An Unusual Carbapenem Resistant Carrying Plasmid-mediated AmpC and Mutated in A Patient with Recurrent Urinary Tract Infections.

We describe a case of carbapenem resistant isolated from urine in an 87-year-old woman with recurrent urinary tract infections. Using whole genome sequencing (WGS), we identified the carbapenem resistance mechanism to be a combination of porin loss and plasmid-mediated AmpC gene , which was not detected by routine molecular and phenotypic carbapenemase assays. Our case raises a concern for the limitation of current CRE screening tools for emerging resistance mechanisms and demonstrates the utility of WGS as a better tool for characterization of CRE in the clinical setting.