In mBio this week:
new findings on what is and is not needed for Streptococcus pneumoniae to make a biofilm on the nasopharynx.
Between 10 and 15% of adults are colonized with S. pneumoniae at any given time, a status that's thought to precede
invasive pneumococcal disease, but many - if not most - studies of pathogen
biofilm formation are done with in vitro
models.
Fig. 2 Pneumococcal biofilms are present on mucosal epithelial cells in the septa of experimentally infected mice.
Blanchette-Cain et al. used scanning electron microscopy to
study the development of biofilm aggregates of increasing complexity
in vivo on murine nasal septa after
intranasal inoculation. Among other observations, they note that the morphology
of
S. pneumoniae biofilms
in vivo is strikingly distinct from that
of biofilms formed on the surface of polystyrene microtiter plates. Importantly,
biofilms within the nasopharynx "were neither confluent nor contiguous and
incorporated host cells". Biofilms on mucosal epithelial cells transitioned
from spotty aggregates on top of ciliated cells to larger clumps and structures
attached directly to the basement membrane. These are phenomena that you simply
can't study
in vitro.
There are plenty of reasons for using in vitro models for studying biofilms, but what are we missing when
we do?
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