title: Pre-clinical development of antifungal susceptibility test methods for the testing of the novel antifungal agent E1210 versus Candida: comparison of CLSI and European Committee on Antimicrobial Susceptibility Testing methods.
abstract: OBJECTIVE
  To compare European Committee on Antimicrobial Susceptibility Testing (EUCAST) and CLSI broth microdilution (BMD) methods for testing the novel antifungal E1210 against a recent collection of 102 clinical isolates of Candida spp.
  
  
  METHODS
  Candida isolates (102) were tested by CLSI and EUCAST methods; 21 Candida albicans, 20 Candida glabrata, 25 Candida parapsilosis, 24 Candida tropicalis and 12 Candida krusei, including echinocandin- and azole-resistant isolates. CLSI and EUCAST MIC endpoints of 50% and 100% inhibition were determined using visual reading at 24 and 48 h of incubation and spectrophotometric reading at 24 h of incubation, respectively.
  
  
  RESULTS
  E1210 CLSI MIC results ranged from ≤0.008 to only 1 mg/L (excluding C. krusei) depending on species, duration of incubation and endpoint criteria (EC). E1210 was not active against C. krusei (MIC(50) >16 mg/L). Overall essential agreement (EA; ±2 doubling dilutions) between the 24 and 48 h CLSI readings was 100% and 97.6% using the 50% and 100% inhibition EC, respectively. Slightly more trailing growth at 48 h was observed with the 100% inhibition EC. Comparison of the 50% and 100% endpoints at 24 h of incubation showed an overall EA of 100%. Comparison of CLSI and EUCAST read at 24 h of incubation and either 50% or 100% inhibition revealed an EA of 97.8% using the 50% inhibition EC and 88.9% using the 100% inhibition EC.
  
  
  CONCLUSIONS
  E1210 was found to have potent in vitro activity against Candida spp. when tested by both CLSI and EUCAST BMD methods, with the highest overall EA (97.8%) obtained when E1210 MIC results were read after 24 h of incubation using a partial inhibition EC.
authors.affiliation: JMI Laboratories, North Liberty, IA 52317, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Pfaller
authors.forename: Naoaki
authors.initials: N
authors.lastname: Watanabe
authors.forename: Mariana
authors.initials: M
authors.lastname: Castanheira
authors.forename: Shawn A
authors.initials: SA
authors.lastname: Messer
authors.forename: Ronald N
authors.initials: RN
authors.lastname: Jones
mesh_terms: D000631:Aminopyridines / Q000494:pharmacology*; D000935:Antifungal Agents / Q000494:pharmacology*; D002175:Candida / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D002177:Candidiasis / Q000382:microbiology; D055808:Drug Discovery; D005060:Europe; D017261:Glycosylphosphatidylinositols / Q000096:biosynthesis; D006801:Humans; D007555:Isoxazoles / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests / Q000379:methods*
chemical_list: C570438:APX001A; D000631:Aminopyridines; D000935:Antifungal Agents; D017261:Glycosylphosphatidylinositols; D007555:Isoxazoles