Mimicking Bacterial Middle Ear Infection in the Lab

Bacterial infections in the human body mostly involve biofilms - locally dense populations of bacteria that are extremely difficult to treat with antibiotics.

Understanding antibiotic-biofilm interactions is crucial if we are to design better antibiotic treatment regimes to avoid the emergence of antibiotic resistance.

In biofilms, bacteria are surrounded by a biopolymer matrix which can inhibit the motion of antibiotic molecules, leading to complex diffusive behaviour.

Yet it is not known how these biophysical matrix-antibiotic interactions influence bacterial killing in a spatially complex infection model. Answering this question is the objective of my proposal.

I will set up a lab model that mimics Acute Otitis Media -bacterial infection of the middle ear- and I will use advanced microscopy methods to track antibiotic molecules as they interact with bacterial biofilms.

I will answer the following questions: A) what is the spatio-temporal distribution of antibiotic molecules in the biofilm? and B) What is the effect of biofilm structure on the antibiotic response, at the single-cell level?

After establishing materials and protocols (objective 1), I will use fluorescence-correlation-spectroscopy (FCS) to characterize the spatial distribution of antibiotic molecules (objective 2).

Next, I will use state-of-art 2D STED-FCS method (combination of FCS with stimulated-emission depletion microscopy) to track in unprecedented detail how antibiotics kill individual bacteria within a biofilm (objective 3).

Finally, by tracking bacterial growth over long times, I will determine how antibiotic resistance emerges in these spatially complex biofilms (objective 4).