A common step to revision surgery for infected total knee replacement (TKR) is a thorough debridement. Whilst surgical and mechanical debridement are established as the gold standard, we investigate a novel adjuvant chemical debridement using an Acetic Acid (AA) soak that seeks to create a hostile environment for organisms, further degradation of biofilm and death of the bacteria. We report the first orthopaedic in vivo series using AA soak as an intra-operative chemical debridement agent for treating infected TKR's. We also investigate the in vitro efficacy of AA against bacteria isolated from infected TKR's. A prospective single surgeon consecutive series of patients with infected TKR were treated according to a standard debridement protocol. Patients in the series received sequential debridement of surgical, mechanical and finally chemical debridement with a 10 minute 3% AA soak. In parallel, we isolated, cultured and identified bacteria from infected TKR's and assessed the in vitro efficacy of AA. Susceptibility testing was performed with AA solutions of different concentrations as well as with a control of a gentamicin sulphate disc. The effect of AA on the pH of tryptone soya was also monitored in an attempt to understand its potential mechanism of action. Physiological responses during the AA soak were unremarkable. Intraoperatively, there were no tachycardic or arrythmic responses, any increase in respiratory rate or changes in blood pressure. This was also the case when the tourniquet was released. In addition, during the post-operative period no increase in analgesic requirements or wound complications was noted. Wound and soft tissue healing was excellent and there have not been any early recurrent infections at mean of 18 months follow up. In vitro, zones of inhibition were formed on less than 40% of the organisms, demonstrating that AA was not directly bactericidal against the majority of the clinical isolates. However, when cultured in a bacterial suspension, AA completely inhibited the growth of the isolates at concentrations as low as 0.19%v/v. This study has shown that the use of 3% AA soak, as part of a debridement protocol, is safe. Whilst the exact mechanism of action of acetic acid is yet to be determined, we have demonstrated that concentrations as low as 0.19%v/v in solution in vitro is sufficient to completely inhibit bacterial growth from infected TKR's

Aim. Chemical debridement is a fundamental step during Periprosthetic joint infection (PJI) surgery. Antiseptic solutions are commonly used, but evidence on the optimal antiseptic, concentration, and irrigation time is lacking. The aim of this study is to analyze and compare the anti-biofilm capacity of povidone iodine, H. 2. 0. 2. , acetic acid and Bactisure™ after different exposure times, as well as their combinations. Method. Surgical steel discs inoculated with methicillin susceptible (MSSA) and resistant S. aureus (MRSA), P. aeruginosa, and S. epidermidis were exposed to the following antiseptic solutions: 0.3% (PI0.3) and 10% povidone iodine (PI10), H. 2. 0. 2. , 3% Acetic acid (AA3) and Bactisure™. Combinations included AA3, H. 2. 0. 2. , and PI10 in various orders. Exposure time for the antiseptics solutions was 1, 3 and 5 minutes, while combinations had a 9-minute total exposure, 3 minutes per antiseptic sequentially. All experiments were performed in triplicate and with a sterile saline control. nThe reduction in colony-forming units (CFU) was measured after sonication, and biofilm structure was analyzed via scanning electron microscopy. Results. PI showed the highest antibiofilm activity. PI0.3 eradicated bacteria on the discs after 3 and 5 minutes of exposure, but only achieved a 77.1% reduction after 1 minute. After PI10 treatment, we did not recover any bacteria regardless of exposure time. H. 2. 0. 2. , AA3, and Bactisure™ reached a significantly lower bacterial decrease at all exposure times compared to PI0.3 and PI10. AA3 was less effective against MSSA and S. epidermidis. H. 2. 0. 2. showed less activity against MRSA than PI0.3, PI10, and Bactisure™. Combinations of antiseptics starting with AA3 showed the best results in terms of CFU reduction and cell viability. Conclusions. We propose a sequential combination of AA3 + H. 2. 0. 2. + PI10 with an exposure time of 9 minutes for the chemical debridement in PJI surgery. First, AA3 performs debridement and disruption of the biofilm. Then, H. 2. 0. 2. has a bactericidal effect and increases the porosity of the cell wall, and PI10 has a final bactericidal effect. If combinations are unavailable, PI is a cost-effective alternative

Aim. Polypropylene (PPE) synthetic mesh is increasingly used in knee arthroplasty surgery to salvage a disrupted extensor mechanism. Despite its clinical success, it is associated with a high rate of periprosthetic joint infection (PJI), which is hypothesized to be caused by bacterial biofilm. The purpose of the current study is to describe the progression of PPE-based biofilm formation over time and to determine if intraoperative antiseptic solutions could be used to effectively remove biofilm when treating PJI. Method. Commercially available knotted monofilament PPE mesh. 1. was cut into 10mm circular shape, immersed in tryptic soy broth (TSB) with methicillin-sensitive staphylococcus aureus and cultured individually in 48-well plates for 10 days to elucidate the biofilm grown on mesh over time. At every 24 hours, a triplicate of samples was retrieved and biofilm on the mesh was dislodged by sonicating at 52 kHz for 15 minutes and quantified by counting colony-forming units (CFUs) after overnight growth. The biofilm growth was also verified using scanning electron microscopy. The effect of saline and antiseptic solutions was verified by exposing 1) 0.05% chlorohexidine gluconate. 2. , 2) acetic acid-based mixture. 3. , 3) diluted povidone-iodine (0.35%), 4) undiluted povidone-iodine (10%). 4. , and 5) 1:1 combination of 10% povidone-iodine & 3% hydrogen peroxide on immature and mature biofilms for 3 minutes, created by culturing with bacteria for 24 hours and 72 hours respectively. All experiments were performed in quintuples and repeated. Antiseptic treatments that produced a three-log reduction in CFU counts compared to controls were considered clinically significant. Results. PPE-mesh produced reliable CFU counts at 24 hours and reached peak growth at 72 hours. For immature biofilm, all formulations of povidone-iodine produced significant reductions in CFU counts compared to controls. Although not meeting the established threshold, saline irrigation removed 86.5% of CFUs, while formulation based on chlorohexidine and acetic acid removed 99.2% and 99.7% respectively. For mature biofilm, formulations based on povidone-iodine and acetic acid produced significant reductions in CFU counts. Conclusions. Our findings suggest biofilm may form on mesh as early as 24 hours after bacterial exposure. Povidone-iodine formulations were consistently the most effective in removing biofilm on mesh surfaces. We recommend that surgeons consider using an antiseptic solution, preferably povidone-iodine-based, in addition to regular saline lavage when attempting to salvage a PPE mesh in the setting of PJI. 1. Marlex mesh (CR Bard, Davol Inc, Warwick, RI), . 2. Irrisept (Irrimax Corp, Gainesville, FL), . 3. Bactisure (Zimmer-Biomet, Warsaw, IN), . 4. Aplicare (Inc, Meriden, CT)

Aim. The management of PJIs is slowed down by the presence of bacteria forming biofilms where they may withstand antibiotic therapy. The use of adjuvant strategies, such as hydrolytic enzymes cocktail targeting biofilm matrices and facilitating their dispersion, is a promising option to limit impact of biofilms. Our aim was to evaluate the effect of enzymes cocktail combined with antibiotic dual therapy of rifampicin and vancomycin in a relevant in-vitro model. Method. Mature methicillin-resistant Staphylococcus aureus biofilms were grown on Ti-6Al-4V coupons by adding 1mL of a 8Log10 ATCC 33591 suspension in TGN (TSB + 1% glucose + 2% NaCl) to 24-wells plates containing the coupons and incubating the plates for 24h at 37°C with a continuous 50rpm agitation. The samples were rinsed and placed in 6 wells plates containing 1ml of the enzymatic cocktail (C.D.D.) solution (tris-buffered (pH 7.0) solution of 400 U/ml of aspecific DNA/RNA endonuclease, 50 U/ml of endo-1,4-b-D-glucanase, and 0.06 U/ml of β-N-acetylhexosaminidase). 9ml of TGN or TGN containing antibiotics RIF/VAN (rifampicin 5µg/mL + vancomycin 8µg/mL) at clinically relevant concentrations found locally in bone or joints, was then added and the samples were incubated in identical conditions for 24h. The samples were then recovered and rinsed. CFU counts were obtained by recovering the bacteria with sonication, serial dilutions, and TSA plating. Biomass was determined via crystal violet staining, followed by dye solubilization in acetic acid, and absorbance measurement using a spectrophotometer. Results. Significant reductions in bacterial counts were observed in biofilms exposed to either RIF/VAN or RIF/VAN+CDD, by respectively 2,6 and 3,7Log10 when compared to samples reincubated with TGN alone (p <0.05). Additionally, CFU counts in samples exposed to RIF/VAN+CDD were reduced by 1,1Log10 when compared to those exposed to RIF/VAN (p<0,05). Significant reduction in biomass (-29,8%, p<0.05) was observed for coupons exposed to RIF/VAN+CDD when compared to C.D.D alone (figure 1). Conclusions. The concurrent utilization of enzymes with rifampicin and vancomycin, holds promise as a feasible method to address periprosthetic joint infections (PJIs). For any tables or figures, please contact the authors directly

Aim. This study aims to evaluate the effectiveness of a pre-formulated irrigation solution. 1. (containing ethanol, acetic acid, sodium acetate, benzalkonium chloride, and sterile water) compared to saline solution in managing acute periprosthetic joint infections (A-PJI) during Debridement, Antibiotic, and Implant Retention (DAIR) surgeries. The primary objective is to assess the healing rate using this solution. 1. versus saline in A-PJI patients, with “cure” defined by a set of criteria including no recurrence, wound issues, or need for ongoing suppressive antibiotics after 1 year. Principio del formularioFinal del formulario. Method. This single-center, randomized controlled trial will involve patients with acute periprosthetic infections undergoing standard DAIR surgery, divided into two groups: one receiving saline solution and the other receiving pre-formulated solution. 1. The study is single-blinded, with patients unaware of their group assignment. The study is registered at ISRCTN: https://doi.org/10.1186/ISRCTN10873696. Inclusion criteria include patients over 18 with hip or knee prostheses suffering from acute or hematogenous periprosthetic infections, while exclusion criteria include a history of prior debridement or multiple infected implants, among others. Principio del formularioFinal del formulario A total of 50 subjects are needed for statistical significance, with a 5% dropout rate anticipated. An interim safety analysis will assess early effectiveness and adverse effects, and the results are presented in this study. Data will be managed in online databases and analyzed using SPSS software, with a significance level of p<0.05. Results. Twenty-four patients were eligible for analysis, twelve in each group. The overall average age was 75 years, and the gender distribution was predominantly female (9 F and 3 M in each group). No significant differences were found at the baseline characteristics level between the two groups (p>0.05). The minimum follow-up of 1 year was achieved in all cases except three due to deaths not related to periprosthetic infection. Regarding efficacy, a non-statistically significant difference was observed (p>0.05), with 58% in the serum group and 42% in the pre-formulated irrigation solution. 1. group (X. 2. = 0.17, p=0.683). The average hospital stay was 38.42 days (SD 26.32) in the pre-formulated irrigation solution group. 1. and 24.42 days (SD 18.72) in the serum group, with this difference being not significant (t=1.5, p=0.148). Conclusions. While the current analysis indicates no significant differences between both groups in terms of efficacy, the study's ongoing progress and the inclusion of a larger sample size could potentially yield more definitive results