[Rapid identification of Yersinia enterocolitica by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS)].

Introduction: Yersinia enterocolitica includes both human pathogenic and non-pathogenic strains. The pathogenic strains belong to two evolutionary lineages: European and American, of mild- and high- pthogenicity, respectively. Y. enterocolitica European bioserotypes 4/O3 and 2/O9 are one of the major etiological agents of human yersiniosis worldwide. American lineage Y. enterocolitica bioserotype 1B/O8 has recently emerged in Europe. Since 2004 this high-pathogenicity bioserotype is increasingly isolated from humans in Poland. The rapid and accurate identification of pathogenic Y. enterocolitica strains is essential for diagnostic purposes. The aim of this study was to assess the usefulness of commercially available MALDI-TOF mass spectroscopy for Y. enterocolitica identification and subtyping.

Methods: A total of 33 strains of Y. enterocolitica belonging to bioserotype: 1B/O8 (n=2), 4/O3 (n=25) and 2/O9 (n=6) isolated from clinical specimens in Poland and 10 reference Y. enterocolitica 1B/O8 strains (Institute Pasteur, France) were used in this study. The identification of the Y. enterocolitica strains by MALDI-TOF MS was performed on MALDI Biotyper system (Bruker Daltonics, USA) with flexControl 3.0 software (Bruker Daltonics) according with the manufacturer's instruction.

Results: All of the tested Y. enterocolitica strains were correctly identified at the species level. However, American and European strains were not differentiated.

Conclusions: Our data indicate that MALDI-TOF MS can be used as a first-line method for rapid identification of Y. enterocolitica strains at the species level in clinical microbiology laboratories.