Fosfomycin resistance mediated by fos genes remains rare among extended-spectrum beta-lactamase-producing Escherichia coli clinical isolates recovered from the urine of patients evaluated at Canadian hospitals (CANWARD, 2007-2017).

Among 162 isolates of extended-spectrum beta-lactamase-(ESBL)-producing Escherichia coli recovered from the urine of Canadian patients (2007-2017), five (3.1%) were not susceptible in vitro to fosfomycin (MIC ≥128 μg/mL). These isolates underwent whole genome sequencing to assess for the presence of fos genes. The fosA3 gene was detected in one isolate.