MALDI-TOF MS as one of the alternative tools for detecting outbreaks of strains carrying the carbapenemase gene

Abstract

Abstract Background Rapid, cost-effective, simple, and reliable bacterial typing methods are essential in clinical infection control. This study aimed to evaluate the clinical applicability and its consistency with conventional typing methods of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) typing function. Methods Here, we collected 126 carbapenem-resistant Klebsiella pneumoniae (CRKP) strains and 24 Enterobacter cloacae complex (ECC) strains, grouped them according to their strain characteristics, and clustered them using different methods, including MALDI-TOF MS, multi-locus sequence typing (MLST), core genome multi-locus sequence typing (cg-MLST), pulsed-field gel electrophoresis (PFGE). Results The results showed that MALDI-TOF MS was poorly matched with MLST and cg-MLST. MALDI-TOF MS was in relatively high agreement with PFGE for ECC, but for CRKP we concluded that the agreement was poor. We speculated that the reasons for this discrepant result might be the large difference in the number of the two strains and the fact that CRKP strains used to compare PFGE and MALDI-TOF MS were all from the ICU unit, which has a high degree of similarity. In addition, we found three possible outbreaks in our hospital after a small cluster analysis according to the time of strain isolation as well as the departments and wards of patients. Conclusion Therefore, although MALDI-TOF MS is less consistent with traditional methods in typing of these specific species, it may be one of the alternative tools for detecting outbreaks of strains carrying the carbapenemase gene to facilitate rapid clinical measures to prevent further spread of the outbreak.