Investigating the Molecular Epidemiology of Extended-Spectrum β-Lactamase-Producing Enterobacterales (ESBL-E) Among Patients Admitted to the Intensive Care Unit.

At a United States hospital, sequencing of ICU rectal surveillance cultures indicated 5% ESBL-E colonization. Of confirmed ESBL isolates, 91% were Escherichia coli or Klebsiella pneumoniae; 6% carried non-bla CTX-M genes. Only 53% of third-generation cephalosporin-resistant Enterobacterales harbored ESBL genes, underscoring the limitations of phenotypic approaches as ESBL surrogates, particularly for non-E. coli/K. pneumoniae species.