MALDI-TOF MS. Learning Objectives. MALDI-TOF MS: a new tool to rapidly assess antibiotic susceptibility. After this presentation, you should

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1 MALDI-TOF MS: a new tool to rapidly assess antibiotic susceptibility Sören Schubert, MD Max von Pettenkofer-Institut Ludwig-Maximilians-University (LMU) Munich, Germany Learning Objectives After this presentation, you should know the principles of MALDI-TOF MS and its application in identification of microorganisms be able to identify and to trace the development of MALDI-TOF MS for the -lactamase activity testing of bacteria record and compare facts about different approaches using MALDI-TOF MS for comprehensive antibiotic resistance testing be able to identify the pros and cons of using MALDI- TOF MS for resistance testing in diagnostic laboratory and will retrace possible future perspectives MALDI-TOF MS MALDI Biotyper Bruker Daltonics Vitek MS biomérieux 1

2 MALDI-TOF: principle Matrix Assisted Laser Desorption/Ionization, Time Of Flight MALDI TOF Identification of bacteria and fungi Intens. [a.u.] m/z E. coli MALDI-TOF MS bacteria identification Workflow 2

3 Identification Antibiotic resistance testing (AST) Disc Diff. Walkaway Vitek 2 Phoenix Time to result h h 7 18 h 8 18 h MALDI-TOF MS 1. Direct detection of resistance factors 3

4 MRSA detection by MALDI-TOF MS? MRSA MALDI TOF detection of MRSA 4

5 Wolters et al., 211 MALDI-TOF for detection of antibiotic resistance -lactamases (ESBL) carbapenemases Problem 5

6 SHV-1 SHV-2 SHV-3 SHV-178 TEM-1 TEM-2 TEM-3 TEM-213 CTX-M-1 CTX-M-2 CTX-M-3 CTX-M-75 OXA-1 OXA-2 OXA-3 OXA-161 CMY-1 CMY-2 CMY-3 CMY-23 IMP-1 IMP-2 IMP-3 IMP-23 > 7 -lactamase - subtypes Conclusion 1: Direct detection of resistance factors Detection of clonal groups No reliable resistance identification -lactamases, PBP2a, Van A Van B MALDI-TOF MS 1. Direct detection of resistance factors (e.g. PBP2a) 2. β-lactamase activity test 6

7 -lactamase activity +H 2 O + 18 Da - 44 Da A B C Ampicillin + ESBL-E. coli Ampicillin + -Lact.-neg. E. coli C A B Sparbier et al., 212 Procedure 1 colony of fresh o/n culture 1 µl antibiotic solution (e.g..5 µg/ml CTX) 1-2 h incubation, 37 C Spin down bacteria Supernatant on MALDI-target plate Mass range 1 1 Da Calibration with suitable molecules 7

8 Cefotaxime (CTX) Intens. [a.u.] x A CTX + ESBL- neg. E. coli Intens. [a.u.] x B CTX + ESBL-pos. E. coli Intens. [a.u.]. x1 4 C m/z CTX / CLAV + ESBL-pos. E. coli Σ peak-intensity hydrolysed log Σ peak-intensity non-hydrolysed.5 mg/ml CAZ in 1 mm NH 4 -hydrogen carbonate 2 h incubation 15 µl sup plus 5 µl.5 ng/µl reserpine 1.5 µl spotted -lactamaseactivity No cleavage spontaneous hydrolysis 8

9 Identification -lactamase activity E. coli directly from positve blood cultures ampicillin 1 Ampicillin MIC >8.5 logrq Ampicillin MIC MIC>256 5 MIC 4 9 MIC 8 1 MIC > MIC > MIC > MIC >256 2 MIC 3 21 MIC 4 22 MIC 3 25 MIC 4 3 MIC 6 31 MIC 4 37 MIC 6 39 MIC 2 4 MIC > MIC 3 42 MIC > MIC > MIC 4 47 MIC> MIC> MIC 4 54 MIC > MIC > MIC > MIC >256 6 MIC > MIC > MIC 4 66 MIC > MIC > MIC 4 72 MIC > MIC > MIC > MIC > MIC > MIC 6 84 MIC > MIC 3 86 MIC > MIC 8 9 MIC 2 91 MIC > MIC >256/4 93 MIC 1,5 94 MIC >256 E. coli ATCC Jung et al., 214 Conclusion 2: MALDI-TOF -lactamase activity test Rapid test h Automated analysis Directly from positive blood cultures Restricted to certain antibiotic resistances -lactamases, e.g. ESBL, carbapenemases 9

10 MALDI-TOF MS 1. Direct detection of resistance factors (e.g. PBP2a) -lactamase activity test 3. Antibiotic susceptibility test - phenotypic assays MBT-RESIST Phenotypic Susceptibility Testing (MBT-RESIST) 13 C 6 15 N 2 -L-Lysin 8Da 8Da For all growing bacteria applicable Susceptible: No integration Resistant: Integration Susceptibility testing using stable isotopes normal Lys Control 1 heavy Lys + antibiotic Susceptible Resistant heavy Lys Control 2 October 22,

11 m/z S. aureus mass spectra gel view MSSA OXA - susceptible strain MRSA OXA - resistant strain normal normal heavy + Oxa heavy + Oxa heavy heavy October 22, MRSA P. aeruginosa MBT MS-RESIST / P. aeruginosa (Tobramycin- susceptible) Intens. [a.u.] _N :B8 MS, BaselineSubtracted, Smoothed normal _H_6 :A1 MS, BaselineSubtracted, Smoothed heavy + TOB Intens. [a.u.] 6 12_H :A7 MS, BaselineSubtracted, Smoothed heavy 2 Jung et al., EJCMID 213 October 22,

12 MS-RESIST/ P. aeruginosa (Tobramycin-resistant) Intens. [a.u.] _N :G1 MS, BaselineSubtracted, Smoothed normal _H_6 :G1 MS, BaselineSubtracted, Smoothed heavy + TOB 1.25 Intens. [a.u.]x _H :F11 MS, BaselineSubtracted, Smoothed heavy m/z Jung et al., EJCMID 213 October 22, ciprofloxacin Pseudomonas aeruginosa meropenem tobramycin Jung et al., 214 MALDI-TOF MS 1. Direct detection of resistance factors (e.g. PBP2a) -lactamase activity test 3. Antibiotic susceptibility test - phenotypic assays MBT-RESIST MBT-ASTRA 12

13 3. Antibiotic susceptibility testing by phenotypic assays Phenotypic assay without isotopes? MALDI-TOF MS as a quantitative growth monitor MBT-ASTRA BHI McF.5 Incubation 37 C Species dependent time Antibiotic Cell lysis Lysis reagent with internal standard Target preparation Acquisition of MS profile spectra spectra view Klebsiella pneumoniae Standard [M+ H] 2+ Standard [M+ H] + Standard [M+ H] 2+ Standard [M+ H] + BHI + Meropenem 8 µg/ml susceptible BHI only Meropenem resistant Lange et al., J Clin Microbiol

14 Conclusion (1) Direct detection of resistance factors Detection of clonal groups May help to identify distinct clonally distributed resistance factors False positive and negative results possible! (yet) no direct detection of -lactamases, PBP2a, Van A/B, Conclusion (2) -lactamase activity test Rapid test h Automated analysis Directly from positive blood cultures Restricted to certain resistances -lactamases All -lactamases detectable? Conclusion (3) Phenotypic resistance test (MBT-RESIST / MBT-ASTRA) Rapid tests 2 3 h Automated analysis available Stable Isotopes: A rather complex workflow kits and cards are needed All bug-drug combinations analyzable? 14

15 MALDI-TOF MS for antibiotic resistance testing Pro Reduction of time to result: 12 h 2.5 h Phenotypic assay irrespective of underlying molecular mechanism High-throughput feasible Low costs of consumables Cons Initial culture necessary plus h High costs of MALDIhardware (Yet) no determination of MIC values (Yet) no test kits available hands on time is high Max von Pettenkofer-Institut Jette Jung Theresa Eberl Christina Popp Julia Walker Christina Hamacher Lukas Schmidt Birgit Gross Andreas Wieser ForBIMed FöFoLe 15