[0001 ] The invention relates to a biofilm disrupting composition. The composition is useful for the disruption and/or removal of bacterial biofilms from a range of surfaces such as medical devices and environmental surfaces.

Background of Invention

[0002] A biofilm is any group of microorganisms in which cells stick to each other and often these cells adhere to a surface. These adherent cells are frequently embedded within a self-produced matrix of extracellular polymeric substance (EPS). The biofilm EPS is typically comprised of a polymeric conglomeration generally composed of extracellular DNA, proteins, and polysaccharides. Biofilms may form on living or non-living surfaces and can be prevalent in natural, industrial and hospital settings. The microbial cells growing in a biofilm are physiologically distinct from planktonic cells of the same organism, which, by contrast, are single-cells that may float or swim in a liquid medium.

[0003] Typically, the formation of a biofilm commences by the adsorption of proteins, polysaccharides, and other materials onto the surface to form a conditioning layer. Early colonization of the surface covered with this conditioning layer by bacterial species may then occur. Initially, bacterial cell attachment is reversible.

[0004] The adhesiveness of the layer is also mediated by the presence of glycoproteins and adhesins released by the early colonizing cells, forming a basal layer to the biofilm. In the case of adhesins, it has been shown that disulfide links provided by the amino acid cysteine are found near the ligand-binding sites of a wide range of microbial adhesive proteins, including the FimH adhesion, a two-domain protein located on the tip of type 1 fimbriae, 0.5-1 μιη long organelles primarily composed of FimA polymers found on the bacterial surface of Escherichia coli. The disulphide linkages provided by the cysteine moieties have been demonstrated to be critical for bacterial adhesion under flow conditions (see Nilsson et al, Molecular Microbiology, 2007, 65(5), 1 158-1 169). [0005] As the biofilm matures, many of the adhered bacterial cells become irreversibly adsorbed onto the surface. The number of irreversibly attached cells increases due to bacterial cell replication, a process that will be limited by

physiological processes and the concentration of rate-limiting nutrients. This will in turn lead to the transition of affixed cells from their planktonic form to their attached form, a process governed by change in genetic up-regulation that also results in the release of polysaccharides to form the biofilm EPS.

[0006] Microbes form a biofilm in response to many factors, which may include cellular recognition of specific or non-specific attachment sites on a surface, nutritional cues, or in some cases, by exposure of planktonic cells to sub-inhibitory concentrations of antibiotics. When a cell switches to the biofilm mode of growth, it undergoes a phenotypic shift in behavior in which large suites of genes are differentially regulated.

[0007] ESKAPE organisms are a group of clinically relevant multi-drug resistant organisms. These are Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp, all of which are capable of forming biofilm, and also capable of serious infections in hospitals, particularly in ICU's. In particular, several of these organisms are implicated in biofilm-mediated medical conditions. Pseudomonas for example is implicated in diseases such as cystic fibrosis, whereas multi-organism biofilms have been implicated in diabetic wound ulcers.

[0008] Similarly, glutathione has also been found to be efficacious in the disruption of biofilm. It is thought that glutathione impacts the integrity of the biofilm by its interaction with pyrocyanin, a toxin typically produced by Pseudomonas.

[0009] Pyocyanin is a blue, secondary metabolite with the ability to oxidise and reduce other molecules and therefore can kill microbes competing against P.

aeruginosa as well as mammalian cells of the lungs which P. aeruginosa has infected during cystic fibrosis. Due to its redox-active properties, pyocyanin generates reactive oxygen species that lead to oxidative stress of mammalian cells. [0010] Pyocyanin also intercalates directly with eDNA, thereby conferring structural integrity to the biofilm through increased cell surface hydrophobicity, which enhances intercellular aggregation.

[001 1 ] Several therapies have been developed to address biofilm mediated conditions. For example, inhaled glutathione (GSH) therapy has been used to reduce oxidative stress in cystic fibrosis patients and inhibit proliferation of Pseudomonas infections in cystic fibrosis patients, including increasing susceptibility of the

Pseudomonas to antibiotics {Zhang and Duan, Science in China Series C: Life Sciences 2009 Jun;52(6):501 -5).

[0012] It has also been found that GSH and DNase 1 can be combined for treating chronic Pseudomonas infections in individuals with cystic fibrosis (Klare et al., Canberra ASM meeting, July 2015). Further, GSH and DNase 1 have been found to be useful in the disruption of Pseudomonas biofilms in cystic fibrosis-like media and increasing susceptibility of the Pseudomonas aeruginosa to antibiotics (Klare et al., 2016 Antimicrobial Agents and Chemotherapy 60 (8) 4539-4551 ).

[0013] A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that that document or matter was known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims.

[0014] It would be desirable to provide a composition which is effective against biofilms and in particular biofilms caused by ESKAPE organisms.

Summary of Invention

[0015] It has been surprisingly found that a composition comprising a combination of a redox based viscosity modifier, a biofilm disrupter and a biocide provides enhanced biofilm disruption. The composition of the invention has been found to be effective against biofilms caused by ESKAPE organisms.

[0016] Disclosed herein is a biofilm disrupting composition comprising:

(i) at least one redox based viscosity modifier;

(ii) at least one biofilm disruptor; and (iii) at least one biocide.

[0017] More specifically, according to a first embodiment of the invention there is provided a biofilm disrupting composition comprising:

(i) at least one redox based viscosity modifier;

(ii) at least one biofilm disruptor; and

(iii) at least one biocide wherein the redox based viscosity modifier is capable of reducing disulfide links in biofilm components.

[0018] According to a second embodiment of the invention there is provided a biofilm disrupting composition when used for disruption and/or removal of bacterial biofilms from a surface, comprising:

(i) at least one redox based viscosity modifier;

(ii) at least one biofilm disruptor; and

(iii) at least one biocide. wherein the redox based viscosity modifier is capable of reducing disulfide links in biofilm components.

[0019] According to a third embodiment of the invention there is provided a process of preparing a biofilm disrupting composition comprising combining at least one redox based viscosity modifier, at least one biofilm disruptor, and at least one biocide, to form said composition.

[0020] According to a fourth embodiment of the invention there is provided the use of a composition according to the first or second embodiments to disrupt biofilms on, and/or remove bacterial biofilms from, a surface.

[0021 ] According to a fifth embodiment of the invention there is provided a method of disruption of biofilm on, and/or removal of biofilm from, a surface, comprising applying to said surface a biofilm disrupting composition according to the first or second embodiments in an amount which effectively disrupts and/or removes said biofilm. [0022] Throughout the description and claims of the specification, the word "comprise" and variations of the word, such as "comprising" and "comprises", is not intended to exclude other additives, components, integers or steps.

[0023] The ingredients of the composition of the invention act synergistically providing superior biofilm disruption. Without wishing to be bound by theory, it is believed that the redox based viscosity modifier, by virtue of its low molecular weight and therefore high diffusivity, reduces the viscosity of the biofilm, thus facilitating the diffusion in of the enzymes, allowing greater access to the biopolymer chains, leading to more efficient scission. Finally, with the biofilm EPS degraded, the biocide will have greater access to the microbial species.

Detailed Description of the Invention

[0024] Redox based viscosity modifier

[0025] The composition of the invention comprises at least one redox based viscosity modifier. This is a biologically and pharmaceutically acceptable compound capable of reducing disulphide bonds and therefore is capable of disrupting disulphide cross-links found within glycoproteins and adhesins typically found in the basal layers of most biofilms. Typically, such compounds will have a redox potential in the range of -0.05V to -0.50V.

[0026] Redox based viscosity modifiers that may be used in the composition of the invention are reducing agents known to reduce disulphide bonds.

[0027] Examples of redox based viscosity modifiers include mercaptoethanol, N- acetyl cysteine (NAC), glutathione (GSH), thiamphenicol glycinate acetylcysteinate (TGA), sodium mercaptoethane sulfonate, dithiothreitol (DTT), dithiobutylamine and other similar compounds. Other examples of suitable redox based viscosity modifiers are compounds such as lipoic acid or erdosteine, which are capable of generating free thiol groups in vivo following first pass metabolism.

[0028] One potential issue with the use of a thiol based redox based viscosity modifier will be the tendency for the sulfhydryl group to undergo atmospheric oxidation, particularly in solution. In a preferred embodiment, the inventive biofilm disrupting compositions will be in the form of a powder blend composition, intended for either dissolution in water prior to use, or applied directly to the biofilm soiled surface.

[0029] In a particularly preferred embodiment, the redox based viscosity modifier is comprised of a phosphine derivative selected from the group comprising Tris(2- carboxyethyl)phosphine (TCEP), TCEP monomethyl ester, TCEP dimethyl ester, and TCEP trimethyl ester. Other redox based viscosity modifiers used in the composition of the invention may be other esters of TCEP, such as the ethyl, propyl, isopropyl and butyl esters.

[0030] Other redox based viscosity modifiers, being reducing agents, which may be used in the composition of the invention are sodium dithionite, sodium thiosulfate and sodium bisulfite.

[0031 ] Redox based viscosity modifiers not containing a sulfhydryl group or a disulphide link may also be used in the composition of the invention. These will typically comprise biologically acceptable antioxidants such as ascorbic acid. Other examples include coumarin derivatives and flavonoid derivatives, which are typically recognised as antioxidants, and compounds capable of reducing oxidative stress within living tissue. Examples of coumarin and flavonoid derivatives suitable for use in the compositions of the invention may be found in "The Antioxidant Activity of Coumarins and Flavonoids", GB Bubols et al, Mini Rev Med Chem. 2013

Mar;13(3):318-34, incorporated herein as a reference.

[0032] As described in by Cline et al, (Biochemistry, 2004 Dec 7;43(48):15195- 203), the use of the various esters of TCEP allows for the modification of the reactivity of the TCEP towards disulphide bonds by virtue of modifying the phosphorus pKa values. pKa

Unesterified TCEP 7.6

TCEP monomethyl ester 6.8

TCEP dimethyl ester 5.8

TCEP Trimethyl ester 4.7 [0033] At pH 5.0, the order of reactivity against disulphide bonds in a model peptide is as follows:

[0034] trimethyl- > dimethyl- > monomethyl- > TCEP » DTT.

[0035] The trimethyl TCEP ester is 35-fold more reactive than TCEP. Under these conditions, the thiol based agent dithiothreitol (DTT) is essentially unreactive.

Esterification of the TCEP also increases lipophilicity, allowing the TCEP trimethyl ester to penetrate phospholipid bilayers rapidly (>30-fold faster than DTT), whereas the parent TCEP is impermeant.

[0036] Biofilm Disruptor

[0037] The biofilm disruptor is an agent that can either lead to scission of the biopolymers that make up the biofilm, or lead to a disruption of the adhesive forces that help attach the biofilm to its supporting surfaces. The biofilm disruptor breaks down the polymeric components of the EPS of bacterial biofilm into smaller, more diffusible components. The redox based viscosity modifier in the composition of the invention is believed to act synergistically with the biofilm disruptor by reducing the cross-linking between the various EPS biopolymers, and thus lowering the viscosity of the biofilm, so allowing the biofilm disruptor to more readily diffuse into their substrate biopolymers, and also allowing the more ready outward diffusion of the resultant biopolymer fragments following enzyme degradation.

[0038] The biofilm disruptor may be at least one enzyme selected from the group consisting of protease, amylase, cellulase, and DNase. Preferably one or more of the enzymes is DNase. More preferably, the composition of the invention will contain two or more of these enzyme types.

[0039] Given that the tertiary structure of most of the enzymes used in the composition of the invention is globular, the diffusion of the enzyme molecule into its substrate is likely to be limited by the high viscosity likely to be encountered in the biofilm EPS. When the enzyme in the composition of the invention is DNase, it is believed that it degrades the extracellular chains of DNA and other nucleic acids released into the extracellular matrix by the lysis of bacterial cells, thus releasing the cell genetic material into the EPS. Other DNA packages, such as plasmids, which are small circular sections of double stranded DNA found separate from chromosomal DNA within most bacterial species may also be released and taken up by live bacteria within the biofilm, thus providing a mechanism for the exchange of genetic information such as antibiotic resistance. It is believed that, by using DNase into the composition of the invention, this may serve to restrict further genetic exchange.

[0040] Alternatively, or in addition, the biofilm disruptor may comprise a blend of surfactants and/or solvents which preferably lower the surface tension of the composition to at least 35 imN/m. Preferably, the surfactants are non-toxic and non- irritating at the in-use concentration. The surfactants may be selected from the group consisting of anionic, cationic, zwitterionic or non-ionic surfactant types, or compatible mixtures thereof.

[0041 ] When a cationic surfactant is used, this may also function as a biocide. Examples of biocidal cationic surfactants which may be used in the composition of the invention include benzalkonium chloride, benzethonium chloride, dimethyl

didecylammonium chloride etc. It is recognized that cationic surfactants will typically be incompatible with anionic surfactants, and therefore mixtures of surfactants containing cationic surfactants will not contain anionic surfactants and vice versa.

[0042] Preferred are mixtures of non-ionic surfactants such as alkyl

polyglucosides, alcohol ethoxylates, polyethylene glycol/polypropylene glycol block copolymers (Pluronics™), N-alkyl pyrrolidinones (e.g. Surfadone™).

[0043] Representative examples of surfactants which may be used in the composition of the invention may be found in US6855678, incorporated herein in its entirety by way of reference. More specifically, the at least one surfactant may be selected from the group consisting of an alkyl polysaccharide surfactant, a nonionic surfactant, an alkyl, aryl or amine halide surfactant, a polyethoxylate of an alkylamine surfactant, and a lauric mono, di- or triethanolamine. More preferably, said nonionic surfactant may be selected from the group consisting of a nonionic surfactant containing from 8 to 18 carbon atoms and/or from 6 to 12 moles of ethyleneoxide; an amine oxide containing from 12 to 18 carbon atoms; an ethoxylate alkyl amine containing from 10 to 14 carbon atoms and 1 to 6 moles of ethylene oxide; an alkyl (C8-12) dimethyl benzyl amine halide; and a lauric mono, di- or triethanolamine. [0044] Solvents which act as a biofilm disruptor which may be used in the composition of the invention are preferably selected from the group consisting of one or more low molecular weight polar water soluble solvents selected from the group consisting of primary or secondary alcohols; glycols; esters; ketones; aromatic alcohols; and cyclic nitrogen solvents containing 8 or less carbon atoms. More preferably, the one or more solvent is selected from the group consisting of a (C1 -6) alcohol; ester; ether; ketone; glycol; or their methyl and ethyl esters and ethers; an aromatic alcohol containing 8 or less carbon atoms; pyrrolidone; and methyl pyrrolidone.

[0045] The surfactant and/or solvent have the added advantage of providing a composition with improved surface wetting characteristics. In a more preferred embodiment, the composition of the invention will comprise one or more

surfactants/solvents providing a surface tension of the solution of less than 40nN/m. In an even more preferred embodiment, the surfactant/solvent(s) will be selected in order to reduce the surface tension of the composition to below 30nN/m.

[0046] Without wishing to be bound by theory, it is believed that solutions with a very low surface tension (i.e. 35 nN/m or less) can penetrate between the biofilms basal layer and the substrate on which the biofilm has grown thus leading to detachment of the biofilm from the surface. This can lead to clumps of biofilm detaching from the surface, thus being available from attack from both anterior and posterior surfaces.

[0047] Biocide

[0048] The composition of the invention comprises at least one biocide. The biocide may be selected from an antibiotic or a disinfectant, depending on the intended use of the composition.

[0049] In the case of a composition intended for the in-vivo removal of a biofilm, such as that found in the lungs in cystic fibrosis patients, the biocide will be a pharmacologically acceptable antibiotic preferably selected from the group consisting of ciprofloxacin, dexamethasone, amoxicillin/clavulanate, cefixime, cefaclor, clarithromycin, levofloxacin, moxifloxacin and telithromycin. [0050] When the biofilm is found on an environmental surface, or on the surface of a medical device such as a catheter, the biocide may typically be one found in disinfectants such as benzalkonium chloride (BAK), dimethyl didecylammonium chloride (DDAC), chlorhexidine gluconate (CHG), polyhexamethylene biguanide (PHMB), alexidine, hydrogen peroxide, peracetic acid, phenolic disinfectants such as chloroxylenol, o-phenylphenol, chlorocresol, etc.

[0051 ] The function of the biocide is to kill the organisms responsible for the formation of the biofilm. This will have the secondary effect of removing the

propensity of the biofilm to release infectious agents that often lead to chronic illnesses with in-vivo biofilms, or indeed serve as an environmental reservoir of infectious organisms.

[0052] The at least one redox based viscosity modifier and the at least one biofilm disruptor within the composition of the invention act synergistically with the biocide. Typically, microorganisms found within biofilms will show a high level of resistance to biocidal agents, predominantly due to the fact that microorganisms are embedded deep within the EPS and thus shielded from biocides. A second factor for the resistance of the organisms to biocidal compounds is the fact that many organisms within the biofilm may exchange genetic information, such as resistance to

antimicrobial species.

[0053] Ancillary agents

[0054] The biofilm disrupting composition may optionally contain other ingredients such as tonicity modifiers, pH buffers, colourants, preservatives and perfumes.

[0055] Tonicity modifying agent

[0056] The composition of the invention may also contain tonicity modifying ingredients. These may comprise inorganic salts, for example sodium bromide, potassium bromide, sodium chloride, potassium chloride, sodium acetate, potassium acetate, sodium citrate, potassium citrate, sodium phosphate, potassium phosphate, or may comprise organic tonicity modifiers such as propylene glycol, glycerol, mannitol, arabitol, glucose, fructose etc. The composition of the invention may be isotonic (i.e. 250 -350mOsmal/Kg) or hypotonic (i.e. <250mOsmal/Kg). Preferably the composition of the invention will not be hypertonic as this may lead to dehydration of the biofilm, resulting in a reduced tendency of the composition to diffuse into the biofilm and attack it.

[0057] Colouring agent

[0058] The composition of the invention may also comprise colouring agents. The colouring agents may be added to provide a function to the composition, such as the staining of components found within the bacterial biofilm, or may just be added to provide an aesthetically pleasing solution.

[0059] When the colouring agent is added to stain components of the biofilm, the resultant staining may provide a visual cue as to the presence of the biofilm, thus also provide a means of monitoring its removal. Suitable colouring agents capable of staining biofilm components (for example protein, polysaccharide or bacterial cell walls) will include Coomassie Brilliant Blue, Crystal Violet, erythrosine and tartrazine.

[0060] Processing aids

[0061 ] The biofilm disrupting composition may be in solid form, or the composition may be a solution. In the case of a solid mixture of ingredients, the mixture may comprise one or more processing aids such as mannitol, starch, glucose, sucrose etc in order to allow the composition to be processed into micronized particles, preferably with a mean particle size of less than 500 microns. In a more preferred embodiment, the micronized composition will have a mean particle size of less than 100 microns, and in a particularly preferred embodiment, the micronized composition will have a mean particle size of less than 40 microns. The micronized composition of this particularly preferred embodiment is suitable for inhalation and useful for the disruption and removal of bacterial biofilms found in the lungs in conditions such as cystic fibrosis, bronchitis, chronic obstructive pulmonary disease (COPD), and other airway infections in which biofilms are implicated, such as recurrent rhinosinusitis or pharyngotonsillitis. Examples

[0062] Example 1

[0063] Example 1 is a ready to use formulation for the removal of biofilm from lumened medical instruments such as endoscopes. The biocides in this formulation are cationic surfactants, which also serve as biofilm disrupting agents.

[0064] Gardiquat 1450 is a 50% benzalkonium chloride solution provided by Albright and Wilson. Arquad 2.10-80 is an 80% solution of Didecyldimethylammonium chloride supplied by Stepan, and Vantocil IB is a 20% aqueous solution of

polyhexamethylene biguanide, supplied by Lonza.

[0065] Example 2

[0066] Example 2 is an example of a biofilm removing concentrate, intended to be diluted with water at a dilution rate of 1 :100. In this example, the redox based viscosity modifier is TCEP, the biofilm disruptor is provided by surfactant/solvent blend, and the biocide is benzalkonium chloride. Ingredient % w/v Function

Deionised water 73.97 Aqueous Solvent

redox based viscosity

Tris(2-carboxyethyl)phosphine (TCEP) 3.00 modifier

Dissolvine E39 2.55 Chelating agent

80% Lactic acid 2.07 Buffering agent

48.5% sodium hydroxide solution 0.92 Buffering agent

Alkadet A20 2.49 Surfactant

Gardiquat 1450 9.90 Surfactant/biocide

Cetrimide 4.00 Surfactant/biocide

Ethylene diglycol monoethyl ether 4.98 Solvent

Citral 0.05 Perfume

Coomassi Brilliant Blue 0.003 colourant

[0067] Dissolvine is a solution of 39% ethylenediamine tetraacetic acid tetrasodium salt supplied by Akzo Nobel, Alkadet A20 is an alkyl polyglucoside surfactant supplied by Huntsman. Gardiquat 1450 is a 50% benzalkonium chloride solution provided by Albright and Wilson

[0068] Example 3

[0069] In this formulation, intended to be used at a dilution of 5ml/litre, Tris(2- carboxyethyl)phosphine serves as the redox based viscosity modifier, a blend of protease and amylase enzymes serve as the biofilm disrupting agents, and benzalkonium chloride serves as the biocide.

Ingredient % w/v Function

Deionised water 50.00 Aqueous solvent

Buffering agent/enzyme

Boric acid 1 .00 stabiliser

Tris(2- redox based viscosity

carboxyethyl)phosphine 1 .00 modifier

48.5% sodium hydroxide 1 .80 Buffering agent

sodium gluconate 2.00 Chelating agent Propylene glycol 20.00 solvent

Glycerine 1 1 .40 solvent

Ethylene diglycol monoethyl

ether 6.50 solvent

Pluronic PE6400 5.18 surfactant

Emulan TXO 5.50 Surfactant

Gardiquat 1450 1 .73 Surfactant/biocide

Spezyme AA 1 .50 Amylase enzyme

Effectenz P150 3.07 Protease enzyme

Papain 6000L 0.20 Protease enzyme

[0070] Pluronic PE6400 is an ethylene glycol/propylene glycol block copolymer nonionic surfactant provided by BASF. Emulan TXO is an alkyl alkoxide nonionic surfactant provided by BASF, Gardiquat 1450 is a 50% benzalkonium chloride solution provided by Albright and Wilson. Spezyme AA is a liquid alpha amylase enzyme supplied by Novozymes. Effectenz P150 is a serine protease enzyme supplied by DuPont, and Papain 6000L is a cysteine protease enzyme supplied by Novozymes.

[0071 ] Example 4

[0072] In this formulation, intended to be used at a dilution of 2ml/litre, glutathione serves as the redox based viscosity modifier, a blend of protease and amylase enzymes serve as the biofilm disrupting agents, and zinc chloride serves as the biocide.

Ingredient % w/v Function

Dl water 44.00 Aqueous solvent

Boric acid 1 .00 enzyme stabiliser

Glutathione 1 .00 redox based viscosity modifier

48% Potassium hydroxide

solution 4.09 Buffering agent

Gluconodeltalactone 4.08 Chelating agent

Propylene glycol 20.00 Solvent 85% TEA 20.00 solvent

85% phosphoric acid 7.00 Buffering agent

Effectenz P150 10.00 Protease enzyme

Spezyme AA 4.00 Amylase enzyme

Zinc chloride 5.00 Biocide

[0073] Spezyme AA is a liquid alpha amylase enzyme supplied by Novozymes. Effectenz P150 is a serine protease enzyme supplied by DuPont.