Emergence and Spread of Clostridioides difficile Isolates with Reduced Fidaxomicin Susceptibility in an Acute Care Hospital.

In an acute care hospital, we conducted a 3-year cohort study of patients with C. difficile infection (CDI) to determine the frequency of infection with isolates with reduced fidaxomicin susceptibility and the impact on response to fidaxomicin treatment. Stool specimens were cultured for C. difficile, and susceptibility testing was performed using agar dilution. Whole genome sequencing was used to identify mutations associated with reduced fidaxomicin susceptibility and to determine relatedness of isolates. Of 108 fidaxomicin-treated patients, we identified 6 (5.6%) infected with isolates possessing reduced fidaxomicin susceptibility (MICs 8-32 ug/mL) that harbored mutations in RNA polymerase associated with reduced susceptibility. This work was supported by a grant from the US Department of Veterans Affairs Office of Research and Development as part of funding for VA SeqCURE (grant number N/A) which in turn received funding from the American Rescue Plan Act funds. The data is provided by Chetan Jinadatha from the Central Texas Veterans Healthcare System, Temple, Texas, USA.