Late Prosthetic Joint Infection Research Articles

1312. Incidence and Microbiology of Prosthetic Joint Infection According to Time Following Total Knee Arthroplasty: A Retrospective Cohort Study Among US Veterans

Abstract Background Despite the frequency of total knee arthroplasty (TKA) and clinical impact of prosthetic joint infections (PJIs), the incidence and microbiology of these infections in the United States remains unclear. Our objective was to determine the incidence of PJI occurring ≤ 3 months (early), between > 3 and ≤ 12 months (delayed), and > 12 months (late) after primary TKA and to identify the organisms isolated from microbiologic cultures during each of these periods. Methods We conducted a retrospective study of patients in the Veterans Aging Cohort Study- National Cohort who underwent elective primary TKA in the VA between October 1, 1999 to September 30, 2019. The primary outcome was incident hospitalization with PJI. We estimated incidence rates (events/10,000 person-months) with 95% confidence intervals (CIs) of early, delayed, and late PJI. Poisson regression was used to estimate the incidence rate ratio (IRR) with 95% CI of early and delayed PJI compared to late PJI. The Kaplan-Meier method was used to demonstrate the cumulative incidence of PJI at 3, 12 and 24 months. We measured the frequency of Gram-positive, Gram-negative, fungal, polymicrobial, and culture-negative PJI occurring within each of the three time periods and compared frequencies of interest using Pearson’s chi-squared tests. Results Among 82,401 VHA patients who underwent primary TKA, a total of 1,605 incident PJIs (1.9%) were identified. The incidence rate of PJI was higher in the first 12 months after primary TKA surgery, with an IRR of 20.4 (95% CI, 18.2-222.8) for early and 4.2 (95% CI, 3.7-4.8) for delayed periods when compared to late. The cumulative incidence of PJI at 3 months was 0.77% (95% CI, 0.71-0.83%), at 12 months was 1.25% (95% CI 1.17-1.33%), and at 24 months was 1.56% (95% CI 1.48-1.65%) (Figure 1). Staphylococcus aureus was the most common organism isolated (33.2%) across the periods. Gram-negative bacteria were isolated in 11.1% of all infections, and 15.1% of early PJIs (Table 1). Kaplan Meier failure curves for prosthetic joint infection for the overall study period (upper panel) as well as the first 24 months (lower panel) following primary total knee arthroplasty. Abbreviations: PJI, prosthetic joint infection; CI, confidence interval.Table 1.Organisms isolated from synovial fluid or operative tissue cultures of early, delayed and late prosthetic joint infections after primary total knee arthroplasty. aAmong the 1,605 PJIs in the Overall Cohort, the microbiology data for 103 were missing and 1,502 PJIs with available microbiology data were included in these results. bPolymicrobial defined by multiple genera of organisms identified cIncludes: Micrococcus species, diphtheroids dIncludes: Salmonella, Pasteurella, Citrobacter, Morganella, Acinetobacter, Pasteurella, Burkholderia species, and Gram-negative organisms not otherwise specified eAll fungal infections were identified as Candida species fNumbers may not sum to group totals or percentages as polymicrobial infections with more than one organism were possible Abbreviations: PJI, prosthetic joint infection. Conclusion Incidence rates of early and delayed PJI were significantly higher than late PJI following primary TKA. Gram-negative organisms were more prevalent in early compared to delayed or late PJI. Empiric Gram-negative antibiotic therapy should be considered with a suspected PJI within 3 months after elective primary TKA. Disclosures Alisa Stephens-Shields, PhD, Gilead Sciences: Advisor/Consultant Charles Nelson, MD, Stryker: Advisor/Consultant|Zimmer-Biomet: Advisor/Consultant|Zimmer-Biomet: Grant/Research Support

Incidence, Microbiological Studies, and Factors Associated With Prosthetic Joint Infection After Total Knee Arthroplasty

Despite the frequency of total knee arthroplasty (TKA) and clinical implications of prosthetic joint infections (PJIs), knowledge gaps remain concerning the incidence, microbiological study results, and factors associated with these infections. To identify the incidence rates, organisms isolated from microbiological studies, and patient and surgical factors of PJI occurring early, delayed, and late after primary TKA. This cohort study obtained data from the US Department of Veterans Affairs (VA) Corporate Data Warehouse on patients who underwent elective primary TKA in the VA system between October 1, 1999, and September 30, 2019, and had at least 1 year of care in the VA prior to TKA. Patients who met these criteria were included in the overall cohort, and patients with linked Veterans Affairs Surgical Quality Improvement Program (VASQIP) data composed the VASQIP cohort. Data were analyzed between December 9, 2021, and September 18, 2023. Primary TKA as well as demographic, clinical, and perioperative factors. Incident hospitalization with early, delayed, or late PJI. Incidence rate (events per 10 000 person-months) was measured in 3 postoperative periods: early (≤3 months), delayed (between >3 and ≤12 months), and late (>12 months). Unadjusted Poisson regression was used to estimate incidence rate ratios (IRRs) with 95% CIs of early and delayed PJI compared with late PJI. The frequency of organisms isolated from synovial or operative tissue culture results of PJIs during each postoperative period was identified. A piecewise exponential parametric survival model was used to estimate IRRs with 95% CIs associated with demographic and clinical factors in each postoperative period. The 79 367 patients (median (IQR) age of 65 (60-71) years) in the overall cohort who underwent primary TKA included 75 274 males (94.8%). A total of 1599 PJIs (2.0%) were identified. The incidence rate of PJI was higher in the early (26.8 [95% CI, 24.8-29.0] events per 10 000 person-months; IRR, 20.7 [95% CI, 18.5-23.1]) and delayed periods (5.4 [95% CI, 4.9-6.0] events per 10 000 person-months; IRR, 4.2 [95% CI, 3.7-4.8]) vs the late postoperative period (1.3 events per 10 000 person-months). Staphylococcus aureus was the most common organism isolated overall (489 [33.2%]); however, gram-negative infections were isolated in 15.4% (86) of early PJIs. In multivariable analyses, hepatitis C virus infection, peripheral artery disease, and autoimmune inflammatory arthritis were associated with PJI across all postoperative periods. Diabetes, chronic kidney disease, and obesity (body mass index of ≥30) were not associated factors. Other period-specific factors were identified. This cohort study found that incidence rates of PJIs were higher in the early and delayed vs late post-TKA period; there were differences in microbiological cultures and factors associated with each postoperative period. These findings have implications for postoperative antibiotic use, stratification of PJI risk according to postoperative time, and PJI risk factor modification.

The first genomic characterization of a stable, hemin-dependent small colony variant strain of Staphylococcus epidermidis isolated from a prosthetic-joint infection

Phenotype switching from a wild type (WT) to a slow-growing subpopulation, referred to as small colony variants (SCVs), supports an infectious lifestyle of Staphylococcus epidermidis, the leading cause of medical device-related infections. Specific mechanisms underlying formation of SCVs and involved in the shaping of their pathogenic potential are of particular interest for stable strains as they have been only rarely cultured from clinical specimens. As the SCV phenotype stability implies the existence of genetic changes, the whole genome sequence of a stable, hemin-dependent S. epidermidis SCV strain (named 49SCV) involved in a late prosthetic joint infection was analyzed. The strain was isolated in a monoculture without a corresponding WT clone, therefore, its genome was compared against five reference S. epidermidis strains (ATCC12228, ATCC14990, NBRC113846, O47, and RP62A), both at the level of the genome structure and coding sequences. According to the Multilocus Sequence Typing analysis, the 49SCV strain represented the sequence type 2 (ST2) regarded as the most prominent infection-causing lineage with a worldwide dissemination. Genomic features unique to 49SCV included the absence of the Staphylococcal Cassette Chromosome (SCC), ~12 kb deletion with the loss of genes involved in the arginine deiminase pathway, and frameshift-generating mutations within the poly(A) and poly(T) homopolymeric tracts. Indels were identified in loci associated with adherence, metabolism, stress response, virulence, and cell wall synthesis. Of note, deletion in the poly(A) of the hemA gene has been considered a possible trigger factor for the phenotype transition and hemin auxotrophy in the strain. To our knowledge, the study represents the first genomic characterization of a clinical, stable and hemin-dependent S. epidermidis SCV strain. We propose that previously unreported indels in the homopolymeric tracts can constitute a background of the SCV phenotype due to a resulting truncation of the corresponding proteins and their possible biological dysfunction. Streamline of genetic content evidenced by the loss of the SCC and a large genomic deletion can represent a possible strategy associated both with the SCV phenotype and its adaptation to chronicity.

Debridement, antimicrobials, and implant retention in the treatment of late acute and early acute Staphylococcus aureus prosthetic joint infections

Background Staphylococcus aureus is the most common microbe in prosthetic joint infections (PJIs). Debridement, antimicrobials, and implant retention (DAIR) are often-recommended treatment modality for acute PJIs, even though it has had relatively poor outcomes in some studies. In this study, we wanted to examine treatment results with a multidisciplinary team in a specialised centre and obtain further information for treatment decisions in acute Staphylococcus aureus PJIs. Methods All consecutive haematogenous late acute and postoperative early acute hip and knee Staphylococcus aureus PJIs treated with DAIR during 2011–2016 were included in this retrospective study. DAIR within three weeks from symptom onset and the exchange of modular parts were required. Results Eighty-five acute Staphylococcus aureus PJIs were treated with DAIR in 83 patients: 28 late acute and 57 early acute PJIs. The late acute PJI patients were older and had malignancies more often than the early acute PJI patients. Bacteraemia was present in 50.6% of Staphylococcus aureus PJI patients, more often in late acute (73.1%) than in early acute (40.4%) patients (p = .006). The implant was retained in 80.0%: 89.3% of the late acute and 75.4% of the early acute PJIs. In 17 joints, DAIR failed and the joint had to be removed. Fourteen of these joints were successfully replaced. One infection-related death occurred. The one-year all-cause mortality rate was 3.6%. Suppressive antimicrobial treatment was given to 22 (26.5%) patients. Conclusions Reasonably good treatment results for acute Staphylococcus aureus PJIs are achievable by DAIR in a specialised centre with a strict treatment protocol and a multidisciplinary team. If the DAIR fails, a two-stage exchange is usually still possible, with good results.

Biofilm formation is associated with poor outcome in prosthetic joint infections caused by Staphylococcus lugdunensis

Background Staphylococcus lugdunensis has been described as a pathogen of increasing importance in prosthetic joint infections (PJI). Our aim was to describe the clinical presentation of PJI caused by S. lugdunensis, and to correlate the biofilm-forming ability of the bacterial isolates to clinical outcome. Method S. lugdunensis isolates from PJI episodes during 2015–2019 were included and analysed for biofilm formation using a microtiter plate assay. Medical records from the corresponding patients were reviewed. Results We identified 36 patients with PJI caused by S. lugdunensis during the study period. Early postoperative PJIs were most frequent (n = 20, 56%). Surgical intervention was performed in a majority of the patients (n = 33, 92%), and the dominating type of antibiotic treatment was a combination of rifampicin and ciprofloxacin (n = 27, 75%). The treatment success-rate was 81% (n = 29). All isolates causing PJI were able to form biofilm in vitro. Biofilm formation was significantly stronger in isolates causing relapsing vs non-relapsing PJI (mean OD550 3.1 ± 0.23 vs 1.14 ± 0.73 p = .001) and strong biofilm formation was also associated with late acute hematogenic PJI (mean OD550 1.8 ± 0.93 vs. 0.93 ± 0.81, p = .01). Conclusion Strong biofilm production in S. lugdunensis isolates was associated with relapse in PJI.

Total Hip Arthroplasty in a Patient With Fascioscapulohumeral Dystrophy

Facioscapulohumeral dystrophy is an autosomal dominant disorder that results in progressive muscle weakness. Patients most commonly present with facial and periscapular muscle weakness, which progresses to involve their upper and lower extremities as well as truncal muscles. We present a patient with facioscapulohumeral dystrophy who underwent staged bilateral total hip arthroplasties but developed late prosthetic joint infection. This case also reports the management of periprosthetic joint infection after total hip arthroplasties through explant and placement of an articulating spacer as well as both neuraxial and general anesthetic management for this uncommon neuromuscular disorder.

Effectiveness and Optimal Duration of Adjunctive Rifampin Treatment in the Management of Staphylococcus aureus Prosthetic Joint Infections After Debridement, Antibiotics, and Implant Retention.

BackgroundRifampin is recommended as adjunctive therapy for patients with a Staphylococcus aureus prosthetic joint infection (PJI) managed with debridement, antibiotics, and implant retention (DAIR), with no solid consensus on the optimal duration of therapy. Our study assessed the effectiveness and optimal duration of rifampin for S aureus PJI using Veterans Health Administration (VHA) data.MethodsWe conducted a retrospective cohort study of patients with S aureus PJI managed with DAIR between 2003 and 2019 in VHA hospitals. Patients who died within 14 days after DAIR were excluded. The primary outcome was a time to microbiological recurrence from 15 days up to 2 years after DAIR. Rifampin use was analyzed as a time-varying exposure, and time-dependent hazard ratios (HRs) for recurrence were calculated according to the duration of rifampin treatment.ResultsAmong 4624 patients, 842 (18.2%) received at least 1 dose of rifampin; 1785 (38.6%) experienced recurrence within 2 years. Rifampin treatment was associated with significantly lower HRs for recurrence during the first 90 days of treatment (HR, 0.60 [95% confidence interval {CI}, .45–.79]) and between days 91 and 180 (HR, 0.16 [95% CI, .04–.66]) but no statistically significant protective effect was observed with longer than 180 days (HR, 0.57 [95% CI, .18–1.81]). The benefit of rifampin was observed for subgroups including knee PJI, methicillin-susceptible or -resistant S aureus infection, and early or late PJI.ConclusionsThis study supports current guidelines that recommend adjunctive rifampin use for up to 6 months among patients with S aureus PJI treated with DAIR.

Epidemiology and antibiotic resistance of prosthetic joint infections according to time of occurrence, a 10-year study

ObjectivesTo describe the microorganisms responsible for prosthetic joint infections (PJIs) and their antimicrobial susceptibilities, and to propose appropriate empirical antimicrobial treatments (EATs) according to time of occurrence MethodsThis 10-year retrospective study presents the bacterial etiology of 282 consecutive PJIs in a French hospital according to time of occurrence (adapted from Zimmerli's classification: early, <3 months; delayed, 3–12 months; late acute, >12 months with hematogenous seeding or contiguous spread; late chronic, >12 months without hematogenous seeding). The expected efficacy of various EATs was analyzed for each PJI. ResultsStaphylococci were the most commonly found bacteria (S. aureus (44.3%), coagulase-negative staphylococci (25.2%) with 15.2% and 49.3% methicillin resistance, respectively), followed by Gram-negative bacilli (GNB) (17.7%) and streptococci (14.9%). The distribution of species varied between categories, but antibiotics targeting GNBs were required in all categories. Imipenem-vancomycin was the most effective combination (99.3%) but should be reserved for patients with suspected resistant GNB. Cefotaxime-vancomycin was less effective in early/delayed and late PJIs (91.1% and 86.1%, respectively), due to resistant GNB and polymicrobial infections. Piperacillin/tazobactam-vancomycin appeared to be appropriate in all situations (>96% efficacy). ConclusionProposing universal recommendations remains challenging, but a good understanding of the local epidemiology is important for optimizing EATs.

Factors associated with late microbiological documentation of prosthetic joint infection.

Purpose: To describe the number of prosthetic joint infections (PJIs) with late documentation and to identify associated factors. Methods: Bacterial PJIs with surgical management between November 2015 and November 2019 in a French center were analyzed. Results of short (72h) and late culture (at 14days) were analyzed. Results: A total of 160 PJIs were reported with 215 bacteria. Twenty-nine patients had late documentation (18.1%). The bacteria most involved were coagulase-negative staphylococci and Cutibacterium spp. (60%). In multivariate analysis, late chronic PJI (odds ratio =2.47) and antibiotic therapy before surgery (odds ratio =3.13) were associated with late-documented infection. Conclusion: A better knowledge of the factors associated with late-documented infections is essential in order to simplify antibiotic treatment at the appropriate time.

Differing Microorganism Profile in Early and Late Prosthetic Joint Infections Following Primary Total Knee Arthroplasty — Implications for Empiric Antibiotic Treatment

BackgroundProsthetic joint infection (PJI) is the leading cause of revision following total knee arthroplasty (TKA). Prior to microorganism identification, the choice of the correct empiric antibiotics is critical to treatment success. This study aims to 1) compare the microorganism and resistance profile in early and late PJIs; 2) recommend appropriate empiric antibiotics. MethodsA multicentre retrospective review was performed over a 15-year period. First episode PJIs were classified by both the Tsukayama Classification and Auckland Classification. For each PJI case, the causative organism and antibiotic sensitivity were recorded. ResultsOf eligible patients, 232 culture-positive PJI cases were included. Using either classification system, early PJIs (<4 weeks or <1 year since primary) were significantly more likely to be resistant and polymicrobial. The predominant organisms were coagulase-negative Staphylococci in early PJIs while Staphylococcus aureus was the most common in late PJIs. The distribution of gram-negative cases was higher in early Class-A than late Class-C PJIs (25% versus 6%, P = .004). Vancomycin provided significantly superior coverage when compared to Flucloxacillin for early infections, and addition of a gram-negative agent achieved coverage over 90% using both classification systems. ConclusionBased on the microbiological pattern in Tsukayama criteria, Vancomycin with the consideration of Gram-negative agent should be considered for Class-A infections given the high proportion of resistant and polymicrobial cases. For Class-C infections, Cephazolin or Flucloxacillin is likely sufficient. We recommend antibiotics to be withheld in Class-B infections until cultures and sensitivities are known.

The poor accuracy of D-dimer for the diagnosis of prosthetic joint infection but its potential usefulness in early postoperative infections following revision arthroplasty for aseptic loosening

BackgroundD-dimer was introduced in 2018 as an alternative biomarker for C-reactive protein (CRP) in the diagnostic of prosthetic joint infection (PJI) criteria of the Musculoskeletal Infection Society. We assessed the accuracy of plasma D-dimer for the diagnosis of early, delayed, and late PJI according to Infectious Diseases Society of America (IDSA) criteria, and whether persistently high levels of D-dimer in cases of aseptic loosening (AL) may be predictive of subsequent implant-related infection.MethodsA prospective study of a consecutive series of 187 revision arthroplasties was performed at a single institution. Septic (n = 39) and aseptic revisions (n = 141) were classified based on IDSA criteria. Preoperative assessment of CRP, erythrocyte sedimentation rate (ESR) and D-dimer was performed. Receiver operating curves were used to determine maximum sensitivity and specificity of the biomarkers. The natural progress of D-dimer for AL cases was followed up either until the date of implant-related infection at any time during the first year or 1 year after revision in patients without failure. Clinical outcomes for those AL cases included infection-related failure that required a new surgery or need for antibiotic suppression.ResultsPreoperative D-dimer level was significantly higher in PJI cases than in AL cases (p = 0.000). The optimal threshold of D-dimer for the diagnosis of PJI was 1167 ng/mL. For overall diagnosis of PJI, C-reactive protein (CRP) achieved the highest sensitivity (84.6%), followed by erythrocyte sedimentation rate (ESR) and D-dimer (82% and 71.8%, respectively). Plasma D-dimer sensitivity was lower for all PJI types. When combinations of 2 tests were studied, the combined use of ESR and CRP achieved the best accuracy for all types of PJI (76.9%). 4.25% of AL cases had implant failure due to implant-related infection during the first year after the index revision arthroplasty, only the cases with early failure maintained high D-dimer levels.ConclusionsPlasma D-dimer did not offer an improvement over the individual or combined diagnosis for any type of PJI according to IDSA criteria. Persistently raised levels of D-dimer after revision arthroplasty in AL cases might be used to effectively diagnose early postoperative infection.

Analysis of Prosthetic Joint Infections Following Invasive Dental Procedures in England

Dentists in the United States are under pressure from orthopedic surgeons and their patients with prosthetic joints to provide antibiotic prophylaxis before invasive dental procedures (IDP) to reduce the risk of late prosthetic joint infection (LPJI). This has been a common practice for decades, despite a lack of evidence for an association between IDP and LPJI, a lack of evidence of antibiotic prophylaxis efficacy, cost of providing antibiotic prophylaxis, and risk of both adverse drug reactions and the potential for promoting antibiotic resistance. To quantify any temporal association between IDP and subsequent LPJI. This cohort study used a case-crossover and time trend design to examine any potential association between IDP and LPJI. The population of England (55 million) was chosen because antibiotic prophylaxis has never been recommended to prevent LPJI in England, and any association between IDP and LPJI would therefore be fully exposed. All patients admitted to hospitals in England for LPJI from December 25, 2011, through March 31, 2017, and for whom dental records were available were included. Analyses were performed between May 2018 and June 2021. Exposure to IDP. The main outcome was the incidence of IDP in the 3 months before LPJI hospital admission (case period) compared with the incidence in the 12 months before that (control period). A total of 9427 LPJI hospital admissions with dental records (mean [SD] patient age, 67.8 [13.1] years) were identified, including 4897 (52.0%) men and 4529 (48.0%) women. Of these, 2385 (25.3%) had hip prosthetic joints, 3168 (33.6%) had knee prosthetic joints, 259 (2.8%) had other prosthetic joints, and 3615 (38.4%) had unknown prosthetic joint types. There was no significant temporal association between IDP and subsequent LPJI. Indeed, there was a lower incidence of IDP in the 3 months prior to LPJI (incidence rate ratio, 0.89; 95% CI, 0.82-0.96; P = .002). These findings suggest that there is no rationale to administer antibiotic prophylaxis before IDP in patients with prosthetic joints.

99mTc-HMPAO-WBC SPECT/CT versus 18F-FDG-WBC PET/CT in chronic prosthetic joint infection: a pilot study.

The aim of this study was to compare 99mTc-HMPAO-WBC-SPECT/CT combined with 99mTc-nanocollloid SPECT/CT and 18F-FDG-WBC-PET/CT combined with 99mTc-Nanocollloid SPECT/CT for the diagnosis and treatment evaluation of chronic prosthetic joint infection (PJI). Patients with suspected chronic PJI were examined with 99mTc-HMPAO-WBC SPECT/CT, 18F-FDG-WBC PET/CT, and 99mTc-nanocolloid SPECT/CT (to visualize bone marrow). The location and patterns of uptake were noted and compared between the two leukocyte examinations. Both leukocyte examinations were evaluated visually for infection. The PET examinations were also evaluated semiquantitatively. Chronic PJI was verified clinically by microbial culture and successfully treated PJI was confirmed by 12 months symptom-free follow-up after cessation of antibiotics. Nineteen patients were included with 10 hip prostheses and nine knee prostheses. Fourteen were diagnosed with chronic PJI and five with successfully treated PJI. The sensitivity of visual evaluation of 99mTc-WBC-HMPAO SPECT/CT for all joints was 0.31 and for 18F-FDG-WBC PET/CT 0.38. The specificity was 0.80 and 0.83, respectively. All patients with a true-positive SPECT examination had a false-negative PET examination and vice versa. Semiquantitative evaluation of the hips gave an area under the curve of 0.905 using the iliac crest as the background. Semiquantitative evaluation of the knees did not produce significant results. This pilot study showed no difference in the sensitivity or specificity of 99mTc-HMPAO-WBC SPECT/CT and 18F-FDG-WBC PET/CT when combined with 99mTc-nanocollloid SPECT/CT in the diagnosis or treatment evaluation of suspected late chronic PJI.

Dental Antibiotic Prophylaxis and Prosthetic Joint Infections: A Narrative Review

Prosthetic joint infection (PJI) is the 3rd most common cause of revision in total hip arthroplasty (THA) and the most common cause of revision in total knee arthroplasty (TKA). It is associated with high costs/economic burden and mortality. The most common cause of late PJI is due to haematogenous seedling of bacteria into the joint from remote site infection (RSI). Oral flora constitutes 6-13% of burden in PJI. Dental interventions in patients who have undergone joint replacement surgery (JRS) are at increased risk of PJI due to bacteraemia. Dental antibiotic prophylaxes (DAP) are known to reduce this bacteraemia which in-turn may reduce the incidence of PJI. Significant controversy exists Re: the role and use of DAP in preventing PJI. This narrative review attempts to answer key questions surrounding its use based on extensive literature review in English language over past four decades.

The diagnostic value of routine preliminary biopsy in diagnosing late prosthetic joint infection after hip and knee arthroplasty.

Biopsy of the periprosthetic tissue is an important diagnostic tool for prosthetic joint infection (PJI) as it enables the detection of the responsible microorganism with its sensitivity to antibiotics. We aimed to investigate how often the bacteria identified in the tissue analysis differed between samples obtained from preoperative biopsy and intraoperative revision surgery in cases of late PJI; and whether there was a therapeutic consequence. A total of 508 patients who required revision surgery of total hip arthroplasty (THA) (n = 231) or total knee arthroplasty (TKA) (n = 277) because of component loosening underwent biopsy before revision surgery. The tissue samples collected at biopsy and during revision surgery were analyzed according to the criteria of the Musculoskeletal Infection Society (MSIS). In total, 178 (113 THA, 65 TKA) were classified as infected. The biopsy procedure had a sensitivity of 93.8%, a specificity of 97.3%, a positive predictive value (PPV) of 94.9%, a negative predictive value (NPV) of 96.7%, and an accuracy of 96.1%. Of the 178 infected patients, 26 showed a difference in the detected bacteria from the biopsy and the revision surgery (14.6%). This difference required a change to antibiotic therapy in only two cases (1.1%). Biopsy is a useful tool to diagnose PJI, but there may be a difference in the detected bacteria between the biopsy and revision surgery. However, this did not affect the choice of antibiotic therapy in most cases, rendering the clinical relevance of this phenomenon as low. Cite this article: Bone Joint J 2020;102-B(3):329-335.

A retrieval analysis perspective on revision for infection.

BackgroundRetrieval analysis has long served the orthopaedic community as a tool for understanding implant failure modes; however, what retrieval studies can reveal about the nature of prosthetic joint infection (PJI) remains unknown. We hypothesize that records from a comprehensive joint retrieval program should corroborate clinically-reported temporal characteristics of prosthesis-related infection.MethodsWe examined 2527 records documenting a decade of explanted hip and knee components to quantify the following: (1) the relative contribution of infection to revision arthroplasty; (2) the effects of joint type, revision status, and reason for retrieval on indwelling time; and (3) whether the temporal distribution of infected explants reflects clinical experience.ResultsIn this series, 20% (507/2527) of explants were performed for infection, with PJI being more commonly implicated in the retrieval of revision implants than of primaries. Infected prostheses were explanted 23.2 months sooner on average than those retrieved for other causes. Within the subset of infected devices, revision components were explanted 11.2 months sooner than primaries, with no appreciable difference observed between hips and knees. Retrieval-based temporal distributions were most similar to PJI studies with endpoint enrollment or long duration follow-up, suggesting a later average onset of infection than reported in comparable clinical studies with short (<10-year) follow-up.ConclusionsInfection represents a major cause of revision arthroplasty, and is associated with shorter indwelling times in revision components than in primaries. Studies with less than 10 years of follow-up are likely to under-report late PJI.

Epidemiological and clinical features of prosthetic joint infections caused by gram-negative bacteria.

To review the clinical literature focusing on epidemiology, clinical presentation and outcomes of prosthetic joint infections (PJIs) due to gram-negative bacteria (GNB) and to report the experience of a multicentric cohort. A retrospective, observational, cohort study was performed in three Italian hospitals. All consecutive PJIs caused by GNB over a 12-year period (from May 2007 to March 2018) were enrolled. Epidemiological, clinical, microbiological and therapeutic features were described. Factors related to treatment failure (defined as the occurrence of death, amputation or starting long-term antimicrobial suppression therapy) were analysed with a Cox regression model. A total of 82 PJIs due to GNB (42.7% men; median age 73 years) were studied. The implants included 65 (79.3%) hip, 16 (19.5%) knee and one (1.2%) shoulder. An early PJI was diagnosed in 16.2% of patients, a delayed PJI in 29.4% and a late PJI in 54.4%. The most common isolated organisms were Escherichia coli (21.7%) and Pseudomonas spp. (20.9%). 13.4% of the isolates were carbapenem-resistant bacteria (CRB). In 53.8% of cases a two-stage exchange arthroplasty was performed and in 32.5% a Girdlestone excision arthroplasty. The average therapeutic failure occurred in 17.7% of cases. The therapeutic failure rate of the two-stage was 10%. PJI due to CRB was identified as a potential risk factor for failure (aHR 4.90; IC 95%, 0.96-25.08; p=0.05). The therapeutic failure rate in the CRB group was 50%. The treatment with the two-stage procedure for PJIs caused by GNB seems to be associated with a low rate of failure, while PJI due to CRB seems to be related to the worst outcome.

Is Gram staining still useful in prosthetic joint infections?

Introduction: Staphylococcus aureus is an independent risk factor for DAIR failure in patients with a late acute prosthetic joint infection (PJI). Therefore, identifying the causative microorganism in an acute setting may help to decide if revision surgery should be chosen as a first surgical approach in patients with additional risk factors for DAIR failure. The aim of our study was to determine the sensitivity of Gram staining in late acute S. aureus PJI.Material and methods: We retrospectively evaluated all consecutive patients between 2005-2015 who were diagnosed with late acute PJI due to S. aureus. Late acute PJI was defined as the development of acute symptoms and signs of PJI, at least three months after the index surgery. Symptoms existing for more than three weeks were excluded from the analysis. Gram staining was evaluated solely for synovial fluid.Results: A total of 52 cases were included in the analysis. Gram staining was positive with Gram positive cocci in clusters in 31 cases (59.6%). Patients with a C-reactive protein (CRP) > 150 mg/L at clinical presentation had a significantly higher rate of a positive Gram stain (30/39, 77%) compared to patients with a CRP ≤ 150 mg/L (4/10, 40%) (p=0.02). A positive Gram stain was not related to a higher failure rate (60.6% versus 57.9%, p 0.85).Conclusion: Gram staining may be a useful diagnostic tool in late acute PJI to identify S. aureus PJI. Whether a positive Gram stain should lead to revision surgery instead of DAIR should be determined per individual case.

Infection after Constrained Condylar Knee Arthroplasty: Incidence and microbiological findings in 100 consecutive complex primary and revision total knee arthroplasties.

Background: To report incidence, microbiological findings, and treatment outcome of prosthetic joint infection (PJI) after constrained condylar knee arthroplasty.Methods: Retrospective study of 100 consecutive complex primary and revision total knee arthroplasties operated with constrained condylar knee arthroplasties between February 2006 and October 2015 at a single institution. Demographic and surgical data were registered, as well as data regarding infection, microbiology and treatment. Follow-up median 43 months; SD 32.Results: The overall incidence of acute postoperative PJI was low (3/100). 1/33 (3%), 1/ 45 (2%), and 1/22 (5%), following primary complex TKA, aseptic revisions, and septic revisions, respectively. The incidence of late acute hematogenous PJI was 5/100. 1/33 (3%),1/45 (2%), and 3/22 (14%) following primary complex TKA, aseptic revisions, and septic revisions, respectively. Late acute hematogenous infections were associated with a lower success rate of treatment with debridement and implant retention compared with acute postoperative PJIs, 1/5 versus 2/3.Conclusion: The risk of late acute hematogenous infections seems increased. Multiple previous surgery, poor soft tissue, and large metal implants may contribute to an increased lifelong susceptibility for bacteremias to cause PJIs.

Clinical outcome and risk factors for failure in late acute prosthetic joint infections treated with debridement and implant retention

Debridement, antibiotics and implant retention (DAIR) is the recommended treatment for all acute prosthetic joint infections (PJI), but its efficacy in patients with late acute (LA) PJI is not well described. Patients diagnosed with LA PJI between 2005 and 2015 were retrospectively evaluated. LA PJI was defined as the development of acute symptoms (≤ 3 weeks) occurring ≥ 3 months after arthroplasty. Failure was defined as: (i) the need for implant removal, (ii) infection related death, (iii) the need for suppressive antibiotic therapy and/or (iv) relapse or reinfection during follow-up. 340 patients from 27 centers were included. The overall failure rate was 45.0% (153/340). Failure was dominated by Staphylococcus aureus PJI (54.7%, 76/139). Significant independent preoperative risk factors for failure according to the multivariate analysis were: fracture as indication for the prosthesis (odds ratio (OR) 5.4), rheumatoid arthritis (OR 5.1), age above 80 years (OR 2.6), male gender (OR 2.0) and C-reactive protein > 150 mg/L (OR 2.0). Exchanging the mobile components during DAIR was the strongest predictor for treatment success (OR 0.35). LA PJIs have a high failure rate. Treatment strategies should be individualized according to patients' age, comorbidity, clinical presentation and microorganism causing the infection.