out local epidemics in hospital wards; generally, PFGE typing
was more discriminatory compared with PCR ribotyping, as
previously reported [19], with few exceptions. One of the
challenges is the question of how to select a representative
sample of isolates from all CDI cases for genotyping. The
simplest way would be to request the clinical microbiology
laboratories to send a predesignated proportion of C. difficile
isolates (e.g. every tenth isolate) to the national reference
laboratory; however, in this study the aim was to understand
especially the genotypes and virulence factors of the isolates
associated with severe cases and support the hospitals struggling
with persistent C. difficile problems. In Finland, it can be
argued that the data on molecular epidemiology of CDI in
2008 are not nationally representative because the isolates
were received from only 5% of the reported CDI cases.
Moreover, there was notable regional variation in numbers
of isolates. No isolates were sent from eight of the 21
regions, and unfortunately, the two regions with highest case
fatalities did not send any isolates at all. Either CDI is not
regarded as causing notable problems in these regions, or
genotyping is seen as useless in solving these issues, or the
criteria for sending isolates are considered too strict.