title: In vitro sensitivity of the amphibian pathogen Batrachochytrium dendrobatidis to antifungal therapeutics.
abstract: Chytridiomycosis, a skin disease caused by Batrachochytrium dendrobatidis, has caused amphibian declines worldwide. Amphibians can be treated by percutaneous application of antimicrobials, but knowledge of in vitro susceptibility is lacking. Using a modified broth microdilution method, we describe the in vitro sensitivity of two Australian isolates of B. dendrobatidis to six antimicrobial agents. Growth inhibition was observed, by measurement of optical density, with all agents. Minimum inhibitory concentrations (µg/ml; isolate 1/2) were - voriconazole 0.016/0.008; itraconazole 0.032/0.016; terbinafine 0.063/0.063; fluconazole 0.31/0.31; chloramphenicol 12.5/12.5; amphotericin B 12.5/6.25. Killing effects on zoospores were assessed by observing motility. Amphotericin B and terbinafine killed zoospores within 5 and 30 min depending on concentration, but other antimicrobials were not effective at the highest concentrations tested (100 µg/ml). This knowledge will help in drug selection and treatment optimization. As terbinafine was potent and has rapid effects, study of its pharmacokinetics, safety and efficacy is recommended.
authors.affiliation: Faculty of Veterinary Science, University of Melbourne, Werribee, Victoria 3030, Australia. Electronic address: woodward.andrewp@gmail.com.
authors.forename: A
authors.initials: A
authors.lastname: Woodward
authors.affiliation: One Health Research Group, School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Townsville, Queensland 4811, Australia.
authors.forename: L
authors.initials: L
authors.lastname: Berger
authors.affiliation: One Health Research Group, School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Townsville, Queensland 4811, Australia.
authors.forename: L F
authors.initials: LF
authors.lastname: Skerratt
mesh_terms: D000663:Amphibians; D000666:Amphotericin B / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001315:Australia; D008411:Chytridiomycota / Q000145:classification / Q000187:drug effects* / Q000502:physiology*; D003881:Dermatomycoses / Q000188:drug therapy / Q000662:veterinary; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D008826:Microbial Sensitivity Tests; D009281:Naphthalenes / Q000494:pharmacology / Q000627:therapeutic use; D000077291:Terbinafine
chemical_list: D000935:Antifungal Agents; D009281:Naphthalenes; D000666:Amphotericin B; D000077291:Terbinafine
keywords: Antifungal testing; Batrachochytrium dendrobatidis; Chytridiomycosis; Treatment