Staphylococcus epidermidis is the major organism causing nosocomial infections
associated with the formation of a biofilm on medical devices. The major
constituent of S. epidermidis biofilm matrix is the polysaccharide PNAG,
synthesized by the proteins encoded in the icaADBC locus. CLSM low energy
lasers allows the observation of living cells, and its penetration ability renders
detailed tridimensional images of the biofilm. Another characteristic of CLSM
associated with fluorochroms labeling is the ability to differentiate between biofilm
cells and other constituents of the biofilm.
In this study, differences in the structure of a S. epidermidis biofilms grown in the
presence or absence of low concentrations of dicloxacillin were assessed by CLSM
observations of biofilms labeled with a fluorescent lectin (wheat germ agglutinin)
that binds to PNAG.
Biofilms were formed in 6 wells polystyrene plates, during 48h at 37ºC and
120RPM in TSB supplemented with 1% of glucose in the presence and absence of
sub-inhibitory concentration of dicloxacillin. The growth medium was carefully
changed after 24h. CLSM observations were performed in a Zeiss LSM510 Meta
microscope, using a single-channel analysis.
The results demonstrated that biofilms formed in the presence of dicloxacillin were
less thick compared with the control. Furthermore biofilms formed in the presence
of dicloxacillin produced lower amounts of PNAG.
The use of CLSM brought a new light into biofilm science by allowing the direct
visualization of several processes that occurs inside the biofilm structure. In this
particular case it was possible to demonstrate that low concentration of antibiotic
alters the biofilm structure and composition.
Publication Type: Abstracts in Conference Proceedings