In-vitro model for bacterial growth inhibition of compartmentalized infection treated by an ultra-high concentration of antibiotics

BACKGROUND: Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli), and Staphylococcus aureus (S. aureus) are common pathogens encountered in infected cardiovascular-implantable electronic device (CIED). Continuous, in-situ targeted, ultra-high concentration antibiotic (CITA) treatment is a novel antibiotic treatment approach for localized infections. CITA provides sufficient local antibiotic concentrations to heavily infected cavities while avoiding systemic toxicity. AIM: In-vitro confirmation of the efficacy of the CITA treatment approach in simulated compartmentalized infections. MATERIALS AND METHODS: A rapid automated bacterial culture analyzing system) Uro4 HB&L™ (was applied to compare the efficacy of selected antibiotics at a standard minimal inhibitory concentration (1MIC), 4MIC, and CITA at 103MIC, for growth inhibition of high bacterial loads (106 colony-forming-units/ml) of ATCC strains of P. aeruginosa, E. coli, and S. aureus. RESULTS: The addition of gentamicin and amikacin at 1MIC concentrations only temporarily inhibited the exponential growth of E. coli and P. aeruginosa. 4MIC level extended the delay of exponential bacterial growth. Increasing concentrations of vancomycin similarly temporarily delayed S. aureus growth. All tested antibiotics at CITA of 103MIC totally inhibited the exponential growth of the tested bacteria through 72 hours of exposure. (P<0.001). CONCLUSION: In this in-vitro model, CITA at 103MIC effectively inhibited exponential bacterial growth of high loads of P. aeruginosa, E. coli, and S. aureus. This model offers preliminary laboratory support for the benefit of the in-situ antibiotic treatment, providing ultra-high concentrations directly at the compartmentalized infection site, not achievable by the conventional intravenous and oral routes.