LIQUID ANTIMICROBIAL COMPOSITION

Abstract

A liquid antimicrobial composition is provided for use in the disinfection of the skin of a human or an animal, in particular where disinfection of a drug resistant organism is required. The composition comprises a cationic, cell membrane-disrupting biocide and a cationic dendrimer capable of inhibiting an efflux pump mechanism of said cell membrane. The cationic, cell membrane-disrupting biocide is preferably any or a combination of chlorhexidine, a polymeric biguanide, octenidine dihydrochloride and a quaternary ammonium compound. The dendrimer is provided to bind and disrupt the cell membranes of microorganisms in order to inhibit or destroy the cell's efflux pump mechanism thereby preventing microorganism strains resistant to the cationic membrane-disrupting biocide from becoming prevalent, particularly if the biocide comprises chlorhexidine. The dendrimer is preferably a G-0 to G-3 dendrimer comprising any or a combination of quaternary ammonium functionalised poly(propylene imine), polylysine, dendrimers with surface groups based on a sugar and polyamide amine (PAMAM) dendrimers. The composition is preferably in the form of an aqueous or aqueous alcohol solution, dispersion or emulsion that may have been adsorbed by a wipe.

Claims

1. Cationic dendrimer for inhibiting an efflux pump mechanism of a cell membrane.

2. Dendrimer according to claim 1, wherein the dendrimer is any of a generation 0 to generation 3 dendrimer or a combination of same.

3. Dendrimer according to claim 1, wherein the dendrimer is of generation 1.

4. Dendrimer according to claim 1, wherein dendrimer is any or a combination of quaternary ammonium functionalised poly(propylene imine), polylysine, dendrimers with surface groups based on a sugar and polyamidoamine (PAMAM) dendrimers.

5. Dendrimer according to claim 1, wherein the dendrimer is poly(propylene imine).

6. Dendrimer according to claim 1, wherein the dendrimer is a polyamidoamine (PAMA) dendrimer.

7. Dendrimer according to claim 1, wherein the dendrimer is a polyamidoamine (PAMAM) dendrimer of generation 1.

8. Antimicrobial composition comprising the dendrimer according to claim 1.

9. Antimicrobial composition according to claim 8 for use in the disinfection of the skin of human or animal.

10. Cationic dendrimer according to claim 1 for use in the disinfection of the skin of human or animal.

11. Dendrimer according to claim 1 for use in the prevention or treatment of an infection by microorganisms, in particular drug-resistant organisms.

12. Antimicrobial composition according to claim 8 for use in the prevention or treatment of an infection by microorganisms, in particular drug-resistant organisms.

13. A method for disinfecting the skin of a human or animal comprising: applying an antimicrobial composition to the skin of the human or animal, wherein the antimicrobial composition comprises a cationic dendrimer for inhibiting an efflux pump mechanism of a cell membrane.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEW OF THE DRAWINGS

[0034] FIG. 1 is a graph showing the MIC test results for formulations comprising chlorhexidine digluconate with and without L61 Block copolymer/PAMAM dendrimer as detailed in the specification.

[0035] FIG. 2 is a graph showing the MIC test results for formulations comprising chlorhexidine digluconate with and without PE 9400 Block co-polymer/PAMAM dendrimer as detailed in the specification.

DETAILED DESCRIPTION OF THE INVENTION

[0036] Compositions in accordance with the present invention as described above minimize the risk of antimicrobial resistance to the cationic, cell membrane-disrupting biocide in the composition developing. The dendrimer interacts with the cell membranes of the microorganisms and gives rise to a decrease in microviscosity. In mammals it has been noted that this is accompanied by inhibition of P-glycoprotein activity. It has been found that similar effects occur in bacteria where the structure of the ABC efflux transporter is similar to the P-glycoprotein (P-gp). Strong energy depletion, inhibition of efflux proteins and subsequent ATP depletion causes a closedown of the drug efflux systems allowing increase of biocide input; essentially a sensitisation of the organism to the biocide.

[0037] Interference with the transporter mechanism can be assayed by both membrane ATPase assay and cellular calcein assays. Porin expression can also be assayed by the ethidium bromide or acridine orange techniques allowing assessment of the efficacy of particular formulations and their relevance to individual aspects of patient care. It is also the case that inhibition of the efflux pump mechanism will also beneficially impact on biofilm production and quorum sensing by the microbial population. This will further improve the efficacy of biocides in formulations covered by this invention.

[0038] Other compounds may also be suitable for inclusion in specific formulations of the invention. In particular, compounds that may also inhibit the efflux pump mechanism. These may be drawn from various chemical groups, including phenothiazine neurologically active drugs, certain essential oils and essential oil components such as berberine, that of Helichrysum italicum, geraniol, pinenes, alpha zingiberine, terpenes, tea tree oil and others as well as some complex surface active agents.

[0039] In order to prove the effectiveness of the use of dendrimers in inhibiting the efflux pump mechanisms of resistant microorganisms, the minimum inhibitory concentration (MIC) of chlorhexidine digluconate against a chosen bacterium was assessed and then compared to chlorhexidine digluconate formulations that include cationic dendrimers. The method adopted was a double dilution (50% dilution) turbidity method for MIC determination. The test was conducted using the BioScreen® C and subsequent software of Thermo Labsystems, Inc., which analyses 2×100 wells in an incubated spectrophotometer. Double dilutions of chlorhexidine digluconate were prepared in the well with or without the addition of various cationic dendrimers in various combinations along with the chosen bacteria. The minimum inhibitory concentrations were determined by optical density at regular time intervals for a period of 24 hours with the micro-plates incubated at 37° C.

[0040] The bacterium chosen for the tests was Pseudomonas aeruginosa because its genome includes the required gene (cepA). The test protocol was adopted because it was able to test multiple formulations at once. Therefore, the method was able to compare the chlorhexidine digluconate control against formulations that included cationic dendrimers when treated with the same conditions.

[0041] Initial tests were conducted to determine the MIC of chlorhexidine digluconate alone as well as negative controls and eliminate potential interferences of other chemical ingredients in the formula. No significant difference was observed between chlorhexidine digluconate alone and the chlorhexidine digluconate containing formulations that excluded cationic dendrimers. It can be seen that the best results were obtained using a combination of chlorhexidine digluconate, a dendrimer and a block co-polymer. However, although the tests demonstrate the effectiveness of the dendrimer and dendrimer block copolymer formulations not all formulations are equally effective.

[0042] The four formulations tested are listed below, two being aqueous solutions and two aqueous alcohol solutions. The chlorhexidine digluconate concentrations were double diluted. In the formulations, only the block copolymers and dendrimer were unchanged, that is they were not diluted. The test results are shown graphically in the accompanying drawings, wherein the graphs in FIGS. 1 and 2 are the MIC results for of chlorhexidine digluconate alone and when combined with cationic dendrimers. The four formulations used in the tests were as follows,

1. Zero Generation (G-0) Dendrimer

[0043]

TABLE-US-00001 Ingredient % w/v Chlorhexidine gluconate 2.0  Propylene glycol 0.50 Tocopheryl acetate 0.03 Fragrance 0.10 Polylsorbate 20 0.50 Caprylyl/Decyl glucoside 0.10 Benzalkonium chloride 0.04 Block copolymer (Pluronic 0.01 PE9400 or Pluronic L61) PAMAM Dendrimer (o-G) 0.1 or 0.2 Citric acid To pH 5.5 Water To 100 ml

2. Zero Generation (G-0) Dendrimer

[0044]

TABLE-US-00002 Ingredient % w/v *Isopropyl alcohol (*% v/v) 70 Chlorhexidine gluconate 2.5 Block copolymer (Pluronic PE9400 0.01 or Pluronic L61) PAMAM Dendrimer (o-G) 0.1 or 0.2 Water To 100 ml

3. First Generation (G-1) Dendrimer

[0045]

TABLE-US-00003 Ingredient % w/v Chlorhexidine gluconate 2.0 Propylene glycol 0.50 Tocopheryl acetate 0.03 Fragrance 0.10 Polylsorbate 20 0.50 Caprylyl/Decyl glucoside 0.10 Benzalkonium chloride 0.04 Block copolymer (Pluronic 0.01 PE9400 or Pluronic L61) PAMAM Dendrimer (1-G) 0.1 or 0.2 Citric acid To pH 5.5 Water To 100 ml

4. First Generation (G-1) Dendrimer

[0046]

TABLE-US-00004 Ingredient % w/v *Isopropyl alcohol (*% v/v) 70 Chlorhexidine gluconate 2.5 Block copolymer ( Pluronic 0.01 PE9400 or Pluronic L61) PAMAM Dendrimer (1-G) 0.1 or 0.2 Water To 100 ml
Apart from the test formulations above, other preferred examples of formulations of antimicrobial compositions in accordance with the present invention are as follows.

Example 1

[0047]

TABLE-US-00005 Chlorhexidine gluconate 2.00% w/v PEO-PPO-PEO block copolymer 1.00% w/v Polypropylenimine (PPI) dendrimer 0.01% w/v Disodium ethylenediaminetetraacetic acid 0.05% w/v (Disodium EDTA) Water to 100%

Example 2

[0048]

TABLE-US-00006 Chlorhexidine gluconate 2.00% w/v Polypropylenimine (PPI) dendrimer 1.00% w/v PEO-PPO diblock copolymer 0.05% w/v HEDP 0.02% Ethanol   70% Water to 100%

Example 3

[0049]

TABLE-US-00007 Chlorhexidine gluconate 4.00% w/v Geraniol 1.00% w/v Polylysine dendrimer 0.05% w/v Polyhexamethylene biguanide hydrochloride 0.50% w/v Phenoxyethanol 0.20% w/v PEG 40 0.50% w/v Water to 100%

Example 4

[0050]

TABLE-US-00008 Benzalkonium chloride 1.00% w/v Cetylpyridinium chloride 0.50% w/v Cationic dendrimer 1.00% w/v Capryl glucoside surfactant 0.05% w/v PEO/PPO block copolymer surfactant 0.50% w/v Water to 100%

Example 5

[0051]

TABLE-US-00009 Octenidine dihydrochloride 2.00% w/v PAMAM dendrimer 1.00% w/v Polysorbate 20 0.50% w/v Glycerine 1.00% w/v Aloe vera 0.50% w/v Essential oil based fragrance 0.10% w/v EDTA di sodium salt 0.05% w/c Water to 100%

Example 6

[0052]

TABLE-US-00010 Chorhexidine gluconate  2.5% w/v Isopropyl alcohol 70.0% w/v Polypropyleneimine dendrimer  1.5% w/v Phenoxyethanol  0.2% w/v Water to 100%

[0053] It will be appreciated that formulations suitable for human skin application may include further conventional ingredients such as emollients, fragrances, and skin conditioning agents dependent on the properties desired in addition to disinfection. Such formulations are suitable for use as surgical scrubs, cleansers for skin wounds, preoperative skin preparations, germicidal hand rinses and the like. In all cases the cationic membrane-disrupting biocide is preferably present in a concentration between 0.25% w/v and 6.00% w/v inclusive. Other similar applications include those in veterinary medicine and animal husbandry, for example in dairy hygiene products, particularly pre-milking hygiene preparations and teat dips.

[0054] The composition of the present invention may be used in combination with a wipe, for example a wipe of woven, knitted or nonwoven material, a sponge and a composite material, for example as a shampoo cap for convenient use. Suitable wipes may be made of any or a mixture of polyolefin, polyester, viscose, cotton, cellulose or other fibres. Sponge wipes may be made of polyurethane. The composition may be adsorbed by such a composite, wipe or sponge, which may be then be packaged ready to be dispensed from a tub, a bucket, a flow-wrap pack or an individually sealed wrapper or sachet.