During the period from 1999 – 2013, prosthetic joint infections (PJIs) occurred in 22.2% of the 396,472 Australians who underwent a primary total knee replacement and 17.1% of the 280,522 Australians who had a total conventional hip replacement. A severe PJI can leave a patient without a joint and on long term suppressive antimicrobials.
Traditionally PJIs are highly dependent on the use of conventional antibiotics and debridement surgery. Current treatments are considered ineffective as the prosthetic joint is covered in biofilms that are up to 1000 fold more resistant to antimicrobials than the planktonic bacteria. Typical drug delivery techniques have little effect on biofilms making it seemingly impossible to fully penetrate the biofilm matrix. Prevention of biofilm growth is the best treatment and there is a clear need to halt infections before it is severe enough to require further strenuous surgeries that cause pain and stress for the patient.
The aim of this project is to optimise protocols in the growth of biofilms to develop a high through-put pathway to assess antimicrobial therapy in the efficiency of halting biofilm production. Currently the protocols for biofilm growth are centred on Pseudomonas spp. and are limited regarding Staphylococcus spp. Clinically relevant strains of Staphylococcus aureus and Staphylococcus epidermidis will be tested using the Minimum Biofilm Eradication (MBEC) assay and Biofilm Prevention Concentration (BPC) assay. These are optimised to best produce biofilms to allow for standardised testing. Quantification of potential biofilm growth will be measured by optimised Crystal Violet staining, to obtain biomass, and optimised resazurin assay, to determine cell viability within the biofilm.
It is anticipated that a standardised biofilm model for S. aureus and S. epidermidis will allow for high through-put testing of current and novel antimicrobials for efficacy against biofilms on PJIs, thus helping to identify more effective treatments.