr). It is a branched, glycerol monoaikyl ether known to be gentle to the skin and to exhibit antimicrobial activity against a variety of Gram-positive bacteria, such as Micrococcus iuteus,

Goryn&bacterium aquaticum, Corynebacierium flavescens, Coryn ^' ebaoterium caHunae, and Cor/nehacteriu nephredl. Sensiva© SC 50 is used in various skin deodorant preparations at concentrations between about 0.2 (2,000 ppm) and 3 weight (wt) % (30,000 ppm).

In U.S. Patent Application Number 2007/0287752, an aqueous ophthalmic composition comprising a branched glycerol monoaikyl ether, such as Sensiva© SC 50, present in a total amount of from 0.05 ppm (0.000005 wt %) to 1 ,000 ppm (0.1 wt %), and an antimicrobial agent, including poly(hexamethylene biguanide) and alexidine, at a concentration of from 0.01 ppm (0.000001 wt % to 100 ppm (0.01 wt %), with a preference at 3 ppm (0,0003 wt %}, where the presence of the branched glycerol compound enhances the biocidal efficacy of the aqueous ophthalmic composition. The compositions are used as a disinfecting solution, a preservative- solution or packaging solutio for contact lenses. No biocidal studies were conducted on biofiim.

U.S. Patent 7,670,99? discusses an aqueous ophthalmic composition and method of inhibiting the formation of foam: in an aqueous ophthalmic composition that includes a surfactant, comprising a branched, glycerol monoaikyl compound and a fatty acid monoester with an antimicrobial agent such as aiexidine, ch!orhexidine or poly{hexamethylene biguanide). The fatty acid monoester comprises an aliphatic fatty acid portion having six to fourteen carbon atoms and an aliphatic hydroxy! portion, with decanoyiglycerol being preferred. In a tens care solution, poly{hexamethyiene biguanide) is used in concentration of from 0.01 ppm (0.000001 wt %) to 3 ppm (0.0003 wt %} with alexidine at a concentration of 4.5 ppm (0.00045 wt %}, including Sensiva® SC 50 at a concentration of 0.15 wt % (1 ,500 ppm) and decanoyiglycerol at a concentration of 0.12 wt % (1 ,200 ppm). Synergistic biocidal activity towards colony forming units of Candida albicans and Fusarium soiani is reported for interactions of the branched, glycerol monoaikyl compound and the fatty acid glyceryl monoester, No studies were conducted on biofiim with these ingredients.

U.S. Patent Application Publication 2008/0051385 discusses a method of killing or inactivating microorganisms on mammalian tissue by an antiseptic, a hydrophiiic component, a surfactant, and a hydrophobic vehicle, where the antiseptic includes biguanides and

bisblguanides. This study did not include an analysis of biofiim elimination.

U.S. Patent App!ication Publication 2007/0282008 A1 discusses a polymeric biguanide or a bts(biguanide) compound, a chelating agent and a buffering agent for the prevention or treatment of skin and ear tissue infections. The antiseptic behavior of bis(biguanides). such as alexidine and chlorhexidine, and polymeric biguanides, such as poiyfhexamethyiene biguanide) (FH B), Is discussed for treatment of infection. However, there is no discussion about the Incorporation of a monoaikyl glycol, a monoacy! glycerol, or a glycerol alkyl ether, or the interaction of these individual or combined ingredients with a biofiim.

U.S. Patent Application Publication 2009/0202615 discusses compositions containing high concentrations of a surface active agent (surfactant) and a sub-lethal amount of an antimicrobial agent for contacting a microbial biofiim. The Examples utilize high surfactant concentrations (> 46 %). The sub-ietbai amount of antimicrobial agent is defined as less than the standard therapeuticall effective amount to effectively eradicate or inhibit the growth of hlofilm forming microorganisms or pathogens, or inhibit bio i!m formation or eradicate formed bioflims. This application recommends a sub-lethal amount of the antimicrobial agent, such as silver sulfadiazine, to be equal to or less than 1 % by weight (10,000 ppm) of the composition. Regrowth of the bioflim was not considered.

U.S. Patent Application 2007/0202008 discusses the use of one or more higuanldes to kill bacterial endospores, particularly from the genus Bacillus and the genus Clostridium. This study did not include the use of an antimicrobial vicinal dioi. Additionally, biofiim elimination was not considered.

U.S. Patent 5,516,510 discusses deodorant compositions containing

poiy(hexamethylene biguanide) at a concentration of from 0.01 % to 0.5 % with a short chain monohydric alcohol, such as ethane! at a concentration of 20-80 %, in a nonpolar propeiiant, which also contains water and a polarity modifier, the latter including dodecanoi. 1 -(2-ethylhexyl) glycerol ether (Senslva® SC 50), and ketones such as acetone. The amount of monohydric short chain alcohol and nonpolar propeiiant can be as high as 99 %. There is no discussion on the elimination of a short chain monohydric alcohol o a polarity modifier such as acetone, both of which can cause irritation and stinging on skin, or the use of such a composition to reduce or eradicate biofiim.

The use of commercial wound cleansers that incorporate a biocidai agent have recently gained in importance, particularly to treat wounds highly infected by microorganisms. Three such commercial products include Prontosan© Wound Irrigation Solution and Gel from Braun Medical, Inc., and Microsyn® Skin and Wound Cleanser and Dermacyn® Wound Care from Oculus Innovative Sciences. Prontosan® Wound Irrigation System is based upon a surfactant with the blocide of poiy(bexamethyiene bisbiguanide) (PHMB). Prontosan© Wound Irrigation Solution and Gel Is used for cleansing, moisturizing and decontaminating acute and chronic wounds to aid In efficient wound bed preparation. The Microsyn® and Dermacyn® Wound Care Solution are active oxychlorine compounds and super-oxidized solutions intended for use in the treatment of infection In acute and chronic wounds and in the debridement, irrigation and moistening of acute and chronic wounds, ulcers, cuts, abrasions and bums. Such products are reported to reduce the microbial load and assist in creating a moist environment in order for the body to perform its own healing process. The biocidai activity of such products appears to be based upon a dilute sodium hypochionte/hydrochlorous acid solution. White both Prontosan™ and Microsyn® solutions are reported to reduce the biofilm bioburden of wounds, neither has been reported to eliminate regrowth of the biofilm by providing total kill. It is the intent of this invention to provide a solution that is capable achieving this result in order to provide more rapid, more effective wound healing than exists by current methods.

SUMMARY OF THE INVENTION

The present invention provides an antimicrobial composition that is capable of either reducing a microbial biofilm by 4 log orders in 10 minutes and by elimination of the biofilm with no regrowth within 24 hours. The microbial biofilm eliminated or reduced by 4 log orders can foe of a microbe including, but not limited to, Aspergillus niger, Candida albicans, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coii Enterocooci. Such an antimicrobial solution is particularly effective against biofilms that occur in chronic wounds. It is postulated that the decreased or esiminated biofilm in and on such wounds would greatly expedite wound healing, thus reducing patient suffering and associated medical costs.

An antimicrobial composition exhibiting a synergistic interaction of at least one polymeric biguanide and at least one antimicrobial vicinal dioS, where the vicinal diol comprises at least one monoalkyi glycol, monoaikyl glycerol or monoacyl glycerol, Is described. Monoaikyl glycerols are also referred to as giycero! a!kyi ethers, while monoacyl glycerols are also referred to as glycerol alky! esters. The substituents on the monoalkyi glycol, the monoaikyl glycerol and the monoacyl glycerol are preferentially aliphatic, and can be linear or branched, and saturated or unsaturated,

Biguanides have a broad spectrum of activity against bacteria, fungi, protozoa, and viruses, while glycerol aikyi ethers, monoalkyi glycols, and monoacyl glycerols are particularly effective against Gram positive bacteria and yeasts. Surprisingly, the antimicrobial

compositions described herein are capable of diminishing or eliminating biofilm formation, particularly in wounds and bums, by complete kill with no regrowth of the microorganism. The antimicrobial composition can be utilized both as a wound irrigation solution and as an antimicrobial wound gel for wound bed preparation. The antimicrobial composition can also be in the form of an aqueous solution or gel that can be used as a surface disinfectant., as a coating on a catheter or on a foam or on other backing and placed upon a wound in either the hydrated forrrs or dried thereon. Additionally, the antimicrobial composition can be used for disposable, absorbent materials, such as on diapers and products for adult incontinence and feminine hygiene, as well as for personal, body wipes, in addition to industrial wipes. It has unexpectedly been discovered that a synergistic interaction for biofiim reduction and complete elimination can be obtained in an antimicrobial composition comprising at least one polymeric biguanide and at least one antimicrobial vicinal dioL The vicinai diol can include at least one monoaikyi glycol, monoaikyi glycerol, or monoacyl glycerol. The monoaikyl glycol can include an antimicrobial monoaikyi-substituted 1 ,2-diol; the monoaikyi glycerol can include an antimicrobial glycerol ether, and the monoacyl glycerol can include an antimicrobial glycerol ester.

The antimicrobial compositions described herein can also provide a synergistic interaction between a gel comprising at least one polymeric biguanide and at least one antimicrobial vicinal diol, where the vicinal diol comprises at least one monoaikyi glycol, monoaiky! glycerol, or monoacyl glycerol, to give no re-growth of a microbial biofiim.

The antimicrobial compositions described herein can also provide a synergistic interaction between at least one biguanide and at least one antimicrobial vicinal diol, and a chelating agent to give enhanced reduction or total elimination of a microbial biofiim.

The antimicrobial compositions described herein can also provide a synergistic

Interaction between at least one biguanide and at least one antimicrobial vicinal diol as well as, a surfactant and a chelating agent to remove necrotic debris and to give enhanced reduction or total elimination of a microbial biofiim.

The antimicrobial compositions described herein can also include polymeric biguanide- and low molecular weight bis{biguanide)-in combination with other ingredients to synergisticaliy reduce or eliminate microbial biofiim in wounds.

The antimicrobial compositions described herein are also intended to be used to treat acute and chronic wounds, as well as, burn wounds.

The antimicrobial compositions described herein can be used to reduce and eliminate Gram positive and Gram negative bacteria in wounds, surfaces and devices.

The antimicrobial compositions described herein can be used to reduce and eliminate fungi in wounds, surfaces and devices.

The antimicrobial compositions described herein can be used to reduce and eliminate yeast in wounds, surfaces and devices.

The antimicrobial compositions described herein can be used to reduce and eliminate moid in wounds, surfaces and devices.

The antimicrobial compositions described herein can be used to reduce and eliminate protozoa in wounds, surfaces and devices. The antimicrobial compositions described herein can be used to reduce and eliminate mycoplasma in wounds, surfaces and devices.

The antimicrobial compositions described herein can be used to reduce and eliminate viruses in wounds, surfaces and devices.

The antimicrobial compositions described herein can be used to reduce bacteria! growth by incorporation of a chelating agent to the antimicrobial composition.

The antimicrobial compositions described herein can be used to facilitate wound healing by deactivating matrix metalioproteases in a wound by a chelating agent

The antimicrobial compositions described herein can provide biguanide-containing compositions that are non-cytotoxic to human epidermal and dermal cells.

The antimicrobial compositions described herein can provide biguanide-containing compositions that do not cause tissue irritation upon contact with tissue.

The antimicrobial compositions described herein can provide biguanide-containing compositions that have a pH that is mildly acidic to enhance wound healing.

The antimicrobial compositions described herein can provide biguanide-containing compositions that are mildly hypotonic to enhance blocidal efficacy,

The antimicrobial compositions described herein can incorporate antimicrobial essential oils to augment the antimicrobial activity of the compositions.

The antimicrobial compositions described herein can incorporate antimicrobial essential oils that provide a pleasing fragrance to the compositions.

The antimicrobial compositions described herein can provide a rapid, synergistic biocida; activity against a microbial biofi!rrt.

The antimicrobial compositions described herein can provide a synergistic interaction between one polymeric biguanide and at least one monoalkyl glycol, glycerol aikyi ether, and monoacyi glycerol deposited on a surface or a device to give enhanced or total elimination of a microbial biofiim.

These and other objectives and advantages of the antimicrobial compositions described herein, some of which are specifically described and others that are not, will become apparent from th detailed description and claims that follow,

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a graph showing Pseudomonas aeruginosa biofiim regrowth for saline,

P GNTOSAN ^® and solutions 1-8 and 10-13. Figure 2 is a graph showing Pseudomonas aeruginosa biofiimiog kill graph for saline, PRO TOSAN ^® and solutions 1-6 and 11-13.

Figure 3 is a graph showing Staphylococcus aureus biofilm regrown for saline,

FRONTON SA ^® and soiuiions 1-8 and 10-13.

Figure 4 is a graph showing Staphylococcus aureus biofilm log kill graph for saline. PRONTONSAN ^® , and solutions 1-8 and 11-13.

Figure 5 is a graph showing Candida albicans biofilm regrown for saline,

P ONTONSAN ^® and soiuiions 4-9 and 12-15.

DETAILED DESCRIPTIO OF THE INVENTION

Antimicrobial soiuiions comprising an aqueous mixture of at least one antimicrobial polymeric biguanide and at least one antimicrobial vicinal dioi are described. The vicinal dioi can include at least one monoaikyl glycol, monoaikyl glycerol, or monoacyl glycerol.

The monoalkyl glycol can have a structure represented as follows:

wherein R - C ₃ - O branched or unbranched alkyi group or alkyiene group, in some antimicrobial compositions, R - C ₃ - C< ₂ branched or unbranched aikyl group or alkyiene group, or R ~ C ₃ - {¾ branched or unbranched aikyl group or alkyiene group, or R ~ C ₃ - C« branched or unbranched alky! group.

The monoaikyl glycerol (alternately referenced as a glycerol aikyl ether) can have a structure represented as follows;

wherein R ^™ C ₃ -~ C< ₈ branched or unbranched aikyl group or alkyiene group. In some antimicrobial compositions, R = C§ - C _5S branched or unbranched aikyl group or alkyiene group, or R ^™ C ₇ - C ₂ branched or unbranched aikyl group or alkyiene group, or R ~ C? - C ₁₂ branched or unbranched aikyl group. The monoacyi glycerol can have a structure represented as follows:

wherein R « C ₃ - C _1S branched or unbranched aikyl group or alkylene group. In some antimicrobial compositions, ~ Cs ~ C< ₆ branched or unbranched alky! group or alkylene group, or R - Ce - C branched or unbranched aikyl group or alkylene group, or R = C _? - C > branched or unbranched aikyi group.

For each of the vicinal dlo!s, when R Is branched, the respective compound can exist as a racemic mixture of D,L components, as a pure enantiomer of D or L configuration, or as an enantiomer enriched mixture.

The antimicrobial composition can also include a metal ion chelating agent, a surfactant, or both. The antimicrobial composition can have a pH in the range 4.5-7.0 and an osmolality of 10-320 mOsm/kg. Where the antimicrobial composition is a solution, a water-soluble polymer can be added to increase solution viscosity and to prolong residence time of the antimicrobial composition on the surface of the wound, A hydrophobic fatty acid ester and a hydrophobic monoalkyl alcohol can be added to increase biocidal activity. Though fatty acid esters and hydrophobic monoalkyl alcohols are normally water insoluble or difficultly water soluble, they can be solubllized In the antimicrobial compositions described herein using a surfactant in conjunction with a hydrophobic glycol or hydrophobic glycerol.

The aqueous antimicrobial compositions described herein can include biocidal polymeric biguanides at a concentration ranging from 0.05 wt % (500 ppm) to 1 weight % (10,000 ppm), or ranging from 0.075 wt % (750 ppm) to 0.5 wt % (5,000 ppm), or ranging from 0.1 wt % (1 ,000 ppm) to 0.15 wt % (1 ,500 ppm). Bis(higuanides), such as alexidi e and its salts and

ehiorhexidine and Its salts, can also be added to the antimicrobial compositions in

concentrations from 10 ppm (0.001 wt %} to 350 ppm (0.035 wt %}.

The antimicrobial composition can include the biocidal monoalkyl glycol, glycerol aikyl ether, and monoacyi glycerol at a combined concentration of from 0.05 wt % (500 ppm) to 4 wt % (4,000 ppm), or from 0.1 wt % (1 ,000 ppm) to 1 wt % (10,000 ppm), or from 0.4 wt % (4,000 ppm) to 0.8 wt % (6,000 ppm). The monoalkyl glycol, glycerol aikyl ether, and monoacyi glycerol can be hydrophobic because of the iength of the R substituents. As used herein, hydrophobic refers to repelling water, being insoluble or relatively insoluble in water, and lacking an affinity for water. Hydrophobic compounds with hydrophilic substituents, such as vicinal diols may form emulsions In water, with or without added surfactant.

When the antimicrobial composition is applied to a substrate or medical device in either the hydrated or dried form, the mixture can contain polymeric biguanides. at a concentration of from 0.05 wt % (500 ppm) to 1.5 weight % (15,000 ppm), or from 0,075 wt % (750 ppm) to 0.75 wt % (7,500 ppm), or from 0.1 wt % (1 ,000 ppm) to 0.5 wt % (5,000 ppm). and antimicrobial glycols and antimicrobial glycerols at a concentration of from 0.05 wt % (500 ppm) to 6 wt % (60,000 ppm), or from 0.1 wt % (1 ,000 ppm) to 1 wt % (10,000 ppm), or from 0.3 wt % (3,000 ppm) to 0.6 wt % (6,000 ppm).

The ratio of polymeric biguanide to vicinal diols (i.e., monoaikyi glycol, glycerol aiky! ether, and monoacyi glycerol combined) in the antimicrobial composition - whether hydrated or dried - can range from 1 :0.05 to 1 :500, or from 1 :0.5 to 1:100, or from 1 :0.75 to 1 :75, or from 1 : to 1 :50, wherein the minimum concentration of polymeric biguanide Is 0.02 wt % (200 ppm).

Any of the antimicrobial compositions described herein can be aqueous compositions. As used herein, "aqueous" compositions refer to a spectrum of water-based solutions including, but not limited to, homogeneous solutions In water with so!ubilized components, emulsified solutions in water stabilized by surfactants or hydrophilic polymers, and viscous or gelled homogeneous or emulsified solutions in water.

When present, the surfactant can be present at a concentration of from 0.1 wt % (1,000 ppm) to 4 wt % (40,000 ppm), or from 0.75 wt % (7,500 ppm) to 3 wt % (30,000 ppm), or from 1 wt % (10,000 ppm) to 2 wi % (20,000 ppm). The surfactant lowers the surface tension of the solution, facilitating wetting of a wound surface (or any surface) for enhanced activity of th biocidal agent and for assistance with debridement.

When present, the chelating agent can be present at a concentration of from 0,01 wt % (100 ppm) to 1 wt % (10,000 ppm), or from 0.025 wt % (250 ppm) to 0.5 wt % (5,000 ppm), or from 0.05 wt % (500 ppm) to 0.2 wt % (2,000 ppm). It is believed that the chelating agent enhances biocidal activity by removing multivalent metal sons from microbial surfaces, as well as, potentially facilitating wound healing b deactivating matrix metai proteases to enhance tissue regeneration.

Some preferred antimicrobial agents include polymeric biguanides and polymeric bis(blguanides), Optionally, at least one low molecular weight bis(blguanide) can be added as an additional antimicrobial agent. Combinations of antimicrobial biguanldes may enhance efficacy against the number and type of pathogenic microbial species.

A preferred polymeric biguanide is poly(hexamethylene biguanide), commercially available from Arch Chemicals, inc., Smyrna,. ΘΑ under the trademark Cosmocil™ CQ.

Poly(hexamethylene biguanide) polymers are also referred to as poly(hexamethylene biguanide) (PHMB), poly(hexamethylene bisbiguanide) (PHMB), poiy(hexamethyiene guanide) (PHMB), poSyCaminopropyl biguanide) (PAPB), polyjaminopropyl bis(biguanide)] (PAPB), polyhexanide and poiy(iminoirnidocarbonyl)iminohexamethylene hydrochloride: however, PHMB is the preferred abbreviation for this biocidal polymer. PHMB is a broad spectrum antimicrobial and has been used in contact tens multipurpose solutions, wound rinsing solutions, wound dressings, perioperative cleansing products, mouthwashes., surface disinfectant, food disinfectant, veterinary applications, cosmetic preservative, paper preservative, secondary oil recovery disinfectant, industrial water treatment, and in swimming pool cleaners. It is normally obtained commercially in the hydrochloride form in water.

Low molecular weight bis(biguanides) for antimicrobial activity are described in U.S. Patent Number 4,870,592, the entirety of which is incorporaied herein b reference. Preferred low molecular weight bis(biguanides) are alexidine (ALEX) and chlorhexidine (CHG), with alexidine being most preferred. Alexidine often exists in the dibydroehloride form while chlorhexidine Is often in its gluconate form. Alexidine dihydrochloride is available from Toronto Research Chemicals, Inc., Toronto, Ontario, Canada. Alexidine is also listed chemically as 1 , - hexamethyienebis(5-(2-ethyjhexyi}blguanide] dihydrochloride. Chlorhexidine gluconate is available from Sigma Life Science, Sigma-A!drich Corp., St. Louis, MO USA. Chlorhexidine gluconat is also listed chemically as 1 , 1 ^! -hexamethyieneb$s 5-(p-ch{oropheny!)b guanide] di-D- giuconate. Chlorhexidine has been used in many biomedical applications, while alexidine has been used primarily In mouthwash and in contact lens solutions.

Biguanldes are described in U.S. Patent Numbers 3,428,578, 4,670,592, 4,758,595 and 5,990,174, which are Incorporated herein by reference in their entirety . Biguanide salts can be gluconates, nitrates, acetates, phosphates, sulfates, halides and the like. The preferred biguanldes due to their ready commercial availability and superior biocidal effectiveness are poly(hexameihyiene biguanide) hydrochloride (PHMB) and alexidine dihydrochloride (ALEX).

Other antimicrobial polymers can also be added, such as polyquaternium 1 ,

polyquaternium 6, polyquaternium 10, cafionic guar, and water-soiuble derivatives of chifosan.

The antimicrobial composition can also include at least one vicinal dio! selected from hydrophobic monoa!kyi glycol, hydrophobic glycerol alkyi ethers, hydrophobic monoacyl glycerols and combinations thereof, in addition to being branched or unbranched, these compounds can either be saturated or unsaturated.

One or more hydrophobic monoaikyi or monoa!kyiene alcohol can also be added to the antimicrobial composition to enhance biocidai activity. The monoaikyi alcohol can include a single hydroxy! group, / ^' ,©., is not a poiyoL The. monoaikyi alcohol can be solubillzed by a surfactant. Preferred hydrophobic monoaikyi alcohols include, but are not limited to. 1-octanoi, 1-nonanoi, 1-decanoi, 1-undecanol, 1-dodecanol, 1-indecanoi, 1-tetradecanoi, 1-pentadeeanoi, 1-hexadecanol 1-heptadecanoi, 1-octadecanoi, and 3,7, 11 , 15-t©trarnethyi-2-hexadecen~1 ~oi (phytoi). Long-chain alcohols with fewer than seven carbon atoms and more than 18 carbon atoms are not preferred. The antimicrobial composition can be free of short chain monohydric alcohols, such as methanol, ethanol, propanol, butanol, pentanoi, hexanol, hepiano!, isomers ■hereof, or any combination thereof. More preferred monoaikyi or monoalkyiene alcohols are 1- dodecano!, 1-tridecanol, and 3,7, 1 1 ,15~tetrame£hyi-2-hexadecen-1-ol (phytoi).

Antimicrobial sugar esters can also be added to Increase biocidai activity. Sugar esters are effective for Bacillus sp. _> Lactobacillus plantawm, Escherichia co.¾ and various members of Clostridium. Such sugar esters comprise sucrose monocaprylate, sucrose monoiaurate, sucrose monomyristate and sucrose monopaimitate.

Exemplary monoaikyi glycols include, but are not limited to, 1 ,2-propanedioi (propylene glycol), 1 ,2-butanedioL 1 ,2-pentanedioi, 1 ,2-hexanedioL 1 ,2-heptanediol, 1 ,2-ocianediol (caprylyi glycol), 1 ,2-nonanediol, 1 ,2-decanedioL 1 ,2-undecanediol, 1 ,2-dodecanedioi, 1 ,2- tridecanedlol, 1 ,2-tetradecanedlol, 1 ,2-pentadecanediol, 1 ,2-hexadecanedloi, 1 ,2- hepiadecanediol and 1 ,2-ociadecanediol. Non-vicinai glycols can also be ad ed to enhance biocidai activity, Exemplary, non-vicinal glycols include, but are not limited to, 2-methyi-2,4- pentanedioi, 1,3-butanedioi, diethylene glycol, Methylene glycol, and glycol bis(hydroxyethyl) ether.

Exemplary glycerol alkyl ethers include, but are not limited to, 1-O-heptyigiyceroi, 1-0- octylglyceroi, 1 -O-nonylglycerol. 1 -O-decyig!ycerol, 1 -O-undecyiglycerol, 1 -O-dodecylglycerol, 1-O-tridecyigiyceroi, 1 -Otetradecy!glyceroi, 1-0-pentadecylgiyceroi,1 -0-hexadecyigiycerai (chimyl alcohol}, 1-O-heptadecylgiyceroi, 1~G-octadecylglycerai (batyi alcohol). 1-O-octadec-S- enyl glycerol (selachyl alcohol), glycerol 1~(2-ethylhexyl) ether (also known as octoxyglycerin, 2- efhy!hexyi glycerin, 3-(2-ethyihexyioxy}propane-1 ,2-dioi, and Sensiva® SC 50), glycerol 1-heptyi ether, glycerol 1-octyi ether, glycerol 1-decyi ether, and glycerol 1-dodecyl ether, glycerol 1 - tridecyi ether, glycerol 1-teiradecyi ether, glycerol 1 -pentadecyi ether, glycerol 1 -hexadecyl ether and glycerol 1-octadecyi ether. Exemplary monoacyl glycerols include, but are not limited to, 1 -O-decanoy!glycerol (monocaprin), 1 -O-undecanoylgiycerol, 1 -O-undecenoylglycerol 1 -O-dodecanoy!g!yceroi (monolaurin, also called glycerol monolaurate and Lauricldin®), 1 -O-tridecanoyigiycerol.1 -0« tetradecanoylglycerol {monomyristin}, 1-O-pentadecanoy!g!yceroi, 1 -O-hexadecanoyigiyceroi, 1 - O-heptadecanoy!g!yceroi, and 1 -O-octanoylg!ycero! (monocapryiin). In general, glycerols substituted in the 1-G-position are more preferred than those substituted in the 2-O-position, or dlsubstituted in the 1-0 and 2-0 positions.

The Sensiva® SC 10 Multifunctional Cosmetic Ingredient available from SchGSke & Mayr, which includes both 1 ,2~oetanediol (a monoa!kyi glycol) and 2-ethyihexyi glycerin (glycerol 1-{2- ethylhexyl) ether){a monoaikyl glycerol), is an exemplary vicinal diol composition for use in the antimicrobial compositions described herein. Sensiva® SC 10 is reported to combine the excellent skin care and deodorizing properties of 2~ethylhexyiglyeerin (Sensiva® SC 50) with the moisturizing and antimicrobial properties of caprySyi glycol. Additionally, the vicinal diois can contribute to the antimicrobial stability of cosmetic formulations. Vicinal diols can also be used to improve the efficacy of traditional cosmetic preservatives, such as parabens or phenoxyelhanci (Schulke & ayr, Sensiva© SC 10 Multifunctional Cosmetic ingredient).

Sensiva® SC 50 reliably inhibits the Gram positive odor-causing bacteria on the skin and Is used in deodorant formulations, it is reported to boost the efficacy of traditional preservatives. In addition, screening tests with Sensiva© SC 10 have shown that it reliably inhibits the growth and multiplication of Gram positive odor causing bacteria, while at the same time it does not affect beneficial skin flora. The antimicrobial efficacy of meth l para ben preservative is accelerated by Sensiva© SC 10 In reduction of cfu/ ^' mi for Aspergillus n ger (ATCC 8275), Candida albicans (ATCC 10231), Staphylococcus aureus (ATCC 6538) , Pseudomonas aeruginosa (ATCC 15442} and Escherichia coil (ATCC 1 1229), The compositions studied were 0.2 (wt) % rnethylparaben, 1.0 (wt) % (10,000 ppm) Sensiva© SC 10, and a combination of 0.2 (wt) % rnethylparaben and 1.0 (wt) % Sensiva© SC 10. The recommended preservative use concentration for Sensiva© SC 10 by Schulke & Mayr is 0.5 (5,000 ppm) to 2.0 % (20,000 ppm).

Since the antimicrobial monoaikyl vicinal diois of this invention have adjacent hydrophilic •■-OH groups, but often with low or negligible water solubility, it is preferred that a surfactant be added to aid in solution compatibiiization and homogeneity of these compounds.

The antimicrobial compositions can Include one or more additional surfactants to effect surface cleaning, particularly for debridement of wounds. Suitable surfactants include, but are not limited to, cationic, anionic, nonlonsc, amphoteric and ampholyte surfactants. Preferred surfactants are nonlonlc and amphoteric surfactants. The surfactants can have an HLB (hydrophiiic-lipQpbJic balance) value of 18-30 in order to maintain the blocidal activity of the antimicrobial agents, while facilitating a non-cytotoxic solution.

Suitable nonionic surfactants incfude the ethylene o-xide/propylene oxide block

copolymers of poloxamers, reverse poloxamers, pofoxamlnes, and reverse poioxamines.

Poloxamers and poloxamines are preferred, and poloxamers are most preferred, Poloxamers and poloxamines are available from BASF Corp. under the trade names of Piuronic® and Tetronic®.

Suitable Piuronic surfactants comprise but are not limited to Piuronic F38 having a HLB of 31 and average molecular weight (AMW) of 4,700, Piuronic F88 having a HLB of 29 and A W of 8,400, Piuronic 68LF having a HLB of 26 and AMW or 7,700, Piuronic F77 having a HLB of 25 and AMW of 6,600, Piuronic F87 having a HLB of 24 and AMW of 7,700, Piuronic F88 having a HLB of 28 and AMW or 11 ,400, Piuronic F98 having a HLB of 28 and AMW of 13,000, Piuronic F1 8 having a. HLB of 27 and AMW of 14,600, Piuronic F127 (also known as Poioxamer 407) having a HLB of 8-23 and AMW of 12,600, and Piuronic L35 having a HLB of 19 and AMW of 1 ,900.

Another class of surfactant is that of the diamine block copolymers of ethylene oxide and propylene oxide sold by BASF Corp. under the trade name TetronicCs ⁾ . An exemplary surfactant of this type is Tetronic 1 107 (also known as Poloxarriine 1 107),

In addition to the above, other surfactants may be added, such as for example polyethylene glycol esters of fatty acids, e.g., coconut, polysorbate, poiyoxyethylene or polyoxypropyiene ethers of higher alkanes (C _1f .-C ₁₈ ), polysorbat 20 available under the trademark Tween 20, poiyoxyethylene (23) lauryl ether available under the trademark Brij 35, poiyoxyethylene (40) stearate available under the trademark Myrj 62, and poiyoxyethylene (25) propylene glycol stearate available under the trademark Atlas G 2812, all available by Akzo Nobel, Chicago, it. Other neutral surfactants Include nonylpheno! ethoxylates such as

nonylpheno! ethoxylates, Triton X-100, Brij surfactants of poiyoxyethylene vegetable-based fatty ethers, Tween 80, deeyl glycoside, and lauryl giucoside,

Amphoteric surfactants suitable for use in antimicrobial compositions according to the present Invention include materials of the type offered commercially under the trademark

Miranol (Rhodia), Another useful class of amphoteric surfactants is exemplified by

cocoaroidopropyl Detains, commercially available from various sources.

Examples of suitable tonicity adjusting agents include, but are not limited to; sodium chloride and potassium chloride, glycerin, propylene glycol, mannito! and sorbitol. These agents are typically used individually In amounts ranging from about 0.01 to 2.5 % (w/v) and preferably, from about 0,05 to about 1.5 % <w/v). Preferably, the tonicity agent will be employed in an amount to provide a final osmotic value of from 10 to 320 mQsm kg and more preferably between about 200 to about 300 rnQsm/kg, and most preferably between about 280 to about 290 mOsm/Kg, Sodium chloride is most preferred to adjust the antimicrobial composition tonicity.

The pH of the antimicrobial composition is adjusted to between 4.5 to 7.0, with pH 5.0 to pH 6.5 being more preferred, and pH 5.5 to 6,0 being most preferred. The role of wound bed pH is of fundamental Importance during the healing of chronic wounds, and prolonged acidification of the wound bed has been shown to increase the healing rate in chronic venous leg ulcers (Wilson l.A.l, Henry ., Quill R.D., and Byrne P.J., VASA 1979, vol.8, pages 339-342). The principal explanation for the mechanism of interaction between the acidic wound bed and the wound healing process is related to the potential to increase tissue oxygen availability through oxygen dissociation and to reduce the histotoxicity of bacterial end products, thus stimulating the wound's healing process.

Suitable buffers to adjust pH can include sodium citrate, potassium citrate, citric acid, sodium dshydrogen phosphate, disodium monophosphate, boric acid, sodium borate, tartrate, phthaiate, succinate, acetate, propionate, maleate salts, tnsihydroxymethyljaminomethane, amino alcohol buffers, and Good buffers (such as ACES, PIPES, and GPQSO), and mixtures thereof. One or more buffers can be added to antimicrobial compositions of the present invention in amounts ranging between approximately 0.01 to 2,0 weight percent, by volume, but more preferably between approximately 0,05 to 0.5 weight percent by volume.

Additionally, the pH of the antimicrobial composition can be adjusted by the combination of ethy!enediaminetetracetlc acid disodium and trisodium salt chelating agents, with this method being most preferred.

Emollients/moisturizers and humectants can be added to the antimicrobial formulation to provide a more soothing antimicrobial composition. Emollients/moisturizers function b forming an oil layer on the top of the skin that traps water in the skin. Petrolatum, lanolin, mineral oil, dimethicone, and siloxy compounds are common emollients. Other emollients include isopropyi palmitate, isopropyi myristate, isopropyi isostearate, Isostearyl isostearate, dlisopropyi sebacate, propylene dipelargonate, 2-ethylhexyl isononoate, 2-ethyShexyj stearate, cetyl lactate, lauryl lactate, isopropyi !anolate, 2-ethylhexyl salicylate, cetyl myristate, oleyl myristate, oleyi stearate, oleyl oleate, hexyi laurate, and isohexyl !aurate, lanolin, olive oil, cocoa butter, shea butter, ocfyidodecanoi, hexy!deeanol, dicaprylyl ether and decyi oieate. Humectants include glycerin, lecithin, 1 ,2-propyiene glycol, dipropyiene glycol,

polyethylene glycol, 1 ,3-butyiene glycol, and 1 ,2,6-hexanethoi. Humectants function by drawing water into the outer layer of skin,

Antiinflammatory agents can also be added, such as water soluble derivatives of aspirin, vitamin C, methylsuifonylmethane, tea tree oil, and non-steroidal anti-inflammatory drugs.

The water-insoluble additive compounds can be SQfubi!ized using a surfactant, particularly in combination with at least one antimicrobial hydrophobic monoaikyi vicinal dioi, antimicrobial hydrophobic monoaikyi glycerol and antimicrobial hydrophobic monoacyl glycerol.

It is often desirable to include water-soluble viscosity builders in the antimicrobial compositions of the present invention. Because of their demulcent effect and possible hydrophobic interactions with biological tissue, water-solubie polymers have a tendency to enhance the interaction with a wound by means of a hydrated film on the wound surface.

Because of this behavior, such water-soluble polymers can increase the residence time of the antimicrobial composition or gel on a wound.

Water-solubie viscosity builders useful herein Include, but are not limited to,

methyiceliuiose. hydroxyethyicel!ulose, hydroxypropylceiiuiose, hydroxypropylmethylcei!uiose, carboxyrrsethylceiiulose, poiyquafernium-1. poiyquaternium-6, poiyquaternium-10, guar, hydroxypropylguar, hydroxypropyimethylguar. cationic guar, carboxymethyiguar,

hydroxvmethylchitosan, hydroxypropylchitosan, carboxymethylchitosan, N-[{2-hydroxy-3- tn ^" methyiammonium}propyl]chitosan chloride, water-soluble chitosan, hyaluronic acid and its salts, chondroltin sulfate, heparin, dermatan sulfate, amylQse, amylopectin, pectin, locust bean gum, alginate, dextran, carrageenan, xanthan gum, geilan gum, scleroglucan, sehizophylian, gum arable, gum ghatti, gum karaya, gum tragacanth, pectins, starch and its modifications, tamarind gum, pol vi l alcohol), polyethylene oxide), poiy{ethylene glycol), poiy(methyl vinyl ether), polyacrylamide, poiy(N,N-dimethylacrylamlde), poly(N-viny!acetamide), poly( - vsnyiformamide), poly{2-hydroxyethyi methacrylate), poiy(giyceryi methacryiate), poiy(N- vinylpyrroiidone), polyfdlmethylaminoethyl methacrylate), po!y(dlmethyiaminopropyi acrylamide), polyvinylamine, poly(N-jsopropyiacrylamsde) and poiy{N-vinylcaprolactam), the latter two hydrated below their Lower Critical Solution Temperatures, and the like, and combinations thereof. Such viscosity builders may be employed in amounts ranging from about 0.01 to about 10.0 weight percent for preparation of free flowing antimicrobial compositions to viscous gels.

If anionic ytirophiiic polymers are utilised for enhancing viscosity, the overall polymer negative charge may electrostatically attract and accumulate the cationic biguanide biocide and a greater concentration of biguanide will then be needed to provide biocidai efficacy comparable to the utilization of a neutral or cationic water-soluble polymer. Thus, preferred water soluble polymers are neutral in charge, such as hydroxyethy!ceiSulose, hydroxypropylcellulose, hydroxypropyimethyiceiiulose, guar, hydroxypropyiguar, hydrcxypropyimethyiguar,

polyethylene oxide), and poiy{N~vfnyipyrrolidone), or cationic in charge, such as cationic chiiosans, cationic cellulosics, and cationic guar. Chitosan polymers may also enhance the antimicrobial behavior of the antimicrobial composition, More preferred hydrophliie polymers comprise hydroxypropylmethy!cellulose, hydroxypropylcellulose, hydroxypropyiguar,

hydroxymethyiehltosan, poiy(etbylene oxide), M~ (2-hydroxy~3- irime†hyiammonium)propyl]chitosan chloride, with hydroxymethyipropylcellulose being most preferred.

Chelating agents enhance the susceptibility of bacteria and other organ sms to the biocidai effects of the antimicrobial agent, thus rendering a wound care solution or device containing a chelating agent more effective in combating infection. Additionally, chelating agents deactivate matrix metaiioproteases (MMPs), enzymes that can impede tissue formation and healing by breaking down collagen. IVIMPs are often found at elevated levels in chronic wounds. Chelating agents bind to zinc ions, which are necessary for MMP activity, disrupting the M P. causing deactivation, and thus facilitating healing.

The chelating agent is selected from any compound that is able to sequester monovalent or polyvalent metal ions, such as sodium, lithium, rubidium, cesium, calcium, magnesium, barium, cerium, cobalt, copper, iron, manganese, nickel, strontium or sine, and is

pharmaceutically or veterinariiy acceptable. The outermost surface of bacterial cells universally carries a net negative charge, which is usually stabilized by divalent cations such as Mg ^+Z and Ca* ² . This is associated with the teschoic acid and polysaccharide elements of Gram-positive bacteria, the iipopoiysaccharide of Gram-negative bacteria, and the cytoplasmic membrane Itself. Thus, the chelating agent aids in destabilizing m croorganisms. Additionally, the chelating agent may deactivate matrix metaiioproteases, such as in inflammatory wounds, facilitating collagen development.

Suitable chelating agents comprise, but are not limited to, aminocarboxylic acids, ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid, nitriiotn ^' propio.nic acid,

dlethylenetriaminepentaacetic acid, 2-hydroxyethyfethylenediaminetriaceflc acid, 1 ,6- diaminohexamelhylenetetraacetic acid, 1 ,2-diaminocyciohexanetetfaacetic acid, 0.0'-bis(2~ aminoethyl)ethylenegiycoiietraacetic acid, 1 ,3-diaminopropanetefraacetic acid, ,N'-bis(2~ hydroxybenzyi)ethylenedsamine-N,N'-diaceiic acid, ethy!enedlamine-N,N'~diacetic acid, ethyienediamine-N^'-dipropiortic acid, iriethytenetetraaniinehexaacetic acid, ethyienediamine- N ,N -bis(methylenephosphonic acid), iminodiacetic acid, N ₍ N-bis(2-hydroxyeihyi)giycine, 1 ,3- dlamino-2-hydroxypropanetetraaceiic acid, 1 ,2-diaminopropanetetraacetic ac d,

ethytenediamtnetetrakis{meihylenephosphonic acid), N-(2-hydroxyethyi)iminodiaceiic acid and biphosphonates suc as editronate, and sails thereof. Suitable chelating agents Include for example but are not limited to hydroxyalkyiphosphonates as disclosed in U.S. Pat. No.

5,858,937, specifically the tetrasodiurn salt of 1 -hydroxyethy!idene-1 , 1 -diphosphonic acid, also referred to as tetrasodiurn etidronate, commercially available from Monsanto Company as DeQuest 2018 diphosphonic acid sodium sail or phospbonate.

Especially preferred chelating agents are mixed salts of EDTA such as disodium.

trisodium, tetrasodiurn, dipotassium, fripotasslum, tetrapotasssium. lithium, diiiChium, ammonium, dlammonlum, tnammoniu , tetraammonium, calcium and calcium-disodium, more preferably disodium, trisodium or tetrasodiurn salts of EDTA, and most preferably disodium EDTA and trisodium EDTA.

The concentration of chelating agent can range from 0.01 weight % to 1.0 weight %, or from 0,025 to 0.5 weight %, or from 0.06 to 0.15 weight %.

it is also possible to prepare the wound cleanser as an emulsion, a miniemulsion, a microemulsion or an Inverse emulsion utilizing the surfactant to soiubliiize an active, normally water insoluble or difficult to solubiiize component. The solubilization of organic and inorganic species could inciude antimicrobials, antibiotics, silver salts and silver nanoparticies,

antibacterial agents, antifungal agents, antiviral agents, antiprotozoal agents, essential oils, analgesics, protease inhibitors, antialfergenics, antMnfiarnmatories. vasoconstrictors, vasodilators, antic!otting agents, hormones, peptides, nucleic acids, saccharides, lipids, glycoiipids. glycoproteins, endocrine hormones, growth hormones, growth factors, heat shock proteins, immunological response modifiers, anti-cancer agents, cytokines, and mixtures thereof, as well as organic solvents that provide increased oxygen to ischemic wounds. Of significance are the addition of organic solvents, such as siloxanes and fiuorocarbons. which increase oxygen solubility and transport. Of particular significance is the use of a volatile, non- burning, non-stinging, non-sensitizing, siioxane solvent of hexamethyidlsiloxane (HMDS). The emulsion is prepared by slowly adding the HMDS to the composite wound care composition up to the concentration wherein phase separation occurs between the organic solvent and the emulsified solution.

Essential oils can also be added to the formulation as fragrance or aromatic agents, and/or as antimicrobial agents, including thymol, menthol, sandalwood, camphor, cardamom. cinnamon, jasmine, lavender, geranium, juniper, menthol, pine, lemon, rose, eucalyptus., clove, orange, mint, lina!ooi. spearmint, peppermint, iemongrass, bergamot, citronella, cypress, nutmeg, spruce, tea tree, wintergreen (methyl salicylate), vanilla, and the like, More preferred essential oils include thymol, sandalwood oil, winiergreen oil and eucalyptol for antimicrobial properties and pine oil for fragrance. Thymol and sandalwood oil are the most preferred essential oils.

In topical applications, the antimicrobial composition product may be delivered in different forms. Exemplary forms include, but not limited to, liquids, creams, foams, lotions, gels and aerosols. The antimicrobial composition can also be Imbibed by swabs, cloth, sponges, foams, wound dressing materials and non-woven and paper products, such as paper towels and wipes. Topical formulations of the subject antimicrobial compositions may additionally comprise organic solvents, emuisifiers, gelling agents, moisturizers, stabilizers, time release agents, dyes, perfumes, and like components commonly employed In formulations for topical administration.

The antimicrobial compositions or gels may also be added to catheters In a hydrated or dried form to provide a coating that can be inserted into a body In order to prevent biofiim attachment to the catheter.

Alternatively, the antimicrobia! composition may be added to a solid or porous support and dried, such as a polymeric foam, a polymer film, a woven, knitted or nonwoven material, and then applied directly to a wound. In this case the polymeric foam may also absorb wound exudate, creating a hydrated environment for controlled release of synergistic biguanide activity with the antimicrobial mortoalkyi vicinal diol on the wound surface. Such foam wound dressings can comprise up to 1.0 weight % biguanide. Foam dressings of this type would be effective against biofiims such as Pseadomonas aeruginosa, methicillin-resistani Staphylococcus aureus and vancomycin-resistant Enterococci.

Furthermore, the above compositions may be used in dentistry to control or eradicate biofiim populations In oral applications, such as for gingivitis. In addition, the above

compositions may be utilized for biofiims in the middle ear that have been found in chronic otitis media.

The above compositions may be used to disinfect surfaces, such as bedding, surger tables, tubing, and reusable medical equipment.

Examples

Antimicrobial solutions containing PH B are well recognized for their antimicrobial behavior and for their contributions to wound management. Recently, a commercial product, Profonsan® Wound Irrigation Solution with PHMB {poly(hexamethylene biguanide), poiyhexanide). was introduced by B. Braun into the U.5 and Europe markets for moistening and cleansing of acute and chronic wounds or burns to help reduce necrotic burden, control exudate and remove foreign material. It can be used on colonized, critically colonised, and infected wounds. Additionally, Prontosan® Wound Irrigation Solution has been reported to

decontaminate encrusted, contaminated and chronic skin wounds, and can have a dramatic influence of the quality of life for such patients (Horrocks A. _; Br. J. Nurs., 2006 Dec 14-2007 Jan 10; f 5(22): 222, 1224-8). Because Prontosan® Wound Irrigation Solution contains PHMB, it is used as a positive control for the biofiim reduction and elimination examples in this invention.

The following examples serve to illustrate the invention without limiting it thereby. It will be understood that variations and modifications can be made without departing from the spirit and scope of the invention.

The antimicrobial agents, surfactant, viscosity enhancing agent, chelating agents and skin care and deodorizing agent used in these examples include:

PHMB: (Poiy{hexamethylene biguanide)}, Cosmocsi™ CQ. Arch Chemical lot 1 1 RC 1 18995). ALEX: (Alexldine Dihydrochloride), Toronto Research Chemicals, lot 4-VVG-119-2.

CHG: (Chlofhexidine gluconate), Spectrum Chemicals, !ot 2Q1023.

P-407: (Poioxamer 407, Pluronie F127), Spectrum Chemicals, lot 1AO0265.

TW 80: (Tween 80, Polysorbate 80), Spectrum Chemicals, sot XF0356

HPMG: (Hydroxypropylrnetbyloeliulose, Hypromeiiose), Spectrum Chemicals, lot 1AC0441 , 2% solution viscosity ^™ 50 mPa.s,

EDTA-2; (Ethyienediaminetetraacetic acid disodium salt), Spectrum Chemicals, lot 1AE0430, EDTA-3: {Ethyienediaminetetraacetic acid trisodium salt), Spectrum Chemicals, lot YL0044, SC 50: (Sensiva® SC 50, Glycerol 1-{2-ethyihexy!) ether), Schulke & Mayr, lot 1 179743.

SC 10: (Sensiva® SO 10, 1 ,2-Dihydroxyoctane), Schuike & Mayr, lot 1178933.

G L: (Glycerol Monoiaurate, Lauricidln®), IV!ed-Chem Laboratories, lot 4010608422.

SAN: (Sandalwood oil, East Indian Sandalwood tree, Santalum album), ViroXis Corporation, Sodium Chloride; Spectrum Chemical, lot 1AA0110.

Water: (Purified, USP), Ricca Chemical Company, lot 1 102304.

Since the Prontosan® solution contains PHMB at 0.1 wt % (1 ,000 ppm) and a surfactant, undecyienamidoprop i betaine (0,1 wt %, 1 ,000 ppm), this aqueous solution was used as a positive control, with saline as the negative control, in comparing PHMB containing solutions of this invention at 1000 ppm (0.1 wt %) and 1500 ppm (0, 15 wt %) with the addition of Sensiva® SC 50 at 0.3 wt % (3,000 ppm) and Sensiva© SC 10 at 0.1 wt % (1 ,000 ppm) for their efficacy against bioflims of Pseudomonas aeruginosa, Staphylococcus aureus., and Candida albicans. Additional ingredients included a!exidine (ALEX) and chlorhexidine (CHG) bis(biguanides). EDTA-2Na and EDTA-3 a chelating agents, and pH adjustment by ethyienediaminetetraacetic acid disodium and trisodiuro sails, Poioxamer 407 surfactant, and hyaYoxypropyimethylceliuicse viscosity enhancer, with the osmolality adjusted by sodium chloride.

in Table 1 are listed fifteen antimicrobial compositions that were prepared for comparison against the controls.

Tabie 1. Solutions for Biofilm Studies

Biofilms were established and assayed as follows, For each organism, 96-peg MSEC™ pegs were placed in a 96 well plate with 100 μ! of 0.1 OD 600 log phase bacterial culture per well. The biofilms were allowed to grow on the pegs for 36 to 48 hours. Excess bacteria were then rinsed in a 96 well plate with 200 μΐ weii of PBS for 10 ± 1 minutes. The cells were then treated with the antimicrobial compositions and positive and negative controls in a 96 well plate at 200 ul per well for 8 ± 2 min. The plates were then rinsed as above in a fresh plate. The pegs were then transferred to a neutralization plate containing 200 μί per well of Dey-Engley broth and lightiy sonicated for 15 min to release the planktonic organisms associated with the pegs. After sonicatlon, the peg plate was moved to a regrowih plate with 200 μ! of Tryptic Soy Broth (TS8) and incubated for -24 hours. The assay was completed fay reading the absorbance at 800 nm in a Molecular Devices M2 microplate reader (C. albicans was aiso read at -48 hours.) The antimicrobial compositions contained poiy(hexamethy!ene biguanide) hydrochloride

(PHMB) bioc!de at either 1000 ppm {0.1 wi %) or 1500 ppm (0. 5 wt %), with aiexidine (ALEX) at 0 ppm or 10 ppm (0,001 wt %), with chlorhexidine digl conate (GHG) at 0 ppm or 200 ppm {0.02 wt %}, with EDTA chelating agent at 0.05 wt % (500 ppm) or 0.1 wt % (1 ,000 ppm), with Poioxamer F12? (P-4Q7) surfactant at 1 wt % (10,000 ppm) or 2 wt % (20,000 ppm). with HP C viscosity enhancer at 0.2 wt % (2,000 ppm), with Sensiva® SC 50 (SC 50), an emollient and humectant that inhibits the growth of Gram positive odor causing bacteria, at 0 wt % to 0,3 wt % (3,000 ppm). with Sensiva® SC 10 (SC 10), an emollient and humectant with deodorizing and antimicrobial properties, at 0 wt % or 0.1 wt % (1 ,000 ppm), and with Sandalwood oil (SAN), an essential oil, at 0 wt % to 0, 125 wt % (1 ,250 ppm). Additionally, pH was obtained by no added ingredients (i.e., pH 4.9) or by the addition of trisodium EDTA (EDTA-3Na) to discdium EDTA {EDT.A~3Na) (i.e., pH 5.5 and 6). The osmolality was either 282 or 280 mOsm/kg, forming mildly hypotonic solutions. The antimicrobial compositions were undiluted and compared for their effects on biofilm growth and relative kill efficacy vs. controls.

Protonsan® positive control was determined to have a pH of 6 and an osmolality of 11 mOsm Kg.

The following two bacterial biofilm species were tested: Pseudomonas aeruginosa (ATCC strain 27853, Gram negative bacteria) and methiciilin-resistant Staphylococcus aureus (MRSA; ATCC strain 700699, Gram positive bacteria). For fungi, the biofilm of Candida albicans (ATCC strain 10231 , yeast) was analyzed. All antimicrobial compositions were studied for regrowth over a 24 hour period. Solutions exposed to Candida albicans were also analyzed for regrowih at 48 hours because of the slower growth of this microorganism.

Figure 1 is a graph of antimicrobial compositions 1 -8 and 1 -13 relative to a biofilm of Pseudomonas aeruginosa, ATCC 27853, based upon the absorbance of total bacteria at 800 nm before treatment with the antimicrobial compositions, followed by a 10 minute exposure to the solutions, and then by regrowth analysis after 24 hours. Graphs with no error bars signify no regrowth and are representative of the absorbance of dead microorganisms. Figure 1 shows that with the saline positive control, almost total regrowth occurs within 24 hours. For Prontosan®, which has PH B at a concentration of 1000 ppm and a surfactant at 0.1 wt %, substantial regrowth also occurs within 24 hours. Similarly, for solutions 1 , 2, 3, 10, and 1 1 , which have neither vicinal diol constituent (Sensiva® SC 50 and Sensiva® SC 10), substantial regrowth also occurred. Comparing solutions 4 and 6, solutions that are similar other than the addition of 10 ppm alexidine to solution 6, it is seen that the addition of the alexidine had a negligible effect on the biocidal behavior in that a small error bar is noted in the optical density (OD) measurement. When there is no error bar in the measurement, the optical density measurement signifies the presence of exclusively dead microorganisms. In other words; the reading does not change because there is no regrowth of the microorganism. Solutions 4. 5, 8 and 12, 13 each contained 0.3 wt % Sensiva® SC 50 and 0.1 wt % Sensiva® SC 10. Each of these had the lowest optical densit readings after 24 hours, Indicating little or no regrowth of Pseudomonas aeruginosa. Solutions 4, 5, and 12 had no error bars, indicating total eradication of the Pseudomonas aeruginosa biofiirn.

In comparing solutions 4, 5 and 8, each with 1000 ppm PHMB, solution 6 also contains

10 ppm alexidine while solutions 4 and 5 do not. Also, solution 5 also contains 0.125 wt % sandalwood oil. while solutions 4 and 6 do not. Solution 8 with alexidine has a slight error bar in its OD measurement, while solutions 4 and 5 do not. There is no significant difference in solutions 4 and 5, indicating that for the 24 hour time period of the test all bacteria were dead, and the addition of sandalwood oil could not be discerned.

Solutions 12 and 13 both contained 500 ppm of PHMB, with solution 13 also containing 0, 125 wt % sandalwood oil. The results show a slight error bar for solution 13, which Indicates that solution 12 was more effective. Additionally, there was no significant difference between solutions 4, 5 and 12, indicating that for these formulations the combination of a polymeric biguanide at a concentration of at least 1000 ppm, with vicinal diol containing Sensiva® SC 50 and Sensiva© SC 10 at a concentration of 0,3 wt % and 0,1 wt %, respectively, effectively eliminates a Pseudomonas aeruginosa biofiirn within a 10 minute exposure to the antimicrobial composition. The approximate two times difference in the total EDTA content between solution 12 and solutions 4 and 5 also indicated that there was no significant difference in the biocidal efficacy of these three solutions.

Combined with the results of the solutions without Sensiva® SC 50 and Senssva® SC 10 present (solutions 1 , 2, 3, 10 and 11), it is apparent that the combination of a polymeric biguanide with a vicinal diol, In particular monoalkyl glycerol {/,&, glycerol 1-(2~ethylhexyi) ether, also known as octoxygiycerin, 2-ethyihexy! glycerin, and Sensiva® SC 50} and a monoalkyl glycol {i.e., caprylyi glycol, 1 ,2-dihy roxyoctane; in combination with glycerol 1-(2- ethyihexyi)ether constitutes Sensiva® SC 10), gives an enhanced biocidai interaction against biofiims for solutions 4, 5 and 12. Since the Sensiva® products are reportedly effective against odor causing Gram positive bacteria, the superior results of the PHM8 antimicrobial

compositions with Sensiva® SC 50 and Sensiva® SC 10 against Gram negative Pseudomonas aeruginosa biofiims are quite surprising and further demonstrate the synergistic biocldal interaction between a polymeric biguanide and the vicinal diols.

in Figure 2 is a Pseudomonas aeruginosa log kill graph of CPU's before treatment with the antimicrobial compositions, followed by a 10 minute exposure to the solutions _. , and then by regrowth after 24 hours with for the same solutions of Figure 1. That is, solutions 1 -6 and 10- 13, wherein the Optical Density measurements of Figure 1 were converted to colony forming units (CPU) of Pseudomonas aeruginosa biofilm calculated as a conversion of the Absorbance at 800 nm (A600) to CFU based on a standard curve established for Pseudomonas aeruginosa. The limit of detection by the spectrophotometer used is 0.001 (Molecular Devices M2 micropiate reader}, which means the equivalent of 10 ⁴ ceils/ml is the lower limit that can be measured. The debris from Figure 1 was considered baseline. Thus, while the data In Figure 2 can be interpreted as a kill of at least 8 log orders of Pseudomonas aeruginosa, the lower limit of quantitation indicates that the effective kill of the bacteria was approximately 5 log orders for the most efficacious solutions, I.e., solutions 4, 5, 6 _: 12 and 13, with solutions 4, 5 and 6 being the most effective antimicrobial compositions against Pseudomonas aeruginosa biofilm. Solutions 4, 5, 6, 12, and 13 were the only solutions with the combination of a polymeric biguanide and Sensiva® SC 50 and Sensiva© SC 10. Prontosan®, the positive control with a similar PH B content to solutions 4, S, and 6 but with neither Sensiva® SC 50 nor Sensiva© SC 10, had an effective kill of Pseudomonas aeruginosa biofilm of 1 log order. These results further

demonstrate the synergistic interaction of the polymeric biguanide and a hydrophobic monoaikyl vicinal diol in reducing and eliminating a biofilm of Pseudomonas aeruginosa.

The log kill data is presented in Table 2. Solutions 4, 5, 6, 2, and 13 are reported as BLOQ. for values Below the Limit of Quantitation. Table 2. Ps&udo anas. aeruginosa Biofilm Log Kill Tabulated Data for Solutions 1-6 and 11-13, with Saline and Prontosan®.

Figure 3 is rs of regro th for solutions 1-8 and 10- 3 in comparison to saline and Prontosan© relative to a biofilm of

Staphylococcus aureus, ATCC strain 700699, based upon the absorbance of total bacteria before treatment with the antimicrobial compositions, following a 10 minute exposure to the solutions, and then by regrowth after 24 hours. Graphs with no error bars signify no regrowth.

Figure 3 shows that the saline negative control Had regrowth, as did solutions 1, 2.. 3, 10, and 1 , as well as the positive control Prontosan®. None of the f ve test antimicrobial compositions with regrowth {solutions 1, 2, 3, 10 and ) had the combination of Sensiva® SC

50 and Sensiva® SC 10 with PHMB. in contrast, solutions 4, 5, 6, 12 and 13, which Included a polymeric biguanlde (PHMB) and vicinal dio!s (Sensiva© SC SO and Sensiva® SC 10) exhibited no regrowth of Staphylococcus aureus biofilms. These biocida! effects against biofilms are consistent with those observed for Pseudornonas aeruginosa biofilms in Figure 1.

Figure 4 is a Staphylococcus aureus log kill graph of CFU's before treatment with the antimicrobial compositions, followed by a 10 minute exposure to the solutions, and then by regrowth analysis after 24 hours with the same solutions used to generate Figures 1 -3. That is, solutions 1-6 and 10-13, wherein the Optical Density data of Figure 3 was converted to colony forming units of Staphylococcus aureus biofilm calculated as a conversion of the Absorbance at 600 nm (A600) to CFU based on a standard curve established for Staphylococcus aureus, ATCC 700699, Th limit of detection of the spectrophotometer used was 0.001 , which means the equivalent of 10* cfu/mi was the lower limit that can be measured. The debris from Figure 3 was considered baseline, Thus, while the data in Figure 4 can be interpreted as a kill of at least 8 logs of Staphylococcus aureus, the lower limit of quantitation indicates that the effective kill of the bacteria was at least 4 logs for the most efficacious solutions, i.e.. solutions 4, 5, 6, 12 and 13, with solutions 4, 5 and 6 being the most effective antimicrobial compositions against Pseudomonas aeruginosa biofi!m. In contrast, Prontosan® had an effective kill of approximately 1.7 log orders, with regrowth evident in Figure 3 and 4, Thus, similar to the antimicrobial results obtained with Pseudomonas aeruginosa in Figure 2, the data of Figure 4 and Tabfe 3 further support the synergistic interaction of the polymeric biguanide with monoaikyi vicinal diols (e.g., hydrophobic monoaikyi glycol and a hydrophobic monoaikyi glycerol) in reducing or eliminating a Staphylococcus aureus biofilm.

Table 3. Staphylococcus aureus Biofilm Log Kill Tabulated Data for Solutions 1 -6 and 11-13, with Saline and Prontosan©

In Figure 5, solutions 4 - 9 and 12 - 15, all with PHMB and Sensiva® SC 50 and

Sensiva® SC 10, were studied in comparison to saline and Prontosan*© for the regrowth of a biofilm of Candida albicans before treatment with the antimicrobial compositions, followed by a 10 minute exposure to the solutions, and then by regrowth analysis after 24 hours and 48 hours. This regrowth study was conducted up to 48 hours because of the slower growth of the Candida albicans biofilm In comparison to that of the two bacteria studied. Although all of the test solutions (4 - 15} solutions contained PHMB and Sensiva® SC 50 and Sensiva© SC 10, some of these solutions contained aiexidine or chlorhexidine, with or without sandalwood oil. Neither saline negative control nor Prontosan® positive control contained Sensiva© SC 50 and

Sensiva® SC 10.

The study shows that saline solution had the most regrowth, followed by Prontosan® and solutions 8, 9, and 15. The other solutions, 4-7 and 12-14, had little to no regrowth at 24 hours and some regrowth at 48 hours. Solutions 8. 9, and 15 each contained 200 ppm

chiorhexidine, in addition to PHMB, indicating that the combination of PHMB and chiorhexidine was not as effective as thai of PHMB and aiexidine (solutions 6, 7 and 14). Solutions 6, 7, 12, and 3 appeared the most effective against the Candida albicans .biofiim. Solution 12, which contained 1 ,500 ppm PHMB, appeared slightly more effective than the other solutions.

Thus, the combination of the polymeric biguanlde PHMB with the antimicrobial vicinal dio!s of a monoalkyi glycol and a monoaiky! glycerol (Sensiva® SC 50 and Sensiva® SC 10), in contrast to the poorer regrowth behavior of Prontosan® solution with PHMB, demonstrated synergistic biocidal abilit against the biofiim of Candida albicans.

In Table 4, solutions containing glycerol monoiaurate (GML, Lauricidin®, monolaurin), an antimicrobial vicinal dlol of a monoacyi glycerol, were prepared with PHMB and with Sensiva® SC 50, and with and without Sensiva® SC 10. Solutions containing 0,2 wt % glycerol monoiaurate formed needle-like crystals when standing at room temperature, whereas those with 0.1 weight % glycerol monoiaurate remained homogeneous at room temperature. The solubility of glycerol monoiaurate was enhanced by the combination of surfactant, Sensiva® SC 50 and Sensiva® SC 10.

Using glycerol monoiaurate in combination with PHMB and Sensiva© SC 50, with and without Sensiva® SC 10, a minimum inhibitory concentration (MIC) study was conducted using a biofiim of Ps&udornonas aeruginosa, ATCC 15442, in comparison to Prontosan® for solutions 18 - 21. These solutions were also varied as to whether they contained aiexidine and the surfactant Poioxamer 407 or Tween 80 (TW 80), The MIC study was conducted for three trials per solution and represents the lowest concentration of solution where no bacterial growth is demonstrated. Solutions 18 and 20 had the lowest MIC values of dilution 1 :32 of the Initial concentration in Table 4, wh le solutions 16 and 21 had a MIC dilution of 1:16, and solution 19 was equivalent to Prontosan© at an MIC of 1 :8. Solution 17 was the least effective, with an MIC dilution of 1:2, Indicating that the absence of antimicrobial Sensiva® SC 10, containing 1,2- dihydroxyoctane, a hydrophobic monoalkyi glycol, and the use of Tween 80 as a surfactant, negatively impacted this MIC. These results showed that an antimicrobial composition containing PHMB with the antimicrobial vicinal diols, in particular a hydrophobic monoacyi glycerol (glycerol monolaurate), a hydrophobic monoaikyJ vicinal diol (1 ,2-dihydroxyociane), and a hydrophobic monoalkyl glycerol (glycerol 1-(2-ethyihexyl) ether 2-ethylhexyigiycen ^' n) is highly effective in the reduction and elimination of Pseudomonas aeruginosa biofilm.

Table 4, MIC of Pseudomonas aeruginosa with Gl cerol Monolaurate (lauricidm®)

Antimicrobial Dressings

Tests of adsorption of dried solution 4 were also conducted on wound dressing materials, including (a) CVS Dressings Sponges, a rayon/polyester biend used for heavy draining wounds, (b) CVS Gauze Sponges, 100 % cotton used for wound dressings and wound packing, (c) CVS Surgical Dressing, a rayon/polyester blend for absorbing fluids, and (d) CVS Eye Pad, a rayon/polyester biend for covering and protecting the eyes. Table 5 provides the results of the amount of dried ingredients from solution 4 that were incorporated into wound dressing materials a - d.

Table 5, Wei ht Percent of Dried, Absorbed Solution 4

Test samples were cut in weights of approximately 0,5 grams. The dressing materials were placed on a glass slide and 3 ml of solution was pipetted onto them. The dressing materials were removed from the slide, which contained excess solution that was not absorbed. The test samples were dried at room temperature for 48 hours in a hood and then weighed. Each of the samples exhibited initial stiffness, but became flexible with manipulation. All dried samples had increased smoothness compared to the original dressing.

For the four substrate materials tested, the amount of solution 4 absorbed, minus water, ranged from 23.7 wt % for the Surgical Dressing to 50,0 wt % for the Dressing Sponge, For the dried Dressing Sponge, the PHMB concentration is calculated to be 2.94 wt % of the dried solution 4 formulation, which includes sodium: chloride. Therefore, the concentration of PHMB absorbed into the Dressing Sponge is 1.43 wt %, the concentration of Senssva® SC 50 is 4,29 wt %, and the concentration of Senslva© SC 10 is 1 .43 wt %. The remaining ingredients maintained the same ratio to PHMB for solution 4 as in Table 1 ,

B drying the antimicrobial compositions on dressing materials, such materials can be used for controlled delivery of the initial antimicrobial composition to a wound surface because of hydration of the dressing material over time by the wound.

Viscous and Gelled Solutions

In order to Increase the concentration of all ingredients for solution 4, viscous solutions and a gel were prepared in concentrations 2, 5 and 10 times (2X, 5X and 10X) the concentration of solution 4, Since the approach used in Table 6 would result in salt concentrations significantly greater than isotonic when said solutions were dried on a dressing, the addition of sodium chloride was eliminated from the 2X, 5X, and 0X solutions derived from solution 4. Solutions 2X and 5X were viscous solutions, with 5X considerably more viscous than 2X, while solution 10X was a firm gel, Concentrated soiutions of this type could be applied to dressing materials or coated on a surface, giving higher biocidal activity than the soiutions of Table 1.

Table . Concentrated Solutions of Solution 4

While the above specification contains many specifics, these should not be construed as limitations on the scope of the invention, but rather as examples of preferred embodiments thereof. Many other variations are possible. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.