CONICET | Buscador de Institutos y Recursos Humanos

Bacterial biofilms are communities embedded in an exopolysacchiridic matrix. Biofilms of the opportunistic pathogen Pseudomonas aeruginosa cause infections in immunocompromised patients and contaminate prosthetic devices and indwelling catheters of hospitalized patients. Common antimicrobial techniques are often ineffective against biofilms. The use of gas-discharge plasma is a potentially useful alternative to traditional sterilization techniques. This study examines the effects of gas discharge plasma on 1, 3, and 7-day-old biofilms of P. aeruginosa (PAO1) grown on either polycarbonate, stainless steel, or borosilicate coupons in a CDC biofilm reactor (BioSurface Tech, MT). An atmospheric pressure plasma jet was generated with an AtomfloTM 250 reactor (Surfx Tech. CA) using a mixture of He and N2 gases. Biofilms were exposed to plasma for various exposure times and processed to determine CFUs/mL after incubation. Results indicate nearly 100% of biofilm inactivation after 5-minutes of plasma exposure. The inactivation kinetics are similar for 1, 3, and 7 day-old biofilms and show a rapid decline in the number of surviving cells followed by a much slower decline. Cell concentration for the control is two log units higher for 3 day-old biofilms compared to 7 day old ones, suggesting that the attachment is time-dependent and decreases after time. No differences were observed for the 3 materials used. AFM images show changes in cell morphology and biofilm structure for various plasma exposure times. Micromechanical properties of biofilms are presently being studied through force versus distance curves. Results indicate the potential of plasma as an alternative method for biofilm removal.