TREATMENT OF MICROBIAL INFECTIONS

Abstract

The present application relates to an anti-microbial system for use in the treatment of microbial infections or control of microbial contamination, which avoids the use of antibiotics. Such infections include mastitis, tuberculosis, cystic fibrosis and the contamination that may result from biofilm formation on medical devices.

Claims

1. A microbiocidal composition comprising a reactive oxygen species or components capable of producing a reactive species, the composition being capable of delivering the reactive oxygen species to a level of at least 0.4 millimoles per litre, over a 24 hour period.

2. A composition as claimed in claim 1 capable of delivering the reactive oxygen species to a level of at least 0.5 millimoles per litre, over a 24 hour period.

3. A composition as claimed in claim 1 or 2 wherein the reactive oxygen species is produced by the reaction of a peroxidase, a substrate for the peroxidase and hydrogen peroxide.

4. A composition as claimed in any preceding claim where the reactive oxygen species is selected from the group comprising hypothiocyanate (hypothiocyanite, SCNO.sup.−), hypoiodate (IO.sup.−) and hypochlorite (CLO.sup.−).

5. A composition as claimed in claim 3 or 4 wherein the peroxidase enzyme is selected from the group comprising a lactoperoxidase, a chloroperoxidase, a bromoperoxidase and an iodooxidase.

6. A composition as claimed in claim 5 comprising a lactoperoxidase enzyme and further comprising iodide or thiocyanate ions.

7. A composition as claimed in claim 5 comprising a chloroperoxidase enzyme and further comprising chloride ion.

8. A composition as claimed in any of claims 3 to 7 where the source of hydrogen peroxide is a solution of the hydrogen peroxide.

9. A composition as claimed in any preceding claim where the hydrogen peroxide is released by a hydrogen peroxide releasing compound selected from the group comprising percarbonates, citric acid and perhydrates, or by enzymatic methods.

10. A composition as claimed in any of claims 3 to 9 where the hydrogen peroxide is produced by an enzymatic reaction between a sugar and its appropriate oxidoreductase

11. A composition as claimed in claim 10 wherein the oxidoreductase is galactose oxidase and/or glucose oxidase.

12. A composition as claimed in claim 11 further comprising free monosaccharide sugar(s).

13. A composition as claimed in any of claims 3 to 12 further comprising a disaccharide sugar, and its corresponding glycoside hydrolase to produce a source of hydrogen peroxide.

14. A composition as claimed in claim 13 wherein the glycoside hydrolase is Beta-galactosidase, and the disaccharide sugar is lactose.

15. A composition as claimed in any preceding claim wherein a glycoside hydrolase and/or an oxidoreductase is used to react with sugars present at the infection site.

16. A composition as claimed in claim 10 wherein the additional source of hydrogen peroxide is derived from the reaction of a polyol (sugar alcohol) with its relative oxidase enzyme.

17. A composition as claimed in claim 16 wherein the polyol is glycerol and its relative oxidase enzyme is glycerol oxidase, or wherein the polyol is mannitol and its relative oxidase enzyme is mannitol oxidase.

18. A composition as claimed in any of claims 2 to 17 wherein the hydrogen peroxide is produced from the enzymatic reaction of L-amino acids with L-amino acid oxidase or xanthine (or hypoxanthine) and xanthine oxidase.

19. A composition as claimed in any preceding claim further comprising either hypoxanthine or xanthine or both.

20. A composition as claimed in claim 19 further comprising free amino acids.

21. A composition claimed in any preceding claim additionally comprising lactoferrin, or a glucocorticoid.

22. A composition claimed in claim 21 wherein the glucocorticoid is prednisolone or prednisone.

23. A composition as claimed in any preceding claim adapted for intramammary infusion or nebulisation, for use as an antimicrobial solution, emulsion or dried product, for use as an antimicrobial solution to be added to a poultice for a burn lesion to the skin, for use as an antimicrobial solution to be used as a nasal rinse, for use as an antimicrobial solution to be used as a surface cleaner.

24. An intramammary infusion delivery device loaded with a composition as claimed in any preceding claim.

25. A composition as claimed in any preceding claim where the solution is prepared as an emulsion, or dried product.

26. A composition as claimed in any preceding claim wherein the compounds are adhered to the surface of a medical device.

27. A composition as claimed in any preceeding claim where the components are adapted for delivery sequentially or cumulatively to the infection site.

28. A composition as claimed in any preceeding claim where the components are allowed to react before addition to the infection site.

29. A composition as claimed in any preceeding claim where the components are allowed react before addition to the infection site, and treated with catalase to remove excess hydrogen peroxide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0077] FIG. 1 depicts the susceptibility of E. coli to inhibition by H.sub.2O.sub.2. Growth, measured by optical density at 595 nm, was inhibited at dilutions of 1/8 and 1/16, but not 1/32.

[0078] FIG. 2 depicts the susceptibility of E. coli to H.sub.2O.sub.2 in the presence of KI/LP. Growth, measured by optical density at 595 nm, was inhibited at dilutions of 1/8 and 1/16, but not 1/32.

[0079] FIG. 3 depicts the susceptibility of E. coli to peroxide released by the addition of percarbonate. Growth, measured by optical density at 595 nm, was inhibited at dilutions of 1/8 and 1/16, but not at a dilution of 1/32.

[0080] FIG. 4 depicts the susceptibility of E. coli to peroxide released by the addition of percarbonate in the presence of KI and LP. Growth, measured by optical density at 595 nm, was inhibited at dilutions of 1/8 and 1/16, but not at a dilution of 1/32.

[0081] FIG. 5 depicts the susceptibility of E. coli to peroxide produced from Glucose by enzymatic activity via glucose oxidase.

[0082] FIG. 6 depicts the susceptibility of E. coli to peroxide releasing enzymatic glucose and glucose oxidase in the presence of supplemented KI and LP.

[0083] FIG. 7 depicts the proposed schematic model of hydrogen peroxide levels over time.

[0084] FIG. 8 depicts the standard curve of thiocyanate levels against optical density.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

[0085] An antimicrobial composition was produced by the addition of 150 mg potassium iodide, 4 mg lactoperoxidase (>80 units/mg), and 2 mg glucose oxidase (˜200 units/mg) to 7 ml sterile water. This embodiment is referred to as ‘KI-Dose-150’. Similarly, a composition was prepared using 150 mg potassium thiocyanate, and is referred to as ‘Thio-Dose-150’. The antimicrobial properties of these compositions were tested using a doubling dilution 96-well plate growth assay-based method. An aliquot of the composition was added to 150 μl growth medium (with 1-2% glucose present) containing 10.sup.7-8 bacterial cells, and brought to a final volume of 300 The composition concentration was doubly diluted by the removal of 150 μl of the mixture and transfer to the next well containing 150 μl of identical growth medium, lacking the ROS producing components. The optical density of the medium was measured for 24 hours at 595 nm. The concentration required to completely inhibit the bacteria was the lowest concentration of the composition employed that resulted in no visible signs of growth in the medium after the 24 hours. Controls included wells to which none of the composition was supplemented, or wherein, one of the components was removed from the composition. This method was used to determine the antimicrobial potency of the compositions against a variety of micro-organisms, notably Escherichia coli, Staphylococcus aureus, Psuedomonas aeruginosa, Burkholderia cepaciae, Streptococcus dysglactiae, Streptococcus uberis, a non-haemolytic coliform. These organisms are the often described as causative agents of numerous infections, notably bovine mastitis, cystic fibrosis lung infections, skin infections, burns infections, etc and, as such, represent the variety of organisms that the composition will be used to treat. The relative susceptibility of the organisms to the compositions is described in Table 1 (Ratio indicates the lowest dilution of the composition at which no growth was still recorded, for example, 1:800 had the composition diluted to the equivalent of 1 μl composition for every 800 μl of growth medium) and are the lowest concentrations of the composition that inhibited growth. The estimated level of the antimicrobial reactive oxygen species (ROS) produced over the course of 24 hours is also provided (see also Example 19 below).

TABLE-US-00001 TABLE 1 Susceptibility of bacterial strains to ‘Thio-Dose-150’ and ‘KI-Dose-150’. Thiocyanate Iodide Strain Dilution ROS MIC Dilution ROS MIC E. coli ATCC 25922 1:400 0.4-0.8 1:800   0.25-0.5 Strep. dys 143   1:48,000 0.003-0.007 1:48,000 0.005-0.01 Strep. dys 160   1:48,000 0.007-0.01  1:48,000 0.005-0.01 Strep. uberis   1:24,000 0.007-0.01  1:24,000 0.005-0.01 Staph. aureus 15676 1:800 0.3-0.6 1:800   0.25-0.5 Burk. cepacia 1:800 0.3-0.6 1:1,600  0.075-0.15 P. aeruginosa PA01 1:800 0.3-0.6 1:1,600  0.075-0.15 Non-haemolytic coliform 1:400 0.4-0.8 1:800   0.25-0.5 The MIC indicates the level of reactive oxygen species below which bacteriocidal effects were not noted (millimoles per litre produced over 24 hours).

Example 2

[0086] The lactoperoxidase system has been discussed in terms of its bacteriostatic or inhibitory qualities. The protocol described in Example 1 was performed in larger scale volumes (an initial 500 μl aliquot of KI-Dose-150 or Thio-Dose-150 was added to 10 ml growth medium containing the test organism and doubly diluted). After 48 hours of incubation, the bacteriocidal qualities of the system were investigated by the sub-culture of the inoculated broths to agar plates. The composition was deemed to be bacteriocidal for a bacterial strain at a particular concentration if no more than 0.0001% of cells were recoverable after 24 hours following sub-culture to the fresh agar plate (ie 72 hours after exposure to the antimicrobial composition). The compositions were bacteriocidal to each of the tested strains at concentrations that would be achievable for an infection treatment (lowest dilutions at which inhibition was noted are presented in Table 1 above.

Example 3

[0087] The choice of hydrogen peroxide source can be shown to affect the the LP system and also the ability to produce an antimicrobial composition based on ROS at bactericidal concentrations. Aliquots (20 ml) of nutrient broth were inoculated with 10.sup.8 cells of E. coli ATCC 25922, and 150 μl of the inoculated broth were added to wells in a 96 well growth plate. This was repeated with the inoculated broth being further supplemented with LP (37.5 μl of a 4 mg/ml solution) and KI (75 μl of a 40 mg/ml solution) to the medium.

[0088] Sources of hydrogen peroxide were added (150 μl) to well 1 and doubly diluted to well 11, but not to well 12, which acted as a control. The sources of hydrogen peroxide were as follows: [0089] 5 ml water containing 40 μl H.sub.2O.sub.2 (30% w/v) [0090] 5 ml water containing 50 mg sodium percarbonate [0091] 5 ml glucose (20%)+47 μl glucose oxidase (2.5 mg/ml, 200 Units/mg)

[0092] FIG. 1 illustrates that 1:8 and 1:16 dilutions of the H.sub.2O.sub.2 solution were inhibitory to E. coli, though the 1:32 dilution was not. Repetition of this assay in the presence of supplemented KI and LP did not accentuate the effects observed using H.sub.2O.sub.2 directly, with a 1:32 dilution still not inhibitory to the bacteria (FIG. 2), although the levels of H.sub.2O.sub.2 would have been significantly reduced during the incubation, in this case. This is because the supplemented LP would use available peroxide to catalyse the production of reactive oxygen species using the supplemented KI as substrate.

[0093] The pattern of inhibition caused by the addition of the sodium percarbonate solution to inoculated broths (FIG. 3) was identical to that observed following direct H.sub.2O.sub.2 addition. It is clear that there was no difference as regards inhibition, following supplementation of KI and LP when using sodium percarbonate as the source of hydrogen peroxide (FIGS. 3 and 4) although the peroxide would have been used to produce the less toxic reactive oxygen species, hypoiodate, during the incubation.

[0094] It was clear that only a 1:2 and 1:4 dilution of the glucose/glucose oxidase solution added produced sufficient H.sub.2O.sub.2 to be inhibitory (FIG. 5), but not at dilutions of 1:8 (partial), 1:16 or 1:32. It was clear, however, that on repetition of the glucose/glucose oxidase assay in the presence of the KI and LP (FIG. 6), inhibition of E. coli occurred at a much greater dilution (up to and including a 1:32 dilution) than achievable in the absence of added KI and LP (FIG. 5).

[0095] This result clearly indicates that the enzymatic production of hydrogen peroxide at levels greatly lower than those that are inhibitory to bacteria are sufficient to drive the production of inhibitory concentrations of antimicrobial reactive oxygen species. This offers a method to deliver a therapeutic dose of the antimicrobial reactive oxygen species without accumulation of potentially toxic H.sub.2O.sub.2.

Example 4

[0096] Volumes of milk (10 ml) were inoculated with E. coli and supplemented with the lactoperoxidase, glucose oxidase, potassium iodide and Beta-galactosidase as a mechanism to generate the antimicrobial composition of the invention. Concentrations of 3.75 mg/L glucose oxidase (˜200 units/mg), 12 mg/L lactoperoxidase (≥80 units/mg), 120 mg/L potassium iodide/thiocyanate, and 400 ml/L Beta-galactosidase (≥2,600 units/ml) or greater were sufficient to observe antibacterial activity. At the optimised concentrations these mixtures proved lethal to up to 10.sup.8 cells/ml of E. coli (subculture of the solution to fresh agar plates resulted in no recoverable cells.). Concurrent negative controls (excluding each of the components) resulted in an increase of bacterial numbers over the proceeding 24 h in the milk. The composition, generated in this manner, worked efficiently in the first 2 hours to eradicate bacteria.

[0097] A preparation was designed for use in the treatment of bovine mastitis by an intramammary infusion method. A field trial (6 cows, 6 quarters) was conducted wherein cows were treated on 4 occasions post milking with the proposed bactericidal composition produced by an enzymatic system (in this case, using Beta-galactosidase milk activation as an object of the present invention). The preparation contained lactoperoxidase (4 mg≥80 units/mg), glucose oxidase (2 mg, ˜200 units/mg), Beta-galactosidase (0.4 ml, ≥2,600 units/ml), and potassium iodide (150 mg) per dose. Significant decreases were noted in somatic cell counts of the animals as a result of treatment, recorded between 5 and 30 days after treatment. Results from the trial are tabulated below (Table 2), farms C and D.

TABLE-US-00002 TABLE 2 Somatic Cell Counts of treated animals. Initial SCC After 30 % Cow # (in millions) 5 days days Reduction Farm C 1 8.9 1.46 84 2 11.58 0.36 97 3 2.32 0.647 72 Farm D 118 11.094 1.234 89 529 24.942 18.278 27 207 22.835 4.214 82

[0098] An attempt was made to determine the effects of the milk pasteurisation process on the enzymatic components, which can be used to produce the reactive oxygen species of the composition of the present invention. Working concentrations of the enzymes were heated in 50 μl volumes to 72° C. and held for 15, 30, 60, 300 or 600 seconds.

[0099] Appropriate concentrations of these aliquots were then transferred to milk containing the necessary components of the system and ˜10.sup.8 cells/ml E. coli. Total viable counts were performed after 24 hrs incubation at 37° C. This allowed the determination of whether the enzymes were still active after heating. Glucose oxidase demonstrated activity after 300 seconds heating, as did lactoperoxidase. The activity of Beta-galactosidase was, however, impaired by the heating process, with a typical pasteurisation cycle (72° C. for 15 seconds) completely inactivating the enzyme. This would suggest that bacterial starter cultures used in post-processing of milk (yogurt and cheese) would not be inhibited by the use of the described preparations to generate the reactive oxygen species of the present invention.

[0100] A 10 ml volume of milk was used a model to test the hypothesis that a chloroperoxidase enzyme could be used instead of lactoperoxidase to generate antimicrobial reactive oxygen species. Milk was again spiked with E. coli (˜10.sup.7 cells/ml). A suitable concentration of both Beta-galactosidase (2-3 μl, ≥2,600 units/ml) and glucose oxidase (15 μl of a 2.5 mg/ml solution, ˜200 units/mg) was supplemented to the milk. A preparation of chloroperoxidase (0.5 μl, ≥11,100 units/ml) was then added, and resulted in a complete eradication of E. coli cells within 24 hours, at 37° C. Control experiments, without each, or two of the enzymes, resulted in the proliferation of a bacterial numbers within the same incubation conditions (10.sup.8-9 cells/ml).

Example 5

[0101] A field trial was conducted using a supplemented glucose based enzymatic system to produce the reactive oxygen species and to assess the efficacy of such an approach to producing the antimicrobial agents. A number of cows (8) were treated twice a day for two days with the supplied system. These cows demonstrated a marked decrease in their somatic cell counts (in the region of 50% after 5 days, see Table 3, Farms A and B, followed by a similar decrease after a further 5 days for Farm B, where subsequent data was available), a proxy method of measuring bacterial load. This demonstrated the efficacy of the lactoperoxidase system in generating the antimicrobial species, without use of Beta-galactosidase, to give assurance that it was a feasible source for generation of the bactericidal species.

TABLE-US-00003 TABLE 3 Somatic Cell Counts of treated animals using a glucose supplementation system to produce the antimicrobial reactive oxygen species. Initial SCC After 10 % Cow # (in millions) 5 days days Reduction Farm A 438 3.016 1.68 42.3 852 6.981 3.476 50.2 892 1.56 0.516 66.9 717 6.331 0.218 96.6 Farm B 794 3.4 0.926 0.59 82 501 0.71 0.47 0.394 44.5 831 3.5 3.3 0.995 71 823 0.812 0.554 0.186 77

Example 6

[0102] A trial was conducted to determine the ability of the proposed composition to eradicate biofilm-based bacterial cells. This was performed using two culturing techniques. A continuous culture of E. coli was established using a chemostat. This system is designed to allow the operator the ability to control the growth rate of the organism. Most infections will occur as a result of slow growing cells (due to limited nutrient availability). This phenotype will have an effect on the tolerance of cells to antimicrobials, and is more realistic of the host environment. Further to this, these cultures were used to grow biofilms on a Modified Robbins Device, wherein, the cells were allowed to attach and proliferate on the surface of a polyurethane coupon. These cells share the phenotype of biofilm cells noted in a typical infection in mastitis, CF/TB lungs, wounds, burns, and on medical devices and respond in a similar fashion and offer a viable model for antimicrobial testing.

[0103] The antimicrobial species were produced on test coupons using the lactoperoxidase based system, containing lactoperoxidase (2 mg/L, ≥80 Units/mg), potassium iodide, (300 mg/L), glucose (12.5 g/L) and glucose oxidase (0.57 mg/L, ≥200 Units/mg), by submerging the coupon in the solution at 37° C. for 24-48 hours. Control coupons were also treated with a saline solution or a mixture of the system lacking in one of the components.

[0104] Cells were then recovered from the surface of the coupons by means of sonication, and their viability determined. Cells treated with saline only were viable (10.sup.5 cells/coupon), as were those tested with the system lacking in one of the components required to produce the antimicrobial species. No viable cells were recovered from the coupons wherein cells were exposed to the antimicrobial species produced by a fully functioning LP system. This result compares favourably with similar previously reported treatment regimes using a variety of antibiotics (“Linezolid compared with eperezolid, vanocmycin, and gentamicin in an in vitro model of antimicrobial lock therapy for Staphycoccus epidermidis central venous catheter-related biofilm infections”, Curtin et al., 2003, Antimicrobial Agents and Chemotherapy, Vol. 47, No. 10, p 3145-3148), wherein cells were still recoverable after 10 days with treatment of 10 g/L gentamycin and 7 days with treatment of 10 g/L vancomycin, though better results were recorded for linezolid and eperezolid. Such concentrations are far greater (up to 1,000 fold) than those that would be lethal to the same strain grown planktonically. By contrast, the concentrations of the antimicrobial species generated in the present experiment were of the same order of magnitude as those used to kill planktonic cells.

Example 7

[0105] The susceptibility of a number of P. aeruginosa strains to the KI-Dose-150 composition was tested using the method described in Example 1. These strains were of interest as they demonstrated increased tolerance to a variety of key antibiotics typically used to treat lung infections associated with cystic fibrosis, and were recovered from the sputum of cystic fibrosis patients presenting with lung infection. The relative susceptibilities are described in Table 4. As evident from Table 4, the antibiotic tolerant strains of P. aeruginosa are no more tolerant to KI-Dose-150, indicating that the system would be effective at treating such infections when delivered to the lung. ‘S’ denotes sensitive, ‘R’ denotes resistant or increased tolerance.

TABLE-US-00004 TABLE 4 Susceptibility of antibiotic tolerant P. aeruginosa strains to ‘KI-Dose-150’. Amikacin Tobramycin Ciprofloxacin Gentamicin MIC PA01 (wild type) s s s s 0.25 mM R550/2012 9026 R R R R 0.12 mM R468/2012 9027 R s s s 0.06 mM R479/2012 9028 R R s R 0.12 mM R480/2012 9029 R s R R 0.12 mM P. aeruginosa s s R s 0.25 mM D12 The MIC value represents the minimum level of reactive oxygen species (hypoiodate) required to kill the strains (millimoles per litre produced over 24 hours).

Example 8

[0106] The treatment of respiratory infections by antibiotics will typically be delivered using oral or intra venous drugs. The aerosolised form of the antibiotics can also be used to counteract the poor transfer of drug from blood across the alveoli of the lung to infection sites. Various embodiments of the proposed antimicrobial composition were aerosolised using an AeroNeb nebuliser (courtesy of Aerogen Ltd.). Solutions of hydrogen peroxide/glucose/glucose oxidase/lactoerpoxidase/iodide/or thiocyanate were passed through the nebuliser one at a time, or mixed together and passed through the nebuliser, and the aerosol collected in a sterile 25 ml container. The antimicrobial potency of the aerosolised forms was compared to un-aerosolised forms (as described in Example 1), using doubling dilutions on a multi-well plate based assay. The proposed composition did not show any decreased activity when compared to the solutions that were not aerosolised. In addition, it was demonstrated that the enzymatic system, which can be used to produce the antimicrobial species was not affected by nebulisation. Specifically, the solutions did not show any reduced enzyme activity, or decreased levels of compound present when compared to stock solutions of the same components. This model would suggest that the proposed antimicrobial system would be a good target or candidate for successful aerosol delivery to the lung to treat respiratory infections.

Example 9

[0107] Lactoferrin is a mammalian protein that has been characterised to exercise antimicrobial properties, particularly on biofilm. As such, it is a good potential compound that could target and disrupt biofilm production in an infection model, and one that could act synergistically with a system such as the antimicrobial composition of the invention. The relative antimicrobial potencies of KI-Dose-150 and Thio-Dose-150 were tested as described in Example 1, both in the presence and absence of varying concentrations of lactoferrin. The presence of supplemented lactoferrin to the thiocyante model did not enhance the antimicrobial properties already present (ratios of lactoferrin to thiocyanate were 1:1, 1:2, 1:4). This would suggest that the presence of lactoferrin at significant concentrations does not inhibit the actions of a lactoperoxidase-thiocyanate model to produce the antimicrobial species. Planktonic cells were used, allowing the possibility that an accentuated antimicrobial effect would be noted for treatment of an actual infection.

[0108] The same ratios for lactoferrin to iodide did, however, lead to a noted two-fold increase in antimicrobial activity of the lactoperoxidase-iodide model for production of the antimicrobial species, suggesting that it would be a suitable companion in a proposed treatment regime. In the absence of lactoferrin, a 256-fold dilution of the system was still inhibitory to E. coli. With the addition of lactoferrin (at the three described ratios), a dilution factor of 512 was also inhibitory to the bacterial culture. Infection sites will often be composed of biofilm, which would allow an increased activity of the lactoferrin to be noted.

Example 10

[0109] Antibiotic therapies designed for the treatment of bovine mastitis will often induce an inflammation of the udder, leading to an increase in the somatic cell count for the animal. This is disadvantageous in that the price of the sold milk depends on a low somatic cell count. A number of drugs can typically be added to counter the inflammation arising due to the intramammary infusion of an antimicrobial therapy. Prednisone (or its active form, prednisolone) is a glucocorticoid steroid used to minimise an undesired immune response. A dosage of 10-20 mg is often administered in conjunction with antibiotic based intramammary infusions to halt an increase in the somatic cell count. An in vitro experiment using a dose of the proposed lactoperoxidase system (KI-Dose-150) in the absence and presence of either predisone or prednisolone did not result in any decrease in antimicrobial potency of the composition. This would indicate that the use of a typical dose of either drug would not interfere with the ability of the composition of the invention to eradicate bacteria in the udder (or other environment), and would help minimise increase of the somatic cell count.

Example 11

[0110] The ability of an enzymatic system to produce the antimicrobial species on a continuous basis was determined by repeat inoculations of bacterial culture to an antibacterial component containing solution. A 10 ml volume of LB growth medium was supplemented with glucose oxidase (15 μl of 2.5 mg/ml, 200 Units/mg), beta-galactosidase (30 μl, 10 mg/ml, 48,000 Units/mg), lactoperoxidase (20 μl mg/ml, 80 Units/mg) potassium iodide (30 μl, 40 mg/ml), with a final concentration of 2% lactose. Approximately 10.sup.8 cfu of E. coli ATCC 25922 were added and the mixture was incubated overnight, at 37° C. After 24 hours, no cells were recoverable to a fresh nutrient agar plate. A further inoculum of approximately 10.sup.8 cfu of E. coli ATCC 25922 cells was then added to the volume and the mixture was again allowed to incubate overnight. Similar, subsequent inoculations (ten inoculations, at one day intervals) of the broth with the bacterium did not result in growth or the recovery of bacterial cells. This result demonstrates that the concentration of the antimicrobial reactive species was held sufficiently above bactericidal levels over a significant time period.

Example 12

[0111] The effect of substrate choice on the potency of the composition produced by various systems was determined using variations of an inhibition growth assay, firstly, where the concentration of H.sub.2O.sub.2 (produced by the enzymatic reaction of glucose and glucose oxidase) was constant and the concentration of the chosen substrates was altered. Secondly, an assay where the concentration of substrates was maintained constant, and the H.sub.2O.sub.2 levels were varied was employed.

(i) Constant H.sub.2O.sub.2

[0112] E. coli (50 μl of an overnight culture) was added to Mueller Hinton broth containing 5 μl glucose oxidase (2.5 mg/ml) and 10 μl LP (4 mg/ml). This was aliquoted (150 μl) to rows of a 96-well plate. Equal volumes (150 μl) of either potassium iodide or potassium thiocyanate (both 40 mg/ml) were added to the initial well. The samples were doubly diluted as far as well 11, leaving well 12 as a control. The plate was incubated overnight at 37° C., and the optical density measured throughout.

[0113] Result: Thiocyanate concentrations in dilutions 1 to 9 were at a level sufficient for complete inhibition of the bacteria. Iodide concentrations in dilutions 1 to 8 were at a level sufficient for complete inhibition of the bacteria. This result would initially indicate that there was no significant difference in the potency of the reactive species produced by either substrate, and whatever differences were noted could have been as a result of the difference in molarity of the concentrations.

(II) Constant Substrate E. coli (200 μl of an overnight culture) was added to 20 ml Mueller Hinton broth already containing 40 μl LP (4 mg/ml) and 60 μl of either potassium iodide or potassium thiocyanate (40 mg/me. This was aliquoted (150 μl) to a 96 well plate. Samples of a H.sub.2O.sub.2 producing system (2 ml 20% glucose containing 10 μl glucose oxidase, 2.5 mg/ml) were added to the initial well, and doubly diluted, leaving well 12 as a control.

[0114] Result: Using a broth with a constant thiocyanate concentration, there was inhibition in the two highest dilutions of sample (H.sub.2O.sub.2). However, on using iodide, there was inhibition of bacterial growth up to, and including, six dilutions of sample. This results indicates that there is a significant difference in the potency of the antimicrobial species produced using an enzymatic system, which releases lower levels of hydrogen peroxide, when the substrate level is maintained at a constant level. This would imply that there would be a distinct advantage in using iodide when lower levels of H.sub.2O.sub.2 production are typical. Differences in molarity cannot explain the apparent difference in outcome when using iodide instead of thiocyanate.

[0115] Repetition of (i) and (ii) using milk as the growth medium showed very similar results and patterns. Using an alternative source of H.sub.2O.sub.2 (direct addition in this case) did not show up the peculiar outcome difference between iodide and thiocyanate.

Example 13

[0116] A protocol was drawn up that allows an operator to determine the appropriate concentrations of the antimicrobial species of the invention for use in the inhibition/killing of bacterial cells in broth. The protocol is based on doubling dilutions of the components, similar to that used in 96-well plate described in Example 1. A bacterial culture (10.sup.7 cfu/ml) is established and aliquoted to tubes (5 ml volumes added to 15 ml tubes would allow sufficient headspace for required oxygen, with the first tube to contain double the volume, 10 mls. The broth should contain sufficient appropriate sugar if using enzymes to produce H.sub.2O.sub.2, for example, glucose if using glucose oxidase, with 1-2% being typically sufficient).

[0117] An aliquot (preferably no more than 5% of the total volume of the solution, 500 μl) of the hydrogen peroxide producing components are added to the initial volume, and doubly diluted. After 24 hours the level of innate tolerance for a bacterial strain to hydrogen peroxide can be determined by the pattern of growth/no growth in the tubes. The hydrogen peroxide producing components could consist of a monosaccharide or disaccharide sugar and their appropriate cleaving enzymes (notably lactose and beta-galactosidase and glucose oxidase, or glucose and glucose oxidase) or more simply hydrogen peroxide can be added directly, or as hydrogen peroxide releasing percarbonate or citric acid, etc.

[0118] In conjunction with the test to determine the innate hydrogen peroxide sensitivity of the test strain, the same test would also be used using a reactive oxygen species producing solution (such as Thio-Dose-150 or KI-Dose-150, as described in example 1), wherein the hydrogen peroxide producing components are present, as well as the peroxidise enzyme (chloroperoxidase or lactoperoxidase, and their appropriate substrates) are also present.

[0119] Although various ratios and concentration variations of the LP system, for example, can be employed to yield antimicrobial and bactericidal concentration of the reactive species, the authors recommend a possible ratio of 75:2 of substrate to lactoperoxidase (for example, 150 mg KI and 4 mg lactoerpoxidase (at least 80 Units/mg). Similarly, if H.sub.2O.sub.2 is to be produced by the enzymatic cleavage of glucose, for example, the authors recommend a 75:2:1 of substrate, lactoperoxidase, and glucose oxidase (200 Units/mg glucose oxidase). The samples should be incubated at the appropriate temperature, and shaken overnight. Control cultures (without, for example, LP components or H.sub.2O.sub.2) should yield bacterial growth. At sufficiently high concentrations of H.sub.2O.sub.2 (initial few tubes), growth should not be observed but as the H.sub.2O.sub.2 level drops (more dilute cultures), growth will be evident. This will allow the operator to determine the innate tolerance of the strain to the actions of H.sub.2O.sub.2. Often, Streptococci strains are very susceptible to the actions of H.sub.2O.sub.2, as they lack catalase required to cleave the H.sub.2O.sub.2 molecule, whilst other species will be tolerant of H.sub.2O.sub.2 at levels of ˜2 mM (some yeasts, for example). The addition of the substrate and lactoperoxidase to the initial tube should result in no growth at levels of H.sub.2O.sub.2 that were not previously inhibitory as the more potent reactive species are produced. Similarly, there will be a level at which the dilution was such that growth occurred. The difference in outcome between ‘H.sub.2O.sub.2 only’ and H.sub.2O.sub.2 and substrate and LP′ will inform the operator as to concentration of the LP-system components necessary to kill the test strain, or to inhibit its growth over 24 or 48 hours, as required. The authors recommend choosing a concentration at which the H.sub.2O.sub.2 is not inhibitory in itself. Data described in Example 3 describes the use of an enzymatic cleavage of sugar, which allows a ‘window’ where the H.sub.2O.sub.2 levels produced in the solution are insufficient to cause inhibition, though sufficient to drive the production of the antimicrobial reactive oxygen species by the LP reaction (in instances where the strain does not produce catalase, and is therefore extremely susceptible to the actions of H.sub.2O.sub.2, the authors recommend using levels sufficient to kill typical catalase producing strains). A sub-culture to appropriate agar plate at 24/48/72 hour time points will allow the operator to determine at which concentration the components are produced at bactericidal concentrations, as opposed to bacteriostatic levels. The composition will be determined as bacteriocidal when no more than 0.001% of the starting cell numbers are recoverable from the broth.

[0120] This test allows the operator to determine the bacteriocidal concentration of the dose, and also the concentrations of hydrogen peroxide required to produce the components using an enzymatic system, without generating inhibitory levels of hydrogen peroxide. Such information will be valuable if contemplating introducing an enzymatic system to a sensitive environment, such as the mammalian lung.

[0121] Existing statistical models will allow the operator to then ‘scale up’ appropriately to determine the necessary levels required to treat infections or large volumes of liquid etc, for example, the udder or lung.

Example 14

[0122] The lower limits of each of the components in an enzymatic system, required to produce inhibitory biocidal concentrations of the antimicrobial agents, were determined (for example Table 1 and Table 5). To establish these lower limits for each component, minimum inhibitory concentrations for each were calculated using doubling dilutions on a 96-well plate, in a manner similar to that described in Example 1, wherein the concentration of the component of choice is lowered until no effect on growth is noted. In 10 ml LB broth growth medium (with 2% glucose), replete with 120 mg/L KI, 320 units LP, at least 0.5 unit glucose oxidase/ml is required to produce hydrogen peroxide.

[0123] Concentrations below this resulted in insufficient hydrogen peroxide being produced to provide for the further production of the reactive oxygen species at a bactericidal concentration. Similarly, the reduction of glucose levels requires an increase of glucose oxidase levels to compensate; 1% glucose required 1 units/ml, while 0.5% glucose required 2 units/ml activity glucose oxidase. In solutions where the glucose levels and glucose oxidase levels are sufficient, the level of required iodide (or thiocyanate) substrate was approximately 0.5 mM. At levels below this, there was insufficient reactive oxygen species produced to result in effective bactericidal activity. The level of LP required for a reaction to produce the reactive oxygen species at the required concentrations was determined at 0.15 unit activity/ml (1 mM KI present). Levels below this resulted in little antibacterial activity. This embodiment of the invention suitable for the therapeutic treatment of mastitis also included beta-galactosidase to convert the lactose present in milk to glucose. An in vitro examination of the required level of this enzyme was performed in milk (5% lactose), with 1 mM KI, 0.75 units/ml glucose oxidase activity/ml (levels below this will produce a ‘bottleneck’ in the enzymatic pathway resulting in insufficient reactive oxygen species being produced), and 1 unit lactoperoxidase activity/ml present The required activity of beta-galactosidase lay at approximately 1.5 units activity/ml. Beta-galactosidase activity at levels below this did not result in the inhibition of bacterial growth or in killing of bacterial cells, but rather in bacterial proliferation.

Example 15

[0124] It is possible to produce the antimicrobial reactive oxygen species of the composition of the invention before adding it to the site of infections. This may be achieved by the mixing of the required enzymatic components ensuring that the resulting reactive oxygen species (ROS; hypothiocyanate, hypoiodate, or hypochlorate) is produced outside of the treatment site. Further to this, any excess hydrogen peroxide left after the reaction can be removed by the addition of catalase (which reacts with hydrogen peroxide, producing oxygen gas and water). This may prove a very safe method of delivering the chosen ROS without the potentially disadvantageous hydrogen peroxide molecules.

[0125] Similarly, it is possible to introduce the catalase at the infection site also to help ‘quench’ the potential build-up of harmful hydrogen peroxide.

[0126] To demonstrate this, the potency of the KI-Dose-150 and Thio-Dose-150 compositions were tested, using the protocol described in Example 1, in a broth growth medium containing catalase (20 μl of a 4 mg/ml, >1,000 units/mg to 20 ml broth). The potency of the doses was not reversed. A 1:1024 dilution of the doses was inhibitory in the absence of catalase, and a 1:512 dilution of the doses was inhibitory in the presence of catalase.

[0127] As a comparison, the test was performed using only hydrogen peroxide (0.85 M), both in the presence and absence of catalase. The catalase level was sufficient to completely reverse the inhibitory nature of hydrogen peroxide, indicating that the catalase levels used for the experiment were sufficient to ‘quench’ the activity, and thus, would be appropriate component to ‘mop up’ excess hydrogen peroxide produced if the iodide or thiocyanate substrate is used up, but not inhibit the reaction per se when substrate is still present.

[0128] This may serve to protect mammalian tissue.

Example 16

[0129] A further example of a pre-activated system was employed as follows: solutions (4 ml volumes) containing 0.85 M H.sub.2O.sub.2 plus none or 2.5 M NaCl/5 μl chloroperoxidase (˜10,000 Units/ml) were allowed incubate. The solutions were then split and either catalase treated (50 μl of a 4 mg/ml, >1,000 units/mg) or were not catalase treated. The relative antimicrobial properties of the solutions were then tested using the protocol as described in Example 1 using E. coli supplemented broth. Inhibition of the bacteria was noted at >1:640 dilutions for hydrogen peroxide only, hydrogen peroxide+chloroperoxidase/NaCl, and the catalase treated hydrogen peroxide+chloroperoxidase/NaCl samples. However, there was no inhibition noted for the catalase treated hydrogen peroxide sample. This result would suggest that it is possible to remove any excess hydrogen peroxide by means of catalase treatment, without reducing the potency of the reactive oxygen species. The solutions were allowed to incubate for longer, after which time (72 hours) the result was repeated. This would suggest that this form of the ROS was relatively stable and could be prepared in advance of use.

Example 17

[0130] The protocol described in Example 1 was used to test ‘KI-Dose-150’, a version lacking iodide and lactoperoxidase, as well as version lacking glucose oxidase. All three were tested against Candida glabrata, Candida krusei, Candida tropicalis, Candida albicans and Saccharomyces cerevesiae. Protocols were carried out for the Candida strains and Saccharomyces strain in nutrient broth and LB broth respectively, each supplemented with 2% glucose using the method described in Example 1. Results are presented in Table 5. It is clear from Table 5 that all strains are inhibited by the actions of ‘KI-Dose-150’ and that the reactive oxygen species are thus antimicrobial and not just antibacterial. The levels of hydrogen peroxide produced in these dilutions of the composition were themselves non-inhibitory to the tested strains.

TABLE-US-00005 TABLE 5 Susceptibility of fungal and yeast strains to ‘KI-Dose-150’. MIC Candida albicans 0.25-0.5 mM Candida tropicalis 0.12-0.25 mM Candida glabrata 0.25-0.5 mM Candida krusei 0.25-0.5 mM Saccharomyces cerevisiae 0.12-0.25 mM The MIC value represents the minimum level of reactive oxygen species (hypoiodate) required to kill the strains (millimoles per litre produced over 24 hours)

Example 18

[0131] The results presented in Example 3 demonstrate that there are three crucial levels of H.sub.2O.sub.2. These levels can be described using a schematic model, as illustrated in FIG. 7. Firstly, there is a higher threshold level of H.sub.2O.sub.2, at or above which inhibition of bacterial growth occurs as a direct result of the concentration of H.sub.2O.sub.2 in the growth medium. This is not the preferable mechanism of action for an antimicrobial composition, as H.sub.2O.sub.2 is toxic to host cells, and has been linked to mammalian tissue damage, for example.

[0132] The second threshold level of H.sub.2O.sub.2 is that required for the effective production of the antimicrobial reactive oxygen species. The experiments presented herein (Example 3) describe the distinct advantage that is conferred by the use of an enzymatic method of H.sub.2O.sub.2 production, wherein the levels of H.sub.2O.sub.2 can be maintained within this required ‘window’ (FIG. 7) for a longer period of time (i.e. these are concentrations of H.sub.2O.sub.2 that are effective at allowing the production of the required concentration of reactive oxygen species, but that are not toxic in themselves).

[0133] Lastly, the third threshold level of H.sub.2O.sub.2 is one at which there is insufficient H.sub.2O.sub.2 to inhibit or provide for the production of the reactive oxygen species using an enzymatic system.

[0134] Using a more direct source of peroxide (such as the sodium percarbonate or hydrogen peroxide itself) results in a high initial concentration of H.sub.2O.sub.2 that quickly decreases to a level that is ineffective for the production of the desired reactive oxygen species (FIG. 7).

Example 19

[0135] The conversion of substrate to the antimicrobial reactive oxygen species (ROS) was estimated by direct measurement of the relevant substrate concentration during conversion and, for example, after 24 hours. The various antimicrobial reactive oxygen species are relatively short-lived, but have variable half-lives depending on the substrate used, so a direct titration was not useful. For example, Thiocyanate concentrations, at 1× (1.36 mM) and 5× (6.8 mM) levels, were compared before and after incubation in a solution containing glucose, lactoperoxidase, and glucose oxidase. These were compared to a standard concentration curve of thiocyanate levels (0, 0.0625, 0.125, 0.25, 0.5, 1, 2, and 5× concentrations) using a colourometric assay as follows:

Five grams ferric chloride was suspended in 50 ml water. Any undissolved ferric chloride was removed by centrifugation, leaving ˜30 ml ferric chloride solution. To cuvettes, 150 μl of the ferric solution was added, followed by the addition of 700 μl water. A volume of 10× thiocyanate was added to each cuvette (200 μl, 160 μl, 100 μl, 40 μl, 20 μl, 10 μl, 5 μL, 25 μl (1:10), 12.5 μl (1:10), 0 μl). The final volume in the cuvette was brought to 1,050 μl by the addition of water. For the sample, 50 μl of the previously incubated 1× or 5× dilutions were added, plus 150 μl water. The optical density was recorded at 460 nm, and the concentrations were then calculated using a standard curve. The resulting standard curve had an r2 value of >0.99, (see FIG. 8) indicating that it was an accurate method of determining an unknown concentration of thiocyanate.

[0136] The 1× dose (left incubating overnight with the enzyme system), read as 0.17× dose after 24 hours. Similarly, the 5× dose (left incubating overnight with the enzyme system), read as a 1.1× dose after 24 hours. Both of these results would indicate that, under these conditions, there was an 80-85% drop in thiocyanate levels. Assuming a 1:1 ratio of thiocyante loss to ROS production (in this case, OSCN-), this allows the determination of the ROS levels produced to be in the region of 1 mM, and 5 mM over the 24 hours for the 1× and 5× doses, respectively. This value can be adapted using a higher substrate concentration, whilst maintaining efficiency in conversion, at least within the range tested here.

[0137] The specific levels of ROS disclosed here as providing bactericidal and fungicidal activity are greater than the levels produced using the LP system elsewhere. The concentration dependent microcidal effect described in this application; and the ability to determine minimum inhibitory concentrations for the ROS against target strains and in various media and settings, allows the use of the composition of the invention as a targeted bacteriocidal and microcidal therapeutic and antimicrobial composition, as opposed to applications with merely general non-specific bacteriostatic effects.

Example 20

[0138] The ability to achieve potentially therapeutic doses of the reactive oxygen species in vivo was investigated, again using a milk model. The intramammary infusion method was used to introduce the described protoype of Example 4, [150 mg KI, 4 mg lactoperoxidase (320 units), 2 mg glucose oxidase (400 units), and Beta-galactosidase, (1,350 Units)] to a bovine udder. This was performed after milking of the animal. At the next milking, a sample of milk was obtained. Aliquots (10 ml volumes) of the milk were spiked with approximately 10.sup.7 cfu/ml of bacterial strains (E. coli, P. aeruginosa, or S. dysgalactiae) and allowed incubate overnight at 37° C. whilst shaking. A total viable count was performed using agar plates. The milk was completely inhibitory to the strains. This would indicate the presence of the reactive oxygen species in the milk at a concentration sufficient to kill these mastitis causing organisms. This is important in demonstrating the technology as a therapeutic, Further to this, because the reactive oxygen species are relatively short-lived, it is likely that the concentration would have been higher in the udder itself, increasing the effectiveness of the treatment further.

Compositions Suitable for Administration.

[0139] A solution containing containing 1-100,000 Units activity glucose oxidase, 1-100,000 Units activity of lactoperoxidase, and 0.1-10,000 mg thiocyanate/iodide, and 0.01-100,000 Units activity of beta-galactosidase would be suitable to be administered to the udder of an animal as an intramammary infusion

[0140] A solution containing containing 1-100,000 Units activity galactose oxidase, 1-100,000 Units activity of lactoperoxidase, and 0.1-10,000 mg thiocyanate/iodide, and 0.01-100,000 Units activity of beta-galactosidase would be suitable to be administered to the udder of an animal as an intramammary infusion

[0141] A solution containing containing 1-100,000 Units activity glucose oxidase, 1-100,000 Units activity of lactoperoxidase, and 0.1-10,000 mg thiocyanate/iodide, and 0.01-100,000 mg glucose would be suitable to be administered to the udder of an animal as an intramammary infusion

[0142] A solution containing containing 1-100,000 Units activity glucose oxidase, 1-100,000 Units activity of lactoperoxidase, and 0.1-10,000 mg thiocyanate/iodide, and 0.01-100,000 mg glucose would be suitable to be administered to the lungs for the treatment of bacterial infection as a nebulised spray.

[0143] The same solution as above containing supplemented lactoferrin (0.01-100,000 mg), prednisone (0.01-100,000 mg), or prednisolone (0.01-100,000 mg), catalase (1-1,000,000 Units) or a combination of two or more of these.

[0144] A solution containing containing 1-100,000 Units activity glucose oxidase, 1-100,000 Units activity of chloroperoxidase, and 0.1-10,000 mg chloride ion, and 0.01-100,000 mg glucose to be administered to the lungs for the treatment of bacterial infection as a nebulised spray.

[0145] The same solution as above containing supplemented lactoferrin (0.01-100,000 mg), prednisone (0.01-100,000 mg), or prednisolone (0.01-100,000 mg), or a combination of two or more of these. A solution containing containing 1-100,000 Units activity of lactoperoxidase, and 0.1-10,000 mg thiocyanate/iodide, and 0.01-100 ml hydrogen peroxide would be suitable to be administered to the lungs for the treatment of bacterial infection as a nebulised spray.

[0146] A poultice impregnated with 1-100,000 Units activity glucose oxidase, 1-100,000 Units activity of lactoperoxidase and an accompanying gel containing 0.1-10,000 mg thiocyanate/iodide, and 0.01-100,000 mg glucose to be applied to the poultice prior to its use in treating burns or open wounds of a patient.

[0147] A poultice impregnated with 1-100,000 Units activity glucose oxidase, 1-100,000 Units activity of chloroperoxidase and an accompanying gel containing 0.1-10,000 mg chloride ion, and 0.01-100,000 mg glucose to be applied to the poultice prior to its use in treating burns or open wounds of a patient.

[0148] The same poultices as above containing supplemented lactoferrin (0.01-100,000 mg), prednisone (0.01-100,000 mg), or prednisolone (0.01-100,000 mg), catalase (1-1,000,000 Units) or a combination of two or more of these. A variety of medical devices may be coated/impregnated with 1-100,000 Units activity glucose oxidase, 1-100,000 Units activity of lactoperoxidase before insertion into the body of a patient.

[0149] A pre-prepared composition containing iodide/thiocyanate ions (0.1-10,000 mg) allowed to react fully with hydrogen peroxide (0.01-100 ml) in the presence of lactoperoxidase (0.01-1,000,000 Units). The composition is catalase treated (0.01-1,000,000 Units) to remove excess hydrogen peroxide, before the composition is used to treat infection sites.

[0150] A pre-prepared composition containing chloride ions (0.1-10,000 mg) allowed to react fully with hydrogen peroxide (0.01-100 ml) in the presence of chloroperoxidase (0.01-1,000,000 Units). The composition is catalase treated (0.01-1,000,000 Units) to remove excess hydrogen peroxide, before the composition is used to treat infection sites.

[0151] A pre-prepared composition containing chloride ions (0.1-10,000 mg) allowed to react fully with sodium percarbonate (0.01-100,000 mg) in the presence of chloroperoxidase (0.01-1,000,000 Units). The composition is catalase treated (0.01-1,000,000 Units) to remove excess hydrogen peroxide, before the composition is used to treat infection sites.

[0152] A pre-prepared composition containing thiocyanate/iodide ions (0.1-10,000 mg) allowed to react fully with sodium percarbonate (0.01-100,000 mg) in the presence of lactoperoxidase (0.01-1,000,000 Units). The composition is catalase treated (0.01-1,000,000 Units) to remove excess hydrogen peroxide, before the composition is used to treat infection sites.

[0153] A pre-prepared composition containing chloride ions (0.1-10,000 mg) allowed to react fully with glucose (0.01-100,000 mg) and glucose oxidase (0.1-1,000,000 Units) in the presence of chloroperoxidase (0.01-1,000,000 Units). The composition is catalase treated (0.01-1,000,000 Units) to remove excess hydrogen peroxide, before the composition is used to treat infection sites.

[0154] A pre-prepared composition containing thiocyanate/iodide ions (0.1-10,000 mg) allowed to react fully with glucose (0.01-100,000 mg) and glucose oxidase (0.1-1,000,000 Units) in the presence of lactoperoxidase (0.01-1,000,000 Units). The composition is catalase treated (0.01-1,000,000 Units) to remove excess hydrogen peroxide, before the composition is used to treat infection sites.

[0155] The above pre-prepared solutions supplemented with lactoferrin (0.001 mg-10,000 mg), prednisone (0.001 mg-10,000 mg), or prednisolone (0.001 mg-10,000 mg), either individually or a combination of two or more.

[0156] The words “comprises/comprising” and the words “having/including” when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0157] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.