Eva Sapi, PhD, Biofilms and antibiotic resistance of Borrelia burgdorferi, NorVect 2014

The lecture addresses various mechanisms associated with Borrelia infection that may help this bacteria to survive adverse environmental conditions, immune response and even therapeutic interventions. Borrelia species are known pleomorphic pathogens and they are able to adopt alternative, defensive morphologies to evade the immune response and even to increase their antibiotic resistance. One of these morphologies is the cyst or round body form which is known to be resistant to the front line antibiotic treatment. Another possible explanation for persistent clinical symptoms might be the formation of another highly antibiotic resistant form called biofilm. We have employed several modes of microscopy and staining techniques to characterize potential biofilm forms of different Borrelia species. Among optical microscopy techniques, dark field microscopy was used to observe the interaction of peripheral spirochetes with the biofilm, differential interphase microscopy (DIC) revealed the heterogeneity of the biofilm matrix, and fluorescence microscopy enabled observation of the sessile internal biofilm population. A relatively new technique, atomic force microscopy, was used to directly scan the topography of the biofilm. Our results demonstrated that Borrelia is capable of developing biofilms on different abiotic and biotic substrates. Analyzing the extracellular substance of the aggregates for potential exopolysaccharides revealed the existence of both sulfated and nonsulfated/ carboxylated substrates, predominately composed of an alginate with calcium and extracellular DNA present. In summary, we have found substantial evidence that Borrelia is capable of forming biofilm in vitro. In this lecture, we also provide evidence of Borrelia biofilm structures in infected tissues in vivo. In summary, our research findings strongly suggest that the Borrelia biofilm likely provides a refuge for chronic Lyme infection, and offers an additional avenue of attack for potential treatments for Lyme disease. In addition, in this lecture, we also summarize our research data on evaluating different antimicrobial agents that may help to reduce or even eliminate Borrelia biofilms, such as different combinations of known antibiotics