= Emerging. More than 5 years before clinical availability. (24.37%, 2023)
= Expected to be clinically available in 1 to 4 years. (39.50%, 2023)
= Clinically available now. (36.13%, 2023)
MSACL 2023 : Baek

MSACL 2023 Abstract

Self-Classified Topic Area(s): Microbiology > Cases in Clinical MS > Proteomics

Podium Presentation in Steinbeck 3 on Thursday at 10:20 (Chair: Stefani Thomas)

Clinical Performance of the Osmotic Shock-MALDI MS Method to Detect Klebsiella pneumoniae Carbapenemase in Clinical Isolates

Je-Hyun Baek (1), Saeyoung Lee (1), Seohyun Hwang (1), Dong Huey Cheon (1), Heejung Jang (1), Won Suk Yang (1), Min Jin Kim (2), SunHwa Lee (2)
(1) Research and Development Center for Clinical Mass Spectrometry, Seegene Medical Foundation, Seoul, South Korea (2) Department of Laboratory Medicine, Seegene Medical Foundation, Seoul, South Korea

Je-Hyun Baek, Ph.D. (Presenter)
Seegene Medical Foundation (R&D Center for Clinical Mass Spectrometry)


INTRODUCTION: The World Health Organization recently highlighted the serious worldwide problem of the emergence of antibiotic-resistant or antibiotic multidrug-resistant bacteria. Carbapenem-resistant Enterobacterales, including carbapenemase-producing Enterobacterales (CPE), are major antibiotic-resistant bacteria that can be identified by various methods, including antibiotic susceptibility testing, PCR, and immunologic assays. However, there is a need for a faster, more accurate, low-cost, and easy method to detect CPE strains.

OBJECTIVES: We previously developed an osmotic shock matrix-assisted laser desorption/ionization mass spectrometry (OS-MALDI MS) method for directly detecting intact Klebsiella pneumoniae carbapenemase (KPC) using osmotic shock cell lysis. In this study, we evaluated the OS-MALDI MS method and compared it with two other methods (octyl-glucoside-aided direct KPC detection method [OG-MALDI MS] and Bruker's MBT subtyping module indirect method [MBT-SM MALDI MS]).

METHODS: To direct detect KPC-2 protein on MALDI-TOF MS, all Gram-negative bacterial isolates were lysed by the osmotic shock method. We completed an analytical performance evaluation of the OS-MALDI MS method with 24 clinical isolates (12 KPC-2 positive & 12 KPC-negatives) according to Clinical and Laboratory Standards Institute guidelines. Upon the criteria (e.g., intensity threshold and mass window), clinical testing was performed with 437 clinical isolates, including 292 KPC-producing bacteria and 145 non-KPC-producing bacteria. For OS, OG and MBT-SM MALDI MS, MALDI MS spectrometry was performed in linear and positive mode (m/z range: 12,000 ~ 32,000). Pairwise compassion studies between two methods (OS versus OG, OS versus MBT-SM, and OG versus MBT-SM) were performed by Mann-Whitney test (independent samples) using the MedCalc program (version 20.106).

RESULTS: The OS-MALDI MS and comparator methods (OG-MALDI MS and MBT-SM MALDI MS) were analyzed as a three-way comparison between the candidate method, the comparison method, and diagnostic accuracy criteria according to the CLSI EP12-A2 guideline. OS-MALDI MS showed significantly higher sensitivity than OG and MBT-SM MADLI MS (P-value, 0.05) while all the three methods showed 100% specificity. The difference in sensitivity between the OS-MALDI MS and OG-MALDI MS methods was 62.0% and the difference between the OS-MALDI MS and MBT-SM MALDI MS methods was 70.6%. Accuracy of the OS-MALDI MS, OG-MALDI MS, and MBT-SM MALDI MS methods was 97.3%, 55.9%, and 50.2%, respectively. Based on a disease prevalence of 66.74% (292/437) in the evaluated samples, the OS-MALDI MS method exhibited 95.9% sensitivity (TP / TP +FN), 100.0% specificity (TN / FP + TN), and 100.0% precision (TP / TP + FP) for detecting KPC. The OS-MALDI MS method had a positive predictive value of 99.29% (95%score confidence limit = 97.24% to 99.82%) and a negative predictive value of 91.82% (95% score confidence limit: 86.84% to 95.03%).

CONCLUSION: The OS-MALDI MS method clearly outperformed the other methods, exhibiting the highest accuracy and sensitivity of the three methods. We propose the OS-MALDI MS method as a practical, useful method for clinic environments, which may help guide appropriate antibiotic treatment and contribute to the prevention of the spread of CPE.

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