Use of imipenem to detect KPC, NDM, OXA, IMP, and VIM carbapenemase activity from gram-negative rods in 75 minutes using liquid chromatography-tandem mass spectrometry.
Resistance to extended-spectrum β-lactam antibiotics has led to a greater reliance upon carbapenems, but the expression of carbapenemases threatens to limit the utility of these drugs. Current methods to detect carbapenemase activity are suboptimal, requiring prolonged incubations during which ineffective therapy may be prescribed. We previously described a sensitive and specific assay for the detection of carbapenemase activity using ertapenem and liquid chromatography-tandem mass spectrometry (LC-MS/MS). In this study, we assessed 402 Gram-negative rods, including both Enterobacteriaceae and non-Enterobacteriaceae expressing IMP, VIM, KPC, NDM, and/or OXA carbapenemases, by using imipenem, meropenem, and ertapenem with LC-MS/MS assays. LC-MS/MS methods for the detection of intact and hydrolyzed carbapenems from an enrichment broth were developed. No ion suppression was observed, and the limits of detection for all three drugs were below 0.04 μg/ml. The sensitivity and specificity of meropenem and ertapenem for carbapenemase activity among non-Enterobacteriaceae were low, but imipenem demonstrated a sensitivity and specificity of 96% and 95%, respectively, among all Gram-negative rods (GNR) tested, including both Enterobacteriaceae and non-Enterobacteriaceae. LC-MS/MS allows for the analysis of more complex matrices, and this LC-MS/MS assay could easily be adapted for use with primary specimens requiring growth enrichment.
M/Z Diagnostics, New Haven, Connecticut, USA.
M V
MV
Kulkarni
M/Z Diagnostics, New Haven, Connecticut, USA.
A N
AN
Zurita
M/Z Diagnostics, New Haven, Connecticut, USA.
J S
JS
Pyka
Frank H. Netter School of Medicine, Quinnipiac University, Hamden, Connecticut, USA.
T S
TS
Murray
Department of Laboratory Medicine, Yale School of Medicine, New Haven, Connecticut, USA.
M E
ME
Hodsdon
Department of Laboratory Medicine, Yale School of Medicine, New Haven, Connecticut, USA Pathology and Laboratory Medicine Services, VA Connecticut Healthcare System, West Haven, Connecticut, USA david.peaper@yale.edu.
D R
DR
Peaper
D000900:Anti-Bacterial Agents / Q000378:metabolism*; D001426:Bacterial Proteins / Q000032:analysis*; D002853:Chromatography, Liquid / Q000379:methods*; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000201:enzymology*; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology; D006801:Humans; D015378:Imipenem / Q000378:metabolism*; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry / Q000379:methods*; D001618:beta-Lactamases / Q000032:analysis*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015378:Imipenem; D001618:beta-Lactamases; C063912:carbapenemase