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While the detrimental effects of periprosthetic joint infections (PJIs) are well known, the process of biofilm formation on orthopaedic hardware is unclear. Previous work has shown that encasement of explant hardware in agar can aid in identifying biofilms. This study tested the utility of agar 'candle dip' method in detecting and mapping the location of biofilm on infected orthopedic components. Explant components from 15 patients were rinsed, briefly submerged in agar to create a surface coating, and incubated. Larger components were coated by pipetting agar over them. After incubation, colony outgrowth on the component surface was documented (candle dip status). Data were compared with clinical laboratory results (clinical culture status) and the PJI diagnosis using Musculoskeletal Infection Society criteria (MSIS status). All six patients classified as MSIS and clinical culture positive were also positive with the candle dip technique. Of the nine candle dip negative cases, four were positive and five were negative for both MSIS and clinical culture status. Candle dip may be negative in few cases due to the residual antibiotic eluting from the spacers, limiting the growth of bacterial biofilms on the components. The candle dip method shows promise for biofilm mapping but requires additional testing to evaluate the clinical diagnostic potential., (© 2019 APMIS. Published by John Wiley & Sons Ltd.)

Antibiotic-loaded calcium sulfate beads (CS-B) are used to treat biofilm-related periprosthetic joint infections (PJI). A previous study has shown that such beads are effective in reducing lawns biofilms grown on agar plates; however, the ability of CS-B to eradicate biofilms grown on solid orthopedic material surfaces has not been investigated. We grew biofilms of bioluminescent strains of Pseudomonas aeruginosa Xen41 and a USA300 MRSA Staphylococcus aureus SAP231 on ultra-high molecular weight polyethylene (PE), hydroxyapatite (HA), and 316L stainless steel (SS) coupons for three days under static growth conditions, with daily nutrient exchange. The coupons were rinsed with sterile phosphate buffered saline (PBS) to remove planktonic bacteria and placed in a petri dish, surrounded by four either antibiotic vancomycin and tobramycin loaded (CS-B V+T ) or unloaded beads (CS-B U ). A thin layer of agar was overlaid to simulate a periprosthetic infection where an implant abuts soft tissue and then incubated for 72 h. The amount of biofilm was measured by bioluminescence imaging (BLI) for activity and viable cell count (CFUs). Coupons exposed to CS-B V+T showed a significant reduction in the amount of biofilm within 24 h, regardless of the bacterial strain or material type. The coupons exposed to control CS-B U had no effect on bacteria over 72 h. Statement of Clinical Significance: Antibiotic-loaded calcium sulfate beads (CS-B) were effective in significantly reducing mature biofilms of P. aeruginosa and S. aureus from orthopedic relevant surfaces in our in vitro agar model. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3081-3085, 2018., (© 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Bacterial infection after hardware implantation in orthopedic surgery is a devastating issue as it often necessitates increased hospital costs and stays, multiple revision surgeries, and prolonged use of antibiotics. Because of the nature of hardware implantation into the body, these infections are commonly in the form of attached biofilms. The current literature on a range of methodologies to study clinically explanted infected orthopedic hardware, with potential biofilm, in the laboratory setting is limited. General methods include traditional and advanced culturing techniques, microscopy imaging techniques, and techniques that manipulate genetic material. The future of diagnostic techniques for infected implants, innovative hardware design, and treatment solutions for patients all depend on the successful evaluation and characterization of clinical samples in the laboratory setting. This review provides an overview of current methods to study biofilms associated with orthopedic infections and insight into future directions in the field., (© 2017 APMIS. Published by John Wiley & Sons Ltd.)