Evaluation the effect of MALDI-TOF MS on the detection of carbapenemase produced by enterobacteriaceae / 中华检验医学杂志

ABSTRACT

Objective To evaluate the effect of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)on the detection of carbapenemase producing enterobacteriaceae. Methods A total of 21 carbapenem non-susceptible enterobacteriaceaeclinical strains were collectedfrom the Second Affiliated Hospital of Soochow University during January to May, 2018, including 11 strains of Klebsiella pneumonia, 3 strains of Klebsiella oxytoca, 3 strains of Enterobacter cloacae, and 4 strains of Escherichia coli. All the isolates were incubated with 0.5g/L meropenem solution for 2 hours. The supernatant was centrifuged and collected for MALDI-TOF MS detection. The characteristic peaks were captured to determin whether the strain was producing carbapenemase or not. And then, the results were compared with PCR results by Kappastatistical analysis. Results The PCR results showed that all the strains were positive for carbapenmase genes, among them 15 isolates were encoding KPC genes, 6 isolates encoding GES genes, 2 isolates encoding NDM genes, 1 isolate encoding VIM genes, 4 isolates encoding GIM and 1 isolate encoding SIM. And the strains could carry one or more carbapem-resistant determinants. MALDI-TOF MS showed that meropenem were hydrolyzed by 21 isolates and a characteristic drug hydrolysis peak appeared at 199 m/z, as a result of carbapenemase produced by enterobacteriaceae. The assay of MALDI-TOF MS was highly consistentwith PCR results. Conclusions The investigation showed that MALDI-TOF MS can directly detect the carbapenemase by capture the characteristic drug hydrolysis peak.