bla _KPC RNA expression correlates with two transcriptional start sites but not always with gene copy number in four genera of gram-negative pathogens

Klebsiella pneumoniae carbapenemase (KPC)-producing organisms are therapeutically and diagnostically challenging. It is possible that bla _KPC gene expression plays a role in the variability observed in clinical susceptibility testing. bla _KPC transformants together with 10 clinical isolates representing four genera were evaluated for bla _KPC copy number and gene expression and correlated with β-lactam MIC data. The data suggest that mechanisms other than gene copy number and expression of bla _KPC contribute to variability in susceptibility when testing KPC-producing isolates.