title: Polyhexamethylene biguanide and calcineurin inhibitors as novel antifungal treatments for Aspergillus keratitis.
abstract: OBJECTIVE
  To establish polyhexamethylene biguanide (PHMB) as an effective treatment for Aspergillus keratitis in a novel murine model. To determine the ability of the calcineurin inhibitors tacrolimus (FK506) and cyclosporine A (CSA) to enhance the activity of PHMB, amphotericin B (AMB), and voriconazole (VCZ) against Aspergillus keratitis.
  
  
  METHODS
  
  
  
  METHODS
  Broth antifungal susceptibility tests were performed with PHMB, AMB, VCZ, and FK506, individually and in combination against Aspergillus fumigatus. Minimum inhibitory concentrations (MIC) and fractional inhibitory concentration index (FICI) values were used to analyze antifungal activity. In vivo studies: A novel murine model was created to establish Aspergillus keratitis. Infected mice were randomly assigned to treatment groups receiving saline, CSA, AMB, VCZ, PHMB, AMB+CSA, VCZ+CSA, or PHMB+CSA. An ophthalmologist blinded to the treatment groups assessed disease severity daily based on a grading scale. The mean end change in disease score was compared between groups.
  
  
  RESULTS
  
  
  
  METHODS
  FK506 in combination with PHMB, VCZ, or AMB enhanced fungal growth inhibition. FICI values showed an additive effect between FK506 and PHMB, AMB, or VCZ. PHMB monotherapy eliminated Aspergillus growth starting at 4 μg/mL. In vivo studies: All treatment groups showed a significant improvement in disease score compared to the control group. CSA significantly worsened VCZ activity against Aspergillus keratitis.
  
  
  CONCLUSIONS
  PHMB is an effective inhibitor of Aspergillus growth. Further investigation of the role of calcineurin inhibitors in the treatment for Aspergillus keratitis is warranted.
authors.affiliation: Duke University Eye Center, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Rachelle A
authors.initials: RA
authors.lastname: Rebong
authors.forename: Ricardo M
authors.initials: RM
authors.lastname: Santaella
authors.forename: Brian E
authors.initials: BE
authors.lastname: Goldhagen
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Majka
authors.forename: John R
authors.initials: JR
authors.lastname: Perfect
authors.forename: William J
authors.initials: WJ
authors.lastname: Steinbach
authors.forename: Natalie A
authors.initials: NA
authors.lastname: Afshari
mesh_terms: D000666:Amphotericin B / Q000494:pharmacology; D000818:Animals; D001228:Aspergillosis / Q000188:drug therapy* / Q000382:microbiology; D001232:Aspergillus fumigatus / Q000187:drug effects*; D001645:Biguanides / Q000494:pharmacology / Q000627:therapeutic use*; D065095:Calcineurin Inhibitors; D003320:Corneal Ulcer / Q000188:drug therapy* / Q000382:microbiology; D016572:Cyclosporine / Q000494:pharmacology / Q000627:therapeutic use; D004202:Disinfectants / Q000494:pharmacology / Q000627:therapeutic use; D004357:Drug Synergism; D015821:Eye Infections, Fungal / Q000188:drug therapy* / Q000382:microbiology; D007166:Immunosuppressive Agents / Q000494:pharmacology / Q000627:therapeutic use*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008826:Microbial Sensitivity Tests; D011446:Prospective Studies; D011743:Pyrimidines / Q000494:pharmacology; D016559:Tacrolimus / Q000494:pharmacology; D014230:Triazoles / Q000494:pharmacology; D065819:Voriconazole
chemical_list: D001645:Biguanides; D065095:Calcineurin Inhibitors; D004202:Disinfectants; D007166:Immunosuppressive Agents; D011743:Pyrimidines; D014230:Triazoles; C031233:polihexanide; D000666:Amphotericin B; D016572:Cyclosporine; D065819:Voriconazole; D016559:Tacrolimus