Thermal Shock Eradication of Single-Species and Polymicrobial Biofilms of Pseudomonas Aeruginosa and Staphylococcus Aureus

Bacterial biofilm infections on medical implants cost the healthcare industry billions of dollars each year. Bacterial biofilms are highly resistant to antibiotic treatment, often requiring surgical removal of the medical implant. A new device must then be surgically implanted with twice the likelihood of infection. The surgery and recovery process are painful, time-intensive, and often ineffective. Recent research has highlighted the potential of controlled in-vivo thermal shocks as a biofilm eradication strategy. In-vitro thermal shocks have been shown to reduce or eliminate bacterial biofilms of Staphylococcus aureus and Pseudomonas aeruginosa, bacteria common in medical implant infections. Research thus far has focused on the thermal eradication of single-species biofilms; however, many implant infections are comprised of multiple species. More specifically, polymicrobial biofilms of P. aeruginosa and S. aureus have been linked to worsening patient outcomes in medical implant infections. The interactions of multiple species in a polymicrobial infection may impact the efficacy of a thermal shock. This study compares the thermal shock resistance of mono-cultured (single-species) and co-cultured (polymicrobial) biofilms of P. aeruginosa and S. aureus as a strategy for biofilm elimination. Results confirm thermal shocks at varying time and temperature combinations can eliminate bacterial biofilm infections of P. aeruginosa and S. aureus. Within mono-cultured biofilms P. aeruginosa was found to have significantly lower thermal resistance than S. aureus. When co-cultured the presence of P. aeruginosa in the polymicrobial biofilms significantly decreased the thermal resistance of S. aureus, while the thermal resistance of P. aeruginosa was not significantly impacted. Subsequent re-incubation of thermally shocked co-cultured and mono-cultured biofilms confirmed their elimination at clinically relevant time and temperature combinations. These results indicated no post-shock die-off of P. aeruginosa or S. aureus biofilms with the potential for regrowth even when bacteria population was dropped below the detection limit. Complete elimination of P. aeruginosa and or S. aureus was required to prevent biofilm regrowth. The results from this study can be utilized to develop more effective treatment for single-species and polymicrobial medical implant infections.