(193b) Thermally Triggered Biofilm Dispersion

Biofilm infections on medical implants are a multi-billion dollar problem afflicting hundreds of thousands of patients in the U.S. each year. They cannot be eliminated by antibiotics, so strategies to replace the current standard of care—explantation and replacement—have attracted significant interest. By applying a localized thermal shock, we have shown that these biofilms can be reduced and eliminated, though the mechanism of elimination has been unclear. Moreover, we found that applying antibiotics during the thermal shock, dramatically reduced the required time and temperature to eliminate biofilms infections of both Pseudomonas aeruginosa and Staphylococcus aureus cultured using two different protocols (shaker table, drip flow reactor). One hypothesis for this synergistic efficacy is that the thermal shock triggers a change in bacterial phenotype, prompting the bacteria to disperse from the biofilm in the planktonic state, and thereby making them susceptible to antibiotic elimination.

Flow cell (1 x 1 x 6 inches) with mature Pseudomonas aeruginosa biofilms placed at the bottom and a constant flow of diluted TSB at room temperature was used to determine the bacterial dispersion rate from the biofilms. We did high flow rate trials at 800 ml min^-1, and we learned that bacterial dispersion is so high that despite the large volume of effluent, dispersed bacteria concentrations are still large enough for quantification, but there’s also concern about debridement even without elevated temperature. Further trials at a lower flow rate 80 ml min^-1 established a baseline dispersion event with little observed debridement, and subsequent in situ thermal shock at 70°C for 5 min triggered a spike in effluent bacteria. This supports our hypothesis thermal shock promote biofilm bacterial dispersion to planktonic state which is more susceptible to antibiotics and suggests that biofilms on medical implant devices can be mitigated by combining localized thermal shock with antibiotics.