Different microbiological profiles between hip and knee prosthetic joint infections

Increased Involvement of Staphylococcus epidermidis in the Rise of Polymicrobial Periprosthetic Joint Infections

BACKGROUND

In this study, we aimed to analyze the temporal distribution of polymicrobial periprosthetic joint infections (PJIs), while also evaluating the patient risk factors associated with these infections following total joint arthroplasty at our institution across 2 distinct periods.

METHOD

This retrospective cross-sectional study evaluated 259 patients who had knee or hip PJI from 2001 to 2006 and 2018 to 2022. A PJI was diagnosed using the 2018 International Consensus Meeting criteria. We utilized the Polymicrobial Pathogens' Co-occurrence Network Analysis, a novel approach that leverages network theory to map and quantify the complex interplay of organisms in PJIs.

RESULTS

Of the 259 patients who had polymicrobial PJI, 58.7% were men, with mean age 67 years (range, 24 to 90). Of the 579 identified pathogens, Staphylococcus epidermidis was the most common (22.1%), followed by Staphylococcus aureus (9.0%) and Cutibacterium acnes (7.8%). The co-occurrence analysis indicated that Staphylococcus epidermidis frequently coexisted with Cutibacterium acnes (26 cultures) and Staphylococcus capitis (22 cultures). A notable increase in body mass index from 27.7 ± 4.4 in 2001 to 2006 to 29.7 ± 6.2 in 2018 to 2022 was observed (P = .001). Moreover, infections from Staphylococcus epidermidis, Cutibacterium acnes, and Staphylococcus capitis saw a significant uptick (P < .001).

CONCLUSIONS

The study shows that from 2001 to 2022, there was a significant change in the pathogens responsible for polymicrobial PJIs, particularly an increase in Staphylococcus epidermidis, Cutibacterium acnes, and Staphylococcus capitis. Alongside these microbial changes, there was a rise in body mass index and shifts in comorbid conditions, such as more renal disease and fewer cases of congestive heart failure. These changes highlight the dynamic interplay between host and microbial factors in the pathogenesis of polymicrobial PJIs, necessitating adaptive strategies in both surgical and postoperative care to mitigate the rising tide of these complex infections.

Diagnosis and Prevention of Periprosthetic Joint Infections by Staphylococcus aureus after Hip Fracture: A Systematic Review of the Literature

Hip arthroplasties are surgical procedures widely performed all over the world, seeking to return functionality, relieve pain, and improve the quality of life of patients affected by osteoarthritis, femoral neck fractures, osteonecrosis of the femoral head, among other etiologies. Periprosthetic joint infections are one of the most feared complications due to the high associated morbidity and mortality, with a high number of pathogens that may be associated with its etiology. The aim of the present study was to analyze aspects correlated with the occurrence of infection, diagnosis and prevention of periprosthetic joint infections in the hip associated with Staphylococcus aureus after corrective surgery for hip fractures. This is a systematic review of the literature carried out in the databases indexed in the Medical Literature Analysis and Retrieval System Online (MEDLINE) carried out in accordance with the precepts established by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology. Twenty studies that addressed the diagnosis and prevention of periprosthetic joint infections after hip fractures were selected for analysis. It is observed that there is no consensus in the literature on preventive measures for the occurrence of such infectious processes. Among the risk factors for the occurrence and severity of infections by S. aureus after hip arthroplasties, obesity, longer surgical time, older age, immunosuppression, recent use of antibiotics, and multicomorbidities were mentioned. The use of biomarkers for early diagnosis, as well as screening, decolonization, and antibiotic prophylaxis processes are among the preventive procedures proposed in the literature.

Second-Line Antibiotic Agents in Patient-Reported Penicillin or Cephalosporin Allergy Have No Negative Impact on Antibiotic Resistance After Hip and Knee Arthroplasty

BACKGROUND

The aim of the present study was to compare causative bacteria and their antibiotic resistance profiles in patients developing a periprosthetic joint infection (PJI) based on preoperative prophylactic antibiotic regimens in primary total hip (THA) and primary total and unicompartmental knee arthroplasty (TKA/UKA).

METHODS

We reviewed all cases of PJI occurring after primary THA and primary TKA/UKA, between 2011 and 2020 in a tertiary referral hospital. The standard preoperative prophylactic antibiotic for primary joint arthroplasty was cefuroxime and recommended second-line agent was clindamycin. Patients were divided by the replaced joint and analyzed independently.

RESULTS

In the THA group, culture-positive PJI was detected in 61 of 3,123 (2.0%) cefuroxime-administered cases and 6 of 206 (2.9%) noncefuroxime-administered cases. In the TKA/UKA group, culture positive PJI was identified in 21 of 2,455 (0.9%) cefuroxime-administered cases and in 3 of 211 (1.4%) noncefuroxime administered cases. The most commonly isolated bacteria in both groups were coagulase negative staphylococci (CNS). There were no statistically significant differences of pathogen spectrum depending on the preoperative antibiotic regimen detected. Antibiotic resistance of isolated bacteria was significantly different in 4 of 27 (14.8%) analyzed antibiotics in THA and in 3 of 22 (13.6%) analyzed antibiotics in TKA/UKA. In all cohorts, a high occurrence of oxacillin-resistant CNS (50.0 to 100.0%) and clindamycin-resistant CNS (56.3 to 100.0%) has been observed.

CONCLUSION

The use of the second-line antibiotic did not influence the pathogen spectrum or antibiotic resistance. However, an alarmingly high proportion of CNS strains was resistant to clindamycin.

Outcomes of Enterobacter cloacae-Associated Periprosthetic Joint Infection Following Hip Arthroplasties

Background

Periprosthetic joint infections (PJIs) represent a serious complication following total hip arthroplasty (THA) and are associated with significant morbidity. While recent data suggest that Enterobacter cloacae is an emerging source of PJI, characteristics and outcomes of E. cloacae-associated infections are rarely described. The study aimed to present and describe the findings and outcomes of E. cloacae-associated PJI in our department.

Methods

This is a retrospective descriptive study of patients who underwent revision THA for E. cloacae-associated PJI between 2011 and 2020 and has a minimum follow-up of 2 years. Outcomes included organism characteristics as well as clinical outcomes, represented by the number of reoperations needed for PJI eradication and the Musculoskeletal Infection Society (MSIS) outcome reporting tool score. Of 108 revision THAs, 12 patients (11.1%) were diagnosed with E. cloacae-associated PJI.

Results

The majority of cases had a polymicrobial PJI (n=8, 66.7%). Five E. cloacae strains (41.7%) were gentamicin-resistant. Six patients (50.0%) underwent 2 or more revisions, while 3 of them (25.0%) required 4 or more revisions until their PJI was resolved. When utilizing the MSIS outcome score, the first surgical intervention was considered successful (MSIS score tiers 1 and 2) for 5 patients (41.7%) and failed (tiers 3 and 4) for 7 patients (58.3%).

Conclusions

E. cloacae is emerging as a common source of PJI following hip arthroplasty procedures. The findings of our study suggest that this pathogen is primarily of polymicrobial nature and represents high virulence and poor postoperative outcomes, as represented by both an increased number of required revision procedures and high rates of patients with MSIS outcome scores of 3 and 4. When managing patients with E. cloacae-associated PJI, surgeons should consider these characteristics and inform patients regarding predicted outcomes.

Deploying a Novel Approach to Prepare Silver Nanoparticle Bellamya bengalensis Extract Conjugate Coating on Orthopedic Implant Biomaterial Discs to Prevent Potential Biofilm Formation

This study is based on the premise of investigating antibacterial activity through a novel conjugate of silver nanoparticles (AgNPs) and antimicrobial peptides (AMPs) in line with a green synthesis approach by developing antimicrobial-coated implants to prevent bacterial resistance. The AMPs were obtained from Bellamya Bengalensis (BB), a freshwater snail, to prepare the nanocomposite conjugate, e.g., AgNPs@BB extract, by making use of UV-Visible spectroscopy. The antimicrobial assessment of AgNPs@BB extract conjugate was performed using the Resazurin Microtiter Assay Method (REMA), followed by the use of three biocompatible implant materials (titanium alloys, Ti 6AL-4V stainless steel 316L, and polyethylene). Finally, the coating was analyzed under confocal microscopy. The results revealed a significant reduction of biofilm formation on the surfaces of implants coated with conjugate (AgNPs@BB extract) in comparison to uncoated implants. For the MTT assay, no significant changes were recorded for the cells grown on the AgNPs/AMP++ sample in high concentrations. Staphylococcus epidermidis, however, showed more prominent growth on all implants in comparison to Staphylococcus aureus. It is evident from the results that Staphylococcus epidermidis is more susceptible to AgNPs@BB extract, while the minimum inhibitory concentration (MIC) value of AgNPs@BB extract conjugates and biosynthesized AgNPs was also on the higher side. This study indicates that AgNPs@BB extract carries antibacterial activity, and concludes that an excessive concentration of AgNPs@BB extract may affect the improved biocompatibility. This study recommends using robust, retentive, and antimicrobial coatings of AgNPs@BB extract for implantable biocompatible materials in accordance with the novel strategy of biomaterial applications.

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 Intraoperative Use of Defensive Antibacterial Coating (DAC®) in the Form of a Gel to Prevent Peri-Implant Infections in Orthopaedic Surgery: A Clinical Narrative Review

Periprosthetic joint infections (PJIs) in arthroplasty and osteosynthesis-associated infections (OAIs) in reconstructive surgery still represent a challenging complication in orthopaedics and traumatology causing a burden worsening the patient's quality of life, for caregiver and treating physicians, and for healthcare systems. PJIs and OAIs are the result of bacterial adhesion over an implant surface with subsequent biofilm formation. Therefore, the clinical pathological outcome is a difficult-to-eradicate persistent infection. Strategies to treat PJIs and OAIs involve debridement, the replacement of internal fixators or articular prostheses, and intravenous antibiotics. However, long treatments and surgical revision cause discomfort for patients; hence, the prevention of PJIs and OAIs represents a higher priority than treatment. Local antibiotic treatments through coating-release systems are becoming a smart approach to prevent this complication. Hydrophilic coatings, loaded with antibiotics, simultaneously provide a barrier effect against bacterial adhesion and allow for the local delivery of an antibiotic. The intraoperative use of a hyaluronan (HY)-derivative coating in the form of a gel, loaded with antibiotics to prevent PJI, has recently raised interest in orthopaedics. Current evidence supports the use of this coating in the prophylaxis of PJI and IRIs in terms of clinical outcomes and infection reduction. Thus, the purpose of this narrative review is to assess the use of a commercially available HY derivative in the form of a gel, highlighting the characteristics of this biomaterial, which makes it attractive for the management of PJIs and IRIs in orthopaedics and traumatology.

Microbiological Profile of Periprosthetic Knee Infections in a Brazilian Unified Health System Hospital Specialized in Highly Complex Orthopedic Surgeries

Objective  We studied the microbiological profile of periprosthetic knee infections treated in a Brazilian tertiary hospital. Methods  The study included all patients undergoing revision surgery for total knee arthroplasty (RTKA) between November 2019 and December 2021, with a diagnosis of periprosthetic infection confirmed per the 2018 International Consensus Meeting (ICM) criteria. Results  Sixty-two patients had a periprosthetic joint infection (PJI) per the 2018 ICM criteria. Cultures were monomicrobial in 79% and polymicrobial in 21% of cases. The most frequent bacterium in microbiological tissue and synovial fluid cultures was Staphylococcus aureus , observed in 26% of PJI patients. Periprosthetic joint infection with negative cultures occurred in 23% of patients. Conclusion  Our results show the following: i) a high prevalence of Staphylococcus as an etiological agent for knee PJI; ii) a high incidence of polymicrobial infections in early infections; iii) the occurrence of PJI with negative cultures in approximately one fourth of the subjects.

Antibiotic Prophylaxis in One-Stage Revision of Septic Total Knee Arthroplasty: A Scoping Review

BACKGROUND

Total knee replacement (TKA) is becoming a routine procedure in orthopedic surgery. One of the possible complications of this surgery is periprosthetic joint infection (PJI). The purpose of this study is to identify, through a literature review, which antibiotic is used as prophylaxis for septic one-stage revision TKA and what is the rationale for its use.

METHODS

We searched: MEDLINE, Embase, PsycINFO on Ovid, the Cochrane Library, and the Google Scholar Database. The searches were limited by date (January 2005 to September 2022) and to the English language. All types of original research were considered, including prospective or retrospective longitudinal studies, cross-sectional studies, and randomized trials. The specific search terms were ((antibiotic [MeSH]) AND (prophylaxis)) and (TKA OR TKR OR "Arthroplasty, Replacement, Knee" [MeSH] OR ((knee) adj2 (replace* OR arthroplasty* OR prosthe*))).

RESULTS

Despite our research efforts, we found no article capable of answering the question of which antibiotic to use as surgical prophylaxis for a septic revision one-stage TKA.

CONCLUSIONS

Although the research results are inconclusive, we would recommend using the same antibiotic prophylaxis as for primary joint replacement, i.e., cefazolin, as it was recommended for its low side effect rate and relative effectiveness.

The Challenge of Periprosthetic Joint Infection Diagnosis: From Current Methods to Emerging Biomarkers

Due to the increase in the life span and mobility at older ages, the number of implanted prosthetic joints is constantly increasing. However, the number of periprosthetic joint infections (PJIs), one of the most severe complications after total joint arthroplasty, also shows an increasing trend. PJI has an incidence of 1-2% in the case of primary arthroplasties and up to 4% in the case of revision operations. The development of efficient protocols for managing periprosthetic infections can lead to the establishment of preventive measures and effective diagnostic methods based on the results obtained after the laboratory tests. In this review, we will briefly present the current methods used in PJI diagnosis and the current and emerging synovial biomarkers used for the prognosis, prophylaxis, and early diagnosis of periprosthetic infections. We will discuss treatment failure that may result from patient factors, microbiological factors, or factors related to errors during diagnosis.

Microbiological profiles and antibiotic resistance of periprosthetic joint infection after hip replacement in patients with fracture or non-fracture: A comparative study

BACKGROUND

Periprosthetic joint infection (PJI) is one of the worst complications following total joint arthroplasty (TJA). Unfortunately, effective prevention strategies to reduce the burden of PJI have not been fully determined in hip replacement patients with fracture and non-fracture.

OBJECTIVE

This study aimed to analyze and compare the demographic characteristics, microbiological profiles and antibiotic resistance of PJI after hip replacement between patients with fracture and non-fracture.

METHODS

We retrospectively analyzed the data of 132 patients who treated PJI. There were divided into two groups: non-fracture group (64 patients infected after hip replacement for fracture) and non-fracture group (68 patients infected after hip replacement for non-fracture). Microorganisms were obtained from the synovial fluid and infected necrotic tissue in the joint capsule, medullary cavity, or acetabulum in all patients, and microbiological profiles and antibiotic resistance were evaluated.

RESULTS

Coagulase-negative staphylococci (CoNS) were the most common pathogenic microorganisms in all patients. Methicillin-resistant Staphylococcus (MRS) accounted for 25% in all pathogenic microbes. Staphylococci showed high drug resistance rates to clindamycin, levofloxacin, and all of the first- and second-generation cephalosporins. MRS isolates in non-fracture group had higher drug resistance rates to clindamycin and levofloxacin than than those in fracture group. Gram-negative bacilli (GNB) showed high drug resistance rates to Aztreonam, gentamicin and all of the third- and fourth-generation cephalosporins. Furthermore, GNB isolates in the non-fracture group showed higher resistance rates to gentamicin and all of the third- and fourth-generation cephalosporins.

CONCLUSIONS

MRS isolates in the non-fracture group showed higher drug resistance rates to clindamycin and levofloxacin, and GNB isolates in non-fracture group showed higher drug resistance rates to gentamicin and all of the third- and fourth-generation cephalosporins.

Periprosthetic Hip Joint Infection with Flavonifractor plautii: A Literature Review and Case Report

The purpose of this case report and review of the literature is to provide documentation on periprosthetic hip joint infection with Flavonifractor plautii (formerly known as Eubacterium plautii), a strictly anaerobic bacterium, and to report on a successful pathway for management including staged surgical revisions and extended antibiotic therapy. A systematic review of the literature was conducted, which identified this case as only the fifth documented case of human infection with this organism; as a result, conduct of further research is warranted, based on the paucity of reports in the literature addressing anaerobic periprosthetic joint infection.

Nontuberculous mycobacteria peri-prosthetic joint infection: An outcome analysis for two stage revision arthroplasty

PURPOSE

Nontuberculous mycobacteria periprosthetic joint infection (NTMPJI) is a rare complication of hip or knee joint arthroplasty. The experience for outcomes of NTMPJI treatment is still limited. The objective of this study was to investigate the outcome of hip or knee nontuberculous mycobacteria periprosthetic joint infection following treatment with two-stage exchange arthroplasty.

MATERIAL AND METHODS

From 1995 to 2020, 12 patients with NTMPJI were treated with two-stage exchange arthroplasty at our institution. We collected and analyzed variables including demographic data, comorbidity, microbiological data, treatment outcome and antibiotic formula in bone cement.

RESULTS

Mycobacterium abcessus (n = 6) and Mycobacterium chelonae (n = 2) constitute the majority of the cases. Five patients had early-onset PJIs and the other seven patients were late onset. The success rate of two-stage exchange arthroplasty was 66.7% (8 of 12). Three patients experienced infection relapse, and one patient had soft tissue compromise complication. Post-operative antibiotic therapy may not improve the success rate (4 of 6 cases, 66.7%). Based on in vitro study, the most commonly used effective antibiotic in bone cement spacer for nontuberculous mycobacteria was amikacin.

CONCLUSIONS

nontuberculous mycobacteria is a rare cause of PJIs and should be suspected especially in relatively immunocompromised patients. Resection arthroplasty with staged reimplantation is the preferred approach. Prolonged post-operative antibiotic therapy before reimplantation may not improve the success rate. Delayed revision surgery may not be needed and can be performed once C-reactive protein level is normal after a drug holiday.

Higher reinfection rate after two-stage revision arthroplasty in patients with refractory diabetes mellitus: a retrospective analysis with a minimum ten-year follow up

Background

Treatment protocols for two-stage revision arthroplasty with diabetes mellitus (DM) have not yet been established. The control of glycated hemoglobin (HbA1c) in two-stage revision arthroplasty is still debated. This study aimed to clarify the importance of preoperative HbA1c levels before each stage of revision arthroplasty and to analyze the risk factors for reinfection.

Methods

Five hundred eighty-eight patients suffered from first-time PJI and was treated in our institute from January 1994 to December 2010 were reviewed. The mean follow-up time was 13.8 (range, 10.2–24.8) years. Patients underwent two-stage revision arthroplasty with DM at presentation were included. The endpoint of the study was reinfection of the revision arthroplasty. Demographic, survivorship, and surgical variables were also analyzed.

Results

Eighty-eight patients were identified and grouped by HbA1c level before the first stage surgery: Groups 1 and 2 had HbA1c levels < 7% and ≥ 7%, respectively. Reinfection was identified in 4.55% (2/44) and 18.18% (8/44) of the patients in Groups 1 and 2, respectively. Survivorship analysis revealed correction of the HbA1c before the final stage of revision arthroplasty as an independent factor (p < 0.001). The identified risks for reinfection were HbA1c levels ≥ 7% before final-stage surgery, ≥ 3 stages of revision arthroplasty, and extended-spectrum beta-lactamase (ESBL)-Escherichia coli PJI.

Conclusion

The HbA1c level before the final stage of revision arthroplasty could affect staged revision arthroplasty outcomes. Therefore, the necessity of postponing the elective final-stage revision arthroplasty procedure for HbA1c control should be further investigated in the future.

Microbiological Trends and Antibiotic Susceptibility Patterns in Patients with Periprosthetic Joint Infection of the Hip or Knee over 6 Years

We sought to analyze trends of the causative pathogens and their antibiotic susceptibility patterns in patients with periprosthetic joint infections (PJI) of the hip and knee to get better insights and improve treatment. Retrospective evaluation of all consecutive patients with microbiological detection of a causative pathogen at a tertiary endoprothetic referral center between January 2016 and December 2021 in Germany was performed. Overall, 612 different microorganisms could be detected in 493 patients (hip: n = 293; knee: n = 200). Evaluation did not show a change in the relative abundance of pathogens detected, with coagulase-negative staphylococci (n = 275; 44.9%) found frequently, followed by S. aureus (n = 86; 14.1%), Enterococcus species (n = 57; 9.3%), Streptococcus species (n = 48; 7.8%), and Gram-negative bacteria (n = 80; 13.1%). Evaluation of the antibiotic susceptibilities showed increasing rates of oxacillin-resistant coagulase-negative staphylococci (60.4%; 46.8−76.7%) and piperacillin-tazobactam-resistant Gram-negative bacteria (26.5%; 0−57.1%), although statistically not significant. Resistance of Gram-positive bacteria to vancomycin (<1%) and Gram-negative microorganisms to meropenem (1.25%) remained an exception. In summary, coagulase-negative staphylococci, as the most frequent pathogen, displayed a continuously high rate of oxacillin resistance. For the highest antimicrobial coverage in the case of an empiric therapy/unknown pathogen, vancomycin might be chosen. Level of evidence: IV.

A comparison of the microbiology profile for periprosthetic joint infection of knee arthroplasty and lower-limb endoprostheses in tumour surgery

Abstract. Aims: this study compared the patient and microbiological profile of prosthetic joint infection (PJI) for patients treated with two-stage revision for knee arthroplasty with that of lower-limb endoprostheses for oncological resection. Patient and methods: a total of 118 patients were treated with two-stage revision surgery for infected knee arthroplasty and lower-limb endoprostheses between 1999 and 2019. A total of 74 patients had two-stage revision for PJI of knee arthroplasty, and 44 had two-stage revision of oncology knee endoprostheses. There were 68 men and 50 women. The mean ages of the arthroplasty and oncology cohorts were 70.2 years (range of 50–89) and 36.1 years (range of 12–78) respectively (p<0.01). Patient host and extremity criteria were categorized according to the Musculoskeletal Infection Society (MSIS) host and extremity staging system. The patient microbiological culture, the incidence of polymicrobial infection, and multidrug resistance (MDR) were analysed and recorded. Results: polymicrobial infection was reported in 16 % (12 patients) of knee arthroplasty PJI cases and in 14.5 % (8 patients) of endoprostheses PJI cases (p=0.783). There was a significantly higher incidence of MDR in endoprostheses PJI, isolated in 36.4 % of cultures, compared with knee arthroplasty PJI (17.2 %, p=0.01). Gram-positive organisms were isolated in more than 80 % of cultures from both cohorts. Coagulase-negative Staphylococcus (CoNS) was the most common Gram-positive organism, and Escherichia coli was the most common Gram-negative organism in both groups. According to the MSIS staging system, the host and extremity grades of the oncology PJI cohort were significantly worse than those for the arthroplasty PJI cohort (p<0.05). Conclusion: empirical antibiotic prophylaxis against PJI in orthopaedic oncology is based upon PJI in arthroplasty, despite oncology patients presenting with worse host and extremity staging. CoNS was the most common infective organism in both groups; however, pathogens showing MDR were significantly more prevalent in oncological PJI of the knee. Therefore, empirical broad-spectrum treatment is recommended in oncological patients following revision surgery.

Microbiological Profiles of Patients with Periprosthetic Joint Infection of the Hip or Knee

Periprosthetic joint infections (PJI) are one of the most devastating consequences after total joint arthroplasty. We sought to analyze the causative pathogens of patients with PJI to get better insights and improve treatment. We performed a retrospective study of all patients with PJI of the hip and knee with microbiological detection of a causative pathogen at a tertiary endoprothetic referral center between January 2016 and March 2021. A total of 432 cases with PJI (hip: n = 250; knee: n = 182) were included. The most common causative pathogen were coagulase-negative staphylococci (n = 240; 44.2%), of which Staphylococcus epidermidis (n = 144; 26.7%) was the most frequently detected, followed by S. aureus (n = 77; 14.3%) and enterococci (n = 49; 9%). Gram-negative pathogens and fungi could be detected in 21% (n = 136) and 2.4% (n = 13) of all cases. Overall, 60% of all coagulase-negative staphylococci were oxacillin-resistant, while none of these displayed to be vancomycin-resistant. In summary, the majority of pathogens in cases of PJI could be identified as coagulase-negative staphylococci. For empirical therapy vancomycin might provide the highest antimicrobial coverage in case of an unknown pathogen.

Antifungal-Loaded Acrylic Bone Cement in the Treatment of Periprosthetic Hip and Knee Joint Infections: A Review

Little is known about the clinical use of antifungal-loaded acrylic bone cement in the treatment of periprosthetic hip and knee joint infections (PJIs). Hence, we performed a literature search using PubMed/MEDLINE from inception until December 2021. Search terms were “cement” in combination with 13 antifungal agents. A total of 10 published reports were identified, which described 11 patients and 12 joints in which antifungal-loaded cement was employed. All studies were case reports or case series, and no randomized controlled trials were identified. In 6 of 11 patients, predisposing comorbidities regarding the emergence of a fungal PJI were present. The majority of the studies reported on infections caused by Candida species. In six cases (seven joints), the cement was solely impregnated with an antifungal, but no antibiotic agent (amphotericin B, voriconazole, and fluconazole). In the other five joints, the cement was impregnated with both antibiotic(s) and antifungals. Great discrepancies were seen regarding the exact loading dose. Four studies investigated the local elution of antifungal agents in the early postoperative period and observed a local release of antifungals in vivo. We conclude that there is a paucity of data pertaining to the clinical use of antifungal-loaded bone cement, and no studies have assessed the clinical efficacy of such procedures. Future studies are urgently required to evaluate this use of antifungals in PJI.

Assessment of Staphylococcal Clinical Isolates from Periprosthetic Joint Infections for Potential Bacteriophage Therapy

BACKGROUND

Bacteriophage therapy is a potential adjunctive treatment for periprosthetic joint infections (PJIs) given the capabilities of bacteriophages to degrade biofilms, self-replicate, and lyse bacteria. However, many aspects of this therapeutic are ill-defined, and the narrow spectrum of bacteriophage activity along with limited available bacteriophage strains curb potential use for specific bacteria such as Staphylococcus aureus at the present time. Therefore, the aim of this study was to determine the feasibility of using bacteriophages for PJI by (1) categorizing the causative organisms in hip and knee PJI at a tertiary academic center and (2) evaluating in vitro activity of a group of bacteriophages against clinical S. aureus PJI isolates.

METHODS

Patients with chronic hip or knee PJI after undergoing the first stage of a 2-stage revision protocol from 2017 to 2020 were identified retrospectively by a query of the hospital billing database. The causative pathogens in 129 cases were reviewed and categorized. From this cohort, preserved S. aureus isolates were tested against a library of 15 staphylococcal bacteriophages to evaluate for bacterial growth inhibition over 48 hours.

RESULTS

S. aureus was the most common pathogen causing PJI (26% [33] of 129 cases). Of 29 S. aureus samples that were analyzed for bacteriophage activity, 97% showed adequate growth inhibition of the predominant planktonic colonies by at least 1 bacteriophage strain. However, 24% of the 29 samples demonstrated additional smaller, slower-growing S. aureus colonies, none of which had adequate growth inhibition by any of the initial 14 bacteriophages. Of 5 secondary colonies that underwent subsequent testing with another bacteriophage with enhanced biofilm activity, 4 showed adequate growth inhibition.

CONCLUSIONS

Effective bacteriophage therapeutics are potentially available for S. aureus PJI isolates. The differences in bacteriophage activity against the presumed small-colony variants compared with the planktonic isolates have important clinical implications. This finding suggests that bacteriophage attachment receptors differ between the different bacterial morphologic states, and supports future in vitro testing of bacteriophage therapeutics against both planktonic and stationary states of PJI clinical isolates to ensure activity.

Positivity Trends of Bacterial Cultures from Cases of Acute and Chronic Periprosthetic Joint Infections

Background: There is no clear distinction in the literature regarding the positivity trends of bacterial cultures in acute and chronic prosthetic joint infections. Methods: We prospectively included in this study all consecutive patients, aged over 18 years, that were hospitalized from September 2016 through December 2019, that underwent a joint arthroplasty revision surgery. Results: Forty patients were included in our analysis, 11 acute/acute hematogenous and 29 chronic PJIs. We were able to identify all strains of acute/acute hematogenous PJIs within 3 days, whereas this took 8 days for chronic PJIs. Sonication fluid cultures increased the positivity rate and helped in identifying rare pathogens such as Ralstonia pickettii from chronic PJIs, but also increased the number of identified strains from acute PJIs. Culturing synovial fluid in our study did not seem to have a clear benefit compared to sonication fluid and periprosthetic tissue cultures. Conclusion: There was a different positivity trend in bacterial cultures. Empiric broad-spectrum antibiotic therapy can be re-evaluated after 3 days for acute PJIs. A prolonged incubation time, especially in the case of chronic PJIs, is mandatory; however, extending the incubation period beyond 14 days would not further improve the ability to identify microorganisms.

Addressing the Needs of the Rapidly Aging Society through the Development of Multifunctional Bioactive Coatings for Orthopedic Applications

The unprecedented aging of the world's population will boost the need for orthopedic implants and expose their current limitations to a greater extent due to the medical complexity of elderly patients and longer indwelling times of the implanted materials. Biocompatible metals with multifunctional bioactive coatings promise to provide the means for the controlled and tailorable release of different medications for patient-specific treatment while prolonging the material's lifespan and thus improving the surgical outcome. The objective of this work is to provide a review of several groups of biocompatible materials that might be utilized as constituents for the development of multifunctional bioactive coatings on metal materials with a focus on antimicrobial, pain-relieving, and anticoagulant properties. Moreover, the review presents a summary of medications used in clinical settings, the disadvantages of the commercially available products, and insight into the latest development strategies. For a more successful translation of such research into clinical practice, extensive knowledge of the chemical interactions between the components and a detailed understanding of the properties and mechanisms of biological matter are required. Moreover, the cost-efficiency of the surface treatment should be considered in the development process.

Significant Difference in Antimicrobial Resistance of Bacteria in Septic Revision between Total Knee Arthroplasty and Total Hip Arthroplasty

Antimicrobial resistance (AMR) aggravates the already difficult treatment of periprosthetic joint infections (PJI). Due to many factors influencing AMR, the correct choice of antimicrobial management remains arguable. The primary purpose of this retrospective study was to identify and compare bacteria and their antibiotic resistance profile between septic revision total knee arthroplasty (TKA) and septic revision total hip arthroplasty (THA). A review of all revision TKAs and revision THAs, undertaken between 2007 and 2020 in a tertiary referral hospital, was performed. Included were cases meeting the consensus criteria for PJI, in which an organism has been identified. There were no major differences in tissue sampling between revision TKAs and revision THAs over time. A total of 228 bacterial strains, isolated after revision TKA and THA, were analysed for their resistance to 20 different antibiotics. There was a statistically significant higher occurrence of Gram-negative bacteria identified after revision THAs compared to TKA (p = 0.002). The comparison of antibiotic resistance between revision TKAs and revision THAs was statistically significant in 9 of 20 analysed antibiotics. This has implications for the choice of empirical antibiotic in revision surgery as well as prophylactic antibiotic in primary surgery, depending on the joint that is to be replaced.

Evaluation of the MRSA/SA ELITe MGB Assay for the Detection of Staphylococcus aureus in Bone and Joint Infections

Bone and joint infections represent a potentially devastating complication of prosthetic orthopedic joint replacement, thus requiring both rapid and appropriate antibiotic treatment. Staphylococcus aureus is one of the most common pathogens involved in this pathology. Being able to assert its presence is the first step of efficient patient management. This monocenter study evaluated the MRSA/SA ELITe MGB assay for the molecular detection of S. aureus and methicillin-resistant S. aureus (MRSA) in bone and joint biopsy specimens and synovial fluids. This test, together with conventional techniques, including standard cultures and the 16S rRNA amplification assay, was performed on 208 successive perioperative samples collected prospectively for 1 year obtained from 129 patients. Using conventional techniques, we detected a microbial pathogen in 76 samples from 58 patients, 40 of which were identified as S. aureus. The limit of detection (LOD) of the MRSA/SA ELITe MGB assay was experimentally determined for bone and joint biopsy specimens and synovial fluids using negative samples spiked with S. aureus ATCC 43300. The sensitivities of S. aureus detection with the MRSA/SA ELITe MGB assay were 82.5% (33/40 samples) and 97.5% (39/40 samples) using the manufacturer's LOD and an experimentally determined LOD, respectively. Interestingly, using the osteoarticular specific LOD, 15 additional samples were determined to be positive for S. aureus DNA with the MRSA/SA ELITe MGB assay; in all cases, these samples were obtained from patients considered to be infected with S. aureus according to their clinical and microbiological records. The results were available within 24 h, which could help to expedite therapeutic decisions.

Treatment of Prosthetic Joint Infection due to Listeria Monocytogenes. A Comprehensive Literature Review and a Case of Total Hip Arthroplasty Infection

As reported in contemporary literature, prosthetic joint infection (PJI) caused by Listeria monocytogenes (LM) is a rare infection affecting mainly immunocompromised patients. It is considered a late complication occurring months or years after the arthroplasty that is treated with, or without, implant retention, in one-stage or two-stage surgical procedures, and long-term administration of antibiotics. We reviewed the published studies in the English language and present a case of a patient who underwent total hip arthroplasty (THA) and had been affected by this infection. Our patient was successfully treated with 3 months of antibiotics (ampicillin and TMP/SMX) and a two-stage surgical procedure. The success rates of conservative treatment and one-stage or two-stage procedures are dependent on appropriate patient selection and chronicity of the infection. Ιmmmunocompromised patients are susceptible to PJI caused by LM and should be advised that consumption of unpasteurized dairy products increases the risk of this atypical infection.

Comparative meta-omics for identifying pathogens associated with prosthetic joint infection

Prosthetic joint infections (PJI) are economically and personally costly, and their incidence has been increasing in the United States. Herein, we compared 16S rRNA amplicon sequencing (16S), shotgun metagenomics (MG) and metatranscriptomics (MT) in identifying pathogens causing PJI. Samples were collected from 30 patients, including 10 patients undergoing revision arthroplasty for infection, 10 patients receiving revision for aseptic failure, and 10 patients undergoing primary total joint arthroplasty. Synovial fluid and peripheral blood samples from the patients were obtained at time of surgery. Analysis revealed distinct microbial communities between primary, aseptic, and infected samples using MG, MT, (PERMANOVA p = 0.001), and 16S sequencing (PERMANOVA p < 0.01). MG and MT had higher concordance with culture (83%) compared to 0% concordance of 16S results. Supervised learning methods revealed MT datasets most clearly differentiated infected, primary, and aseptic sample groups. MT data also revealed more antibiotic resistance genes, with improved concordance results compared to MG. These data suggest that a differential and underlying microbial ecology exists within uninfected and infected joints. This study represents the first application of RNA-based sequencing (MT). Further work on larger cohorts will provide opportunities to employ deep learning approaches to improve accuracy, predictive power, and clinical utility.

Prosthetic joint infections and legal disputes: a threat to the future of prosthetic orthopedics

Prosthetic joint infections (PJI) represent one of the major problems in orthopedic prosthetic surgery. The incidence of PJIs varies according to the site of intervention, and different published case studies report occurrence at 0.5 to 3.0% in the event of first implants, with a significant greater risk in the case of prosthesis revisions. The diagnosis of prosthetic infections is seldom simple, needing a multi-specialist approach, which includes the accurate collection of patient anamnesis, its clinical evaluation, the evaluation of inflammation biomarkers, and the use of imaging techniques. It is essential to identify the bacteria responsible for the infection not only for an accurate diagnosis, but also to select the correct antibiotic treatment. Failure to identify the bacteria involved makes it impossible to establish targeted systemic antibiotic therapy. In developed countries such as Italy, the right to health is guaranteed by the Constitution, where the institutions that provide health services must be staffed by a team of medical professionals that can guarantee the safest possible health pathways. Risk management represents the set of actions aimed at improving the quality of the care provided, the adherence to guidelines and good care practices with the final objective of guaranteeing patients' safety. All hospitals, including the ones where prosthetic orthopedic surgery is performed, must adopt clinical risk management procedures which, through prospective tools aimed at preventing errors and complications and by retrospective methods, permit the identification of critical points in the different phases of the process and propose actions for improvement. The constant increase in litigation for malpractice in Western countries, especially in Italy, calls for special attention to the problem of PJIs and the in-depth assessment of medico-legal problems, also considering the new legislative initiatives in the field of medical malpractice. Hospitals need to tackle the onset of PJIs in a transparent and linear fashion by constantly informing the patient on their progress.

Comparative analysis of pathogen structure in patients with PJI after primary total hip and knee arthroplasty

BACKGROUND

Microbiological profile of pathogens causing periprosthetic joint infection (PJI) after primary total hip (THA) and knee (TKA) arthroplasty varies in different regions, clinics and even departments. The objective of this study was to analyze the pathogen structure in patients with PJI after primary THA and TKA and its influence on the effectiveness of the infection eradication after two-stage reimplantation.

MATERIALS AND METHODS

We collected the retrospective data of 364 patients-161 with PJI after primary TKA (113 treated in two stages 48 with failure after spacer implantation) and 203 patients with infected THA (127 after successful two-stage reimplantation and 76 with PJI recurrence after the first stage) within the time period from January 2012 to December 2017, treated with two-stage protocol in the single center. A comparative analysis of pathogen structure was performed between cohorts of patients with hip and knee PJI. A subanalysis was made between the subsets comprised from patients with successful two-stage treatment and the subsets with failure to treat the infection.

RESULTS

Staphylococcus epidermidis was the most commonly identified pathogen in the full hip and knee cohorts: 30.1% and 32.5%, respectively. However, the percentage of methicillin-resistant Staphylococcus epidermidis (MRSE) among all S. epidermidis isolates was higher in the hip cohort-50% compared with 35% in the knee cohort (p = 0.073). Other coagulase-negative Staphylococci were more common to patients with PJI after primary TKA-10.3% compared with 5% (p < 0.02). Streptococcus sp. caused hip PJI in a larger percentage of cases than in knee PJI (p < 0.01)-7% and 2%, respectively (p < 0.01). Polymicrobial associations were significantly more common in hip PJI compared to knee PJI: 45.3% and 14% of cases, respectively (p < 0.001). The presence of polymicrobial infection significantly raised the risk of PJI recurrence [OR 2 (95% CI from 1.24 to 3.24)] in knee PJI patients and reduced the effectiveness of infection eradication from 73.9% to 47.8%.

CONCLUSION

Comparative analysis showed significant differences in the structure of PJI pathogens in the hip and knee. These findings are useful when choosing treatment strategies and empirical antibiotics regimens, in the management of patients with PJIs after primary hip and knee arthroplasty.

Antibiotics- and Heavy Metals-Based Titanium Alloy Surface Modifications for Local Prosthetic Joint Infections

Prosthetic joint infection (PJI) is the second most common cause of arthroplasty failure. Though infrequent, it is one of the most devastating complications since it is associated with great personal cost for the patient and a high economic burden for health systems. Due to the high number of patients that will eventually receive a prosthesis, PJI incidence is increasing exponentially. As these infections are provoked by microorganisms, mainly bacteria, and as such can develop a biofilm, which is in turn resistant to both antibiotics and the immune system, prevention is the ideal approach. However, conventional preventative strategies seem to have reached their limit. Novel prevention strategies fall within two broad categories: (1) antibiotic- and (2) heavy metal-based surface modifications of titanium alloy prostheses. This review examines research on the most relevant titanium alloy surface modifications that use antibiotics to locally prevent primary PJI.

Therapeutic assessment of N-formyl-methionyl-leucyl-phenylalanine (fMLP) in reducing periprosthetic joint infection

Despite many preventive measures, including prophylactic antibiotics, periprosthetic joint infection (PJI) remains a devastating complication following arthroplasty, leading to pain, suffering, morbidity and substantial economic burden. Humans have a powerful innate immune system that can effectively control infections, if alerted quickly. Unfortunately, pathogens use many mechanisms to dampen innate immune responses. The study hypothesis was that immunomodulators that can jumpstart and direct innate immune responses (particularly neutrophils) at the surgical site of implant placement would boost immune responses and reduce PJI, even in the absence of antibiotics. To test this hypothesis, N-formyl-methionyl-leucyl-phenylalanine (fMLP) (a potent chemoattractant for phagocytic leukocytes including neutrophils) was used in a mouse model of PJI with Staphylococcus aureus (S. aureus). Mice receiving intramedullary femoral implants were divided into three groups: i) implant alone; ii) implant + S. aureus; iii) implant + fMLP + S. aureus. fMLP treatment reduced S. aureus infection levels by ~ 2-Log orders at day 3. Moreover, fMLP therapy reduced infection-induced peri-implant periosteal reaction, focal cortical loss and areas of inflammatory infiltrate in mice distal femora at day 10. Finally, fMLP treatment reduced pain behaviour and increased weight-bearing at the implant leg in infected mice at day 10. Data indicated that fMLP therapy is a promising novel approach for reducing PJI, if administered locally at surgical sites. Future work will be toward further enhancement and optimisation of an fMLP-based therapeutic approach through combination with antibiotics and/or implant coating with fMLP.

Free-Floating Aggregate and Single-Cell-Initiated Biofilms of Staphylococcus aureus

Periprosthetic joint infection (PJI) occurring after artificial joint replacement is a major clinical issue requiring multiple surgeries and antibiotic interventions. Staphylococcus aureus is the common bacteria responsible for PJI. Recent in vitro research has shown that staphylococcal strains rapidly form free-floating aggregates in the presence of synovial fluid (SF) with biofilm-like resistance to antimicrobial agents. However, the development of biofilms formed from these aggregates under shear have not been widely investigated. Thus, in this study, we examined the progression of attached biofilms from free-floating aggregates. Biofilms were grown for 24 h in flow cells on titanium discs after inoculation with either pre-aggregated or single planktonic cells. Image analysis showed no significant difference between the biofilm formed from aggregates vs. the planktonic cells in terms of biomass, surface area, and thickness. Regarding antibiotic susceptibility, there were 1 and 2 log reductions in biofilms formed from single cells and aggregates, respectively, when treated with vancomycin for 24 h. Thus, this study demonstrates the formation of biofilm from free-floating aggregates and follows a similar developmental time period and shows similar antibiotic tolerance to more traditionally inoculated in vitro flow cell biofilms.

Occurrence of Rare Pathogens at the Site of Periprosthetic Hip and Knee Joint Infections: A Retrospective, Single-Center Study

The frequency and clinical relevance of rare pathogens at the site of periprosthetic infections of the hip and knee joint and their antibiotic resistance profiles have not yet been assessed in-depth. We retrospectively analyzed all periprosthetic hip and knee joint infections that occurred between 2016 and 2020 in a single center in southwest Germany. Among 165 infections, 9.7% were caused by rare microorganisms such as Veilonella sp., Pasteurella sp., Pantoea sp., Citrobacter koseri, Serratia marcescens, Parvimonas micra, Clostridium difficile, Finegoldia magna, Morganella morganii, and yeasts. No resistance to piperacillin/tazobactam, carbapenemes, fluoroquinolones, or gentamicin was observed. Some bacteria displayed resistance to ampicillin, ampicillin/sulbactam, and cefuroxime. We present follow-up data of patients with infections due to rare pathogens and discuss the importance of close, interdisciplinary collaboration between orthopedic surgeons and clinical microbiologists to carefully select the most appropriate anti-infective treatment regimens for the increasing number of patients with such infections.

Microbiology of Periprosthetic Hip and Knee Infections in Surgically Revised Cases from 34 Centers in Mainland China

Background and Aim

Periprosthetic joint infection (PJI) is one of the most devastating complications after total joint arthroplasty (TJA). However, the antibiotic resistance of infecting pathogens can significantly vary in different parts of the country. In the current study, we analyzed the demographic and microbiological profiles of knee and hip PJI over three years and compared the microbiological differences between them.

Methods

A multicenter retrospective study of PJI patients in 34 referral medical centers in mainland China from January 2015 to November 2017 was performed.

Results

A total of 925 PJI patients were recruited, 452 were identified as knee PJIs, and 473 were hip PJIs. The most common causative pathogens were Staphylococcus aureus (26.5%) and coagulase-negative staphylococci (14.3%). Methicillin-resistant staphylococci were involved in 25.6% (237/925) of all PJI cases. Mycobacterium and fungus only accounted for 6.5% (61) of all cases. Enteric gram-negative bacilli, anaerobes, and polymicrobial pathogens were more common in hip joint prostheses than in knee PJI (P = 0.014; P = 0.006; P = 0.002, respectively).

Conclusion

While the majority of causative pathogens in PJI cases are staphylococcal species, the prevalence of atypical organisms and resistant pathogens should also be given attention and warrant the need for empiric antibiotic treatment.

Efficacy of 16S rRNA variable regions high-resolution melt analysis for bacterial pathogens identification in periprosthetic joint infections

BACKGROUND

Accurate and rapid identification of microorganisms causing periprosthetic joint infections (PJIs) are necessary for choosing an appropriate antibiotic therapy. Therefore, molecular techniques are suggested for diagnosis in suspected PJIs. The Broad-range PCR and High-Resolution Melt Analysis (HRMA) were evaluated for the identification of causative organisms of PJIs in this study.

RESULTS

For 47 of 63 specimens, both the culture and broad-range PCR were positive. The culture was found to be able of organism's detection in 74.6% (47/63) of patients. Of 47 positive cultures, 11 (23.4%) were polymicrobial and 36 (76.59%) were monomicrobial cultures, in which 34 (91.89%) cases were detected by HRM assay. The sensitivity, specificity of HRMA vs monomicrobial culture were 91.89, 93.75%, respectively. The sensitivity, specificity of total HRMA (mono + poly) vs culture were 82.92, 93.75%.

CONCLUSIONS

HRM assay coupled with broad-range PCR are effective screening, rapid, and relatively cost-effective methods for discrimination of PJIs especially in aiding culture method. Using computer programs such as the Matlab-2018b program for HRM data analysis is also valuable and helpful in diagnosis.

Trends in microbiological profiles and antibiotic resistance in periprosthetic joint infections

Objective

This study examined the trends in demographics, the distribution of microorganisms, and antibiotic resistance in patients with periprosthetic joint infection (PJI).

Methods

We conducted a retrospective study of 231 consecutive patients diagnosed with PJI in our hospital from January 2006 to December 2015 (93 and 138 patients diagnosed in 2006–2010 and 2011–2015, respectively). The linear-by-linear chi-squared test was used to assess the trends in demographics, the distribution of microorganisms, and antibiotic resistance.

Results

Gram-positive cocci accounted for 63.9% of all pathogens, and coagulase-negative Staphylococcus (CoNS) accounted for 38.1% of all isolates. The proportion of isolates identified as methicillin-resistant CoNS significantly increased over the study period (39.0% vs. 61.8%). In addition, the proportions of levofloxacin-resistant CoNS (4.9% vs. 21.8%) and Staphylococcus aureus (6.3% vs. 45.0%) isolates significantly increased over the study period. By contrast, the proportions of penicillin-resistant CoNS (82.9% vs. 40.0%) and S. aureus (75.0% vs. 30.0%) isolates decreased over the study period.

Conclusion

Our research revealed changes in the distribution of microorganisms and antibiotic resistance profile of the pathogens responsible for PJI over time, which could complicate treatment. These findings may serve as a reference for strategies to prevent and empirically treat PJI in China.

Eradicating Fungal Periprosthetic TKA "Super-infection": Review of the Contemporary Literature and Consideration of Antibiotic-Impregnated Dissolving Calcium Sulfate Beads as a Novel PJI Treatment Adjunct

Fungal periprosthetic joint infections are an uncommon but potentially devastating complication of arthroplasty surgery. The concurrent presence of a coexistent bacterial pathogen—a so called “super-infection”—adds further complexity. With delays to definitive diagnosis and a large number of procedures before cure, the associated physical and psychological morbidity is considerable. Beyond this, the economic and resource burden can be substantial. This case report presents the successful rapid treatment of an atypical bacterial and fungal periprosthetic super-infection with two-stage revision surgery augmented with a commercially available dissolving calcium sulfate bead system permitting targeted local antifungal elution. While not the panacea for treatment, these beads provide another potentially useful tool in the atypical pathogen eradication armamentarium. Much research is still indicated to define the optimal care pathway for fungal periprosthetic super-infections.

Clinical and Health-Care Cost Analysis of Negative Pressure Dressing in Primary and RevisionTotal Knee Arthroplasty: A Systematic Review and Meta-Analysis

BACKGROUND

Negative pressure wound therapy (NPWT) has been used because of its perceived advantages in reducing surgical site infections, wound complications, and the need for further surgery. The purpose of this study was to assess the infection rates, wound complications, length of stay, and financial burden associated with NPWT use in primary and revision total knee arthroplasty (TKA).

METHODS

We performed a PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) systematic review of the existing literature on using NPWT in primary and revision TKA. PubMed, Embase, Science Direct, and the Cochrane Library were utilized. The risk of bias was evaluated using the ROBINS-I (Risk Of Bias In Non-randomised Studies - of Interventions) tool, and the quality of evidence was evaluated using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) criteria.

RESULTS

Twelve articles that evaluated 1,403 primary TKAs and 279 revision TKAs were reviewed. NPWT significantly reduced complication rates in revision TKA. However, there was no significant difference in infection rates between NPWT and regular dressings in primary or revision TKA. NPWT use in primary TKA significantly increased the risk of blistering, although no increase in reoperations was noted. The analysis showed a possible reduction in length of stay associated with NPWT use for both primary and revision TKA, with overall health-care cost savings.

CONCLUSIONS

Based on a meta-analysis of the existing literature, we do not recommend the routine use of NPWT. However, in high-risk revision TKA and selected primary TKA cases, NPWT reduced wound complications and may have health-care cost savings.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Staphylococcus aureus Aggregates on Orthopedic Materials under Varying Levels of Shear Stress

Periprosthetic joint infection (PJI) occurring after artificial joint replacement is a major clinical issue requiring multiple surgeries and antibiotic interventions. Staphylococcus aureus is the bacterium most commonly responsible for PJI. Recent in vitro research has shown that staphylococcal strains rapidly form aggregates in the presence of synovial fluid (SF). We hypothesize that these aggregates provide early protection to bacteria entering the wound site, allowing them time to attach to the implant surface, leading to biofilm formation. Thus, understanding the attachment kinetics of these aggregates is critical in understanding their adhesion to various biomaterial surfaces. In this study, the number, size, and surface area coverage of aggregates as well as of single cells of S. aureus were quantified under various conditions on different orthopedic materials relevant to orthopedic surgery: stainless steel (316L), titanium (Ti), hydroxyapatite (HA), and polyethylene (PE). It was observed that, regardless of the material type, SF-induced aggregation resulted in reduced aggregate surface attachment and greater aggregate size than the single-cell populations under various shear stresses. Additionally, the surface area coverage of bacterial aggregates on PE was relatively high compared to that on other materials, which could potentially be due to the rougher surface of PE. Furthermore, increasing shear stress to 78 mPa decreased aggregate attachment to Ti and HA while increasing the aggregates' average size. Therefore, this study demonstrates that SF induced inhibition of aggregate attachment to all materials, suggesting that biofilm formation is initiated by lodging of aggregates on the surface features of implants and host tissues.IMPORTANCE Periprosthetic joint infection occurring after artificial joint replacement is a major clinical issue that require repeated surgeries and antibiotic interventions. Unfortunately, 26% of patients die within 5 years of developing these infections. Staphylococcus aureus is the bacterium most commonly responsible for this problem and can form biofilms to provide protection from antibiotics as well as the immune system. Although biofilms are evident on the infected implants, it is unclear how these are attached to the surface in the first place. Recent in vitro investigations have shown that staphylococcal strains rapidly form aggregates in the presence of synovial fluid and provide protection to bacteria, thus allowing them time to attach to the implant surface, leading to biofilm formation. In this study, we investigated the attachment kinetics of Staphylococcus aureus aggregates on different orthopedic materials. The information presented in this article will be useful in surgical management and implant design.

Time to positivity of acute and chronic periprosthetic joint infection cultures

INTRODUCTION

A prolonged incubation time is generally recommended for diagnosing periprosthetic joint infections (PJI). However, in literature, no distinction is made between acute and chronic infections.

METHODS

All patients with a PJI that underwent surgical debridement between November 2015 and February 2019 with or without revision of the prosthesis were retrospectively evaluated. Synovial fluid, 5 intraoperative periprosthetic tissue samples, and the sonicated prosthesis were cultured.

RESULTS

Fifty-nine patients were analyzed, including 21 acute PJIs (33 isolates) and 38 chronic PJIs (46 isolates). In acute PJIs, all isolates grew within 5 days, while this took 11 days for chronic PJIs. Sonication fluid showed the shortest time to positivity (78% at day 2) for chronic PJIs, but no difference was observed for acute PJIs compared to tissue cultures.

CONCLUSION

In contrast to cultures from chronic PJIs, acute PJIs do not need a prolonged incubation time and no clear benefit is observed for sonication.

Prevention of Prosthetic Joint Infection: From Traditional Approaches towards Quality Improvement and Data Mining

A projected increased use of total joint arthroplasties will naturally result in a related increase in the number of prosthetic joint infections (PJIs). Suppression of the local peri-implant immune response counters efforts to eradicate bacteria, allowing the formation of biofilms and compromising preventive measures taken in the operating room. For these reasons, the prevention of PJI should focus concurrently on the following targets: (i) identifying at-risk patients; (ii) reducing “bacterial load” perioperatively; (iii) creating an antibacterial/antibiofilm environment at the site of surgery; and (iv) stimulating the local immune response. Despite considerable recent progress made in experimental and clinical research, a large discrepancy persists between proposed and clinically implemented preventative strategies. The ultimate anti-infective strategy lies in an optimal combination of all preventative approaches into a single “clinical pack”, applied rigorously in all settings involving prosthetic joint implantation. In addition, “anti-infective” implants might be a choice in patients who have an increased risk for PJI. However, further progress in the prevention of PJI is not imaginable without a close commitment to using quality improvement tools in combination with continual data mining, reflecting the efficacy of the preventative strategy in a particular clinical setting.

The World Association against Infection in Orthopaedics and Trauma (WAIOT) procedures for Microbiological Sampling and Processing for Periprosthetic Joint Infections (PJIs) and other Implant-Related Infections

While implant-related infections continue to play a relevant role in failure of implantable biomaterials in orthopaedic and trauma there is a lack of standardised microbiological procedures to identify the pathogen(s). The microbiological diagnosis of implant-related infections is challenging due to the following factors: the presence of bacterial biofilm(s), often associated with slow-growing microorganisms, low bacterial loads, previous antibiotic treatments and, possible intra-operative contamination. Therefore, diagnosis requires a specific set of procedures. Based on the Guidelines of the Italian Association of the Clinical Microbiologists (AMCLI), the World Association against Infection in Orthopaedics and Trauma has drafted the present document. This document includes guidance on the basic principles for sampling and processing for implant-related infections based on the most relevant literature. These procedures outline the main microbiological approaches, including sampling and processing methodologies for diagnostic assessment and confirmation of implant-related infections. Biofilm dislodgement techniques, incubation time and the role of molecular approaches are addressed in specific sections. The aim of this paper is to ensure a standardised approach to the main microbiological methods for implant-related infections, as well as to promote multidisciplinary collaboration between clinicians and microbiologists.