Event Abstract Back to Event Prospective study on the diagnostics and susceptibility testing of infections associated with osseointegrated percutaneous implants Magdalena Zaborowska1, 2, Rickard Brånemark2, 3, 4, Joakim Strömberg3, Peter Thomsen1, 2 and Margarita Trobos1, 2 1 Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Department of Biomaterials, Sweden 2 University of Gothenburg, BIOMATCELL VINN Excellence Center of Biomaterials and Cell Therapy, Sweden 3 Center for Advanced Reconstruction of Extremities, Sahlgrenska University Hospital, Department of Orthopaedics, Sweden 4 Department of Orthopaedics, University of California, International Center for Osseointegration Research Education and Surgery (iCORES), United States Introduction: Biomaterial-associated infections (BAI) are among the main reasons for implant failure, often leading to long-term antimicrobial treatment and implant removal. BAI are mainly caused by biofilm producing bacteria with increased antimicrobial resistance. Proper and rapid diagnosis is important for successful treatment. Sonication is an alternative method for the diagnosis of prosthetic infections with higher sensitivity than standard tissue cultures[1]. The aims of the study were to: i) identify and quantify bacteria causing osteomyelitis associated with osseointegrated percutaneous amputation prostheses by sonication of explanted implants; ii) characterise the isolated strains by their biofilm production abilities and antimicrobial susceptibility. In parallel, the diagnostic laboratory at the hospital performed standard culturing techniques of bone tissue and blood marrow samples. Materials and Methods: A bone-anchored part (fixture) of a prosthesis was extracted due to suspicion of infection according to clinical evaluation. The retrieved fixture was placed in sterile saline, sonicated at 47 KHz for 5 min and vortexed for 1 min. The implant was removed, the remaining solution was centrifuged, pellet was re-suspended in saline and quantitative cultures were made on general purpose agar (blood agar for aerobic and brucella agar for anaerobic cultures) and selective agar plates (staphylococci agar, enterococci agar, streptococci agar, chromogenic orientation agar and pseudomonas agar). Crystal violet (CV) staining and Congo Red (CR) agar plate test was performed to evaluate the biofilm production. Identification of the staphylococcal strains was performed using API Staph. The Calgary Biofilm Device and a custom-made antimicrobial susceptibility plate were used to determine minimum biofilm eradication concentrations (MBEC) and minimum inhibitory concentrations (MIC) to 10 antimicrobial agents. Results and Discussion: We report the first results of an ongoing prospective study where the method has been tested real-time. In the first patient, Enterococcus faecalis (5x104 CFU/implant) and Escherichia coli (102 CFU/implant) were detected after sonication. These strains were both biofilm-producing strains according to CV and CR tests. Biofilms showed increased tolerance to the antimicrobials compared with the standard planktonic MIC values (Table 1). Escherichia coli was the only species detected by standard tissue cultures; in contrast, by the use of sonication, Enterococcus faecalis was further identified indicating the possibility of a polymicrobial infection with potential implications for the choice of the optimal treatment strategy for the patient. Conclusions: An increased detection of the potential causative agents by sonication of retrieved implants may improve the current diagnostics of BAI. In addition, determination of MBEC for clinically relevant antimicrobial agents has the potential to optimize the treatment choices for patients. The BIOMATCELL VINN Excellence Center of Biomaterials and Cell Therapy, the Västra Götaland Region, the Swedish Research Council (K2015-52X-09495-28-4), an LUA/ALF Research Grant (ALFGBG-138721), the IngaBritt and Arne Lundberg Foundation, the Wilhelm and Martina Lundgren Foundation, the Handlanden Hjalmar Svensson Foundation, Doctor Felix Neubergh Foundation and the Area of Advance Materials of Chalmers and GU Biomaterials within the Strategic Research Area initiative launched by the Swedish Government