Rapid Subtyping of Yersinia enterocolitica by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry (MALDI- TOF MS) for Diagnostics and Surveillance

In this study, an alternative to the current traditional bioserotyping techniques was developed for subtyping Y. enterocolitica using matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). The most common pathogenic bioserotypes could easily be distinguished using only a few bioserotype-specific biomarkers. However, biochemical methods should still be used to distinguish biotype 1A from 1B. The genus Yersinia comprises a biochemically heterogeneousgroup, including 17 different species (1). Three of these are regarded as pathogenic for humans; Yersinia pestis, Y. pseudotu-berculosis, and Y. enterocolitica. The last two can cause yersiniosis, which is a zoonotic diseasewhere the identified source of infection most often has been contaminated foods. Y. enterocolitica is the most common cause of yersiniosis and can be classified into six different biotypes on the basis of their phenotypic characteristics. Five of these, 1B, 2, 3, 4, and 5, include strains that are pathogenic (2). Biotype 1A, which is the most heterogeneous one, is generally considered to be nonpathogenic; however, a few studies indicate that some strains might cause gastroenteritis (3–6). The six bio