Intermethod comparability analyses of gepotidacin antimicrobial susceptibility tests using a large collection of globally collected Escherichia coli and Staphylococcus saprophyticus clinical isolates.

Gepotidacin (GSK2140944) is a novel, bactericidal, first in class triazaacenaphthylene bacterial type II topoisomerase inhibitor in development for the treatment of uncomplicated urinary tract infections and gonorrhea. The performance of several antimicrobial susceptibility methods (broth microdilution, gradient diffusion, and disk diffusion) for gepotidacin were evaluated using over 5800 recent Escherichia coli and Staphylococcus saprophyticus clinical isolates. Reference broth microdilution gepotidacin MICs showed an essential agreement of 95.9 % and 98.1 % with MICs by gradient diffusion for E. coli and S. saprophyticus isolates, respectively. Gepotidacin susceptibility using disks produced by 2 manufacturers had good agreement with an R2 values of 0.95 and 99.2 % of overall zone diameters agreeing within 3 mm. A correlation with an overall R2 value of 0.72 between MICs by broth microdilution and zone diameters by disk diffusion was observed. This data should assist in the clinical development of gepotidacin and provide reliable susceptibility methods to evaluate its activity.