WO1998044794A1

WO1998044794A1 - Compositions and methods for skin disinfection employing mandelic acid

Info

Publication number: WO1998044794A1
Application number: PCT/US1998/007105
Authority: WO
Inventors: Robert D. Kross
Original assignee: Alcide Corporation
Priority date: 1997-04-08
Filing date: 1998-04-08
Publication date: 1998-10-15
Also published as: AU6960998A

Abstract

A composition comprising mandelic acid useful for skin disinfection, such as the teat of a dairy cow, is disclosed. The disinfecting composition is in an aqueous form, or upon contact with water yields the same, having a pH of less than about 4.5, such that a significant amount of the mandelic acid is in a nonionic form. A co-acid (other than mandelic acid) or co-base may be added in order to adjust the pH of the composition in the aqueous form to the desired value. The composition may be topically applied to the skin to prevent and to treat skin infections.

Description

COMPOSITIONS AND METHODS FOR SKIN DISINFECTION EMPLOYING MANDELIC ACID

TECHNICAL FIELD

The present invention relates generally to disinfecting compositions and methods for preventing and/or treating microbial infections. The invention is more particularly related to preventing the transmission and propagation of bacterial pathogens in bovine mammary glands utilizing compositions containing mandelic acid.

BACKGROUND OF THE INVENTION Bovine mastitis is one of the most costly and difficult challenges faced by the American dairy industry. It is a complex disease that results from the interaction of the mammary gland, the environment (including milking equipment) and microorganisms. The modern dairy cow, as a result of selective inbreeding, has developed mammary glands with a milk-secreting potential far in excess of the requirements of the newborn calf. Because of size, position, and anatomic adjustment for rapid removal of large volumes of milk, the udders of present day dairy cows are especially prone to mastitis. More than half of the cows in the United States are estimated to have some form of mastitis, and the disease is responsible for an estimated annual loss of $2 billion in U.S. milk production. Many bacterial pathogens can cause mastitis, including Strep, agalactiae,

Staph. aureus, Strep, uberis, Strep, dysgalacήae, E. coli, P. aer ginosa, Enterobacter species, Citrobacter species and Klebsiella species. Of these pathogens, Strep, agalactiae and Staph. aureus are ' associated with infections that arise primarily from contaminated milking equipment. Such infections are known as "contagious mastitis." The other mastitis infections, known as "environmental mastitis," primarily result from pathogens that contact the teat during the inter-milking period. These pathogens may be transferred from wind-borne matter, bedding material or ground contaminants such as soil or manure, that contact the udder when the animal lies down. In all cases, once pathogens have contaminated the teat, the infection usually proceeds from teat skin to teat orifice to streak canal, and finally to the mammary parenchyma.

The proper use of antimicrobial materials can significantly decrease the frequency and intensity of bacterial infections among cows in a herd. Such antimicrobial materials may be incorporated into pre-milking teat-washing sanitizers, or into pre- milking or post-milking surface disinfectants. Typical antimicrobial materials include iodophors, quaternary ammonium compounds, chlorhexidine, dodecylbenzene sulfonic acid (DDBSA), hydrogen peroxide, organic acids (e.g., lactic, capric, lauric), inorganic acids (chlorous and hypochlorous) and bacteriocins. Many of these compounds are very effective in destroying mastitis-causing organisms upon contact, and are thereby effective in protecting against bacteria that cause contagious mastitis. However, they generally have limited effectiveness in preventing environmental mastitis. Some agents (such as peroxides, iodines and chlorous/hypochlorous acids) lose oxidative cidal power during the inter-milking period. Acidic agents are often neutralized with time, and other agents may be diluted by moisture in the streak canal, where effective levels of the cidal species must be maintained to protect against organisms that have migrated into that area.

Effective and commercially successful products for bovine teat disinfection, which function both at milking time and during the subsequent inter-milking period, are sold by Alcide Corporation (Redmond, WA). These products are two-part compositions, one part containing sodium chlorite and the other part an activating acid. Shortly before use, a dairy farmer mixes the two parts together in order to form the activated product. However, many dairymen find the mix-before-use aspect of these teat dips to be a cumbersome task, particularly during inclement and cold weather, so that a similarly-efficient one-part system, not requiring initial mixing, would be simpler to use and more readily acceptable. Accordingly, there is a need in the art for a disinfecting composition that can provide extended germicidal action on mammalian skin, particularly within the streak canal over the inter-milking period, as well as a high level of germicidal action on the teat surface to destroy contagious organisms transferred to the teat during milking. Such a composition is desirably a "one-part" composition, in that no mixing of components by the end user (e.g., the dairy farmer) is required. Preferably, the composition has good substantivity, that is-it is not readily removed from the skin or mucosa by moisture, including internal moisture as may come, for example, from milk remaining in the streak canal. The present invention fulfills these needs and provides further related advantages.

SUMMARY OF THE INVENTION

Briefly, the present invention is directed to a method for disinfecting a substrate such as skin or tissue, particularly a mammalian teat. The method comprises the step of topically applying to the skin or tissue an effective amount of a one-part composition comprising mandelic acid. In one embodiment, the composition is an aqueous composition having a pH of less than about 4.5, and compatible with the skin or tissue. The composition typically contains mandelic acid in an amount ranging from about 0.1% to about 10% by weight. In this embodiment, a preferred composition further comprises one or more thickening agents, and may additionally contain further ingredients, such as one or more film-forming agents and/or humectants.

In another embodiment, the composition is a non-aqueous or dry composition which, upon contact with water (such as residual moisture from milk remaining at a teat orifice), forms an aqueous composition having a pH of less than about 4.5, and compatible with the skin or tissue. In this embodiment, the composition is typically formulated as a dry blend of mandelic acid in combination with one or more suitable carriers or other optional components. Such a dry formulation may be preferred during the winter season, when aqueous compositions could potentially freeze and cause damage to the skin or tissue. Another aspect of the invention is a method for inhibiting the development of a mammary gland infection. The method comprises the step of topically applying to a mammary gland an effective amount of a one-part composition comprising mandelic acid, wherein the composition has a pH ranging from about 2.0 to about 4.5, or upon contact with water forms a composition having a pH below about 4.5.

A further aspect of the invention is an aqueous composition useful in the above method, which comprises mandelic acid and one or more thickening agents and/or film-forming agents. The mandelic acid is preferably present at a concentration of 0.1% to 10.0% by weight, the thickening agent is preferably present at a concentration of 0.5% to 5% by weight, and the film-forming agent preferably present at a concentration of 0.5% to 5% by weight (the percentage being based on the total weight of the composition). For the purpose of adjusting pH, the composition may additionally contain an inorganic acid or a base, which acid or base is present at a concentration such that the pH of the composition ranges from 2.0 to 4.5. In a preferred embodiment, the aqueous composition has a pH ranging from about 2.0 to about 3.8 and contains mandelic acid at a concentration of 0.1% to 10%, and a thickening agent

In still a further aspect, a non-aqueous composition useful in the above method is disclosed comprising mandelic acid and one or more carriers. The mandelic acid may be present in an amount approaching 100%, and typically from 0.1% to about 10% by weight of the composition, while the carrier or other optional components constitute the remaining portion. In a preferred embodiment the carrier is a moisture- absorbing agent, such as powdered cornstarch , and optional components include a coloring agent, a wetting agent and/or a humectant.

These and other aspects will become apparent upon reference to the following detailed description.

DETAILED DESCRIPTION OF THE INVENTION

This invention is generally directed to one-part disinfecting compositions and methods suitable for protecting against and treating microbial infections. The disinfecting compositions may be topically applied to a substrate surface, such as the teat of a mammal, to prevent the transmission and/or propagation of bacterial pathogens. The disinfecting compositions of this invention contain mandelic acid, which has the following chemical structure: CβHs — CH(OH) — COOH.

In the context of the present invention, the term "disinfecting composition" refers to a composition comprising mandelic acid in an aqueous solution, or in a non-aqueous formulation which, upon contact with water, yields an aqueous solution having a pH such that at least about 10%, and preferably at least about 20% of the acid exists in the unionized form. The compositions of this invention are "one-part" systems that do not require initial mixing of multiple components prior to use, and do not include chlorite ions (ClO₂ ^") in the aqueous solution characteristic of some existing two-part systems.

In an embodiment where the composition is in the form of an aqueous solution, the disinfecting compositions of this invention further comprise a thickening agent and/or a film-former, such that the disinfecting composition forms an "adherent matrix" on the substrate surface. As used herein, an "adherent matrix" is a film or thickened deposit that forms upon drying of the disinfecting composition, providing active protection against microbial infection. The term "thickening agent" refers to a component which, when combined with the other components of the disinfecting composition, increases the gelatinous quality or viscosity of the disinfecting composition and/or the adherent matrix formed by the disinfecting composition on the substrate surface. A "film-former" is a composition which, when added to the disinfecting composition, increases the membranous or film-like character of the adherent matrix without significantly affecting the viscosity of the disinfecting composition.

Aqueous forms of the disinfecting compositions of this invention may generally be prepared by formulating an aqueous solution of mandelic acid, which has a pK_a of 3.37, at a pH such that at least about 10% of the mandelic acid exists in the unionized form. The unionized form of mandelic acid is capable of penetrating microbial surfaces, while the corresponding anion cannot. The 10% minimum requirement for mandelic acid therefore ensures that an adequate fraction of antimicrobial agent is present in the disinfecting composition. As shown in Table 1 below, such compositions generally have a pH below about 4.5, and preferably have a pH below about 4.0.

TABLE 1

EFFECT OF PH ON IO ZATION OF MANDELIC ACID

Typically, the pH of the aqueous forms of the disinfecting composition ranges from about 2.0 to about 4.5, preferably from about 2.0 to about 3.8, and more preferably from about 2.5 to about 3.6. It will be apparent to those of ordinary skill in the art that the pH of the aqueous forms of the disinfecting composition may be modified by the addition of one or more acidic or basic compounds. For example, an inorganic acid having a pK_a below the pH of the composition may be added to decrease the pH of the disinfecting composition. Suitable inorganic acids include sulfuric, hydrochloric and phosphoric acid. Suitable basic compounds include sodium hydroxide, potassium hydroxide, disodium and trisodium phosphate, sodium carbonate and bicarbonate, and sodium acetate.

Typically, the pH of the dry composition upon contact with moisture is below about 4.5, where the lowest pH of the moistened composition can approximate 1 or below in the micro-domains where moisture is first absorbed into the dry composition and mandelic acid reaches its aqueous saturation limit of about 16% by weight. The amount of mandelic acid present in the aqueous disinfecting compositions of this invention generally ranges from about 0.1% to about 10.0%, preferably from about 0.25% to about 4.0%, and more preferably from about 0.5% to about 2.5% by weight of the disinfecting composition. The relative amount of unionized mandelic acid required will depend upon the desired efficacy of the system. The more acidic the disinfecting composition, the less mandelic acid will be required, since a higher proportion of the acid will be present in the unionized form. This is directly affected by the selection of the final pH desired, which may require supplemental acid or alkali addition. For example, if 8% mandelic acid is employed, the resulting pH may be below a pH of 2, and thus the pH would have to be adjusted upwards with alkali. Similarly, if 0.1% mandelic acid is employed, the resulting pH may be 2.77, and the pH of the composition could be lowered to 2.0 by addition of an acid, if it is desired to use the lowest quantity of mandelic acid at maximum effectiveness.

With regard to non-aqueous formulations, mandelic acid may be dry- blended with one or more suitable carriers which serve as moisture absorbers, such as cornstarch, sugars and talc in a dry, powdered form, and with further optional components. Such dry-blended forms of the disinfecting composition typically contain mandelic acid in an amount ranging from 0.1% to 10% by weight of the composition. While higher amounts of mandelic acid may be employed, undesirable skin irritation (causing exfoliation of skin surfaces) may result. Also, at levels approaching 100%. by weight mandelic acid, the ability of the dry composition to absorb water is diminished. The remainder of the composition predominantly comprises one or more carriers, which preferably serve as moisture absorbers. Optional components include wetting agents (such as Aerosol OT), color agents (such as a blue pigment), and humectants (such as sorbitol).

Without being bound to any particular theory, it is believed that the presence of a lipophilic phenyl moiety in the α-position of mandelic acid imparts a greater substantivity to the tissues of animals and the cellular envelopes of microorganisms than from α-hydroxy carboxylic acids with aliphatic groups in the same position. In other words, the phenyl moiety provides for increased long-term disinfecting capacity by, for example, resisting removal when contacted with water. When mandelic acid is used as a teat disinfectant, this property facilitates the antimicrobial activity both on the teat surface and within the streak canal. Accordingly, it has been found that teat disinfecting compositions that contain mandelic acid provide superior antimicrobial activity in comparison to compositions containing other α-hydroxy carboxylic acids.

Optionally, the aqueous forms of the disinfecting composition of this invention additionally comprise one or more of the following: a humectant, a chelating agent, a preservative, a colorant, an opacifying agent, a wetting agent, a thickening agent, a film-former and/or an antiseptic. The optional humectant portion of the disinfecting composition comprises any suitable humectant known in the art, including, by way of example, glycerin and sorbitol. A humectant is a hydrophilic material that holds and attracts moisture to the skin, aiding in skin hydration. Humectants generally comprise from about 1% to about 10%, preferably from about 2% to about 8%, and more preferably from about 2.5% to about 7.5% by weight of the disinfecting composition. The optional chelating agent, such as disodium EDTA, may generally be present in the disinfecting composition in an amount ranging from about 0.002% to about 0.1%, preferably from about 0.003% to about 0.05%, and more preferably from about 0.01% to about 0.025% by weight of the disinfecting composition. The optional preservative comprises any suitable preservative known in the art including, by way of example, benzyl alcohol and sodium benzoate. Preservatives optionally comprise up to about 0.1%, typically from about 0.02% to about 0.05%, and preferably from about 0.02% to about 0.04% by weight of the disinfecting composition. The optional colorant may be any suitable dye known in the art including, for example, FD&C Yellow No. 5. The optional opacifying agent may be any suitable material known in the art to aid in visualization of the colored disinfecting composition after deposition on the substrate surface. The level of opacifying agent will generally range from about 0.01% to about 0.10% by weight of the disinfecting composition. The optional wetting agent comprises any compound added to the disinfecting composition to facilitate penetration of skin crevasses. Preferred wetting agents include non-ionic surfactants, such as alkylphenoxy polyoxyethylenes or poly(oxyethylene/oxypropylene) copolymers; anionic surfactants, such as alkylaryl sulfonates; or cationic surfactants, such as cetylpyridinium chloride. The amount of wetting agent in the disinfecting composition will depend upon the nature of the material and the size of the molecule, but will generally be present in an amount ranging from about 0.05% to about 2.0%, typically in an amount ranging from about 0.1 % to about 1.0% by weight of the disinfecting composition.

As noted above, when formulating the disinfecting composition as a barrier-forming composition, a thickening agent and/or film-former may be added. Any thickening agent or film-former that is non-toxic and non-reactive with the other ingredients of the composition may be used. Suitable thickening agents include, for example, cellulose ethers, typically methyl- or hydroxyethyl-cellulose, xanthan gums, high molecular weight polyoxyethylene or polyoxyethylene/polyoxypropylene copolymers, polyacrylamide, or a polysulfonic acid such as poly(2-acrylamido-2- methylpropanesulfonic acid). Suitable film-formers include, for example, polyvinyl alcohol, polyvinyl acetate and partially hydrolyzed polyvinyl acetate. Thickening agents and/or film-formers are typically present in the disinfecting composition in an amount ranging from about 0.5% to about 5.0%, preferably from about 0.8% to about 4.0%, and more preferably from about 1.0% to about 3.0% by weight of the disinfecting composition. Optional antiseptics are known by those skilled in this field and include agents such as chlorhexidine, iodophor, triclosan, p-chloro m-xylenol, quaternary ammonium compounds, hydrogen peroxide, dodecylbenzene sulfonic acid and bacteriocins. Such antiseptics may be present in the composition in an amount ranging from about 0.15% to about 5.0%, and more preferably from about 0.25% to about 4.0% by weight of the composition. In one embodiment, the antiseptic is an agent other than an iodine-containing compound.

The disinfecting compositions described above may generally be topically applied to a substrate, by means that will be apparent to those in the art, to prevent or treat a bacterial infection. In one aspect of this invention, the disinfecting composition may be applied to the teat of a mammal, preferably a cow. In this aspect, aqueous forms of the disinfecting composition may be applied by dipping, as, for example, into one of a variety of commercially available dip cups, or by spraying from a nozzle, which may be adjusted to dispense a solution or thickened formulation. The disinfecting composition may be applied routinely, as a pre- or post-milking teat dip, for preventing mastitis. The disinfecting composition may also be applied to the teat or other portion of the skin of a mammal afflicted with a topical bacterial, fiingal or viral infection, for treatment of the disease. Although an effective amount of disinfecting composition may vary, generally the application of between about 0.5 and 2.0 grams per bovine teat twice a day after milking is sufficient. In dry form, the composition may be dipped or dusted on the substrate such as skin or tissue, such that the disinfecting composition adheres thereto. An effective amount of the dry composition will vary depending on the skin or tissue surface and level of moisture, although generally the application of between about 0.2 and 1.0 grams per bovine teat twice a day after milking is sufficient. An effective amount of the disinfecting composition for application to skin or tissue areas other than the teat can be readily determined by one skilled in this field.

The present invention is illustrated by the following examples, which are to be regarded as illustrative rather than restrictive. Unless otherwise noted, all parts and percentages in the examples, as well as the specification and claims, are by weight.

EXAMPLES

EXAMPLE 1 ANTIMICROBIAL EFFECTIVENESS OF MANDELIC ACID

This example compares the antimicrobial effectiveness of mandelic acid with that of two other α-hydroxy carboxylic acids against two microorganisms of relevance to mastitis, E. coli and Staph. aureus. The study was based on a procedure provided in the 1990 edition of the Official Methods of Analysis of the Association of Official Analytical Chemists (AOAC) using a 30-second contact time (see Staphylococcus aureus Use-Dilution Method, Section 955.15). The levels of each acid were selected so as to provide solutions of comparable pH, by taking into account their molecular weights and ionization constants. The reductions in the logarithmic numbers of initial organisms exposed are shown in Table 2.

TABLE 2 ANTIMICROBIAL ACΠVΠΎ OF CI-HYDROXY ACIDS

The number of E. coli organisms (which cause environmental mastitis) that were destroyed by the mandelic acid solution was more than 3,000 times the number of organism cfu's destroyed by the lactic acid solution. For Staph. aureus, a "contagious-mastitis" organism, the mandelic acid destroyed 20 times more bacterial cfu's than the lactic acid. Accordingly, of the α-hydroxy carboxylic acids tested, mandelic acid displayed superior antimicrobial activity.

EXAMPLE 2

EFFECTΓVΈNESS OF MANDELIC ACID AGAINST GRAM-NEGATΓVΈ

AND GRAM-POSΠTVΈ BACTERIA

This example illustrates the use of a representative disinfecting composition of this invention against five test organisms. The aqueous disinfecting composition contained 2.5% mandelic acid at the pH of the solution formed (pH = 2.17), and the tests were performed as described above in Example 1. The results are shown in Table 3 below. TABLE 3

ANTIMICROBIAL ACTIVITY OF MANDELIC ACID DISINFECTING COMPOSITION

Similar results were obtained using a 2.5% mandelic acid solution that was adjusted to a pH of 2.8 with sodium hydroxide. Thus, mandelic acid solutions are capable of destroying both gram-negative and gram-positive bacteria very rapidly, although fiingal organisms (which are not problematic in dairy operations) are less affected.

EXAMPLE 3

USE OF MANDELIC ACID IN A TEAT DIP FORMULATION

This example compares the effectiveness of a representative disinfecting composition of the present invention with compositions containing other α-hydroxy carboxylic acids as a teat dip for application to cow udders. The compositions were prepared using mandelic, lactic or malic acid dissolved in a 5% glycerin solution. The glycerin was added as a humectant to promote softness and minimize chapping of teat skin. The effectiveness of the formulations were then evaluated against E. coli and Staph. aureus, using an adaptation of the "excised teat" procedure developed by the National Mastitis Counsel, wherein sets of five baby bottle nipples were dipped in a bacterial broth containing milk solids. A control set of nipples was also dipped in a similar, but bacteria-free, medium. The nipples were allowed to dry for 5 minutes, then briefly immersed in the prototype dips and allowed to air dry for 10 minutes. The nipples were then dipped into a buffering, nutrient Letheen broth, and the broths were plated on microbiologic agar, at various dilutions. The average numbers of organisms remaining after each treatment were determined in comparison with the control set. The results are shown in Table 4 below, which presents the logarithmic reductions from the initial titers of 7.08 logs for E. coli, and 6.95 logs for Staph. aureus.

TABLE 4

ANTIMICROBIAL ACTIVITY OF MANDELIC ACID TEAT DP FORMULATION

The results confirm the efficacy of the mandelic acid disinfecting composition against mastitis-associated organisms. The number of E. coli organisms destroyed by mandelic acid was 20 times greater than the amount destroyed by the lactic acid antimicrobial solution. The number of Staph. aureus organisms was 26 times greater than the number destroyed by lactic acid.

EXAMPLE 4

EFFICACY OF MANDELIC ACID COMPARED TO HIBICLENS*

In this example, the efficacy of a mandelic acid composition as a skin disinfectant was tested in comparison to the chlorhexidine-containing Hibiclens^® (Stuart

Pharmaceuticals, Wilmington, DE) cleanser, which is a very commonly used skin disinfectant. Each composition was tested for its ability to reduce bacterial infestation at two separate sites (groin and abdomen) on about 40 subjects. The mandelic acid composition was found to be the more effective, as fewer applications were used to achieve superior bacteria count reductions in comparison to the Hibiclens^® cleanser. The mandelic acid composition which was used in the testing protocol will be referred to herein as "Formulation A," and has the composition shown in Table 5.

TABLE 5

COMPOSITION OF "FORMULATION A"

Formulation A is a liquid with a colorless, clear to slightly hazy appearance. Formulation A has a pH of 2.5-3.0 and a viscosity of >20 cps. Hibiclens^® cleanser contains 4% chlorhexidine gluconate as the active ingredient. Formulation A and Hibiclens^® cleanser are sometimes referred to herein as the test solutions or the products.

Two to three ml of formulation A was liberally applied onto a test site of a subject using a sterile swab for one minute, and allowed to air dry. The Hibiclens^® cleanser was applied liberally onto the test site using a sterile gauze, for two minutes, and then dried with a sterile towel. This procedure was repeated (swab area for two more minutes, then towel dry). In all instances, each of the subjects was physically examined to ensure that no evidence of injury or dermatosis was present at the test sites. A "circumferential outward growing circles" motion was used to apply the solutions, in order to avoid contamination of untreated skin areas with the treated area. Product and site selection were based on a modified block randomization schedule.

At the groin (inguinal) site, Hibiclens^® or Formulation A was applied to the inner aspect of the upper thigh below and parallel to the groin leg crease. A total area of 3 in. x 8 in. was scrubbed. Using a template and a surgical marker, one test site on each contralateral site was delineated. Numbering of sampling areas within each site was done beginning on the subject's innermost side of the thigh with #1, and continued in order through #4. One sample area of each site was sampled immediately before treatment for use as the pre-treatment baseline (baseline #3). The three remaining areas represented the three treatment exposure times of ten minutes, thirty minutes, and six hours.

At the abdominal site, treatment was applied to an area approximately 1" to 2" below and to either side of the umbilicus and above the pubic hairline. An area of 6 in. x 6 in. was scrubbed on the abdomen. Using a template, the corners of each abdomen site were marked as "1," "2," "3," and "4" using surgical skin marker. Numbering was standard for all sites and subjects: number 1 was placed at the top corner of the subject's right; numbers 2, 3 and 4 were assigned in order clockwise from number 1.

Following the above procedures, each subject was prepped with Hibiclens or Formulation A, at the abdomen and inguinal regions. Baseline bacterial samples were taken immediately before the skin was prepped. Time zero started immediately following the last drying step. A sample of each prepped area was taken starting at ten minutes after drying. Subsequent samples were taken at thirty minutes and six hours post prep, where one sample was taken from each quadrant. After each sampling, a sterile gauze bandage was taped over the prepped areas to allow subject mobility and to prevent any microbial contamination.

Abdominal Site Test Results Table 6 shows the mean and standard deviation for both Formulation A and Hibiclens^® cleanser at baseline and each of the three post treatment periods, for testing conducted at the abdominal site. Both compositions, at each post-treatment time period, have significant changes from baseline (all p-values = .0001), and appear to significantly lower the bacteriologic count from baseline. However, Formulation A achieves a more than 2.4 log reduction in bacterial count after 6 hours, while Hibiclens^® cleanser achieves only a 1.5 log reduction in the same time period. In addition, Formulation A achieves a 2.6 log reduction within 30 minutes, while Hibiclens^® cleanser achieves a 2.4 log reduction in the same time period.

TABLE 6 COMPARISON OF POST TREATMENT AND BASELINE COUNTS WΠΉIN PRODUCT

Comparison is Significantly Different with Significance Level = 0.05.

The following Table 7 shows the change from baseline for each post- treatment period to determine if the mean change from baseline differs between the products. From this Table, it can be seen that for post-treatment 10 minutes, 30 minutes, and 6 hours, the mean change from baseline is not statistically significantly different for either of the products. TABLE 7 COMPARISON OF POST TREATMENT CHANGES FROM BASELINE BETWEEN PRODUCTS

Inguinal Site Test Results

Table 8 shows the mean and standard deviation for both solutions

(Formulation A and Hibiclens^® cleanser) at baseline and each of the three post-treatment periods. It is clear that both products, at each post treatment time period, achieve a significant change from baseline (all p- values = .0001). It also appears that both products significantly lower the bacteriologic count from baseline.

TABLE 8 COMPARISON OF POST TREATMENT AND BASELINE COUNTS WITHIN PRODUCTS

*: Comparison is Significantly Different with Significance Level = 0.05.

The following Table 9 shows the change from baseline for each post treatment period to determine if the mean change from baseline differs between the products. It can be seen that for post treatment 10 minutes the mean change from baseline is not statistically significantly different for the products (p-value = .3095). The products do have significantly different means for post treatment 30 minutes change from baseline (p-value = .0121) in favor of Formulation A. TABLE 9 COMPARISON OF POST TREATMENT CHANGES FROM BASELINE BETWEEN PRODUCTS

EXAMPLE 5 REPRESENTATIVE DRY FORMULATION

This example discloses the preparation of a powdered mandelic acid composition suitable for application to cows' teats post-milking, during the winter season, when liquid compositions could freeze on the udder and cause damage to the tissue. The powdered composition clings to the teat surface, upon dipping of the teat into the material, or dusting it on the teat, and it particularly adheres where residual moisture from the milk remains at the teat orifice. Such moisture, from milk or from subsequent environmental contact, facilitates dissolution of some or all of the mandelic acid in the composition and thereby provides antimicrobial action in such moist areas where bacteria might otherwise thrive. In addition, the comstarch acts to absorb that moisture and avoid chapping, and the sorbitol provides humectancy to promote beneficial skin conditioning. A representative dry formulation may be made by mixing the quantities of powders listed in Table 10.

TABLE 10 DRY BLEND 5.0 gms of mandelic acid 5.0 gms of sorbitol

0.75 gms of blue pigment, Chroma-Lite Dark Blue (ISP Van Dyk, Inc.) 89.25 gms of comstarch 100.00 gms total EXAMPLE 6

ANTIMICROBIAL ACΠVΓΓΎ OF DRY BLEND

This example discloses the ability of the powdered composition of Table

10, Example 5, to provide antimicrobial action. It is based on the recognition that small amounts of moisture which contact the powder will create a mixture in which the pH from the dissolved mandelic acid is indicative of the presence of mandelic acid, predominantly in the undissociated form required for antimicrobial activity. Three portions of the powder prepared in Example 5 were combined with small amounts of water, such that the blended compositions had an average solids content of 33.0 ± 1.2%. The average pH of the mixtures was 1.45, at which pH 98.6% of the dissolved mandelic acid is calculated to exist in the active, undissociated form necessary for antimicrobial activity. Lesser quantities of water, such as when the powder contacts damp areas where bacteria might thrive, would create acidic environments where the dissolved mandelic acid exists in even higher proportions as the undissociated form.

From the foregoing, it will be evident that although specific embodiments of the invention have been described herein for the purpose of illustrating the invention, various modifications may be made without deviating from the spirit and scope of the invention.

Claims

1. A method for disinfecting mammalian skin or tissue, comprising topically applying to the skin or tissue an effective amount of a one-part disinfecting composition comprising mandelic acid, wherein the composition is in the form of an aqueous composition or, upon contact with water on the mammalian skin or tissue, forms an aqueous composition, and wherein the aqueous composition has a pH of less than about 4.5.

2. The method of claim 1 wherein the one-part disinfecting composition is applied in the form of an aqueous composition.

3. The method of claim 1 wherein the one-part disinfecting composition is applied in the form of a dry composition.

4. The method of claim 2 wherein the amount of mandelic acid in the aqueous composition ranges from about 0.1% to about 10.0% by weight.

5. The method of claim 2 wherein the amount of mandelic acid in the aqueous composition ranges from about 0.25% to about 4.0% by weight.

6. The method of claim 2 wherein the pH of the aqueous composition ranges from about 2.0 to about 3.8.

7. The method of claim 2 wherein the pH of the aqueous composition ranges from about 2.5 to about 3.6.

8. The method of claim 3 wherein the amount of mandelic acid in the disinfecting composition ranges from about 0.1% to about 10.0% by weight of the disinfecting composition.

9. The method of claim 2 wherein the disinfecting composition further comprises a thickening agent in an amount ranging from about 0.5% to about 5% by weight of the disinfecting composition.

10. The method of claim 9 wherein the amount of thickening agent ranges from about 0.8% to about 4% by weight of the disinfecting composition.

11. The method of claim 9 wherein the amount of thickening agent ranges from about 1% to about 3% by weight of the disinfecting composition.

12. The method of claim 9 wherein the thickening agent is selected from the group consisting of cellulose ethers, xanthan gum, polyoxyethylene, polyoxyethylene/polyoxypropylene copolymers, polyacrylamide and polysulfonic acid.

13. The method of claim 2 wherein the disinfecting composition further comprises a humectant.

14. The method of claim 13 wherein the humectant is glycerin.

15. The method of claim 3 wherein the disinfecting composition further comprises a humectant.

16. The method of claim 15 wherein the humectant is sorbitol.

17. The method of claim 13 or 15 wherein the humectant is present in an amount ranging from about 1% to about 10% by weight of the disinfecting composition.

18. The method of claim 2 or 3 wherein the disinfecting composition further comprises an antiseptic, and wherein the antiseptic is an agent other than an iodine- containing compound.

19. The method of claim 18 wherein the antiseptic is chlorhexidine.

20. The method of claim 3 wherein the disinfecting composition further comprises a moisture-absorbing agent.

21. The method of claim 20 wherein the moisture-absorbing agent is comstarch.

22. The method of claim 3 wherein the disinfecting composition further comprises a wetting agent.

23. The method of claim 3 wherein the disinfecting composition further comprises a color agent.

24. The method of claim 1 wherein the mammalian skin or tissue is a teat.

25. The method of claim 24 wherein the mammal is a cow.

26. The method of claim 25 wherein the disinfecting composition is applied to the teat of the cow to inhibit development of a mammary gland infection.

27. An aqueous composition comprising mandelic acid and a thickening agent, wherein the pH of the composition is less than about 4.5, with the proviso that the composition does not contain chlorite ions.

28. The aqueous composition of claim 27 wherein the mandelic acid is present at a concentration of 0.1% to 10% by weight, based on the total weight of the composition.

29. The aqueous composition of claim 27 wherein the thickening agent is present at a concentration of 0.5% to 5% by weight, based on the total weight of the composition.

30. The aqueous composition of claim 27 further comprising an inorganic acid.

31. The aqueous composition of claim 27 wherein the pH of the same has been upwardly adjusted by addition of a basic compound.

32. The aqueous composition of claim 27 further comprising an antiseptic, wherein the antiseptic is an agent other than an iodine-containing compound.

33. The aqueous composition of claim 32 wherein the antiseptic is chlorhexidine.

34. A dry composition comprising mandelic acid and a moisture-absorbing carrier suitable for application to skin or tissue, wherein the mandelic acid is present in the composition in an amount such that, upon contact with residual water on the skin or tissue, it is capable of forming an aqueous composition having a pH less than about 4.5.

35. The dry composition of claim 34 wherein the mandelic acid is present in an amount ranging from about 0.1% to about 10.0%.

36. The composition of claim 34 wherein the moisture absorbing agent is selected from comstarch, powdered sugars and talc.

37. The dry composition of claim 34, further comprising a humectant.

38. The dry composition of claim 37 wherein the humectant is sorbitol.

39. The dry composition of claim 34, further comprising a color agent.

40. The dry composition of claim 34, further comprising a wetting agent.