Successful prophylactic measures for the eradication of Staphylococcus aureus infections in elective hip primary and revision arthroplasty.

INTRODUCTION: Staphylococcus aureus stands as the predominant etiological agent in postoperative acute prosthetic joint infections (PJI), contributing to 35-50% of reported cases. This study aimed to evaluate the efficacy of dual prophylaxis incorporating cefuroxime and teicoplanin, in combination with nasal decolonization utilizing 70% alcohol, and oral and body lavage with chlorhexidine. MATERIAL AND METHODS: We conducted a retrospective review of electronic health records regarding primary and revision arthroplasties conducted at our institution from 2020 to 2021. Relevant variables linked to prosthetic joint infections (PJI) were documented until the latest follow-up. RESULTS: A total of 539 operations (447 primary arthroplasties and 92 revision arthroplasties) were performed on 519 patients. There were 11 cases of postoperative acute PJI, resulting in infection rates of 1.6% for primary arthroplasties and 4.3% for revision surgeries. Infections were more prevalent in male patients, individuals with an ASA classification > II, and those undergoing longer operations (> 90 minutes). Staphylococcus aureus was not isolated in any of the cases. CONCLUSION: The prophylactic measures implemented in our institution have exhibited a high efficacy in preventing postoperative acute PJI caused by Staphylococcus aureus.

Preventing Infections in Reverse Shoulder Arthroplasty.

PURPOSE OF REVIEW: Reverse shoulder arthroplasty (rTSA) is a commonly performed procedure to treat degenerative conditions of the shoulder. With its growing utilization, techniques to reliably diagnose and treat prosthetic joint infection (PJI) have become increasingly important. In this review we outline the current research and prevention methods of prosthetic joint infection in rTSA. This includes preoperative considerations, intraoperative, and postoperative treatment algorithms. RECENT FINDINGS: There is currently no established standardized protocol for preoperative infection prevention or post operative management. However, recent studies have identified risk factors for infection, as well as successful prevention techniques that can be implemented to minimize infection risk. Although there is no standardized protocol currently utilized to diagnose and treat shoulder PJI, we outline a potential set of preventative measures and postoperative management strategies that clinicians can use to properly diagnose and treat patients with this difficult condition.

Comparison of Five-Day vs. Fourteen-Day Incubation of Cultures for Diagnosis of Periprosthetic Joint Infection in Hip Arthroplasty.

Background: Periprosthetic joint infections (PJI) are among the most morbid complications in total hip arthroplasty (THA). The ideal incubation time, however, for intraoperative cultures for PJI diagnosis remains unclear. As such, the aim of this study was to determine if any differences existed in culture-positive rates and organism detection between five-day and fourteen-day cultures. Methods: This retrospective cohort study consisted of THA cases diagnosed with PJI performed between May 2014 and May 2020 at a single tertiary-care institution. Analyses compared five-day and fourteen-day cultures and carried out a pre-specified subgroup analysis by organism and PJI type. Results: A total of 147 surgeries were performed in 101 patients (57.1% females), of which 65% (n = 98) obtained five-day cultures and 34% (n = 49) obtained fourteen-day cultures. The positive culture rate was 67.3% (n = 99) with Staphylococcus aureus being the most common pathogen identified (n = 41 specimens, 41.4%). The positive culture rate was not significantly different between groups (66.3% five-day, 69.4% fourteen-day, p = 0.852). Fourteen-day cultures had a significantly longer time-to-positive culture (5.0 days) than five-day cultures (3.0 days, p < 0.001), a higher rate of fungi (5.6% vs. 0%), and a lower rate of Gram-negatives (4.5% vs. 18.7%, p = 0.016). Conclusions: Fourteen-day cultures did not increase the positivity rate, had higher rates of slow-growth pathogens, and had a longer time-to-positivization than five-day cultures. Prolonged culture holds may provide more thorough organism detection for PJI without increasing the diagnostic culture yield.

Synovial calprotectin in prosthetic joint infection. A systematic review and meta-analysis of the literature.

INTRODUCTION: Calprotectin is a protein endowed with antimicrobial properties, rendering it a distinctive marker for infection. Two methods are currently available for the assay of calprotectin: the enzyme-linked immunosorbent assay (ELISA) and the lateral flow test (LFT). We aimed to assess the diagnostic accuracy of synovial fluid calprotectin and to compare the accuracy of the laboratory-based test and the qualitative assessment for the diagnosis of hip and knee prosthetic infection. MATERIALS AND METHODS: We searched (from inception to November 2023) MEDLINE, Scopus, EMBASE, Web of Science, and Cochrane for studies on calprotectin in the diagnosis of periprosthetic joint infection (PJI). Sensitivity, specificity, positive and negative likelihood ratio (LR), and diagnostic odds ratio were analyzed. The receiver-operating curve for each method was calculated. RESULTS: We included 14 articles in our meta-analysis, including 902 patients who underwent total hip and knee arthroplasties revision; 331 (37%) had a joint infection according to MSIS, MSIS-modified criteria, ICM 2018 and EBJIS 2021. Considering the false-positive result rate of 6% and false-negative result rate of 7%, pooled sensitivity and specificity were 0.92 (95% CI 0.89-0.94) and 0.93 (0.91-0.95), respectively. The area under the curve (AUC) was 0.93 (95% CI 0.91-0.94). No statistical differences in terms of sensitivity and specificity were found between ELISA and LFT. The pooled sensitivity and specificity of the two calprotectin assessment methods were: LFT 0.90 (95% CI 0.869-0.935) and 0.92 (95% CI 0.894-0.941), respectively; ELISA 0.96 (95% CI 0.914-0.986) and 0.97 (95% CI 0.934-0.988), respectively. The diagnostic odds ratio of the ELISA was superior to that of the LFT (906.6667, 95% CI 271.2686-3030.3712 versus 113.8886, 95% CI 70.4001-184.2414; p < 0.001). The AUC for ELISA and LFT was 0.968 (95% CI 0.944-0.984) and 0.915 (95% CI 0.895-0.933), respectively. CONCLUSIONS: Detection of synovial calprotectin is an accurate test for diagnosis of hip and knee prosthetic infections. The diagnostic accuracy of the two calprotectin assessment methods is almost comparable. The LFT is a valid, rapid, and more available diagnostic tool, particularly to rule out PJI.

The Effect of Nutritional Status in the Treatment of Periprosthetic Joint Infections in Total Hip Arthroplasty.

BACKGROUND: Periprosthetic joint infections (PJIs) continue to be a complication that plagues arthroplasty. Albumin is a surrogate marker for nutrition as well as chronic inflammation, and hypoalbuminemia increases the risk of complications in arthroplasty. Patients with PJI are at increased risk for malnutrition and complications. This study's objective was to analyze patients who underwent treatment of PJI following total hip arthroplasty and investigate the outcome with regards to albumin levels. METHODS: Overall, 48 patients who underwent surgery for a total hip PJI at 1 institution were reviewed. Albumin and C-reactive protein were recorded preoperatively and 2 to 3 weeks postoperatively. Treatment failure was determined by further surgical treatment for PJI or repeat infection, as determined by Musculoskeletal Infection Society guidelines. RESULTS: A debridement, antibiotics, and implant retention procedure was performed in 39 patients, and explant with the placement of an antibiotic spacer was performed in 9. Preoperative mean albumin levels were significantly decreased in patients who failed to clear their infection compared to patients who remained infection-free (2.5 versus 3.3, P < .001). Postoperative albumin levels decreased in this same population (2.6 versus 3.8, P < .001). C-reactive protein was elevated in patients who failed to clear their infection preoperatively (19.9 versus 7.5, P < .001) and postoperatively (7.0 versus 1.7, P < .001). The average time to repeat surgical treatment for their PJI was 9 months CONCLUSIONS: Lower albumin levels are observed in patients with PJI who failed to remain infection-free after surgery. Albumin is a surrogate marker for nutrition, and low albumin is associated with poor immune function. Hypoalbuminemia is found with chronic inflammation as well as malnutrition. Nutritional reserves are diverted to the acute inflammatory response during an infection, which can lead to a deficient state. Further research may develop treatments to alter this modifiable risk factor. LEVEL OF EVIDENCE: Level 4.

Antibiotic-loaded bone cement is associated with a reduction of the risk of revision of total knee arthroplasty: Analysis of the Catalan Arthroplasty Register.

PURPOSE: The purpose of this study was to analyse the impact on peri-prosthetic joint infection (PJI) rate and prosthetic survival using antibiotic-loaded bone cement (ALBC) versus plain cement during total knee arthroplasty (TKA). METHODS: A retrospective cohort study was conducted. The main data source was the Catalan Arthroplasty Register (RACat). TKAs with surgery date between 1 January 2011 and 31 December 2020 were analysed and followed up until 31 December 2023. The main variable of interest was the type of cement (ALBC vs. plain cement), and several endpoints (septic revision, aseptic revision, and all-cause revision) were considered. The analysed outcomes were revision rates, survival rates and risk factors' hazard ratios (HR). RESULTS: A total of 22,781 TKAs were analysed, 13,125 (57.6%) of them with plain cement and 9656 (42.4%) with ALBC. The septic revision rate was lower in the ALBC group after 3 months of follow-up (0.52% vs. 0.78%, p value = 0.04). Prosthetic survival with respect to the aseptic revision endpoint was also higher for the ALBC group during the whole follow-up period (~158 months). Regarding risk factors for infection, ALBC showed a protective effect, HR: 0.53 (0.44, 0.63), while sex (being male) and the analysed comorbidities increased the risk. CONCLUSIONS: ALBC is associated with a reduction in both the septic revision and the aseptic revision rate after TKA, and thus with higher prosthetic survival. LEVEL OF EVIDENCE: Level III, Therapeutic, retrospective.

Total Hip Arthroplasty Complications in Sickle Cell Disease: Systematic Review and Meta-Analysis.

Background: Microvascular occlusions caused by sickle-shaped erythrocytes in patients with sickle cell disease (SCD) can lead to increased intraoperative and postoperative complications during total hip arthroplasty (THA). This systematic review and meta-analysis aimed to estimate the overall rate of complications following THA in patients with SCD and to identify the predictors of these complications including the surgical approach. Methods: The search was conducted across the grey literature, Google Scholar, and seven databases: Scopus, MEDLINE Central/PubMed, ProQuest, SciELO, SAGE, and Web of Science. All observational studies reporting the proportional THA complications in SCD were included. The Newcastle-Ottawa Scale quality assessment tool was used to assess the quality of the studies. The random effect model was applied to estimate the pooled outcomes. A sub-group analysis for the different approaches was performed. A sensitivity analysis and meta-regression were used to explain heterogeneity and to identify the THA complication predictors. Results: Of 3230 citations, only 23 studies were eligible for the meta-analysis. The pooled proportion of total primary THA complications in patients with SCD was 42% (95% CI: 30-56%, I2 = 95%). The sub-group analysis highlighted the anterolateral approach as the approach accompanied with the least complications. The meta-regression revealed that the anterolateral approach decreases the complications significantly, -28.67 (95%CI, -56.45--0.88, p = 0.044), while the number of hips increased the complications by 0.43 (95%CI, 0.30-0.57, p < 0.001). Male gender, age, lateral approach, and HbSS non-significantly affect the THA complications in SCD 52.05, 0.18, 6.06, and 55.78, respectively. The pooled proportions for an SCD crisis 9% (95%CI, 5-14%, I2 = 61%), dislocation 4% (95%CI: 2-7%, I2 = 66%), aseptic loosening 12% (95%CI, 7-20%, I2 = 91%), revision 6% (3-11, I2 = 92%), heterotopic ossification 12% (95%CI, 3-35%, I2 = 95%), and prosthetic joint infection (PJI) 6% (95%CI, 3-11%, I2 = 92%). The most fitted model of meta-regression illustrated that HbSS significantly increases PJI, 0.05 (95%CI: 0.02-0.08, p = 0.009), and male gender and age non-significantly increase PJI, 2.28 (95%CI: -4.99-13.56, p = 0.311) and 0.001 (95%CI: -0.27-0.27, p = 0.990), respectively. Meanwhile, the anterolateral, lateral, and posterior approaches non-significantly decrease PJI, -3.55, -0.92, and -1.27, respectively. The pooled proportion for a sickle cell disease crisis after revision was 16% (95%CI: 6-36%, I2 = 0) and for aseptic loosening after revision, it was 24% (95%CI: 12-43%, I2 = 0). Conclusions: This study revealed the high rate of complications in patients with SCD and highlighted that the anterolateral approach was associated with the lowest rate of complications. Furthermore, this study illustrated that homozygous (HbSS) individuals are more susceptible to prosthetic joint infection.

The effects of chlorhexidine, povidone-iodine and vancomycin on growth and biofilms of pathogens that cause prosthetic joint infections: an in-vitro model.

BACKGROUND: Chlorhexidine gluconate (CHG) and povidone-iodine (PI) are commonly used to prevent prosthetic joint infection (PJI) during total joint replacement; however, their effective concentrations and impact on biofilms are not well defined. AIM: To determine: (1) the in-vitro minimum inhibitory concentration of CHG and PI against model PJI-causing organisms and clinical isolates; (2) their impact on biofilm formation; (3) whether there is a synergistic benefit to combining the two solutions; and (4) whether adding the antibiotic vancomycin impacts antiseptic activity. METHODS: We measured in-vitro growth and biofilm formation of Staphylococcus epidermidis, meticillin-sensitive and meticillin-resistant Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans, as well as recent clinical isolates, in the presence of increasing concentrations of CHG and/or PI. Checkerboard assays were used to measure potential synergy of the solutions together and with vancomycin. FINDINGS: CHG and PI inhibited growth and biofilm formation of all model organisms tested at concentrations of 0.0004% and 0.33% or lower, respectively; highly dilute concentrations paradoxically increased biofilm formation. The solutions did not synergize with one another and acted independently of vancomycin. CONCLUSION: CHG and PI are effective at lower concentrations than typically used, establishing baselines to support further clinical trials aimed at optimizing wound disinfection. There is no synergistic advantage to using both in combination. Vancomycin is effective at inhibiting the growth of S. epidermidis and S. aureus; however, it stimulates P. aeruginosa biofilm production, suggesting in the rare case of P. aeruginosa PJI, it could exacerbate infection.

Risk of Periprosthetic Joint Infection in Patients With Ipsilateral Infected Arthroplasties.

Background: The risk of periprosthetic joint infection (PJI) subsequently developing at a second site after an initial PJI has been documented to be approximately 18%-20%. To the best of our knowledge, only a single study has evaluated the incidence in ipsilateral joints and if the risk of infection would be different. While this was the only other study to evaluate this specific subfield, we set to re-evaluate and confirm the incidence of developing a second PJI in the setting of an ipsilateral prosthesis and possible associated risk factors. Methods: We retrospectively reviewed all patients treated surgically for lower-extremity PJI at our institution by 5 surgeons from 2015 to 2021. Patients with multiple arthroplasties on the ipsilateral extremity were included. Time between initial and subsequent infection, risk factors for infection, bacterial source, and bacteremia were identified. Results: Of 392 patients treated for PJI, 179 (45.6%) had multiple prosthetic joints. Forty-seven of those 179 patients had ipsilateral extremity prosthesis, which made up our study population. Three patients (6.4%) developed a separate infection at an ipsilateral TJA. In total, 10 patients (21.3%) developed a separate PJI. Patients on immunosuppressants had a higher likelihood of developing second PJI on the ipsilateral extremity (P = .02). Conclusions: Our study identified the risk of developing an ipsilateral PJI to not be any greater than that in patients with contralateral TJAs. It appears that sharing an extremity with an infected TJA does not pose substantially increased risk of subsequent infection of the un-involved prosthesis. Furthermore, immunosuppressant use may increase the risk of a separate ipsilateral PJI.

Phase 1 study of the pharmacokinetics and clinical proof-of-concept activity of a biofilm-disrupting human monoclonal antibody in patients with chronic prosthetic joint infection of the knee or hip.

We report the results of a first-in-human phase 1 clinical study to evaluate TRL1068, a native human monoclonal antibody that disrupts bacterial biofilms with broad-spectrum activity against both Gram-positive and Gram-negative species. The study population consisted of patients with chronic periprosthetic joint infections (PJIs) of the knee or hip, including both monomicrobial and polymicrobial infections, that are highly resistant to antibiotics due to biofilm formation. TRL1068 was administered via a single pre-surgical intravenous infusion in three sequentially ascending dose groups (6, 15, and 30 mg/kg). Concomitant perioperative antibiotics were pathogen-targeted as prescribed by the treating physician. In this double-blinded study, 4 patients were randomized to receive placebo and 11 patients to receive TRL1068 on day 1, as well as targeted antibiotics for 7 days prior to the scheduled removal of the infected implant and placement of an antibiotic-eluting spacer as the first stage of the standard of care two-stage exchange arthroplasty. No adverse events attributable to TRL1068 were reported. TRL1068 serum half-life was 15-18 days. At day 8, the concentration in synovial fluid was approximately 60% of the blood level and thus at least 15-fold above the threshold for biofilm-disrupting activity in vitro. Explanted prostheses were sonicated to release adherent bacteria for culture, with elimination of the implant bacteria observed in 3 of the 11 patients who received TRL1068, which compares favorably to prior PJI treatments. None of the patients who received TRL1068 had a relapse of the original infection by the end of the study (day 169). CLINICAL TRIALS: This study is registered with ClinicalTrials.gov as NCT04763759.

High Efficacy of Oral Tetracyclines in Prosthetic Joint Infection Treated With Debridement, Antibiotics, and Implant Retention (DAIR) or Resection Arthroplasty With Destination Spacer Placement.

Prosthetic joint infections are often managed with debridement and implant retention (DAIR) or resection arthroplasty with destination spacer placement. Both surgical approaches require long courses of postoperative antibiotics, for which tetracycline antibiotics have not been well-studied. In this retrospective case series, we included patients at our institution treated for staphylococcal prosthetic joint infection managed with DAIR or destination spacer placement who were switched from IV antibiotics to oral tetracycline within 12 weeks of surgery. Our primary outcome of interest was treatment failure within one year of initial surgery. Among the patients in our series, 88.2% (n = 15) of patients who underwent DAIR and 100% (n = 7) of patients who underwent resection arthroplasty with destination spacer remained event-free for one year. These results demonstrated that the use of oral tetracyclines as long-term therapy in the treatment of these infections was effective and well-tolerated.

The use of long-term antibiotics for suppression of bacterial infections.

Suppressive antibiotic therapy is prescribed when a patient has an infection that is presumed to be incurable by a defined course of therapy or source control. The cohort receiving suppressive antibiotic therapy is typically highly comorbid and the infections often involve retained prosthetic material. In part due to a lack of clear guidelines regarding the use of suppressive antibiotics, and in part due to the complex nature of the infections in question, patients are often prescribed suppressive antibiotics for extremely long, if not indefinite, courses. The risks of prolonged antibiotic exposure in this context are not fully characterised, but they include adverse drug effects ranging from mild to severe, the development of antibiotic resistant organisms and perturbations of the gastrointestinal microbiome. In this narrative review we present the available evidence for the use of suppressive antibiotic therapy in four common indications, examine the gaps in the current literature and explore the known and potential risks of this therapy. We also make suggestions for improving the quality of evidence in future studies, particularly by highlighting the need for a standardised term to describe the use of long-courses of antibiotics to suppress hard-to-treat infections.

Adding corticosteroids to intra-operative periarticular injections in total knee arthroplasty: A systematic review.

BACKGROUND: Adding corticosteroids to intraoperative periarticular injections (PAIs) have become a current trend in total knee arthroplasty (TKA). Periarticular corticosteroid injections (PACSIs) intend to improve postoperative pain and function. However, preoperative corticosteroid injections for symptomatic arthritis increase the rates of prosthetic joint infection (PJI) when given months prior to TKA. The aim of this systematic review was to determine whether the addition of corticosteroids to PAIs during TKA improves patient outcomes and whether such practice increases the risk of PJI? METHODS: A systematic review of the current literature following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines screened 1025 abstracts. Thirteen studies meeting specific eligibility criteria were included for further analysis. RESULTS: Among the studies comparing the PACSIs versus nonsteroidal PAIs, 36% showed a significant reduction in postoperative pain scores, 20% showed significant improvement in range of motion (ROM), and 16% showed a significant reduction in total morphine equivalence (TME). While 100% of the studies comparing PACSI to saline or no injections showed significant improvement in pain, ROM and TME. In total, there were 3 infections in 576 TKA cases receiving PACSIs and 2 infections in 534 cases not receiving a PACSI. However, studies were not powered specifically to assess for infection. CONCLUSIONS: The addition of corticosteroids to intraoperative PAIs do not demonstrate a significant benefit in the majority of studies, and tend to not have an effect on PJI risk; however, studies were not specifically powered to assess PJI risk.

Diagnostic Performance of a Molecular Assay in Synovial Fluid Targeting Dominant Prosthetic Joint Infection Pathogens.

Prosthetic joint infection (PJI) is one of the most serious complications of joint replacement surgery among orthopedic surgeries and occurs in 1 to 2% of primary surgeries. Additionally, the cause of PJIs is mostly bacteria from the Staphylococcus species, accounting for more than 98%, while fungi cause PJIs in only 1 to 2% of cases and can be difficult to manage. The current gold-standard microbiological method of culturing synovial fluid is time-consuming and produces false-negative and -positive results. This study aimed to identify a novel, accurate, and convenient molecular diagnostic method. The DreamDX primer-hydrolysis probe set was designed for the pan-bacterial and pan-fungal detection of DNA from pathogens that cause PJIs. The sensitivity and specificity of DreamDX primer-hydrolysis probes were 88.89% (95% CI, 56.50-99.43%) and 97.62% (95% CI, 87.68-99.88%), respectively, compared with the microbiological method of culturing synovial fluid, and receiver operating characteristic (ROC) area under the curve (AUC) was 0.9974 (*** p < 0.0001). It could be concluded that the DreamDX primer-hydrolysis probes have outstanding potential as a molecular diagnostic method for identifying the causative agents of PJIs, and that host inflammatory markers are useful as adjuvants in the diagnosis of PJIs.

Robinsoniella peoriensis Infections in Humans-A Narrative Review.

Robinsoniella peoriensis is a Gram-positive, strictly anaerobic, spore-forming, rod-shaped bacterium belonging to the phylum Firmicutes and the family Lachnospiraceae. Until now, R. peoriensis is the only species of its genus. It was first isolated in 2003 during a study into the flora of lagoons and manure pits. Given the rarity of this microorganism and the sparse information in the literature about its way of transmission, the way to diagnose its infections and identify it in the microbiology laboratory, and its public health relevance, the present study aimed to identify all the published cases of Robinsoniella, describe the epidemiological, clinical, and microbiological characteristics, and provide information about its antimicrobial resistance, treatment, and outcomes. A narrative review was performed based on a Pubmed/Medline and Scopus databases search. In total, 14 studies provided data on 17 patients with infections by Robinsoniella. The median age of patients was 63 years and 47% were male. The most common types of infection were bone and joint infections, bacteremia, infective endocarditis, and peritonitis. The only isolated species was R. peoriensis, and antimicrobial resistance to clindamycin was 50%, but was 0% to the combination of piperacillin with tazobactam, aminopenicillin with a beta-lactamase inhibitor, and metronidazole which were the most commonly used antimicrobials for the treatment of these infections. The overall mortality depends on the type of infection and is notable only for bacteremia, while all other infections had an optimal outcome. Future studies should better assess these infections' clinical and epidemiological characteristics and the mechanisms of the antimicrobial resistance of this microorganism from a mechanistic and genetic perspective.

Evaluation of the use of sonication combined with enzymatic treatment for biofilm removal in the microbiological diagnosis of prosthetic joint infection.

Sonicating explanted prosthetic implants to physically remove biofilms is a recognized method for improving the microbiological diagnosis of prosthetic joint infection (PJI); however, chemical and enzymatic treatments have been investigated as alternative biofilm removal methods. We compared the biofilm dislodging efficacy of sonication followed by the addition of enzyme cocktails with different activity spectra in the diagnosis of PJI with that of the sonication of fluid cultures alone. Consecutive patients who underwent prosthesis explantation due to infection at our institution were prospectively enrolled for 1 year. The diagnostic procedure included the collection of five intraoperative tissue cultures, sonication of the removed devices, and conventional culture of the sonication fluid. The resulting sonication fluid was also treated with an enzyme cocktail consisting of homemade dispersin B (0.04 µg/mL) and proteinase K (Sigma; 100 µg/mL) for 45 minutes at 37°C. The resulting sonication (S) and sonication with subsequent enzymatic treatment (SE) fluids were plated for aerobic and anaerobic culture broth for 7 days (aerobic) or 14 days (anaerobic). Identification was performed by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (Bruker). We included 107 patients from whom a prosthetic implant had been removed, among which PJI was diagnosed in 36 (34%). The sensitivity of S alone was significantly greater than that of SE alone (82% vs 71%; P < 0.05). Four patients with PJI were positive after sonication alone but negative after sonication plus enzymatic treatment. The four microorganisms missed after the addition of the enzyme cocktail were Staphylococcus aureus, two coagulase-negative Staphylococci, and Cutibacterium acnes. In conclusion, sonication alone was more sensitive than sonication followed by enzymatic treatment. The combination of these two methods had no synergistic effect; in contrast, the results suggest that the combination of both dislodgment methods affects the viability of gram-positive microorganisms. IMPORTANCE: While the potential of sonication and enzymes as biofilm dispersal agents has been previously described, the originality of our work resides in the combination of both methods, which is hypothesized to enhance the ability to remove biofilm and, therefore, improve the microbiological diagnosis of PJI.

Acute Haematogenous Revision Total Knee Arthroplasty Infection by Streptococcus canis Treated by Debridement, Antibiotics, and Implant Retention: A Case Report.

Prosthetic joint infections (PJIs) are one of the most feared complications by orthopaedic surgeons. Haematogenous PJI represents an important part of PJI cases. Streptococcus canis is an extremely rare cause of haematogenous PJI and its medical and surgical treatment and prognosis are not well established. We present a 79-year-old female patient who had a revision total knee arthroplasty (rTKA) surgery three years before. She was admitted to the hospital referring to three days of knee pain, restricted range of motion, and fever. Blood tests demonstrated leukocyte and C-reactive protein elevation. Joint fluid aspiration showed elevated white blood cell count with a high neutrophil differential and its conventional culture was positive for Streptococcus canis. She did not have pets but she took care of her daughter's dog. An acute haematogenous infection of the rTKA was diagnosed and treated with debridement, antibiotics (eight weeks of IV ceftriaxone), and implant retention (DAIR). After one year, the patient remains clinically asymptomatic without changes on X-rays and with normal serum levels of inflammatory blood markers. Streptococcus canis has to be kept in mind as a possible cause of haematogenous TKA infection in patients who have contact with domestic pets and patients should be asked for this contact. We recommend DAIR as a viable treatment option for this type of infection, which may show excellent results.

Determination of vancomycin and meropenem in serum and synovial fluid of patients with prosthetic joint infections using UPLC-MS/MS.

Numerous studies have suggested that intra-articular administration of antibiotics following primary revision surgery may be one of the methods for treating prosthetic joint infection (PJI). Vancomycin and meropenem are the two most commonly used antibiotics for local application. Determining the concentrations of vancomycin and meropenem in the serum and synovial fluid of patients with PJI plays a significant role in further optimizing local medication schemes and effectively eradicating biofilm infections. This study aimed to establish a rapid, sensitive, and accurate ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for determining the concentrations of vancomycin and meropenem in human serum and synovial fluid. Serum samples were processed using acetonitrile precipitation of proteins and dichloromethane extraction, while synovial fluid samples were diluted before analysis. Chromatographic separation was achieved in 6 min on a Waters Acquity UPLC BEH C18 column, with the mobile phase consisting of 0.1% formic acid in water (solvent A) and acetonitrile (solvent B). Quantification was carried out using a Waters XEVO TQD triple quadrupole mass spectrometer with an electrospray ionization (ESI) source in positive ion mode. The multiple reaction monitoring (MRM) mode was employed to detect the following quantifier ion transitions: 717.95-99.97 (norvancomycin), 725.90-100.04 (vancomycin), 384.16-67.99 (meropenem). The method validation conformed to the guidelines of the FDA and the Chinese Pharmacopoeia. The method demonstrated good linearity within the range of 0.5-50 µg/ml for serum and 0.5-100 µg/ml for synovial fluid. Selectivity, intra-day and inter-day precision and accuracy, extraction recovery, matrix effect, and stability validation results all met the required standards. This method has been successfully applied in the pharmacokinetic/pharmacodynamic (PK/PD) studies of patients with PJI.

Outcomes of Antibiotic-Impregnated Calcium Sulfate, Reamer-Irrigator-Aspirator, and Locked Intramedullary Static Spacer in the Treatment of Periprosthetic Joint Infection in the Multiply Revised and Infected Knee: A Single-Center Case Series.

Background: Periprosthetic joint infection after total knee arthroplasty is commonly treated via 2-stage revision utilizing either articulating or static antibiotic cement spacers. While recent literature exhibits a slight functional advantage in favor of articulating spacers, those patients with a history of recurrent infection/multiple revision procedures are frequently excluded from these studies. The purpose of this study was to report infection eradication rates and efficacy of utilizing antibiotic-loaded locked intramedullary nail for infection for the multiply revised, infected total knee arthroplasty. Methods: A retrospective review was performed of all consecutive patients receiving static spacers between 2017 and 2020 at an academic medical center. Surgical techniques for all patients included irrigation and debridement using a reamer-irrigator-aspirator, injection of antibiotic-loaded calcium sulfate into the intramedullary canal, and nail placement. Antibiotic-loaded cement is then used to create a spacer block in the joint space. A Cox proportional hazard regression was run to identify risk factors for reinfection. Results: Forty-two knees in 39 patients were identified meeting inclusion criteria. Overall, there was an 68.8% infection eradication rate at an average of 46.9 months following spacer placement. The only risk factors identified on cox regression were increasing number of previous spacers, a surrogate for previous infections (hazards ratio = 14.818, P value = .021), and increasing operative time during spacer placement (hazards ratio = 1.014, P value = .039). Conclusions: Use of static spacers, in conjunction with reamer-irrigator-aspirator and antibiotic-loaded calcium sulfate, can be effective in treating chronic, complex periprosthetic joint infections in the setting of bone loss and or soft-tissue compromise and produced similar results to more simple infection scenarios.