Prosthetic joint infection

Nanocomposite orthopaedic bone cement combining long-acting dual antimicrobial drugs

Antibiotic loaded bone cements are widely used in total joint replacement (TJR); despite many limitations such as a burst release which leads to antibiotic concentration below inhibitory levels and possibly contributing to the selection of antibiotic resistant strains. In order to address such limitations and to simultaneously address antibiotic resistance and short-term antimicrobial activity, we developed a nanocomposite bone cement capable of providing a controlled release of antimicrobial agents from bone cement to act as prophylaxis or treatment against prosthetic joint infections (PJIs). Gentamicin and chlorhexidine were loaded in combination on silica nanoparticles surface using layer-by-layer coating technique (LbL) combining hydrolysable and non-hydrolysable polymers. The drug release from the nanocomposite continued for >50 days at concentrations higher than the commercial formulation containing the same amount of antimicrobial drugs, where burst release for few days were observed. Moreover, the nanocomposite bone cement showed superior antimicrobial inhibition without adversely affecting the mechanical properties or the ability of osteoblasts to grow. In vivo experiments with an infected bone lesion model along with mass-spectrometric analysis also provided further evidence of efficacy and safety of the implanted nanocomposite material as well as its prolonged drug eluting profile. The developed nanocomposite bone cement has the potential to reduce PJIs and enable treatment of resistant established infections; moreover, the newly developed LbL based nano-delivery system may also have wider applications in reducing the threat posed by antimicrobial resistance.

Clostridial prosthetic joint infections: A series of 16 cases and literature review

OBJECTIVES

Prosthetic joint infections (PJIs) due to the Clostridium species have not been widely investigated. We aimed to characterize these uncommon infections.

METHODS

We conducted a retrospective study between 2003 and 2020 in six French hospitals combined with a review of the literature.

RESULTS

The main conclusions obtained from the 16 patients included were reinforced by the literature analysis: (i) Clostridium perfringens was the most frequently involved species, (ii) patients presented an advanced age at the time of prosthesis placement and infection, (iii) most of the infections were early- or delayed-onset, (iv) the prognosis for these PJIs remains poor, (v) when performed (n = 5), DAIR with 12-week antimicrobial therapy led to a favorable outcome in 80% of cases.

CONCLUSIONS

Given the low incidence of this infection, our work represents the largest series of clostridial PJIs reported to date and highlights some specificities of these infections. Further prospective studies are needed to confirm these results.

Clostridium Bifermentans Infection of a Prosthetic Knee Joint in a Patient With Human Immunodeficiency Virus: A Case Report

We reported a case of Clostridium bifermentans (C. bifermentans) infection in the prosthetic knee joint of a human immunodeficiency virus (HIV) patient, who presented with swelling, discomfort, pain, and redness in the right lower extremity. An uncommon yet potentially lethal human illness triggered by C. bifermentans. Foreign material is especially susceptible to local infection because of the local immunodeficiency close to the implant. Intravenous (IV) cefepime and IV ampicillin/sulbactam were administered to the patient. The idea of performing surgery to eradicate the infection was under consideration, but its necessity remained uncertain, and the decision to proceed with surgery had not been finalized.

Pasteurella Multocida Infection in Humans

Pasteurella multocida (P. multocida) is an immobile, anaerobic, Gram-negative coccobacillus fermenting bacterium. This pathogen is commonly prevalent in the upper airways of healthy pets, such as cats and dogs, but was also confirmed in domestic cattle, rabbits, pigs, birds, and various wild animals. Infection in humans occurs as a result of biting, scratching, or licking by animals and contact with nasopharyngeal secretions. Inflammation at the site of infection develops within the first day from the injury. It is usually confined to the skin and subcutaneous tissue but, in particular situations, may spread to other organs and manifest as a severe systemic infection. Careful history-taking and microbiological confirmation of the infection enable diagnosis and appropriate treatment. Any wound resulting from an animal bite should be disinfected. The preferred and highly effective treatment against local P. multocida infection is penicillin or its derivatives. The prognosis for P. multocida infections depends on the infected site and the patient's comorbidities.

Should We Use Rifampicin in Periprosthetic Joint Infections Caused by Staphylococci When the Implant Has Been Exchanged? A Multicenter Observational Cohort Study

Background

Previous studies demonstrated the efficacy of a rifampicin-based regimen in the treatment of acute staphylococcal periprosthetic joint infections (PJIs) treated with surgical debridement. However, evidence is lacking to support the use of rifampicin in cases where the implant is exchanged during revision.

Methods

We included all consecutive cases of staphylococcal PJIs treated from January 2013 to December 2018 with revision surgery in this international, retrospective, multicenter observational cohort study. PJI was defined according to the European Bone and Joint Infection Society diagnostic criteria. A relapse or reinfection during follow-up, the need for antibiotic suppressive therapy, the need for implant removal, and PJI-related death were defined as clinical failure. Cases without reimplantation or with follow-up <12 months were excluded.

Results

A total of 375 cases were included in the final analysis, including 124 1-stage exchanges (33.1%) and 251 2-stage exchanges (66.9%). Of those, 101 cases failed (26.9%). There was no statistically significant difference in failure of patients receiving rifampicin (22.5%, 42/187) and those not receiving rifampicin (31.4%, 59/188; P = .051). A subanalysis of chronic PJIs treated by 2-stage exchange arthroplasty demonstrated a lower failure rate in cases treated with rifampicin (15%) compared with the no-rifampicin group (35.5%; P = .005). In this subgroup, the use of rifampicin and an antibiotic holiday of >2 weeks were independent predictors of clinical success (odds ratio [OR], 0.36; 95% CI, 0.15-0.88; and OR, 0.19; 95% CI, 0.04-0.90; respectively).

Conclusions

Combination treatment with rifampicin increases treatment success in patients with chronic staphylococcal PJI treated with 2-stage exchange arthroplasty.

Periprosthetic Joint Infection Diagnosis: A Narrative Review

Replacement of native joints aims to restore patients' quality of life by relieving pain and improving joint function. While periprosthetic joint infection (PJI) affects a small percentage of patients, with an estimated incidence of 1-9% following primary total joint replacement, this postoperative complication necessitates a lengthy hospitalisation, extended antibiotic treatment and further surgery. It is highlighted that establishing the correct diagnosis of periprosthetic infections is critical in order for clinicians to avoid unnecessary treatments in patients with aseptic failure. Of note, the PJI diagnosis could not purely rely upon clinical manifestations given the fact that heterogeneity in host factors (e.g., age and comorbidities), variability in infection period, difference in anatomical location of the involved joint and discrepancies in pathogenicity/virulence of the causative organisms may confound the clinical picture. Furthermore, intra-operative contamination is considered to be the main culprit that can result in early or delayed infection, with the hematogenous spread being the most prevalent mode. To elaborate, early and hematogenous infections often start suddenly, whereas chronic late infections are induced by less virulent bacteria and tend to manifest in a more quiescent manner. Last but not least, viruses and fungal microorganisms exert a role in PJI pathogenesis.

What Is the Most Reliable Concordance Rate of Preoperative Synovial Fluid Aspiration and Intraoperative Biopsy to Detect Periprosthetic Joint Infection in Knee, Hip and Shoulder Arthroplasty?

The accuracy of preoperative synovial fluid microbe detection in periprosthetic joint infection (PJI) is widely reported. However, the reliability of this diagnostic modality amongst the different joints is not yet described. We aimed to compare the concordance rate between preoperative synovial fluid and intraoperative tissue cultures in shoulder, knee and hip PJIs. A total of 150 patients who met the 2018 International Consensus Meeting criteria for shoulder, hip and knee PJI were retrospectively reviewed. This cohort was divided into three groups based on the involved joint (should, hip or knee), with 50 patients in each group. Cultures were collected and held for culture for 14 days. The overall concordance rate was 56.7%. Concordance rates between preoperative and intraoperative cultures were 60%, 56% and 54% for the knee, shoulder and hip joints, respectively. The analysis of high- or low-virulence and difficult- or not-difficult-to-treat germs did not reveal any significant differences between preoperative and intraoperative cultures in any of the groups. However, even considering the higher concordance in knee PJI, the overall discordance between preoperative and intraoperative cultures should prompt surgeons not to rely solely on preoperative synovial fluid culture data in determining appropriate treatment and antibiotics.

Comment on Lunz et al. Impact and Modification of the New PJI-TNM Classification for Periprosthetic Joint Infections. J. Clin. Med. 2023, 12, 1262

We read with great interest the article by Lunz et al. [...].

Single, Recurrent, Synchronous, and Metachronous Periprosthetic Joint Infections in Patients With Multiple Hip and Knee Arthroplasties

BACKGROUND

The rate for periprosthetic joint infection (PJI) exceeds 1% for primary arthroplasties. Over 30% of patients who have a primary arthroplasty require an additional arthroplasty, and the impact of PJI on this population is understudied. Our objective was to assess the prevalence of recurrent, synchronous, and metachronous PJI in patients who had multiple arthroplasties and to identify risk factors for a subsequent PJI.

METHODS

We identified 337 patients who had multiple arthroplasties and at least 1 PJI that presented between 2003 and 2021. The mean follow-up after revision arthroplasty was 3 years (range, 0 to 17.2). Patients who had multiple infected prostheses were categorized as synchronous (ie, presenting at the same time as the initial infection) or metachronous (ie, presenting at a different time as the initial infection). The PJI diagnosis was made using the MusculoSkeletal Infection Society (MSIS) criteria.

RESULTS

There were 39 (12%) patients who experienced recurrent PJI in the same joint, while 31 (9%) patients developed PJI in another joint. Positive blood cultures were more likely in the second joint PJI (48%) compared to recurrent PJI (23%) or a single PJI (15%, P < .001). Synchronous PJI represented 42% of the second joint PJI cases (n = 13), while metachronous PJI represented 58% (n = 18). Tobacco users had 75% higher odds of metachronous PJI (odds ratio 1.75, 95% confidence interval: 1.1-2.9, P = .041).

CONCLUSION

Over 20% of the patients with multiple arthroplasties and a single PJI will develop a subsequent PJI in another arthroplasty with 12% recurring in the initial arthroplasty and nearly 10% ocurring in another arthroplasty. Particular caution should be taken in patients who use tobacco, have bacteremia, or have Staphylococcus aureus isolation at time of their initial PJI. Optimizing the management of this high-risk patient population is necessary to reduce the additional burden of subsequent PJI.

LEVEL OF EVIDENCE

Prognostic Level IV.

Impact of preoperative urinary tract infection on postoperative outcomes following total shoulder arthroplasty for osteoarthritis

Introduction

As the utilization of total shoulder arthroplasty (TSA) increases, it is essential to identify risk factors associated with postoperative complications. Urinary tract infection (UTI) is one such example. Our objective is to identify whether UTI is associated with increased rates of prosthetic joint infection (PJI) and determine whether its treatment reduces PJI rates.

Methods

Patients who underwent primary TSA for glenohumeral osteoarthritis between 2010 and 2019 with minimum two-year follow-up were identified in a national database (PearlDiver Technologies) using Current Procedural Terminology and International Classification of Diseases codes. These patients were stratified into two cohorts: those with preoperative UTI within two weeks of TSA and those without. The preoperative UTI cohort was stratified into those treated and those untreated prior to TSA. Univariate and multivariable analyses were performed.

Results

Following multivariable analysis, there were significantly higher odds of postoperative anemia, pulmonary embolism, and death in the UTI cohort. Comparing treated to untreated UTI, there were no significant differences in multivariable analysis for any 90-day medical or two-year surgical complications.

Discussion

This study showed that UTI was not associated with increased rates of PJI. UTI was, however, associated with postoperative medical complications that surgeons should be aware of.

One-stage revision versus debridement, antibiotics, and implant retention (DAIR) for acute prosthetic knee infection: an exploratory cohort study

INTRODUCTION

Studies have shown that debridement, antibiotics, and implant retention (DAIR) is an effective procedure for acute infection of total knee arthroplasty (TKA). This study aimed to explore DAIR and one-stage revision for homogenous cohorts with acute postoperative and acute hematogenous infection of TKA, without compelling indications to perform a staged revision.

MATERIALS AND METHODS

This study was an exploratory analysis that used retrospective data from Queensland Health, Australia, for DAIR and one-stage revision of TKA between June 2010 and May 2017 (3-year average follow-up). The re-revision burden, mortality rate, and the cost of the interventions were explored. Costs were expressed in 2020 Australian dollars.

RESULTS

There were 15 (DAIR) and 142 (one-stage) patients with homogenous characteristics in the sample. The re-revision burden for DAIR was 20%, while for one-stage revision it was 12.68%. Two deaths were associated with a one-stage revision and no death was associated with DAIR. The total cost since the index revision of DAIR, $162,939, was higher than for one-stage revision $130,924 (p value = 0.501), due to higher re-revision burden.

CONCLUSIONS

This study would suggest the use of one-stage revision over DAIR for acute postoperative and acute hematogenous infection of TKA. It suggests that there could be other potential criteria which have not been ascertained that need to be considered for optimal DAIR selection. The study indicates the need for more research and, of note, high-quality randomized controlled trials to provide a well-defined treatment protocol with high level of evidence to guide patient selection for DAIR.

Mycobacterium avium complex prosthetic joint infection: A systematic review of the literature and pooled analysis

BACKGROUND

Mycobacterium avium complex (MAC) prosthetic joint infection (PJI) has been rarely reported.

METHODS

This study aimed to investigate the epidemiology and outcomes of MAC PJI. A systematic review of the literature regarding the MAC infection following total joint arthroplasty including hip and knee joint was performed. Multiple databases were searched for published English-written articles up to May 2023. Studies that reported cases of PJI by MAC were reviewed.

RESULTS

A total of 17 patients were identified and analyzed from 11 published studies. All patients presented with joint symptom of pain or swelling prior to the diagnosis and MAC was confirmed by culture. The most of the patients (16/17 patients, 94.1%) were noted to have underlying medical condition(s) that might have affected immunity. Treatment consisted of anti-MAC medication therapy only in two patients and anti-MAC medication therapy plus surgery in 15 patients. Among the patients who underwent surgery, 14 patients (82.3%) had removal of the prosthesis including seven patients who had two-stage surgery to have reimplantation of the prosthesis. No relapse of MAC infection was reported despite of one case of relapse of infection caused by different pyogenic bacteria. The rate of overall mortality was 29.4%, however, identified attributable mortality due to MAC infection was low (5.9%).

CONCLUSION

PJI by MAC is a rare disease. However, MAC needs to be considered in the differential diagnosis in immunocompromised patients presenting with symptoms of PJI. Two-stage exchange arthroplasty may result in successful treatment outcomes without higher risks of relapse of infection if undertaken in association with appropriate active anti-MAC antibiotic therapy.

Overview of systematic reviews of risk factors for prosthetic joint infection

BACKGROUND

Prosthetic joint infection is one of the most serious complications in orthopedics. Prognostic systematic reviews (SR) detecting and assessing factors related to prosthetic joint infection, allow better prediction of risk and implementation of preventive measures. Although prognostic SR are increasingly frequent, their methodological field presents some knowledge gaps.

PURPOSE

To carry out an overview of SR assessing risk factors for prosthetic joint infection, describing and synthesizing their evidence. Secondarily, to assess the risk of bias and methodological quality.

MATERIAL AND METHODS

We conducted a bibliographic search in 4databases (May 2021) to identify prognostic SR evaluating any risk factor for prosthetic joint infection. We evaluated risk of bias with the ROBIS tool, and methodological quality with a modified AMSTAR-2 tool. We computed the overlap degree study between included SR.

RESULTS

Twenty-three SR were included, studying 15 factors for prosthetic joint infection, of which, 13 had significant association. The most frequently studied risk factors were obesity, intra-articular corticosteroids, smoking and uncontrolled diabetes. Overlapping between SR was high for obesity and very high for intra-articular corticoid injection, smoking and uncontrolled diabetes. Risk of bias was considered low in 8SRs (34.7%). The modified AMSTAR-2 tool showed important methodological gaps.

CONCLUSIONS

Identification of procedural-modifiable factors, such as intra-articular corticoids use, can give patients better results. Overlapping between SR was very high, meaning that some SR are redundant. The evidence on risk factors for prosthetic joint infection is weak due to high risk of bias and limited methodological quality.

Corynebacterium periprosthetic joint infection: a systematic review of 52 cases at 2.5 years follow-up

INTRODUCTION

While large progress has been achieved in identifying and treating the most common pathogens involved in periprosthetic joint infections (PJI), there remains limited knowledge on atypical pathogens such as Corynebacterium. For that reason, we analyzed infection and diagnostical characteristics, as well as treatment outcome in Corynebacterium PJI.

METHODS

A systematic review was performed based on a structured PubMed and Cochrane Library analysis using the PRISMA algorithm. The search was performed by 2 independent reviewers, and articles from 1960 to 2022 considered eligible for inclusion. Out of 370 search results, 12 studies were included for study synthesis.

RESULTS

In total, 52 cases of Corynebacterium PJI were identified (31 knees, 16 hips, 4 elbows, 1 shoulder). Mean age was 65 years, with 53% females, and a mean Charlson Comorbidity Index of 3.9. The most common species was Corynebacterium striatum in 37 cases (71%). Most patients were treated with two-stage exchange (40%), isolated irrigation and debridement (21%), and resection arthroplasty (19%). Mean duration of antibiotic treatment was 8.5 weeks. At a mean follow-up of 2.5 years, there were 18 reinfections (33%), and 39% were for Corynebacterium. Initial infection by Corynebacterium striatum species was predictive of reoperation (p = 0.035) and reinfection (p = 0.07).

CONCLUSION

Corynebacterium PJI affects multimorbid and elderly patients, with one in three developing a reinfection at short term. Importantly, the relative majority of reinfections was for persistent Corynebacterium PJI.

Low Risk of Acute Iatrogenic Periprosthetic Joint Infection After Prosthetic Joint Aspiration

BACKGROUND

Synovial fluid analysis is an essential tool in diagnosing periprosthetic joint infection (PJI) after total knee arthroplasty (TKA). However, concern exists that aspiration may introduce infection into a noninfected joint. Therefore, the purpose of this study was to evaluate the incidence of iatrogenic PJI following diagnostic knee aspiration done within 6 months of the primary TKA.

METHODS

Between 2017 and 2021, the senior surgeon performed over 4,000 primary TKAs and aspirated 155 knees in 137 patients for whom there was a suspicion for PJI within 6 months of their primary TKA. There were 22 knees diagnosed as infected from the initial aspiration and therefore were excluded from the study. The remaining 133 aspirates in 115 patients who were negative for infection were followed for 6 months for signs and symptoms of PJI to elucidate whether aspiration introduced infection into an initially noninfected joint.

RESULTS

There were 70 of 133 knees (52.6%) aspirated between 0 and 6 weeks after index TKA, 40 of 133 (30.1%) between 6 weeks and 3 months, and 23 of 133 (17.3%) between 3 and 6 months. At final follow-up, none of the 133 initially noninfected knees exhibited evidence of subsequent iatrogenic PJI or had subsequent surgery for infection.

CONCLUSION

While joint aspiration is a procedure with inherent risks, this study shows that the rate of iatrogenic PJI is extremely low (0%). Therefore, if infection is suspected, the surgeon should consider joint aspiration, even in the initial postoperative period, as the risk for introducing infection is far outweighed by the risk of missing an infection.

[Translated article] Overview of systematic reviews of risk factors for prosthetic joint infection

BACKGROUND

Prosthetic joint infection is one of the most serious complications in orthopedics. Prognostic systematic reviews (SRs) detecting and assessing factors related to prosthetic joint infection, allow better prediction of risk and implementation of preventive measures. Although prognostic SRs are increasingly frequent, their methodological field presents some knowledge gaps.

PURPOSE

To carry out an overview of SR assessing risk factors for prosthetic joint infection, describing and synthesizing their evidence. Secondarily, to assess the risk of bias and methodological quality.

MATERIAL AND METHODS

We conducted a bibliographic search in 4 databases (May 2021) to identify prognostic SR evaluating any risk factor for prosthetic joint infection. We evaluated risk of bias with the ROBIS tool, and methodological quality with a modified AMSTAR-2 tool. We computed the overlap degree study between included SR.

RESULTS

Twenty-three SRs were included, studying 15 factors for prosthetic joint infection, of which, 13 had significant association. The most frequently studied risk factors were obesity, intra-articular corticosteroids, smoking and uncontrolled diabetes. Overlapping between SR was high for obesity and very high for intra-articular corticoid injection, smoking and uncontrolled diabetes. Risk of bias was considered low in 8 SRs (34.7%). The modified AMSTAR-2 tool showed important methodological gaps.

CONCLUSIONS

Identification of procedural-modifiable factors, such as intra-articular corticoids use, can give patients better results. Overlapping between SR was very high, meaning that some SRs are redundant. The evidence on risk factors for prosthetic joint infection is weak due to high risk of bias and limited methodological quality.

Trends in microbiological epidemiology of orthopedic infections: a large retrospective study from 2008 to 2021

BACKGROUND

This study assessed the distribution characteristics of pathogens isolated from cases of orthopedic infections and focused on the antimicrobial susceptibility of the main pathogens.

METHODS

This retrospective study involved patients with orthopedic infection in a tertiary medical center located in Shanghai, China, from 2008 to 2021.Pathogen information and the basic information of patients were identified from clinical microbiology laboratory data and the institutional medical record system.

RESULTS

In total, the pathogen information of 2821 patients were enrolled in the study. S. aureus (37.71%) was the main causative pathogen responsible for orthopedic infection. Gender, pathogens distribution and polymicrobial infection rates were significantly different (P < 0.05) among patients with different orthopedic infection diseases.The trends in the distribution of pathogens in the total cohort, implant-related infection group (Group A), non-implant-related infection group (Group B), and the sub-group of cases with arthroplasty showed significant linear changes over time. And the polymicrobial infection rates of the total cohort (from 17.17% to 11.00%), Group B(from 24.35% to 14.47%), and the sub-group of cases with internal fixation (from 10.58% to 4.87%) decreased significantly. The antimicrobial susceptibility showed changing trends with time for some main pathogens, especially for S.aureus and Enterobacter spp.

CONCLUSIONS

Our research indicated that the pathogen distribution and antimicrobial susceptibility in orthopedic infections changed over time. And the distribution of pathogens varied significantly among different types of orthopedic infectious diseases. These findings may serve as a reference for prophylaxis and empirical treatment strategies of orthopedic infection.

The value of sonication on orthopaedic implants in an everyday clinical setting - an exploratory study

BACKGROUND

Sonication of removed orthopaedic implants in suspected implant-associated infections (IAI) is widely applied internationally. However, evaluation of the utility of sonication on all implants removed in everyday standard practice is scarce. This exploratory study was performed to evaluate the application of sonication fluid (SF) culture on removed orthopaedic implants, irrespective of the reason for removal.

METHODS

Out of 100 removed orthopaedic implants collected between August 2019 and September 2020, 77 implants with availability of concurrent tissue culture samples were included in the study. Removed implants were categorized into a confirmed or suspected IAI group and a presumed aseptic group based on pre-operative diagnosis by the responsible surgeon. Implants were sonicated and SF culture performed under both aerobic and anaerobic conditions. The significance of all bacterial isolates was evaluated based on the CFU/mL cut-offs of the EBJIS guidelines, except for C. acnes where additional investigations were performed.

RESULTS

The results of SF culture in the two groups were compared with their corresponding tissue cultures. Out of the 12 cases in the confirmed/suspected IAI group, SF culture was positive in 11 cases and had increased diagnostic yield in two (17%) cases compared to tissue culture. Increased diagnostic yield of SF compared to tissue culture was seen in seven (11%) of the 65 implants in the presumed aseptic group. If growth of Cutibacterium species isolates were interpreted based on EBJIS cut-off for SF culture instead of the study-specific criteria, then two isolates considered to represent infection might have been missed while three other isolates considered contaminants would have fallen under the 'infection confirmed' category in the EBJIS guidelines.

CONCLUSION

Sonication with SF culture has increased diagnostic yield compared to tissue cultures in all implants irrespective of reason for removal. However, positive SF cultures with Cutibacterium species should always be interpreted with extreme care.

A Low Rate of Periprosthetic Infections after Aseptic Knee Prosthesis Revision Using Dual-Antibiotic-Impregnated Bone Cement

AIM

The incidence of periprosthetic joint infections (PJI) following aseptic knee revision arthroplasty lies between 3% and 7.5%. The aim of this study was to verify the hypothesis that the use of dual-antibiotic-impregnated cement in knee revision arthroplasty leads to a lower rate of periprosthetic joint infections.

METHODS

We retrospectively reviewed 403 aseptic revision knee arthroplasties performed between January 2013 and March 2021 (148 revisions of a unicompartmental prosthesis, 188 revisions of a bicondylar total knee arthroplasty (TKA), 41 revisions of an axis-guided prosthesis, and 26 revisions of only one component of a surface replacement prosthesis). The bone cement Copal G+C (Heraeus Medical, Wertheim, Germany) with two antibiotics-gentamycin and clindamycin-was used for the fixation of the new implant. The follow-up period was 53.4 ± 27.9 (4.0-115.0) months.

RESULTS

Five patients suffered from PJI within follow-up (1.2%). The revision rate for any reason was 8.7%. Survival for any reason was significantly different between the types of revision (p = 0.026, Log-Rank-test), with lower survival rates after more complex surgical procedures. The 5-year survival rate with regard to revision for any reason was 91.3% [88.2-94.4%] and with regard to revision for PJI 98.2% [98.7-99.9%], respectively.

CONCLUSION

The use of the dual-antibiotic-impregnated bone cement Copal G+C results in a lower rate of periprosthetic infections after aseptic knee prosthesis replacement than that reported in published prosthesis revisions using only one antibiotic in the bone cement.

Performance and Hypothetical Impact on Joint Infection Management of the BioFire Joint Infection Panel: a Retrospective Analysis

Pathogen identification is key in septic arthritis. Culture-based techniques are challenging, especially when patients have been pretreated with antibiotics or when difficult-to-culture bacteria are encountered. The BioFire joint infection assay (BJA) is a multiplex PCR panel which detects 31 of the most prevalent bacterial and fungal pathogens causing septic arthritis. Here, 123 cryoconserved contemporary synovial fluid samples from 120 patients underwent BJA analysis. Results were compared to those of culture-based diagnostics (standard of care [SOC]). Clinical data were collected, and the possible impact of the molecular diagnostic application on patient management was evaluated. Fifteen of 123 synovial fluid cultures grew bacterial pathogens. All on-panel pathogens (9/15) were correctly identified by the BJA. The BJA identified four additional bacterial pathogens in four SOC-negative cases. BJA sensitivity and specificity were 100% (95% confidence interval [CI], 69.2% to 100%) and 100% (95% CI, 96.8% to 100%), respectively. Compared to the SOC, the BJA would have resulted in faster provision of species identification and molecular susceptibility data by 49 h and 99 h, respectively. Clinical data analysis indicates that in BJA-positive cases, faster species ID could have led to timelier optimization of antibiotic therapy. This retrospective study demonstrates high sensitivity and specificity of the BJA to detect on-panel organisms in bacterial arthritis. The usefulness of the BJA in prosthetic-joint infections is limited, as important pathogens (i.e., coagulase negative staphylococci and Cutibacterium acnes) are not covered. Evidence from patient data analysis suggests that the assay might prove valuable for optimizing patient management in acute arthritis related to fastidious organisms or for patients who received antibiotics prior to specimen collection.

Incidence of periprosthetic joint infection after primary total hip arthroplasty is underestimated: a synthesis of meta-analysis and bibliometric analysis

The American Musculoskeletal Society updated the diagnostic criteria for periprosthetic joint infection (PJI) in 2011 and 2018. However, the overall incidence of PJI since the introduction of these new standards has not been assessed. In order to fill this knowledge gap, a single-group meta-analysis was conducted using articles obtained from several databases, focusing on the incidence of PJI after primary total hip arthroplasty (THA). Our study revealed a significant difference in the incidence of PJI reported by different national or regional databases. Moreover, most cases of PJI were found to be underestimated. This highlights the crucial need for standardized diagnostic criteria and monitoring methods to accurately identify and track cases of PJI. Furthermore, a bibliometric analysis was conducted to provide a comprehensive overview of the current state of research on PJI after THA. This analysis explored the most productive countries, organizations, journals, and individuals in this research area. Additionally, it identified the research trends and hotspots of the last decade, highlighting the advancements and areas of focus in this field. By conducting these analyses, the study aims to contribute to the understanding of PJI after THA and provide valuable insights for clinicians, researchers, and policymakers involved in the management of this condition.

Activated mast cells in periprosthetic joint infection-associated tissue

Background

Periprosthetic joint infection (PJI) is a devastating complication of total joint arthroplasty surgery. Increased densities of activated mast cells have been predicted to be present in PJI compared to non-infectious arthroplasty failure based on analysis of transcriptomic data, but their presence in PJI-associated periprosthetic tissues has not been visually confirmed.

Objective

This preliminary study investigated the presence and activation status of mast cells in periprosthetic tissues associated with PJI.

Methods

Periprosthetic tissues from five PJI cases and three arthroplasty failures due to instability and one due to stiffness were immunohistochemically stained using tryptase and microscopically evaluated to enumerate mast cells and evaluate overall activation status within tissue samples. Mast cell activation was evidenced by the release of tryptase into the extracellular space surrounding mast cells.

Results

Mast cells were found in all samples, with average cellular densities of 22 and 26 cells/mm2 tissue in PJI and uninfected samples, respectively (p, 0.6610). Apparent mast cell activation and degranulation was readily observed throughout each of the five PJI samples studied, but not in any of the uninfected samples studied.

Conclusion

While preliminary, these findings provide evidence for a role of mast cells in the immune response in PJI. Additional investigation of the role of mast cells during arthroplasty failure is warranted, providing a better understanding of underlying biology and informing potential diagnostic and treatment targets.

Comparison of microbial detection rates in microbial culture methods versus next-generation sequencing in patients with prosthetic joint infection: a systematic review and meta-analysis

BACKGROUND

Accurate diagnosis of prosthetic joint infection (PJI) enables early and effective treatment. However, there is currently no gold standard test for microbial detection of PJI and traditional synovial fluid culture is relatively insensitive. Recently, it has been reported that sonicating fluid culture and next-generation sequencing (NGS) improve microbial detection rates. Hence, we performed a systematic review and meta-analysis to compare microbial detection rates in microbial culture methods with and without sonication versus NGS.

METHODS

We systematically searched EMBASE, PubMed, Scopus, CINAHL, and Ichushi databases and other sources (previous reviews) until August 2022. We evaluated the detection rates of pathogens in NGS and microbial cultures using samples of synovial or sonicated fluid.

RESULTS

Of the 170 citations identified for screening, nine studies were included. Pooled analysis indicated that NGS had the highest detection rate among the microbial detection methods (NGS vs. sonicated, odds ratios [OR] 5.09, 95% confidential interval [CI] 1.67-15.50; NGS vs. synovial, OR 4.52, 95% CI 2.86-7.16). Sonicated fluid culture showed a higher detection rate than synovial fluid culture (OR 2.11, 95% CI 1.23-3.62).

CONCLUSION

NGS might be useful as a screening tool for culture-negative patients. In clinical settings, sonicated fluid culture is a practical method for diagnosing PJI.

Clinical Outcomes and Infection Rates Following Revision Total Knee Arthroplasty: Aseptic Failure versus Septic Failure

Background

It is controversial whether revision total knee arthroplasty (TKA) due to septic failure shows inferior clinical outcomes compared with TKA due to aseptic failure. Moreover, few studies have compared the infection rates after revision TKA between aseptic and septic failure. We aimed to compare the clinical outcomes and infection rates after aseptic and septic revision TKA.

Methods

Between April 2006 and May 2019, 68 and 26 patients underwent revision TKA due to aseptic failure (aseptic group) and septic failure (septic group), respectively. The postoperative range of motion (ROM), Western Ontario and McMaster Universities Osteoarthritis index, Knee Society Knee Score (KSKS), Knee Society Function Score (KSFS), and infection rates were compared between the two groups.

Results

The mean follow-up durations in the aseptic and septic groups were 44.4 and 54.8 months, respectively. The septic group showed inferior postoperative ROM (124.1° and 109.4°, p = 0.004), KSKS (88.9 and 78.8, p = 0.001), and KSFS (72.8 and 59.0, p = 0.001). Three patients of aseptic group had infection. Three patients of septic group had recurred infection (same pathogen with the first infection) and 1 patient had a new infection (different pathogen). The septic group showed slightly higher but not significantly different infection rates (4.4% and 15.4%, p = 0.089).

Conclusions

Revision TKA with septic failure showed inferior postoperative clinical outcomes compared with aseptic revision surgery. A slightly higher infection rate was observed in the septic group but it was not significantly different.

Materiovigilance in Intensive Care Units: An Active Surveillance

Background: Medical devices are the vital part of healthcare system. The use of medical devices is higher in the intensive care units leading to increased exposure rendering the exponential rise in incidence of medical device associated adverse events (MDAEs). Timely detection and reporting of MDAEs can help reduce the disease and associated liabilities. Objective: To determine the rate, patterns, and predictors of MDAEs. Methods: An active surveillance was carried out in the intensive care units (ICUs) of a tertiary care teaching hospital located in southern India. The patients were monitored for MDAEs which were reported based on MvPI guidance document 1.2. The predictors were calculated using an odds ratio at 95% confidence interval. Results: A total of 185 MDAEs were reported amongst 116 patients, of which the majority [74 (63.7%)] were males. Most of the MDAEs were attributed to urethral-catheters [42 (22.7%)] among which a high majority of 34 were associated with urinary tract infections (UTI), followed by ventilators [35 (18.9%)] with all events causing pneumonia. Urethral catheters and ventilators are both classified as categories B and C respectively based on device risk classification provided by the Indian Pharmacopoeia Commission (IPC). Over 58% of MDAEs were reported among the elderly. The causality assessment was possible for 90 (48.6%) MDAEs whereas 86 (46.4%) were probable. The majority of the MDAEs reported were serious [165 (89.2%)] and only [20 (10.8%)] were found to be non-serious on the severity scale. Most [104 (56.2%)] of the devices attributed to MDAEs were single-use devices, of which [103 (55.6%)] were destroyed and only [81 (43.7%)] were retained in healthcare facilities. Conclusions: Despite the best possible care in the intensive care units (ICUs), MDAEs are inevitable, adding to the burden of patients in terms of suffering, disease, extended hospital stay, and increased costs. MDAEs require rigorous monitoring of patients, especially in the elderly population and patients with increased exposure to multiple devices.

Current relevance of biomarkers in diagnosis of periprosthetic joint infection: an update

With a significant rise in the number of arthroplasty procedures performed worldwide, the increasing revision burden posed by periprosthetic joint infection (PJI) is a matter of growing concern. In spite of various attempts to diagnose PJI, there are no defined tests that can be called a gold standard. Given the importance of early diagnosis in PJI, newer tests and biomarkers have been introduced to improve cumulative diagnostic accuracy. Novel biomarkers like calprotectin, lipocalcin, monocyte-to-lymphocyte ratio, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio and platelet-to-mean platelet volume ratio have demonstrated a potential as diagnostic biomarkers for PJI. This article discusses the relevance of available and newly described diagnostic biomarkers to provide a perspective on the practical applicability in current medical practice, as well as highlights some recent advances in biomarkers for the diagnosis of PJI.

Evaluation of DNA lesions and radicals generated by a 233 nm far-UVC LED in superficial ex vivo skin wounds

The application of a far-ultraviolet C (UVC) light emitting diode (LED) of 233 nm showed significant bactericidal efficacy at an applied dose between 20 and 80 mJ cm-2 as reported recently. In addition, only minor epidermal DNA lesions were observed in ex vivo human skin and in vitro epidermal models <10% of the minimal erythema dose of UVB radiation. To broaden the potential range of applications of such systems, e.g. to include postoperative application on wounds for the purpose of decontamination, we assessed how a disruption of normal anatomic skin structure and function influences the skin damage induced by light from 233 nm far-UVC LEDs. Thus, we induced superficial skin wounds by mechanical detachment of the stratum corneum in ex vivo human skin. Barrier-disruption of the skin could be successfully determined by measuring an increase in the transepidermal water loss (TEWL) and the stratum corneum loss could be determined morphologically by 2-photon microscopy (2-PM). After far-UVC irradiation of the skin, we screened the tissue for the development of cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts (6-4PPs). The abundance of DNA lesions was elevated in wound skin in comparison to intact skin after irradiation with far-UVC. However, no increase in DNA lesions was detected when artificial wound exudate consisting of cell culture medium and serum was applied to the disrupted skin surface prior to irradiation. This effect agrees with the results of ray tracing simulations of the absorption of far-UVC light incident on a superficial skin wound. Interestingly, no significant deviations in radical formation between intact skin and superficially wounded skin were detected after far-UVC irradiation as analyzed by electron paramagnetic resonance (EPR) spectroscopy. In conclusion, 233 nm LED light at a dose of 60 mJ/cm2 could be applied safely on superficial wounds for the purpose of skin antisepsis as long as the wounds are covered with wound fluid.

Antibody-Drug Conjugates to Treat Bacterial Biofilms via Targeting and Extracellular Drug Release

The treatment of implant-associated bacterial infections and biofilms is an urgent medical need and a grand challenge because biofilms protect bacteria from the immune system and harbor antibiotic-tolerant persister cells. This need is addressed herein through an engineering of antibody-drug conjugates (ADCs) that contain an anti-neoplastic drug mitomycin C, which is also a potent antimicrobial against biofilms. The ADCs designed herein release the conjugated drug without cell entry, via a novel mechanism of drug release which likely involves an interaction of ADC with the thiols on the bacterial cell surface. ADCs targeted toward bacteria are superior by the afforded antimicrobial effects compared to the non-specific counterpart, in suspension and within biofilms, in vitro, and in an implant-associated murine osteomyelitis model in vivo. The results are important in developing ADC for a new area of application with a significant translational potential, and in addressing an urgent medical need of designing a treatment of bacterial biofilms.

Microbial Biofilms: Applications, Clinical Consequences, and Alternative Therapies

Biofilms are complex communities of microorganisms that grow on surfaces and are embedded in a matrix of extracellular polymeric substances. These are prevalent in various natural and man-made environments, ranging from industrial settings to medical devices, where they can have both positive and negative impacts. This review explores the diverse applications of microbial biofilms, their clinical consequences, and alternative therapies targeting these resilient structures. We have discussed beneficial applications of microbial biofilms, including their role in wastewater treatment, bioremediation, food industries, agriculture, and biotechnology. Additionally, we have highlighted the mechanisms of biofilm formation and clinical consequences of biofilms in the context of human health. We have also focused on the association of biofilms with antibiotic resistance, chronic infections, and medical device-related infections. To overcome these challenges, alternative therapeutic strategies are explored. The review examines the potential of various antimicrobial agents, such as antimicrobial peptides, quorum-sensing inhibitors, phytoextracts, and nanoparticles, in targeting biofilms. Furthermore, we highlight the future directions for research in this area and the potential of phytotherapy for the prevention and treatment of biofilm-related infections in clinical settings.

Prosthetic knee joint infection caused by α-hemolytic Streptococcus species: a case report

BACKGROUND

Knee arthroplasty is an orthopedic surgical procedure in which a damaged joint is replaced with an artificial one. It is estimated that 1-2% of knee arthroplasties will encounter infection over their lifetime. Although α-hemolytic Streptococcus species play an important role in prosthetic joint infection, they are less common than staphylococcal species.

CASE PRESENTATION

In this report, a 50-year-old Iranian woman was diagnosed with prosthetic knee joint infection based on clinical, radiological, and laboratory findings. She was diabetic and had undergone a left total knee arthroplasty, which, 18 months after the surgery, presented pain, erythema, and edema in that knee. The primary culture of knee aspirate was positive for α-hemolytic Streptococcus species, but following antibiotic medication, culture was negative. The primary antibiotic regime was vancomycin and meropenem, which was changed to cefepime for the management of the infection based on the results of antimicrobial susceptibility testing.

CONCLUSIONS

This report indicated the clinical presentation and management of the patient with prosthetic joint infection in which the patient recovered without any severe complications or surgical intervention.

Repurposed Fenoprofen Targeting SaeR Attenuates Staphylococcus aureus Virulence in Implant-Associated Infections

Implant-associated infections (IAIs) caused by S. aureus can result in serious challenges after orthopedic surgery. Due to biofilm formation and antibiotic resistance, this refractory infection is highly prevalent, and finding drugs to attenuate bacterial virulence is becoming a rational alternative strategy. In S. aureus, the SaeRS two-component system (TCS) plays a key role in the production of over 20 virulence factors and the pathogenesis of the bacterium. Here, by conducting a structure-based virtual screening against SaeR, we identified that fenoprofen, a USA Food and Drug Administration (FDA)-approved nonsteroid anti-inflammatory drug (NSAID), had excellent inhibitory potency against the response regulator SaeR protein. We showed that fenoprofen attenuated the virulence of S. aureus without drug resistance. In addition, it was helpful in relieving osteolysis and restoring the walking ability of mice in vitro and in implant-associated infection models. More importantly, fenoprofen treatment suppressed biofilm formation and changed the biofilm structure, which caused S. aureus to form loose and porous biofilms that were more vulnerable to infiltration and elimination by leukocytes. Our results reveal that fenoprofen is a potent antivirulence agent with potential value in clinical applications and that SaeR is a drug target against S. aureus implant-associated infections.

Selecting a high-dose antibiotic-laden cement knee spacer

Prosthetic joint infection [PJI] after total knee arthroplasty (TKA) remains a common and challenging problem for joint replacement surgeons and patients. Once the diagnosis of PJI has been made, patient goals and characteristics as well as the infection timeline dictate treatment. Most commonly, this involves a two-stage procedure with the removal of all implants, debridement, and placement of a static or dynamic antibiotic spacer. Static spacers are commonly indicated for older, less healthy patients that would benefit from soft tissue rest after initial debridement. Mobile spacers are typically used in younger, healthier patients to improve quality of life and reduce soft-tissue contractures during antibiotic spacer treatment. Spacers are highly customizable with regard to antibiotic choice, cement variety, and spacer design, each with reported advantages, drawbacks, and indications that will be covered in this article. While no spacer is superior to any other, the modern arthroplasty surgeon must be familiar with the available modalities to optimize treatment for each patient. Here we propose a treatment algorithm to assist surgeons in deciding on treatment for PJI after TKA.

Surfaces modified with small molecules that interfere with nucleotide signaling reduce Staphylococcus epidermidis biofilm and increase the efficacy of ciprofloxacin

Staphylococcus epidermidis are common bacteria associated with biofilm related infections on implanted medical devices. Antibiotics are often used in combating such infections, but they may lose their efficacy in the presence of biofilms. Bacterial intracellular nucleotide second messenger signaling plays an important role in biofilm formation, and interference with the nucleotide signaling pathways provides a possible way to control biofilm formation and to increase biofilm susceptibility to antibiotic therapy. This study synthesized small molecule derivates of 4-arylazo-3,5-diamino-1 H-pyrazole (named as SP02 and SP03) and found these molecules inhibited S. epidermidis biofilm formation and induced biofilm dispersal. Analysis of bacterial nucleotide signaling molecules showed that both SP02 and SP03 significantly reduced cyclic dimeric adenosine monophosphate (c-di-AMP) levels in S. epidermidis at doses as low as 25 µM while having significant effects on multiple nucleotides signaling including cyclic dimeric guanosine monophosphate (c-di-GMP), c-di-AMP, and cyclic adenosine monophosphate (cAMP) at high doses (100 µM or greater). We then tethered these small molecules to polyurethane (PU) biomaterial surfaces and investigated biofilm formation on the modified surfaces. Results showed that the modified surfaces significantly inhibited biofilm formation during 24 h and 7-day incubations. The antibiotic ciprofloxacin was used to treat these biofilms and the efficacy of the antibiotic (2 µg/mL) was found to increase from 94.8% on unmodified PU surfaces to > 99.9% on both SP02 and SP03 modified surfaces (>3 log units). Results demonstrated the feasibility of tethering small molecules that interfere with nucleotide signaling onto polymeric biomaterial surfaces and in a way that interrupts biofilm formation and increases antibiotic efficacy for S. epidermidis infections.

Pharmacokinetic and pharmacodynamic considerations for optimizing antimicrobial therapy used to treat bone and joint infections: an evidence-based algorithmic approach

INTRODUCTION

Bone and joint infections (BJIs) are a major health concern causing remarkable morbidity and mortality. However, which antimicrobial treatment could be the best according to specific clinical scenarios and/or to the pharmacokinetic/pharmacodynamic (PK/PD) features remains an unmet clinical need. This multidisciplinary opinion article aims to develop evidence-based algorithms for empirical and targeted antibiotic therapy of patients affected by BJIs.

AREAS COVERED

A multidisciplinary team of four experts had several rounds of assessment for developing algorithms devoted to empirical and targeted antimicrobial therapy of BJIs. A literature search was performed on PubMed-MEDLINE (until April 2023) to provide evidence for supporting therapeutic choices. Four different clinical scenarios were structured according to specific infection types (i.e. vertebral osteomyelitis, prosthetic joint infections, infected non-unions and other chronic osteomyelitis, and infectious arthritis), need or not of surgical intervention or revision, isolation or not of clinically relevant bacterial pathogens from blood and/or tissue cultures, and PK/PD features of antibiotics.

EXPERT OPINION

The proposed therapeutic algorithms were based on a multifaceted approach considering the peculiar features of each antibiotic (spectrum of activity, PK/PD properties, bone penetration rate, and anti-biofilm activity), and could be hopefully helpful in improving clinical outcome of BJIs.

Management of acute periprosthetic knee infection: a comparison of arthroscopic and open debridement

INTRODUCTION

In acute periprosthetic knee infections, debridement and implant retention (DAIR) is the preferred treatment prior to one- and two-stage revisions. The aim of this study is to compare the outcomes of arthroscopic and open debridement of infected primary total knee arthroplasties (TKA).

MATERIAL AND METHODS

We analyzed clinical, laboratory, and antibiotic treatment data, collected in patients with periprosthetic knee infection treated with DAIR at a Swiss Level 1 orthopedic and trauma center over a 10-year period between January 2005 and May 2015. Inclusion criteria were primary total knee arthroplasty and early postoperative or acute hematogenous periprosthetic joint infection (PJI). The primary endpoint was the need for further revision surgery due to persistent infection. The secondary endpoint was the prosthesis salvage in further infection surgeries.

RESULTS

Forty-two patients with 44 acute or hematogenous periprosthetic knee infections were included. We recorded 20 recurrent infections (45%) in our study population: 10 (77%) out of 13 in the arthroscopic DAIR group and 10 (32%) out of 31 in the open DAIR group. Two-stage revision, meaning complete removal of the TKA, insertion of a spacer and replantation at a second stage, had to be performed in three patients treated initially arthroscopically (23%) and in six patients treated initially with an open surgical procedure (21%).

CONCLUSIONS

Open debridement for acute periprosthetic knee infection shows clear benefits in terms of infection eradication and prosthesis salvage compared to arthroscopic DAIR.

Diagnostic performances and therapeutic impact of the Unyvero Implant and Tissue Infection multiplex PCR in periprosthetic joint infections

Aim: We evaluated the diagnostic performances of Unyvero Implant and Tissue Infection multiplex PCR (mPCR) (Curetis) and the clinical impact of this PCR on therapeutic decisions. Materials & methods: A mPCR was performed on 33 joint fluids in addition to standard culture. A group of experts analyzed a posteriori the impact of the mPCR in the patient management. Results: The rate of concordance with culture was 74% (20/27). The sensitivity of the PCR was 59% and the specificity 90%. Clinicians would have started an appropriate treatment sooner for six patients (from 2 to 22 days earlier). Conclusion: The PCR would improve the management of 22% of the patients. For other patients, mPCR results have to be completed with the culture.

Serratia marcescens prosthetic joint infection: two case reports and a review of the literature

BACKGROUND

Despite some studies on Gram-negative bacteria as difficult to treat pathogens in periprosthetic joint infections, there are no detailed analyses on Serratia periprosthetic joint infections. As such, we present two cases of Serratia periprosthetic joint infections and summarize all known cases to date in the course of a PRISMA criteria-based systematic review.

CASE PRESENTATION

Case 1: a 72-year-old Caucasian female with Parkinson's disease and treated breast cancer developed periprosthetic joint infection caused by Serratia marcescens and Bacillus cereus, following multiple prior revisions for recurrent dislocations of her total hip arthroplasty. Two-stage exchange was performed, and the patient remained free of Serratia periprosthetic joint infection recurrence at 3 years. Case 2: an 82-year-old Caucasian female with diabetes and chronic obstructive pulmonary disease presented with a chronic parapatellar knee fistula after undergoing multiple failed infection treatments at external clinics. After performing two-stage exchange and gastrocnemius flap plastic for combined Serratia marcescens and Proteus mirabilis periprosthetic joint infection, the patient was released without any signs of infection, but was subsequently lost to follow-up.

REVIEW

a total of 12 additional Serratia periprosthetic joint infections were identified. Merged with our two cases, the mean age of 14 patients was 66 years and 75% were males. Mean length of antibiotic therapy was 10 weeks with ciprofloxacin most commonly used (50%). Mean follow-up was 23 months. There was a total of four reinfections (29%), including one case of Serratia reinfection (7%).

CONCLUSIONS

Serratia is a rare cause of periprosthetic joint infection affecting elderly with secondary diseases. While the overall reinfection rate was high, the risk of Serratia periprosthetic joint infection persistence was low. Treatment failure in patients may be attributable to the host, rather than the Serratia periprosthetic joint infection itself, thus challenging current concepts on Gram-negatives as a uniform class of difficult-to-treat pathogens.

LEVEL OF EVIDENCE

Therapeutic level IV.

Therapeutics for Vancomycin-Resistant Enterococcal Bloodstream Infections

Vancomycin-resistant enterococci (VRE) are common causes of bloodstream infections (BSIs) with high morbidity and mortality rates. They are pathogens of global concern with a limited treatment pipeline. Significant challenges exist in the management of VRE BSI, including drug dosing, the emergence of resistance, and the optimal treatment for persistent bacteremia and infective endocarditis. Therapeutic drug monitoring (TDM) for antimicrobial therapy is evolving for VRE-active agents; however, there are significant gaps in the literature for predicting antimicrobial efficacy for VRE BSIs. To date, TDM has the greatest evidence for predicting drug toxicity for the three main VRE-active antimicrobial agents daptomycin, linezolid, and teicoplanin. This article presents an overview of the treatment options for VRE BSIs, the role of antimicrobial dose optimization through TDM in supporting clinical infection management, and challenges and perspectives for the future.

Acute Prosthetic Joint Infections with Poor Outcome Caused by Staphylococcus Aureus Strains Producing the Panton-Valentine Leukocidin

The aim of this study was to investigate whether the presence of Staphylococcus aureus (SA) producing the Panton-Valentine leukocidin (PVL) affects the outcome of Prosthetic Joint Infection (PJI). Patients with acute and chronic PJI sustained by SA were prospectively enrolled at the orthopedic unit of "Casa di Cura Santa Maria Maddalena", from January 2019 to October 2021. PJI diagnosis was reached according to the diagnostic criteria of the International Consensus Meeting on PJI of Philadelphia. Synovial fluid obtained via joint aspirations was collected in order to isolate SA. The detection of PVL was performed via real-time quantitative PCR (RT-qPCR). The outcome assessment was performed using the criteria of the Delphi-based International Multidisciplinary Consensus. Twelve cases of PJI caused by SA were included. Nine (75%) cases were acute PJI treated using debridement, antibiotic and implant retention (DAIR); the remaining three (25%) were chronic PJI treated using two-stage (n = 2) and one-stage revision (n = 1), respectively. The SA strains that tested positive for PVL genes were 5/12 (41.6%,). Treatment failure was documented in three cases of acute PJI treated using DAIR, all supported by SA-PVL strains (p < 0.045). The remaining two cases were chronic PJI treated with a revision arthroplasty (one and two stage, respectively), with a 100% eradication rate in a medium follow-up of 24 months. Although a small case series, our study showed a 100% failure rate in acute PJI, probably caused by SA PVL-producing strains treated conservatively (p < 0.04). In this setting, toxin research should guide radical surgical treatment and targeted antibiotic therapy.

Staphylococci planktonic and biofilm environments differentially affect osteoclast formation

INTRODUCTION

The pathophysiology of chronic implant-related bone infections is characterized by an increase in osteoclast numbers and enhanced bone resorption. Biofilms are a major reason for chronicity of such infections as the biofilm matrix protects bacteria against antibiotics and impairs the function of immune cells. Macrophages are osteoclast precursor cells and therefore linked to inflammation and bone destruction.

OBJECTIVE AND METHOD

Investigations on the impact of biofilms on the ability of macrophages to form osteoclasts are yet missing and we, therefore, analyzed the effect of Staphylococcus aureus (SA) and Staphylococcus epidermidis (SE) planktonic and biofilm environments on osteoclastogenesis using RAW 264.7 cells and conditioned media (CM).

RESULTS

Priming with the osteoclastogenic cytokine RANKL before CM addition enabled the cells to differentiate into osteoclasts. This effect was highest in SE planktonic or SA biofilm CM. Simultaneous stimulation with CM and RANKL, however, suppressed osteoclast formation and resulted in formation of inflammation-associated multinucleated giant cells (MGCs) which was most pronounced in SE planktonic CM.

CONCLUSION

Our data indicate that the biofilm environment and its high lactate levels are not actively promoting osteoclastogenesis. Hence, the inflammatory immune response against planktonic bacterial factors through Toll-like receptors seems to be the central cause for the pathological osteoclast formation. Therefore, immune stimulation or approaches that aim at biofilm disruption need to consider that this might result in enhanced inflammation-mediated bone destruction.

Eradication of Staphylococcus epidermidis within Biofilms: Comparison of Systemic versus Supratherapeutic Concentrations of Antibiotics

Biofilm-forming bacterial infections result in clinical failure, recurring infections, and high health care costs. The antibiotic concentrations needed to eradicate biofilm require further research. We aimed to model an in vitro prosthetic joint infection (PJI) to elucidate the activity of traditional systemic concentrations versus supratherapeutic concentrations to eradicate a Staphylococcus epidermidis biofilm PJI. We evaluated S. epidermidis high-biofilm-forming (ATCC 35984) and low-biofilm-forming (ATCC 12228) isolates in an in vitro pharmacodynamic biofilm reactor model with chromium cobalt coupons to simulate prosthetic joint infection. Vancomycin, daptomycin, levofloxacin, and minocycline were used alone and combined with rifampin to evaluate the effect of biofilm eradication. We simulated three exposures: (i) humanized systemic dosing alone, (ii) supratherapeutic doses (1,000× MIC), and (iii) and dosing in combination with rifampin. Resistance development was monitored throughout the study. Simulated humanized systemic doses of a lipoglycopeptide (daptomycin), a fluoroquinolone (levofloxacin), a tetracycline (minocycline), and a glycopeptide (vancomycin) alone failed to eradicate a formed S. epidermidis biofilm. Supratherapeutic doses of vancomycin (2,000 μg/mL) and minocycline (15 μg/mL) with or without rifampin (15 μg/mL) failed to eradicate biofilms. However, a levofloxacin supratherapeutic dose (125 μg/mL) with rifampin eradicated the high-biofilm-producing isolate by 48 h. Interestingly, supratherapeutic-dose exposures of daptomycin (500 μg/mL) alone eradicated high- and low-biofilm-forming isolates in established biofilms. The concentrations needed to eradicate biofilms on foreign materials are not obtained with systemic dosing regimens. The failure of systemic dosing regimens to eradicate biofilms validates clinical findings with recurring infections. The addition of rifampin to supratherapeutic dosing regimens does not result in synergy. Supratherapeutic daptomycin dosing may be effective at the site of action to eradicate biofilms. Further studies are needed.

Positron Emission Tomography-Computed Tomography and Magnetic Resonance Imaging Assessments in a Mouse Model of Implant-Related Bone and Joint Staphylococcus aureus Infection

Osteomyelitis is an infection of the bone, associated with an inflammatory process. Imaging plays an important role in establishing the diagnosis and the most appropriate patient management. However, data are lacking regarding the use of preclinical molecular imaging techniques to assess osteomyelitis progression in experimental models. This study aimed to compare structural and molecular imaging to assess disease progression in a mouse model of implant-related bone and joint infections caused by Staphylococcus aureus. In SWISS mice, the right femur was implanted with a resorbable filament impregnated with S. aureus (infected group, n = 10) or sterile culture medium (uninfected group, n = 6). Eight animals (5 infected, 3 uninfected) were analyzed with magnetic resonance imaging (MRI) at 1, 2, and 3 weeks postintervention, and 8 mice were analyzed with [18F]fluorodeoxyglucose (FDG)-positron emission tomography (PET)-computed tomography (CT) at 48 h and at 1, 2, and 3 weeks postintervention. In infected animals, CT showed bone lesion progression, mainly in the distal epiphysis, although some uninfected animals presented evident bone sequestra at 3 weeks. MRI showed a lesion in the articular area that persisted for 3 weeks in infected animals. This lesion was smaller and less evident in the uninfected group. At 48 h postintervention, FDG-PET showed higher joint uptake in the infected group than in the uninfected group (P = 0.025). Over time, the difference between groups increased. These results indicate that FDG-PET imaging was much more sensitive than MRI and CT for differentiating between infection and inflammation at early stages. FDG-PET clearly distinguished between infection and postsurgical bone healing (in uninfected animals) from 48 h to 3 weeks after implantation. IMPORTANCE Our results encourage future investigations on the utility of the model for testing different therapeutic procedures for osteomyelitis.

Bifunctional antibiotic hybrids: A review of clinical candidates

Antibiotic resistance is a top threat to human health and a priority across the globe. This problematic issue is accompanied by the decline of new antibiotics in the pipeline over the past 30 years. In this context, an urgent need to develop new strategies to combat antimicrobial resistance is in great demand. Lately, among the possible approaches used to deal with antimicrobial resistance is the covalent ligation of two antibiotic pharmacophores that target the bacterial cells through a dissimilar mode of action into a single hybrid molecule, namely hybrid antibiotics. This strategy exhibits several advantages, including better antibacterial activity, overcoming the existing resistance towards individual antibiotics, and may ultimately delay the onset of bacterial resistance. This review sheds light on the latest development of the dual antibiotic hybrids pipeline, their potential mechanisms of action, and challenges in their use.

Combining bacteriophage and vancomycin is efficacious against MRSA biofilm-like aggregates formed in synovial fluid

Background

Biofilm formation is a major clinical challenge contributing to treatment failure of periprosthetic joint infection (PJI). Lytic bacteriophages (phages) can target biofilm associated bacteria at localized sites of infection. The aim of this study is to investigate whether combination therapy of phage and vancomycin is capable of clearing Staphylococcus aureus biofilm-like aggregates formed in human synovial fluid.

Methods

In this study, S. aureus BP043, a PJI clinical isolate was utilized. This strain is a methicillin-resistant S. aureus (MRSA) biofilm-former. Phage Remus, known to infect S. aureus, was selected for the treatment protocol. BP043 was grown as aggregates in human synovial fluid. The characterization of S. aureus aggregates was assessed for structure and size using scanning electron microscopy (SEM) and flow cytometry, respectively. Moreover, the formed aggregates were subsequently treated in vitro with: (a) phage Remus [∼10⁸ plaque-forming units (PFU)/ml], (b) vancomycin (500 μg/ml), or (c) phage Remus (∼10⁸ PFU/ml) followed by vancomycin (500 μg/ml), for 48 h. Bacterial survival was quantified by enumeration [colony-forming units (CFU)/ml]. The efficacy of phage and vancomycin against BP043 aggregates was assessed in vivo as individual treatments and in combination. The in vivo model utilized Galleria mellonella larvae which were infected with BP043 aggregates pre-formed in synovial fluid.

Results

Scanning electron microscopy (SEM) images and flow cytometry data demonstrated the ability of human synovial fluid to promote formation of S. aureus aggregates. Treatment with Remus resulted in significant reduction in viable S. aureus residing within the synovial fluid aggregates compared to the aggregates that did not receive Remus (p < 0.0001). Remus was more efficient in eliminating viable bacteria within the aggregates compared to vancomycin (p < 0.0001). Combination treatment of Remus followed by vancomycin was more efficacious in reducing bacterial load compared to using either Remus or vancomycin alone (p = 0.0023, p < 0.0001, respectively). When tested in vivo, this combination treatment also resulted in the highest survival rate (37%) 96 h post-treatment, compared to untreated larvae (3%; p < 0.0001).

Conclusion

We demonstrate that combining phage Remus and vancomycin led to synergistic interaction against MRSA biofilm-like aggregates in vitro and in vivo.

The role of WNT and IL-1 signaling in osteoarthritis: therapeutic implications for platelet-rich plasma therapy

Different from inflammatory arthritis, where biologicals and targeted synthetic molecules have revolutionized the disease course, no drug has demonstrated a disease modifying activity in osteoarthritis, which remains one of the most common causes of disability and chronic pain worldwide. The pharmacological therapy of osteoarthritis is mainly directed towards symptom and pain relief, and joint replacement is still the only curative strategy. Elucidating the disease pathophysiology is essential to understand which mechanisms can be targeted by innovative therapies. It has extensively been demonstrated that aberrant WNT and IL-1 signaling pathways are responsible for cartilage degeneration, impaired chondrocyte metabolism and differentiation, increased extracellular matrix degradation, and altered subchondral bone homeostasis. Platelet-rich plasma is an autologous blood derivative containing a concentration of platelets that is much higher than the whole blood counterpart and has shown promising results in the treatment of early knee osteoarthritis. Among the proposed mechanisms, the modulation of WNT and IL-1 pathways is of paramount importance and is herein reviewed in light of the proposed regenerative approaches.

Surficial nano-deposition locoregionally yielding bactericidal super CAR-macrophages expedites periprosthetic osseointegration

Tracking and eradicating Staphylococcus aureus in the periprosthetic microenvironment are critical for preventing periprosthetic joint infection (PJI), yet effective strategies remain elusive. Here, we report an implant nanoparticle coating that locoregionally yields bactericidal super chimeric antigen receptor macrophages (CAR-MΦs) to prevent PJI. We demonstrate that the plasmid-laden nanoparticle from the coating can introduce S. aureus-targeted CAR genes and caspase-11 short hairpin RNA (CASP11 shRNA) into macrophage nuclei to generate super CAR-MΦs in mouse models. CASP11 shRNA allowed mitochondria to be recruited around phagosomes containing phagocytosed bacteria to deliver mitochondria-generated bactericidal reactive oxygen species. These super CAR-MΦs targeted and eradicated S. aureus and conferred robust bactericidal immunologic activity at the bone-implant interface. Furthermore, the coating biodegradability precisely matched the bone regeneration process, achieving satisfactory osteogenesis. Overall, our work establishes a locoregional treatment strategy for priming macrophage-specific bactericidal immunity with broad application in patients suffering from multidrug-resistant bacterial infection.

Mechanisms of Rapid Bactericidal and Anti-Biofilm Alpha-Mangostin In Vitro Activity against Staphylococcus aureus

Alpha-mangostin (α-mangostin) was discovered as a potent natural product against Gram-positive bacteria, whereas the underlying molecular mechanisms are still unclear. This study indicated that α-mangostin (at 4 × MIC) rapidly killed Staphylococcus aureus planktonic cells more effectively (at least 2-log₁₀ CFU/ml) than daptomycin, vancomycin and linezolid at 1 and 3 h in the time-killing test. Interestingly, this study also found that a high concentration of α-mangostin (≥4×MIC) significantly reduced established biofilms of S. aureus. There were 58 single nucleotide polymorphisms (SNPs) in α-mangostin nonsensitive S. aureus isolates by whole-genome sequencing, of which 35 SNPs were located on both sides of the sarT gene and 10 SNPs in the sarT gene. A total of 147 proteins with a different abundance were determined by proteomics analysis, of which 91 proteins increased, whereas 56 proteins decreased. The abundance of regulatory proteins SarX and SarZ increased. In contrast, the abundance of SarT and IcaB was significantly reduced (they belonged to SarA family and ica system, associated with the biofilm formation of S. aureus). The abundance of cell membrane proteins VraF and DltC was augmented, but the abundance of cell membrane protein UgtP remarkably decreased. Propidium iodide and DiBaC₄(3) staining assay revealed that the fluorescence intensities of DNA and the cell membrane were elevated in the α-mangostin treated S. aureus isolates. In conclusion, this study reveals that α-mangostin was effective against S. aureus planktonic cells by targeting cell membranes. The anti-biofilm effect of α-mangostin may be through inhibiting the function of SarT and IcaB.

Does Prednisone Dose Affect Rates of Periprosthetic Joint Infection Following Primary Total Hip and Total Knee Arthroplasty?

BACKGROUND

Prednisone use is associated with higher rates of periprosthetic joint infection (PJI) following total joint arthroplasty (TJA). However, the relationship between prednisone dosage and infection risk is ill-defined. Therefore, this study aimed to assess the relationship between prednisone dosage and rates of PJI following TJA.

METHODS

A national database was queried for all elective total hip (THA) and total knee arthroplasty (TKA) patients between 2015 and 2020. Patients who received oral prednisone following TJA were matched in a 1:2 ratio based on age and sex to patients who did not. Univariate and multivariate regression analyses were performed to assess the 90-day risk of infectious complications based on prednisone dosage as follows: 0 to 5, 6 to 10, 11 to 20, 21 to 30, and >30 milligrams. Overall, 1,322,043 patients underwent elective TJA (35.9% THA, 64.1% TKA). Of these, 14,585 (1.1%) received prednisone and were matched to 29,170 patients who did not.

RESULTS

After controlling for confounders, TKA patients taking prednisone were at increased risk for sepsis (adjusted odds ratio [aOR] 2.76, P < .001), PJI (aOR 2.67, P < .001), and surgical site infection (aOR: 2.56, P = .035). THA patients taking prednisone were at increased risk for sepsis (aOR: 3.21, P < .001) and PJI (aOR: 1.73, P = .001). No dose-dependent relationship between prednisone and infectious complications was identified when TJA was assessed in aggregate.

CONCLUSION

Patients receiving prednisone following TJA were at increased risk of PJI and sepsis. A dose-dependent relationship between prednisone and infectious complications was not identified. Arthroplasty surgeons should be aware of these risks and counsel TJA patients who receive prednisone therapy.

Robotic-assisted knee replacement surgery & infection: A historical foundation, systematic review and meta-analysis

Background

An increasing proportion of Knee arthroplasty is performed using robotic-assisted surgical techniques. This study sought to use a meta-analytical approach to establish summary rates of surgical site infection in robotic-assisted procedures and compare the rate of deep infections to those seen in conventional knee arthroplasty.

Methods

This study performed a literature search across four online databases to establish a summary rate of surgical site infection across two categories: deep infection and superficial and pin-site infections. This was processed with the aid of a bespoke data-extraction tool. Risk of Bias analysis was performed using the Cochrane RoB2 tool. Meta-analysis was then performed with tests for heterogeneity and a DerSimonian-Laird random effects model.

Results

A total of 17 studies were identified as appropriate for inclusion in the meta-analysis. The summary rate of overall surgical site infections within one year of robotic knee arthroplasty was found to be 0.568% (SE = 0.183, 95% CI = 0.209-0.927). Deep infections fell to 0.154% (SE = 0.069, 95% CI = 0.018-0.290) and to 0.347% (SE = 0.109, 95% CI = 0.133-0.561) in superficial and pin-site infections.

Conclusion

The surgical site infection rates were found to be low across robotic knee arthroplasty. Further research is required to prove its superiority compared to the conventional, non-robotic technique.