Frequency and Mechanisms of Spontaneous Fosfomycin Nonsusceptibility Observed upon Disk Diffusion Testing of Escherichia coli.

ABSTRACT: Fosfomycin maintains activity against most Escherichia coli clinical isolates, but the growth of E. coli colonies within the zone of inhibition around the fosfomycin disk is occasionally observed upon susceptibility testing. We aimed to estimate the frequency of such nonsusceptible inner colony mutants and identify the underlying resistance mechanisms. Disk diffusion testing of fosfomycin was performed on 649 multidrug-resistant E. coli clinical isolates collected between 2011 and 2015. For those producing inner colonies inside the susceptible range, the parental strains and their representative inner colony mutants were subjected to MIC testing, whole-genome sequencing, reverse transcription-quantitative PCR (qRT-PCR), and carbohydrate utilization studies. Of the 649 E. coli clinical isol

SUBMITTER: Lucas AE 

PROVIDER: S-EPMC5744208 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature