Detection of SPM-1-Producing Pseudomonas aeruginosa and Class D β-Lactamase-Producing Acinetobacter baumannii Isolates by Use of Liquid Chromatography-Mass Spectrometry and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

Abstract

This study evaluates the accuracy of liquid chromatography-mass spectrometry (LC-MS) and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) for detecting carbapenem hydrolytic activity among SPM-1-, GIM-1-, and GES-5-producing Pseudomonas aeruginosa isolates and OXA-143-, IMP-10-, and OXA-58-producing Acinetobacter baumannii isolates. Class A and B carbapenemase activities were rapidly detected by MALDI-TOF in a 2-h assay. However, an extended incubation time was necessary for detection of carbapenem-hydrolyzing class D ␤-lactamase (CHDL) activity in Acinetobacter spp. Over the last two decades, the therapeutic options to treat infections caused by Gram-negative rods have been narrowed by bacterial acquisition of carbapenemase-encoding genes (1). The rapid detection of clinically significant carbapenemases is important for establishing adequate therapy and controlling their spread. Recently, the detection of class A or B carbapenemase activity has been accomplished by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) (2, 3). Although MALDI-TOF MS seems to be a promising tool, there is a lack of evidence showing its usefulness in testing a broader range of carbapenemases. To date, the published studies have mainly focused on KPC-2-and NDM-1-producing Enterobacteriaceae, IMP-1-, VIM-1-, and VIM-2-producing Pseudomonas aeruginosa, and OXA-23-and OXA-24-producing Acinetobacter baumannii isolates (2-4). In the current study, we evaluated the performance of the MALDI-TOF MS assay in detecting carbapenemase activity of GES-5-, GIM-1-, or SPM-1-producing P. aerugi- 128-Ͼ256 64-Ͼ256 64 (7/11) 100 (11/11) 100 (11/11) 100 (11/11) 100 (11/11) 100 (11/11) IMP-1 1 Ͼ256 32 Ͼ256 100 (1/1) 100 (1/1) 100 (1/1) 100 (1/1) 100 (1/1) 100 (1/1) VIM-1 2 256-Ͼ256 256 256 0 (0/2) 100 (2/2) 100 (2/2) 100 (2/2) 100 (2/2) 100 (2/2) GIM-1 4 Ͼ256 128-256 256-Ͼ256 100 (4/4) 100 (4/4) 100 (4/4) 100 (4/4) 100 (4/4) 100 (4/4) Negative control 6 4-Ͼ256 0.5-16 Ͻ0.06-32 0 (0/6) 0 (0/6) 0 (0/6) 0 (0/6) 0 (0/6) 0 (0/6) a ETP, ertapenem; IPM, imipenem; MEM, meropenem; MHT, modified Hodge test; MALDI-TOF, matrix-assisted laser desorption ionization-time of flight mass spectrometry; LC-MS, liquid chromatography-mass spectrometry.

Risk factors for KPC-producing Klebsiella pneumoniae: watch out for surgery

“…Preliminary screening for the presence of carbapenemases was performed by the modified Hodge test (MHT) according to CLSI guidelines (CLSI, 2014). Positive results obtained with the MHT were confirmed by ertapenem hydrolysis using MALDI-TOF MS, as previously described (Carvalhaes et al, 2013).…”

“…Although many studies have reported on the drug resistance profile of K. pneumoniae worldwide (Gupta et al, 2011;Souli et al, 2012;Carvalhaes et al, 2013), there is limited information regarding the epidemiology of this species in Mid-Eastern Brazil. A case-control and molecular study was performed in a public hospital to identify the risk factors associated with carbapenem-resistant K. pneumoniae strains.…”

Detection of carbapenemase activity using VITEK MS: interplay of carbapenemase type and period of incubation

“…Recently, the carbapenemase activity of Gram-negative bacilli has been detected by matrix-assisted laser desorption ionizationtime of flight (MALDI-TOF) MS (Burckhardt & Zimmermann, 2011;Carvalhaes et al, 2013). This method relies on the modification of the mass spectrum profile of the carbapenem molecule by carbapenemases (Burckhardt & Zimmermann, 2011).…”

“…This method relies on the modification of the mass spectrum profile of the carbapenem molecule by carbapenemases (Burckhardt & Zimmermann, 2011). Most studies have evaluated ertapenem hydrolysis by testing the Microflex LT instrument (Bruker Daltonics) (Carvalhaes et al, 2013). To the best of our knowledge, only one recently published study evaluated the detection of carbapenemase activity by using the VITEK MS instrument (bioMérieux) (Knox et al, 2014).…”

“…Recently, we assessed the performance of VITEK MS for detection of carbapenemase activity by testing a wellcharacterized collection of carbapenemaseproducing strains against ertapenem activity. In addition, as carbapenem hydrolysis may depend on many factors, especially carbapenemase type and time required for complete b-lactam hydrolysis (Carvalhaes et al, 2013), the interplay amongst different classes of carbapenemases and period of incubation required for carbapenemase detection by VITEK MS were also addressed in the present study.…”