Towards the early detection of β-lactamase-producing Enterobacteriaceae by MALDI-TOF MS analysis

Abstract

Our clinical validation of the method proved it to be highly reliable, simple to perform and time saving, transforming β-lactam resistance detection by MALDI-TOF MS into a ready-to-use technique in clinical laboratories.

Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for the Rapid Detection of Antimicrobial Resistance Mechanisms and Beyond

“…Oviaño et al evaluated the sensitivities, specificities, and turnaround times for different antibiotics (cefotaxime, ceftazidime, ceftriaxone, cefpodoxime, and cefepime) and also the performance of the automated MALDI Biotyper (MBT) Selective Testing of ␤-Lactamase Activity (STAR-BL) module for Compass software (Bruker Daltonik) relative to qualitative interpretation of spectra for detecting ␤-lactamase resistance (ESBL and AmpC) by MALDI-TOF MS (Bruker Daltonik) (55). Regarding the antibiotics evaluated, ceftriaxone yielded 70% more positive results in relation to detecting resistance at the same incubation time than cefotaxime, 80% more than ceftazidime, and 20% more than cefpodoxime, with 100% specificity.…”

“…This field of work is progressing very rapidly, and since the last review, written by Hrabák et al (52) in 2013, some notable methodological advances have been made. (i) Incubation times have been reduced from around 3 h to 30 min by using ceftriaxone for ␤-lactamase detection (ESBL and AmpC) and by using imipenem for carbapenemase detection (55,61,66). (ii) A larger number of antibiotics have been tested, and ceftriaxone, cefpodoxime, and cefepime can now be analyzed (55).…”

“…(i) Incubation times have been reduced from around 3 h to 30 min by using ceftriaxone for ␤-lactamase detection (ESBL and AmpC) and by using imipenem for carbapenemase detection (55,61,66). (ii) A larger number of antibiotics have been tested, and ceftriaxone, cefpodoxime, and cefepime can now be analyzed (55). (iii) Visual interpretation has been replaced by automatic acquisition and interpretation of spectra, thereby eliminating subjective measurement of mass peaks and making previous expertise in mass spectrometry unnecessary, thus facilitating the implementation of MALDI-TOF MS in routine in clinical microbiology laboratories (66).…”

Detection of AmpC β-lactamase-producing Gram-negative bacteria by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

“…For the MALDI-TOF MS assay, the isolates were incubated overnight on blood agar plates at 37 C. A 1 mL loopful of bacteria was suspended in different reaction buffer solutions (10 mM NH 4 HCO 3 /0.005% SDS at pH 8.0) containing cefotaxime (SigmaeAldrich; 0.50 mg/mL), ceftazidime (SigmaeAldrich; 0.25 mg/mL), ceftriaxone (SigmaeAldrich; 0.50 mg/mL), cefepime (SigmaeAldrich; 0.50 mg/mL) and cefoxitin (Sigmae Aldrich; 0.25 mg/mL and 0.50 mg/mL). Each sample was incubated for 30, 60, 90, 120, or 240 min at 35 C [9]. The suspensions were then centrifuged at 13,000 g for 2 min, and 1 mL of the supernatant was directly spotted on to a FlexiMass target plate (bioMérieux) and left to dry at room temperature.…”

“…The different cephalosporin forms and their respective masses are listed in Table II [9,10]. The following peaks were considered: for non-hydrolysed cefotaxime, 440, 445, 456, and…”