Gas Chromatography-Ion Mobility Spectrometry Reveals Acetoin as a Biomarker for Carbapenemase-Producing Klebsiella pneumoniae.

Abstract

BACKGROUND This study aimed to detect the volatile organic compound (VOC), 3-hydroxy-2-butanone (acetoin) using gas chromatography-ion mobility spectrometry (GC-IMS) in antimicrobial-resistant Klebsiella pneumoniae (K. pneumoniae) carbapenemase (KPC)-producing bacteria. MATERIAL AND METHODS Using stromal fluid of blood culture bottles (BacT/ALERT® SA) as the medium, 3-hydroxy-2-butanone (acetoin) released by K. pneumoniae during growth was detected using GC-IMS. The impact of imipenem (IPM) and carbapenemase inhibitors [avibactam sodium or pyridine-2,6-dicarboxylic acid (DPA)] on the emission of 3-hydroxy-2-butanone (acetoin) from various carbapenemase-producing K. pneumoniae was further investigated. Subsequently, VOCal software was used to generate a pseudo-3D plot of 3-hydroxy-2-butanone (acetoin), and the relative peak volumes were exported for data analysis. Standard strains served as references, and the findings were validated with clinical isolates. RESULTS The pattern of temporal changes in the 3-hydroxy-2-butanone (acetoin) release from K. pneumoniae in the absence of IPM was consistent with the growth curve. After the IPM addition, carbapenemase-positive strains released significantly higher contents of 3-hydroxy-2-butanone (acetoin) than carbapenemase-negative strains at the late exponential growth phase (T2). Notably, adding avibactam sodium significantly decreased the 3-hydroxy-2-butanone (acetoin) content released from the class A carbapenemase-producing strains as compared to the absence of the carbapenemase inhibitor. Conversely, adding DPA significantly decreased the 3-hydroxy-2-butanone (acetoin) content released from the class B carbapenemase-producing strains (both standard and clinical strains, all P<0.05). CONCLUSIONS This study demonstrated the potential of 3-hydroxy-2-butanone (acetoin) as a VOC biomarker for detecting carbapenemase-producing K. pneumoniae, as revealed by GC-IMS analysis.