Pulse lavage (PL) debridement and antibiotic loaded calcium sulfate beads (CS-B) are both used for the treatment of biofilm related periprosthetic joint infection (PJI). However, the efficacy of these alone and in combination for eradicating biofilm from orthopaedic metal implant surfaces is unclear. The purpose of the study was to understand the efficacy of PL and antibiotic loaded CS-B in eradicating bacterial biofilms on 316L stainless steel (SS) alone and in combination in vitro. Biofilms of bioluminescent strains of Pseudomonas aeruginosa Xen41 and a USA300 MRSA Staphylococcus aureus SAP231 were grown on SS coupons for 3 days. The coupons were either, (i) debrided for 3 s with PL, (ii) exposed to tobramycin (TOB) and vancomycin (VAN) loaded CS-B for 24 h, or (iii) exposed to both. An untreated biofilm served as a control. The amount of biofilm was measured by bioluminescence, viable plate count and confocal microscopy using live/dead staining. PL alone reduced the CFU count of both strains of biofilms by approximately 2 orders of magnitude, from an initial cell count on metal surface of approximately 10 CFU/cm . The antibiotic loaded CS-B caused an approximate six log reduction and the combination completely eradicated viable biofilm bacteria. Bioluminescence and confocal imaging corroborated the CFU data. While PL and antibiotic loaded CS-B both significantly reduced biofilm, the combination of two was more effective than alone in removing biofilms from SS implant surfaces. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2349-2354, 2018.

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 ) or unloaded beads (CS-B ). 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 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 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.

Dusane DH. Mapping bacterial biofilms on recovered orthopaedic implants by a novel agar candle dip method. APMIS 2019; 127: 123-130.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.

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Objectives:Technical errors, traumatic re-injury, and biologic failure all play a potential role in failure after ACL reconstruction (ACLR). Recent work has demonstrated the frequent presence of biofilms on failed ACLR grafts. Tunnel widening is commonly observed upon presentation for revision ACLR but the relationship between biofilm presence and tunnel widening is unclear. The purpose of this study is to determine whether tunnel widening is associated with bacterial biofilms in failed ACL reconstructions.Methods:34 consecutive revision ACLR cases and 5 primary ACLR controls were included. Tissue biopsies were obtained from tibial, femoral, and intra-articular segments of revision cases and torn native ligament as well as excess hamstring graft after fixation from primary ACLR controls. Clinical cultures as well as PCR for bacterial DNA with a universal primer were obtained on all patients. Fluorescence microscopy was used to visually confirm presence of biofilm. No patients had clinical signs of infection. Tunnel diameters were measured on pre-operative 3-dimensional imaging.Results:Bacterial DNA was present in 87% of cases and 20% of controls. Cultures were only positive (coagulase negative staphyloccous sp.) in one revision case, the widest measured tunnel diameters were in this same case (20.1 mm for the tibial tunnel and 16.9 mm for the femoral tunnel) Bacterial DNA was positively associated with wider femoral tunnels (median 10.6 mm with detectable bacterial DNA, median 7.6 mm without detectable bacterial DNA; p=0.04 Wilcoxon rank-sum). There was a trend toward higher rates of bacterial DNA in tibial tunnels with diameters greater than 12.5 mm (LR chi square p= 0.12). Fluorescence microscopy confirmed presence of staphylococcal biofilms adherent to the soft tissue graft surface (Figure 1) as well as inert fixation material including monofilament suture, braided suture, and PEEK and metal interference screws.Conclusion:Bacterial biofilms are commonly encountered on failed ACLR grafts. These biofilms do not cause clinically apparent infection symptoms but are associated with tunnel widening and may contribute to biologic failure.