Bismuth-thiols as antiseptics for epithelial tissues, acute and chronic wounds, bacterial biofilms and other indications

Abstract

Compositions and methods, including novel homogeneous microparticulate suspensions, are described for treating acute wounds, chronic wounds and/or a wound or epithelial tissue surface that contains bacterial biofilm, including unexpected synergy between bismuth-thiol (BT) compounds and certain antibiotics, to provide topical formulations including antiseptic formulations, for management and promotion of wound healing and in particular infected wounds. Previously unpredicted antibacterial properties and anti-biofilm properties of disclosed BT compounds and BT compound-plus-antibiotic combinations are also described, including preferential efficacies of certain such compositions for treating gram-positive bacterial infections, and distinct preferential efficacies of certain such compositions for treating gram-negative bacterial infections.

What is claimed is: 
     
         1 . A bismuth-thiol composition, comprising:
 a plurality of microparticles that comprise a bismuth-thiol (BT) compound, substantially all of said microparticles having a volumetric mean diameter of from about 0.4 μm to about 5 μm, wherein the BT compound comprises bismuth or a bismuth salt and a thiol-containing compound.   
     
     
         2 . A bismuth-thiol composition, comprising:
 a plurality of microparticles that comprise a bismuth-thiol (BT) compound, substantially all of said microparticles having a volumetric mean diameter of from about 0.4 μm to about 5 μm and being formed by a process that comprises:   (a) admixing, under conditions and for a time sufficient to obtain a solution that is substantially free of a solid precipitate, (i) an acidic aqueous solution that comprises a bismuth salt comprising bismuth at a concentration of at least 50 mM and that lacks a hydrophilic, polar or organic solubilizer, with (ii) ethanol in an amount sufficient to obtain an admixture that comprises about 25% ethanol by volume; and   (b) adding to the admixture of (a) an ethanolic solution comprising a thiol-containing compound to obtain a reaction solution, wherein the thiol-containing compound is present in the reaction solution at a molar ratio of from about 1:3 to about 3:1 relative to the bismuth, under conditions and for a time sufficient for formation of a precipitate which comprises the microparticles comprising the BT compound.   
     
     
         3 . The bismuth-thiol composition of  claim 2  wherein the bismuth salt is Bi(NO 3 ) 3 . 
     
     
         4 . The bismuth-thiol composition of  claim 2  wherein the acidic aqueous solution comprises at least 5%, 10%, 15%, 20%, 22% or 22.5% bismuth by weight. 
     
     
         5 . The bismuth-thiol composition of  claim 2  wherein the acidic aqueous solution comprises at least 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5% nitric acid by weight. 
     
     
         6 . The bismuth-thiol composition of  claim 2  wherein the thiol-containing compound comprises one or more agents selected from the group consisting of 1,2-ethane dithiol, 2,3-dimercaptopropanol, pyrithione, dithioerythritol, 3,4-dimercaptotoluene, 2,3-butanedithiol, 1,3-propanedithiol, 2-hydroxypropane thiol, 1-mercapto-2-propanol, dithioerythritol, alpha-lipoic acid and dithiothreitol. 
     
     
         7 . A method for preparing a bismuth-thiol composition that comprises a plurality of microparticles that comprise a bismuth-thiol (BT) compound, substantially all of said microparticles having a volumetric mean diameter of from about 0.4 μm to about 5 μm, said method comprising the steps of:
 (a) admixing, under conditions and for a time sufficient to obtain a solution that is substantially free of a solid precipitate, (i) an acidic aqueous solution that comprises a bismuth salt comprising bismuth at a concentration of at least 50 mM and that lacks a hydrophilic, polar or organic solubilizer, with (ii) ethanol in an amount sufficient to obtain an admixture that comprises about 25% ethanol by volume; and 
 (b) adding to the admixture of (a) an ethanolic solution comprising a thiol-containing compound to obtain a reaction solution, wherein the thiol-containing compound is present in the reaction solution at a molar ratio of from about 1:3 to about 3:1 relative to the bismuth, under conditions and for a time sufficient for formation of a precipitate which comprises the microparticles comprising the BT compound. 
 
     
     
         8 . The method of  claim 5  further comprising recovering the precipitate to remove impurities. 
     
     
         9 . The method of  claim 5  wherein the bismuth salt is Bi(NO 3 ) 3 . 
     
     
         10 . The method of  claim 5  wherein the acidic aqueous solution comprises at least 5%, 10%, 15%, 20%, 22% or 22.5% bismuth by weight. 
     
     
         11 . The method of  claim 5  wherein the acidic aqueous solution comprises at least 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5% nitric acid by weight. 
     
     
         12 . The method of  claim 5  wherein the thiol-containing compound comprises one or more agents selected from the group consisting of 1,2-ethane dithiol, 2,3-dimercaptopropanol, pyrithione, dithioerythritol, 3,4-dimercaptotoluene, 2,3-butanedithiol, 1,3-propanedithiol, 2-hydroxypropane thiol, 1-mercapto-2-propanol, dithioerythritol, dithiothreitol and alpha-lipoic acid. 
     
     
         13 . A method for protecting an epithelial tissue surface against a bacterial pathogen, comprising:
 contacting the epithelial tissue surface with an effective amount of a BT composition under conditions and for a time sufficient for one or more of:
 (i) prevention of infection of the epithelial tissue surface by the bacterial pathogen, 
 (ii) inhibition of cell viability or cell growth of substantially all planktonic cells of the bacterial pathogen, 
 (iii) inhibition of biofilm formation by the bacterial pathogen, and 
 (iv) inhibition of biofilm viability or biofilm growth of substantially all biofilm-form cells of the bacterial pathogen, 
   wherein the BT composition comprises a plurality of microparticles that comprise a bismuth-thiol (BT) compound, substantially all of said microparticles having a volumetric mean diameter of from about 0.4 μm to about 5 μm.   
     
     
         14 . The method of  claim 13  wherein the bacterial pathogen is selected from the group consisting of  Staphylococcus aureus  ( S. aureus ), MRSA (methicillin-resistant  S. aureus ),  Staphylococcus epidermidis , MRSE (methicillin-resistant  S. epidermidis ),  Mycobacterium tuberculosis, Mycobacterium avium, Pseudomonas aeruginosa , drug-resistant  P. aeruginosa, Escherichia coli , enterotoxigenic  E. coli , enterohemorrhagic  E. coli, Klebsiella pneumoniae, Clostridium difficile, Heliobacter pylori, Legionella pneumophila, Enterococcus faecalis , methicillin-susceptible  Enterococcus faecalis, Enterobacter cloacae, Salmonella typhimurium, Proteus vulgaris, Yersinia enterocolitica, Vibrio cholera, Shigella flexneri , vancomycin-resistant  Enterococcus  (VRE),  Burkholderia cepacia  complex,  Francisella tularensis, Bacillus anthracis, Yersinia pestis, Pseudomonas aeruginosa , and  Acinetobacter baumannii.    
     
     
         15 . The method of  claim 13  wherein the bacterial pathogen exhibits antibiotic resistance. 
     
     
         16 . The method of  claim 13  wherein the bacterial pathogen exhibits resistance to an antibiotic that is selected from the group consisting of methicillin, vancomycin, nafcillin, gentamicin, ampicillin, chloramphenicol, doxycycline and tobramycin. 
     
     
         17 . The method of  claim 13  in which the epithelial tissue surface comprises a tissue that is selected from the group consisting of epidermis, dermis, respiratory tract, gastrointestinal tract and glandular linings. 
     
     
         18 . The method of  claim 13  in which the step of contacting is performed one or a plurality of times. 
     
     
         19 . The method of  claim 18  in which at least one step of contacting comprises one of spraying, irrigating, dipping and painting the epithelial tissue surface. 
     
     
         20 . The method of  claim 18  in which at least one step of contacting comprises one of inhaling, ingesting and orally irrigating. 
     
     
         21 . The method of  claim 18  in which at least one step of contacting comprises administering by a route that is selected from topically, intraperitoneally, orally, parenterally, intravenously, intraarterially, transdermally, sublingually, subcutaneously, intramuscularly, transbuccally, intranasally, via inhalation, intraoccularly, intraauricularly, intraventricularly, subcutaneously, intraadiposally, intraarticularly and intrathecally. 
     
     
         22 . The method of  claim 13  wherein the BT composition comprises one or more BT compounds selected from the group consisting of BisBAL, BisEDT, Bis-dimercaprol, Bis-DTT, Bis-2-mercaptoethanol, Bis-DTE, Bis-Pyr, Bis-Ery, Bis-Tol, Bis-BDT, Bis-PDT, Bis-Pyr/Bal, Bis-Pyr/BDT, Bis-Pyr/EDT, Bis-Pyr/PDT, Bis-Pyr/Tol, Bis-Pyr/Ery, bismuth-1-mercapto propanol, and Bis-EDT/2-hydroxy-1-propanethiol. 
     
     
         23 . The method of  claim 13  wherein the bacterial pathogen exhibits antibiotic resistance. 
     
     
         24 . The method of any one of  claims 13 - 23  which further comprises contacting the epithelial tissue surface with a synergizing antibiotic, simultaneously or sequentially and in any order with respect to the step of contacting the epithelial tissue surface with the BT composition. 
     
     
         25 . The method of  claim 24  wherein the synergizing antibiotic comprises an antibiotic that is selected from the group consisting of an aminoglycoside antibiotic, a carbapenem antibiotic, a cephalosporin antibiotic, a fluoroquinolone antibiotic, a glycopeptide antibiotic, a lincosamide antibiotic, a penicillinase-resistant penicillin antibiotic, and an aminopenicillin antibiotic. 
     
     
         26 . The method of  claim 25  wherein the synergizing antibiotic is an aminoglycoside antibiotic that is selected from the group consisting of amikacin, arbekacin, gentamicin, kanamycin, neomycin, netilmicin, paromomycin, rhodostreptomycin, streptomycin, tobramycin and apramycin. 
     
     
         27 . A method for overcoming antibiotic resistance on an epithelial tissue surface where an antibiotic-resistant bacterial pathogen is present, comprising:
 contacting the epithelial tissue surface contacting simultaneously or sequentially and in any order with an effective amount of (1) at least one bismuth-thiol (BT) composition and (2) at least one antibiotic that is capable of acting synergistically with the at least one BT composition, under conditions and for a time sufficient for one or more of:
 (i) prevention of infection of the epithelial tissue surface by the bacterial pathogen, 
 (ii) inhibition of cell viability or cell growth of substantially all planktonic cells of the bacterial pathogen, 
 (iii) inhibition of biofilm formation by the bacterial pathogen, and 
 (iv) inhibition of biofilm viability or biofilm growth of substantially all biofilm-form cells of the bacterial pathogen, 
   wherein the BT composition comprises a plurality of microparticles that comprise a bismuth-thiol (BT) compound, substantially all of said microparticles having a volumetric mean diameter of from about 0.4 μm to about 5 μm; and thereby overcoming antibiotic resistance on the epithelial tissue surface.   
     
     
         28 . The method of  claim 27  wherein the bacterial pathogen is selected from the group consisting of  Staphylococcus aureus  ( S. aureus ), MRSA (methicillin-resistant  S. aureus ),  Staphylococcus epidermidis , MRSE (methicillin-resistant  S. epidermidis ),  Mycobacterium tuberculosis, Mycobacterium avium, Pseudomonas aeruginosa , drug-resistant  P. aeruginosa, Escherichia coli , enterotoxigenic  E. coli , enterohemorrhagic  E. coli, Klebsiella pneumoniae, Clostridium difficile, Heliobacter pylori, Legionella pneumophila, Enterococcus faecalis , methicillin-susceptible  Enterococcus faecalis, Enterobacter cloacae, Salmonella typhimurium, Proteus vulgaris, Yersinia enterocolitica, Vibrio cholera, Shigella flexneri , vancomycin-resistant  Enterococcus  (VRE),  Burkholderia cepacia  complex,  Francisella tularensis, Bacillus anthracis, Yersinia pestis, Pseudomonas aeruginosa , and  Acinetobacter baumannii.    
     
     
         29 . The method of  claim 27  wherein the bacterial pathogen exhibits resistance to an antibiotic that is selected from the group consisting of methicillin, vancomycin, nafcillin, gentamicin, ampicillin, chloramphenicol, doxycycline, tobramycin, clindamycin and gatifloxacin. 
     
     
         30 . The method of  claim 27  in which the epithelial tissue surface comprises a tissue that is selected from the group consisting of epidermis, dermis, respiratory tract, gastrointestinal tract and glandular linings. 
     
     
         31 . The method of  claim 27  in which the step of contacting is performed one or a plurality of times. 
     
     
         32 . The method of  claim 31  in which at least one step of contacting comprises one of spraying, irrigating, dipping and painting the epithelial tissue surface. 
     
     
         33 . The method of  claim 31  in which at least one step of contacting comprises one of inhaling, ingesting and orally irrigating. 
     
     
         34 . The method of  claim 31  in which at least one step of contacting comprises administering by a route that is selected from topically, intraperitoneally, orally, parenterally, intravenously, intraarterially, transdermally, sublingually, subcutaneously, intramuscularly, transbuccally, intranasally, via inhalation, intraoccularly, intraauricularly, intraventricularly, subcutaneously, intraadiposally, intraarticularly and intrathecally. 
     
     
         35 . The method of  claim 27  wherein the BT composition comprises one or more BT compounds selected from the group consisting of BisBAL, BisEDT, Bis-dimercaprol, Bis-DTT, Bis-2-mercaptoethanol, Bis-DTE, Bis-Pyr, Bis-Ery, Bis-Tol, Bis-BDT, Bis-PDT, Bis-Pyr/Bal, Bis-Pyr/BDT, Bis-Pyr/EDT, Bis-Pyr/PDT, Bis-Pyr/Tol, Bis-Pyr/Ery, bismuth-1-mercapto-2-propanol, and Bis-EDT/2-hydroxy-1-propanethiol. 
     
     
         36 . The method of  claim 35  wherein the synergizing antibiotic comprises an antibiotic that is selected from the group consisting of clindamycin, gatifloxacin, an aminoglycoside antibiotic, a carbapenem antibiotic, a cephalosporin antibiotic, a fluoroquinolone antibiotic, a penicillinase-resistant penicillin antibiotic, and an aminopenicillin antibiotic. 
     
     
         37 . The method of  claim 36  wherein the synergizing antibiotic is an aminoglycoside antibiotic that is selected from the group consisting of amikacin, arbekacin, gentamicin, kanamycin, neomycin, netilmicin, paromomycin, rhodostreptomycin, streptomycin, tobramycin and apramycin. 
     
     
         38 . A method of treating an acute wound, a chronic wound or a wound or epithelial tissue surface that contains bacterial biofilm in a subject, comprising:
 administering, to a wound site or epithelial tissue surface in the subject, a therapeutically effective amount of a topical formulation that comprises (a) at least one BT compound, and (b) a pharmaceutically acceptable excipient or carrier for topical use.   
     
     
         39 . A method of treating an acute wound, a chronic wound or a wound or epithelial tissue surface that contains bacterial biofilm in a subject, comprising:
 administering, to a wound site or epithelial tissue surface in the subject, a therapeutically effective amount of a topical formulation that comprises (a) at least one BT compound, (b) at least one antibiotic compound that is capable of acting synergistically with the BT compound, and (c) a pharmaceutically acceptable excipient or carrier for topical use.   
     
     
         40 . The method of either  claim 38  or  claim 39  wherein the BT compound is selected from the group consisting of BisBAL, BisEDT, Bis-dimercaprol, Bis-DTT, Bis-2-mercaptoethanol, Bis-DTE, Bis-Pyr, Bis-Ery, Bis-Tol, Bis-BDT, Bis-PDT, Bis-Pyr/Bal, Bis-Pyr/BDT, Bis-Pyr/EDT, Bis-Pyr/PDT, Bis-Pyr/Tol, Bis-Pyr/Ery, bismuth-1-mercapto-2-propanol, and Bis-EDT/2-hydroxy-1-propanethiol. 
     
     
         41 . The method of  claim 40  wherein the BT composition comprises a plurality of microparticles that comprise a bismuth-thiol (BT) compound, substantially all of said microparticles having a volumetric mean diameter of from about 0.4 μm to about 5 μm. 
     
     
         42 . The method of  claim 40  wherein the BT compound is selected from the group consisting of BisEDT and BisBAL. 
     
     
         43 . The method of either  claim 38  or  claim 39  wherein the wound is an acute wound or a chronic wound that contains a bacterial infection. 
     
     
         44 . The method of  claim 43  wherein the bacterial infection comprises one or more of gram-positive bacteria and gram-negative bacteria. 
     
     
         45 . The method of  claim 43  wherein the bacterial infection comprises at least one bacterial population selected from a bacterial biofilm and planktonic bacteria. 
     
     
         46 . The method of  claim 43  wherein the bacterial infection comprises a bacterial biofilm. 
     
     
         47 . The method of  claim 39  wherein the antibiotic compound comprises an antibiotic that is selected from the group consisting of an aminoglycoside antibiotic, a carbapenem antibiotic, a cephalosporin antibiotic, a fluoroquinolone antibiotic, a penicillinase-resistant penicillin antibiotic, and an aminopenicillin antibiotic. 
     
     
         48 . The method of  claim 47  wherein the antibiotic is an aminoglycoside antibiotic that is selected from the group consisting of amikacin, arbekacin, gentamicin, kanamycin, neomycin, netilmicin, paromomycin, rhodostreptomycin, streptomycin, tobramycin and apramycin. 
     
     
         49 . The method of  claim 47  wherein the aminoglycoside antibiotic is amikacin. 
     
     
         50 . An antiseptic composition for treating an acute wound, a chronic wound or a wound or epithelial tissue surface that contains bacterial biofilm, comprising:
 (a) at least one BT compound; (b) at least one antibiotic compound that is capable of acting synergistically with the BT compound; and (c) a pharmaceutically acceptable excipient or carrier for topical use.   
     
     
         51 . The composition of  claim 50  wherein the BT compound is selected from the group consisting of BisBAL, BisEDT, Bis-dimercaprol, Bis-DTT, Bis-2-mercaptoethanol, Bis-DTE, Bis-Pyr, Bis-Ery, Bis-Tol, Bis-BDT, Bis-PDT, Bis-Pyr/Bal, Bis-Pyr/BDT, Bis-Pyr/EDT, Bis-Pyr/PDT, Bis-Pyr/Tol, Bis-Pyr/Ery, bismuth-1-mercapto-2-propanol, and Bis-EDT/2-hydroxy-1-propanethiol. 
     
     
         52 . The composition of  claim 51  wherein the BT composition comprises a plurality of microparticles that comprise a bismuth-thiol (BT) compound, substantially all of said microparticles having a volumetric mean diameter of from about 0.4 μm to about 5 μm. 
     
     
         53 . The composition of  claim 50  wherein the BT compound is selected from the group consisting of BisEDT and BisBAL. 
     
     
         54 . The composition of  claim 50  wherein the antibiotic compound comprises an antibiotic that is selected from methicillin, vancomycin, nafcillin, gentamicin, ampicillin, chloramphenicol, doxycycline, tobramycin, clindamycin, gatifloxacin and an aminoglycoside antibiotic. 
     
     
         55 . The composition of  claim 54  wherein the aminoglycoside antibiotic is selected from the group consisting of amikacin, arbekacin, gentamicin, kanamycin, neomycin, netilmicin, paromomycin, rhodostreptomycin, streptomycin, tobramycin and apramycin. 
     
     
         56 . The composition of  claim 54  wherein the aminoglycoside antibiotic is amikacin. 
     
     
         57 . A method for treating an acute wound, a chronic wound or a wound or epithelial tissue surface that contains bacterial biofilm, comprising:
 (a) identifying a bacterial infection in a wound or epithelial tissue surface in a subject as comprising one of (i) gram positive bacteria, (ii) gram negative bacteria, and (iii) both (i) and (ii);   (b) administering a topical formulation that comprises one or more bismuth thiol (BT) compositions to the wound, wherein:
 (i) if the bacterial infection comprises gram positive bacteria, then the formulation comprises therapeutically effective amounts of at least one BT compound and at least one antibiotic that is rifamycin, 
 (ii) if the bacterial infection comprises gram negative bacteria, then the formulation comprises therapeutically effective amounts of at least one BT compound and amikacin, 
 (iii) if the bacterial infection comprises both gram positive and gram negative bacteria, then the formulation comprises therapeutically effective amounts of one or a plurality of BT compounds, rifamycin and amikacin, 
   and thereby treating the wound or epithelial tissue surface.   
     
     
         58 . The method of  claim 57  wherein treating the wound prevents neuropathy resulting from chronic wound progression. 
     
     
         59 . The method of  claim 57  wherein the bacterial infection comprises one or a plurality of antibiotic-resistant bacteria. 
     
     
         60 . The method of  claim 57  wherein the wound is selected from the group consisting of a venous ulcer, a pressure ulcer, a diabetic ulcer, a decubitis ulcer, a gunshot wound, a puncture wound, a shrapnel wound, an ischemic wound, a surgical wound, a traumatic wound, acute arterial insufficiency, necrotizing fasciitis, osteomyelitis, a wound resulting from radiation poisoning, osteoradionecrosis, soft tissue radionecrosis, pyoderma gangrenosum, a gangrenous wound, a burn, a dermal infection and a malignancy. 
     
     
         61 . The method of  claim 57  wherein the wound is an acute wound or a chronic wound that comprises a bacterial biofilm. 
     
     
         62 . The method of  claim 57  wherein treating the wound comprises at least one of: (i) eradicating the bacterial biofilm, (ii) reducing the bacterial biofilm, and (iii) impairing growth of the bacterial biofilm. 
     
     
         63 . The method of any one of  claims 57 - 62  wherein the BT composition comprises a plurality of microparticles that comprise a bismuth-thiol (BT) compound, substantially all of said microparticles having a volumetric mean diameter of from about 0.4 μm to about 5 μm.