Using matrix-assisted laser desorption ionization-time of flight mass spectrometry to detect carbapenem resistance within 1 to 2.5 hours

Abstract

In recent years, the percentage of carbapenem-resistant bacteria has increased at an alarming pace and become a major threat for patient survival. Carbapenemase-induced carbapenem resistance can be confirmed through the detection of carbapenem degradation using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). This method works for strains carrying NDM-1, VIM-1, VIM-2, KPC-2, and different IMP enzymes.

Fig. 1.

Ertapenem degradation is shown. (a) NDM-1-carrying K. pneumoniae, IMP-1-carrying P. aeruginosa; 60 min of incubation at 36°C; NaCl 0.45%; ertapenem concentration, 0.5 g/liter; x axis, mass per charge in Daltons [m/z (Da)]; y axis, intensity (arbitrary units [a.u.]). Data are representative of more than three independent experiments. (b) IMP-2-carrying P. aeruginosa, KPC-2-carrying K. pneumoniae, VIM-1-carrying K. pneumoniae; 1.5 h of incubation at 36°C; NaCl, 0.45%; ertapenem concentration, 0.5 g/liter; x axis, m/z (Da); y axis, intensity (a.u.). Data are representative of more than three independent experiments. (c) Control strains E. coli (fully susceptible), Klebsiella oxytoca (K1⁺), K. pneumoniae (extended-spectrum β-lactamase positive [ESBL⁺]), VIM-2-carrying P. aeruginosa; 2.5 h of incubation at 36°C; all reactions in 0.45% NaCl; ertapenem concentration, 0.5 g/liter; x axis, m/z (Da); y axis, intensity (a.u.). Data are representative of two independent experiments.