The Effects of Low Frequency Ultrasound on Pseudomonas aeruginosa Pathogenicity Factors

Abstract

Pseudomonas aeruginosa is a common bacterium found in wound infections and is becoming progressively more difficult to treat. P. aeruginosa is naturally resistant to many antibiotics due to a number of factors including its efflux pumps as well as the alginate matrix that surrounds each cell. This species is also capable of forming biofilms, in turn, increasing its resistance to antibiotics which is problematic in antimicrobial chemotherapy and wound care. Low frequency ultrasound (LFU) medical devices, using a frequency of 35 kHz at the terminal end, convert electrical energy into mechanical energy via resonance and transduction with sterile saline as the transducing medium in order to aid in wound cleansing. Previous work has shown that these devices can result in mechanical cell death of pathogens such as Staphylococcus aureus. Due to the mechanisms identified in such previous work, we believe that exposing P. aeruginosa to the energy from an LFU medical device may also make bacteria more susceptible to antibiotics including aztreonam, cefepime, and gentamicin, which are specifically used in the treatment of P. aeruginosa infections. In this work, we found that exposure to the ultrasound energy resulted in an increase in biofilm thickness as well as an increased susceptibility to the previously mentioned antibiotics. These results provide a theoretical framework that could be employed in future treatment of P. aeruginosa infections. Thus, leading to reduced treatment time as well as a decrease in the antibiotic resistance shown by P. aeruginosa during infection treatment.