Mechanisms of allergy and clinical immunologyThe occupant as a source of house dust bacteria
Section snippets
Sample collection
Two female (individuals A and B) and 2 male volunteers (C and D) were recruited for the study. Dust samples from their homes as well as skin surface swab samples of the occupants themselves were taken by a field worker. Floor dust from the living room area was collected in nylon socks by vacuuming 1 m2 of a rug for 2 minutes (individuals A-C) or 4 m2 of smooth floor for 4 minutes (individual D); mattress dust was vacuumed for 2 minutes from the mattress surface. In all cases, freshly covered
Results
A total of 3294 bacterial 16S rRNA gene sequences derived from the individual samples were analyzed (Table I). The sampled species richness—expressed through the number of different SLOTUs detected in each sample—was found to be relatively low for the 4 skin surface swab samples compared with the mattress dust and floor dust samples. The observed bacterial richness as well as the Chao1 estimates of SLOTU richness assuming exhaustive sampling were always higher in the individual floor dust
Discussion
The findings of our study indicate that the human body is a major determinant of the bacterial content in house dust. We demonstrated that the majority of the bacterial sequences detected in mattress dust of 4 urban homes (69% to 88%) had a human origin. These sequences were directly linked to the individuals' skin surface flora or were clearly related to other human sources (mostly of oral, intestinal/fecal, or genital origins). Human-derived bacteria were less frequently found in floor dust
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Supported by the Academy of Finland with grant nos. 106103 and 111177.
Disclosure of potential conflict of interest: The authors have declared that they have no conflict of interest.