The direct examination of tissue and biomaterials from
prosthesis-related infections of twenty-five patients showed that the
causative bacteria grew in glycocalyx-enclosed biofilms that were adherent
to surfaces of biomaterials and tissues in 76 per cent. This high rate of
recovery of adherent biofilm-mediated growth suggests that the process
occurs commonly in the presence of a foreign body or biomaterial-related
infection. Because of the adherent mode of growth of the infecting
organisms, accurate microbiological sampling was difficult. The analysis of
joint fluids or of swabs of excised tissue and of prosthetic surfaces often
yielded only one species from what was a polymicrobial population based on
electron microscopic studies. We adapted direct quantitative sampling
methods from environmental microbiology in order to recover a large number
of species from these infections, but comparison of the organisms isolated
by these techniques with the morphological types that were seen by electron
microscopy indicated that in some instances all bacterial components of the
biofilms were still not being recovered.