Pulse field gel electrophoresis (PFGE) is widely used for listeriosis surveillance.
Although this technique is effective for epidemiology, the data among laboratories are
inconsistent. We previously reported a method for Listeria monocytogenes
subtyping combined with sequence analysis of partial iap and whole genome
restriction fragment length polymorphism (RFLP) using XbaI,
ClaI (BanIII) and PstI. However,
distinguishing subtypes was challenging, because the output comprised complicated fragment
patterns. In this study, we aimed to establish a simple genotyping method that does not
depend on visual observation, rather it focuses on multi-locus sequence typing (MLST)
using three genes, iap, sigB and actA.
Sixty-eight strains of L. monocytogenes including EGD-e as a reference
strain were investigated to ensure consistency with previous data on the genetic
characterization. All strains were grouped into 29 types by both analyses. Although there
are some differences in classification, major clades included the same strains. Simpson’s
indices of diversity (SID) by MLST and iap-RFLP-based typing were 0.967
(95% confidence interval [CI]: 0.955/0.978) and 0.967 (95% CI: 0.955/0.979), respectively.
The discriminatory power of both methods can be considered almost identical. Compared with
the results of 38 selected strains, the strains within the MLST clusters in this study
coincided with those obtained using PFGE. Thus, the MLST strategy could help differentiate
among L. monocytogenes isolates during epidemiological studies.