Foschi, Claudio, et al. New Microbiol, 2015, 38(4), 571-576.
In this work, liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to detect carbapenemase activity in a group of carbapenemase-producing Enterobacteriaceae by meropenem hydrolysis. The method took one hour, had a sensitivity of 94% and a specificity of 100%.
In the LC-MS/MS experiment, 20 μL of 1 μg/mL minocycline-d6 dihydrochloride aqueous solution was added to 20 μL of sample supernatant as internal standard for quantitative analysis. The mass spectrometer was operated in positive electrospray ionization (ESI+) and selected reaction monitoring (SRM) mode. For minocycline-d6, the 464.2-358.2 m/z transition was used as the quantifier ion, declustering potential (DP)= 70, entrance potential (EP)= 10, ollision energy (CE)=43, llision cell exit potentia (CXP)=9. The 464.2-447.2 m/z transition was used as the qualifier ion, DP= 70, EP= 10, CE=28, CXP=12.
The right table showed the bacterial isolates included in this study to evaluate the analytical performance of LC-MS/MS for the detection of carbapenemase activity. A total of 76 CPE isolates were selected for this study: in particular, 41 class A carbapenemase (KPC), 20 class B carbapenemase (MBL) and 15 OXA-48 producers. Moreover, as negative control, 15 carbapenemase-negative bacterial strains were examined, including 6 carbapenem-resistant ESBL producers with porin loss and 9 wild-type microorganisms.
