Rapid identification of Carbapenem-Resistant bacteria by MALDI-TOF-MS via a specifically designed probe

Antibiotic resistance has become a major global health concern, and carbapenems as the last resort antibiotics are in crisis. Resistant bacteria produce carbapenemase, which can destroy the central β-lactam ring of the carbapenems through hydrolysis, leading to the inactivation of the antibiotics. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been widely used in clinical laboratories for bacterial identification, but challenges remain in simultaneous identification of resistant bacteria. Herein, a MALDI-TOF MS probe (4R,5S,6S)-6-((R)-1-hydroxyethyl)-4-methy-1–7-oxo-3-((2-(pyrazin-2-yl)ethyl)thio)-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid (PTACA), was designed and synthesized, which shows high specificity for carbapenemase compared to other prevalent β-lactamases. Using PTACA, 20 of carbapenem-resistant Enterobacteriaceae (CRE) strains have been successfully discriminated among a total of 58 clinical strains (CRE identification rate 100%). CRE strains presented in artificial urine also has been identified, demonstrating application potential of PTACA in timely diagnosis of CRE urinary tract infections. Our study highlights PTACA as a powerful MALDI-TOF MS probe to promote clinical bacteria identification.