Human fingertip microflora is transferred to touched objects and may provide forensically relevant information on individual
hosts, such as on geographic origins, if endogenous microbial skin species/strains would be retrievable from physical fingerprints
and would carry geographically restricted DNA diversity. We tested the suitability of physical fingerprints for revealing
human host information, with geographic inference as example, via microbial DNA fingerprinting. We showed that the transient
exogenous fingertip microflora is frequently different from the resident endogenous bacteria of the same individuals. In only
54% of the experiments, the DNA analysis of the transient fingertip microflora allowed the detection of defined, but often
not the major, elements of the resident microflora. Although we found microbial persistency in certain individuals, time-wise
variation of transient and resident microflora within individuals was also observed when resampling fingerprints after 3 weeks.
While microbial species differed considerably in their frequency spectrum between fingerprint samples from volunteers in Europe
and southern Asia, there was no clear geographic distinction between Staphylococcus strains in a cluster analysis, although bacterial genotypes did not overlap between both continental regions. Our results,
though limited in quantity, clearly demonstrate that the dynamic fingerprint microflora challenges human host inferences for
forensic purposes including geographic ones. Overall, our results suggest that human fingerprint microflora is too dynamic
to allow for forensic marker developments for retrieving human information.
Keywords Microbial forensics - Fingertip microflora - Microbial DNA analysis - Microbial fingerprint - Forensic - PFGE -
Staphylococcus