  Many bacterial species readily develop biofilms that act as a protective
matrix against external challenge, e.g. from antimicrobial treatment.
Therefore, biofilms are often responsible for persistent and recurring
infections. Established methods for studying biofilms are either destructive or
they focus on the biofilm surface. A non-destructive method that is sensitive
to the underside of the biofilm is highly desirable, as it allows studying the
penetration of antibiotics through the film. Here, we demonstrate that the high
surface sensitivity of resonant hyperspectral imaging provides this capability.
The method allows us to monitor the early stages of Escherichia coli biofilm
formation, cell attachment and microcolony formation, in-situ and in real time.
We study the response of the biofilm to a number of different antibiotics and
verify our observations using confocal microscopy. Based on this ability to
closely monitor the surface-bound cells, resonant hyperspectral imaging gives
new insights into the antimicrobial resistance of biofilms.
