Synovial Cultures Research Articles

Sonication of explants enhances the diagnostic accuracy of synovial fluid and tissue cultures and can help determine the appropriate antibiotic therapy for prosthetic joint infections.

This study aimed to evaluate the sensitivity and specificity of the sonication cultures according to the International Consensus Meeting 2018 criteria and to evaluate the effect of sonication on the antibiotic treatment of patients. Sixty-four patients who were scheduled for revision hip or knee arthroplasties were included in the study. Aspiration fluid, tissue, and sonication cultures were performed from all patients and compared in terms of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy. Other targets of the study were to investigate the rate of change in the antibiotic treatment. The sensitivity, specificity, PPV, NPV, and overall accuracy of the fluid culture obtained by the sonication method were 71.4%, 96.6%, 96.2%, 73.7%, and 82.8%, respectively. The sensitivity, specificity, PPV, NPV, and overall accuracy of the fluid culture obtained after tissue sampling were 68.6%, 100%, 100.0%, 72.5%, and 82.8%, respectively. There was no statistically significant difference between the sonication method and tissue culture in terms of sensitivity and specificity (p = 1.0). The sensitivity, specificity, PPV, NPV, and overall accuracy of the fluid culture obtained by the aspiration method were 28.6%, 93.1%, 83.3%, 51.9%, and 57.8%, respectively. Treatment change was applied in 10 (15.6%) patients. Our prospectively collected data revealed that sonication of the explants alone did not increase the sensitivity, and we found that sonicate culture sometimes changed the antibiotic therapy strategy in patients with periprosthetic joint infection because different microorganisms were detected. This study was prospectively registered in a public trials registry ( https://clinicaltrials.gov/ , NCT04304885).

Native joint infections in Iceland 2003–2017: an increase in postarthroscopic infections

ObjectivesNationwide study on the epidemiology, clinical characteristics and outcomes among patients with native joint infection (NJI) in Iceland, 2003–2017.MethodsAll positive synovial fluid culture results in Iceland were identified and medical...

PRIMARY MENINGOCOCCAL ARTHRITIS: A CASE REPORT

Neisseria meningitidis is a gram-negative diplococcus often associated with invasive infections such as meningitis and fulminant sepsis. primary meningococcal septic arthritis (PMSA) is extremely rare. Diagnosis should be prompt and is based on isolation of the germ from synovial fluid or blood culture. This observation reports the case of a 6 -year- old girl who presented to the pediatric emergency room with a painful right knee associated with fever and purpuric spots. The neurological examination was strictly normal with no signs of meningeal involvement. Arthrotomy and drainage were performed. The cytobacteriological examination of the synovial fluid allowed the isolation of a strain of N. meningitidis sensitive to ceftriaxone on culture media. Intravenous antibiotic therapy was then started. The patient improved after adequate treatment. Conclusion: This observation illustrates an unusual presentation of Neisseria meningitidis infections. Prompt bacteriological diagnosis and early treatment combining antibiotics and joint drainage prevented complications in this patient.

Haematogenous synovial sepsis of the digital flexor tendon sheath following contralateral limb foot abscessation in a horse

AbstractA 5‐year‐old Shire mare was presented for investigation of severe right hindlimb lameness and was diagnosed with extensive right hind subsolar and submural foot abscessation. The mare developed severe contralateral limb lameness 11 days following right hind abscess debridement, with investigation revealing synovial sepsis of the left hind digital flexor tendon sheath. Synovial sepsis persisted despite aggressive surgical and medical treatment, resulting in euthanasia. Microbial culture of synovial fluid isolated Bacteroides sp., consistent with haematogenous synovial sepsis. This is the first report to describe haematogenous synovial sepsis as a cause of contralateral limb lameness during the management of foot abscessation in the horse.

242. Rising Incidence of Finegoldia magna among Prosthetic Joint Infections

Background Finegoldia magna is an anaerobic, Gram-positive coccus infrequently associated with osteoarticular infections. Since the adoption of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF), F. magna has been increasingly reported as a cause of osteoarticular infections. Our objective was to determine the incidence of F. magna prosthetic joint infections (PJIs) within our institution. MethodsWe conducted a retrospective longitudinal survey from 1 January 2016 - 31 December 2020 at an academic tertiary care referral center. We constructed two Poisson count models to assess the incidence of Finegoldia magna PJIs: one consisting of a clinical microbiology database of synovial fluid and surgical tissue cultures and one using a PJI registry. Time served as the covariate of interest. We used number of cultures as an offset term in the clinical microbiology model, and number of PJI cases as the offset term in the prosthetic joint registry model –reflecting the relevant denominator for each dataset. The microbiology database was limited to synovial fluid aspirates and surgical tissue cultures to minimize risk of confounding by contaminants. ResultsThe PJI registry included 44 F. magna infections occurring among 4,706 (0.9%) PJIs. The microbiology survey included 99 F. magna isolates from 43,940 (0.2%) cultures sent from joint aspirates or surgical tissue cultures. Among overall synovial and surgical tissue cultures, we found no significant increase in F. magna over time (incidence rate ratio [IRR] 1.0, 95% CI: 0.9-1.2, Figure 1A). Within the PJI registry, however, we observed a 40% per-year increase in F. magna incidence (IRR 1.4, 95% CI: 1.1-1.8, Figure 1B). Figure 1 Incidence of Finegoldia magna Over TimeConclusionAdoption of MALDI-TOF has expanded the clinical microbiology laboratory’s capacity for rapid speciation, sometimes revealing previously unseen epidemiologic trends. While we saw no significant change in overall incidence of F. magna among synovial and surgical tissue cultures, we did detect a significant increase specifically among PJI cases. F. magna warrants attention as an emerging pathogen among PJI. Disclosures All Authors: No reported disclosures

The profile of the causative organisms which lead to septic arthritis of native joints over the last two decades in a single tertiary medical center in the east coast of the United States.

Septic arthritis (SA) is associated with significant morbidity and mortality. Delayed or inadequate treatment may result in joint destruction, osteomyelitis and sepsis. Like other types of infection, the causative agents of SA may have changed over time. Early targeted intervention is important in cases of SA and can be achieved only by understanding the current trends in the microbiology of SA. To determine the trends in the microbiology of SA over the last two decades. We conducted a retrospective study including all patients 18 and older with culture positive, surgically treated, native joint septic arthritis (NJSA), admitted to a single tertiary medical centre in Boston between the years of 1997 and 2015. We excluded cases of osteomyelitis and septic bursitis. We focused our analysis on the microbiology data which included synovial fluid gram stain and culture, blood cultures and synovial biopsy cultures. Among 260 cases, the most common bacteria isolated were Methicillin Sensitive Staphylococcus aureus (MSSA, 36%), Methicillin Resistant Staphylococcus aureus (MRSA, 17.6%), Coagulase Negative Staphylococci (CoNS, 13%) and Group B Streptococcus (GBS, 7.3%). Trends in the rates of these bacteria demonstrated no significant variation. The knee was the most common joint affected, followed by the shoulder and hip. Shoulder SA was most commonly caused by MRSA while MSSA was the leading causative organism in other joints. GBS was a causative bacterium in shoulder SA significantly more often than in knee or hip infections. Although no significant trends were noted in the microbiology of SA over nearly 2 decades, we observed meaningful findings regarding shoulder SA as MRSA was the most common bacterial because of SA in this joint. Prompt joint aspiration, microbiologic testing of synovial fluid and empiric antibiotic therapy that covers MRSA may improve outcomes in SA.

Pasteurella multocida Endocarditis with Septic Arthritis: Case Report and Review of the Literature

Background: There is a paucity of evidence regarding optimal management of Pasteurella spp. endocarditis. The authors report the first case of Pasteurella spp. endocarditis with septic arthritis and review the literature. Case Description: A 79-year-old patient with significant comorbidities, including prosthetic aortic valve, was admitted with left knee swelling, fever, and confusion, having been scratched by a cat 2-weeks prior. At presentation, there was a metallic click, a Grade 3 pan-systolic murmur and Grade 1 flow murmur audible on auscultation. Blood and synovial fluid cultures both isolated Pasteurella multocida, identified by matrix-assisted laser desorption ionisation–time of flight, which was sensitive to penicillin according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST); minimum inhibitory concentration: 0.094). The patient underwent joint washout and received intravenous piperacillin/tazobactam for 3 days before switching to benzylpenicillin once sensitivities were known. Due to continued pyrexia, a transthoracic echocardiogram was obtained, which revealed a small mobile mass on a thickened mitral valve suspicious for a vegetation. On review by the Infective Endocarditis team, conservative management was deemed best, given the presence of comorbidities. Despite requiring further joint washout due to persistent knee pain, the patient was successfully treated with 8 weeks of antibiotic therapy (24 days of benzylpenicillin monotherapy, 2 weeks of benzylpenicillin and ciprofloxacin, and 15 days ciprofloxacin monotherapy). Discussion: Previous literature reviews report a higher mortality of Pasteurella spp. endocarditis when managed without cardiac surgery, thus recommending surgery in all cases. The authors found these to have confounding factors, including inadequate duration of antimicrobials, aortic root abscess, and rapid progression to death. The authors’ case of Pasteurella spp. endocarditis, complicated by septic arthritis, showed successful therapy without cardiac surgery.

Diagnostic Criteria for the Painful Swollen Pediatric Knee: Distinguishing Septic Arthritis From Aseptic Effusion in a Non-Lyme Endemic Area.

Purpose: The child with a painful swollen knee must be worked-up for possible septic arthritis; the classic clinical prediction algorithms for septic arthritis of the hip may not be the best models to apply to the knee.Materials and methods: This was a retrospective case-control study of 17 years of children presenting to one hospital with a chief complaint of a painful swollen knee, to evaluate the appropriateness of applying a previously described clinical practice algorithm for the hip in differentiating between the septic and aseptic causes of the painful knee effusions. The diagnoses of true septic arthritis, presumed septic arthritis, and aseptic effusion were established, based upon the cultures of synovial fluid, blood cultures, synovial cell counts, and clinical course. Using a logistic regression model, the disease status was regressed on both the demographic and clinical variables.Results: In the study, 122 patients were included: 51 with true septic arthritis, 37 with presumed septic arthritis, and 34 with aseptic knee effusion. After applying a backward elimination, age <5 years and C-reactive protein (CRP) >2.0 mg/dl remained in the model, and predicted probabilities of having septic knee arthritis ranged from 15% for the lowest risk to 95% for the highest risk. Adding a knee aspiration including percent polymorphonucleocytes (%PMN) substantially improved the overall model performance, lowering the lowest risk to 11% while raising the highest risk to 96%.Conclusions: This predictive model suggests that the likelihood of pediatric septic arthritis of the knee is >90% when both “age <5 years” and “CRP > 2.0 mg/dl” are present in a child with a painful swollen knee, though, in the absence of these factors, the risk of septic arthritis remains over 15%. Aspiration of the knee for those patients would be the best next step.

DISSEMINATED BLASTOMYCOSIS PRESENTING AS MONOARTICULAR SEPTIC ARTHRITIS

TOPIC: Chest Infections TYPE: Medical Student/Resident Case Reports INTRODUCTION: Blastomycosis is a dimorphic fungus that causes acute or chronic pneumonia with extrapulmonary involvement in a minority of cases. Rarely it is implicated in disseminated disease causing joint involvement leading to septic arthritis. Recognizing blastomycosis as an important cause of septic arthritis and starting treatment is necessary to prevent joint destruction and overwhelming disseminated infection. CASE PRESENTATION: A 29-year-old male with no significant past medical history presented to the hospital with chief complaint of right knee pain of 3 weeks' duration associated with recent onset of productive cough, dyspnea on exertion and chest pain. Admitting vitals were remarkable for tachycardia and fever of 101 F. Physical examination revealed right knee swelling and pain on active and passive range of motion without overlying erythema. Joint aspiration revealed 68,000 WBC with 88% neutrophils with negative crystals. Cultures from synovial fluid grew blastomyces dermatitidis. During the hospital stay, patient's respiratory status worsened, and he was transferred to the ICU and intubated. CT Chest showed diffuse bilateral pulmonary nodules, suspicious for atypical pneumonia versus acute respiratory distress syndrome. Bronchoscopy was done and specimens were sent for culture. He was initially started and then maintained on broad spectrum antibiotics. Once respiratory and synovial cultures grew blastomyces, patient was started on IV amphoterecin. Patient's condition improved dramatically after starting amphoterecin. His remaining ICU course involved extubation, tracheostomy and gradual weaning of pressors. His knee pain and swelling subsided after starting amphoterecin and patient was discharged to rehab in stable condition on itraconazole. DISCUSSION: This case highlights the rare presentation of disseminated blastomycosis as monoarticular septic arthritis. About 3% of patients with blastomycosis have joint involvement. Extrapulmonary blastomycosis is usually seen in association with pneumonia which can often be severe enough to cause ARDS and shock, like our patient. It is important to have a high index of suspicion for blastomycosis in patients presenting with septic arthritis with an active pulmonary process and B symptoms. Diagnosis of blastomycosis is with culture, urinary and serum antigens. Treatment involves amphoterecin B followed by itraconazole for patients with severe disseminated disease. CONCLUSIONS: Disseminated blastomycosis can present with symptoms of extrapulmonary spread of disease. Diagnosis is with antigen identification in serum and urine and by culture. Treatment involves amphoterecin B and itraconazole. REFERENCE #1: Chapman, Stanley W., Andrew C. Lin, Katherine A. Hendricks, Rathel L. Nolan, Mary M. Currier, Ken R. Morris, and Helen R. Turner. "Endemic blastomycosis in Mississippi: epidemiological and clinical studies." In Seminars in respiratory infections, vol. 12, no. 3, pp. 219-228. 1997. REFERENCE #2: Wheat, L. J. "Antigen detection, serology, and molecular diagnosis of invasive mycoses in the immunocompromised host." Transplant infectious disease 8, no. 3 (2006): 128-139. DISCLOSURES: No relevant relationships by Fatima Ayub, source=Web Response No relevant relationships by Muhammad Hasib Khalil, source=Web Response

The concordance between preoperative aspiration and intraoperative synovial fluid culture results: intraoperative synovial fluid re-cultures are necessary whether the preoperative aspiration culture is positive or not

AimsPreoperative aspiration culture and intraoperative cultures play pivotal roles in periprosthetic joint infection (PJI) diagnosis and pathogen identification. But the discordance between preoperative aspiration culture and intraoperative synovial fluid culture remains unknown. We aim to determine (1) the discordance between preoperative and intraoperative synovial fluid (SF) culture and. (2) compared to intraoperative synovial fluid cultures, the sensitivity of preoperative aspiration fluid culture. Then the following question is tried to be answered: Are intraoperative synovial fluid re-cultures necessary if the preoperative aspiration culture is positive?Materials and methodsBetween 2015 and 2019, 187 PJI patients managed with surgeries were included in this study. Compared to intraoperative synovial fluid culture, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of preoperative aspiration culture were calculated. Then, the discordance between preoperative aspiration culture and intraoperative SF culture was analyzed.ResultsThe sensitivity of preoperative aspiration culture was 81.29% compared to intraoperative synovial fluid cultures. Concordance was identified in 147 PJI (78.61%) patients and culture discordance occurred in 40 patients (21.39%). In these discordant PJI patients, 24 patients (60%) were polymicrobial and no intraoperative synovial fluid culture growth was found in 16 PJI cases (40%). Preoperative monomicrobial staphylococcus results had a sensitivity of and a specificity of 80.43% and 83.16%, respectively. Preoperative polymicrobial results had the lowest sensitivity.ConclusionsThe intraoperative synovial fluid re-cultures are necessary if the preoperative aspiration culture is positive and the discordance between preoperative aspiration culture and intraoperative synovial fluid culture should be noted especially when Streptococcus spp. and more than one pathogen was revealed by preoperative aspiration culture.Level of evidence: Level III.

Recommandations françaises récentes sur la prise en charge des arthrites septiques sur articulation native de l’adulte

Septic arthritis (SA) is a rare but severe condition due to its mortality and the risk of joint destruction responsible of functional disability. In 2020, the Société française de rhumatologie (SFR) in cooperation with the Société française de pathologies infectieuse de langue française (SPILF) and the Société française de chirurgie orthopédique et traumatologique (SOFCOT) developed sixteen clinical practice recommendations for the diagnostic and management of adult native joint SA. They remind the importance of initial microbiological investigations, in particular synovial fluid analysis and blood cultures to be carried out if possible before any antibiotic therapy. They also underline the place of additional exams (X-rays, ultrasound, others) and the major therapeutic principles: duration and modalities of antibiotic therapy with proposals adapted to the most frequent germs, place of joint drainage whether medical or surgical, early rehabilitation and monitoring.

Retrospective evaluation of 103 cases of septic arthritis in dogs.

This study examines inciting causes, diagnosis, treatment and risk factors for the recurrence and outcome of septic arthritis (SA) in dogs. Medical records spanning 17 years from five referral hospitals were surveyed for presumptive and confirmed cases of SA. SA was identified in 103 cases. Spontaneous septic SA was the most common inciting cause. The most commonly affected joints were the stifle (40%) and elbow (24%). Pre-existing osteoarthritis (OA) was present in 63% of septic joints and was associated with recurrence (p=0.03). Treatment with antibiotics prior to presentation was associated with a negative synovial fluid culture (p=0.014). A successful outcome was associated with early treatment (p=0.001) and SA due to direct penetration (p=0.04) or spontaneous cause (p=0.003). Recurrence was more likely in dogs with unsuccessful outcomes (p=0.004) and bodyweights>30kg (p=0.009). SA should be considered as a differential diagnosis in large breed dogs with pre-existing OA presenting with either an acute or chronic monoarthropathy. In the majority of cases, a successful outcome was achieved regardless of treatment type. Recurrence rates were low, but associated with pre-existing OA and higher bodyweight. Although treatment should be implemented as soon as possible to maximise outcome success, synovial fluid samples should ideally be obtained before empiric antibiotic administration.

Diagnostic utility of open biopsy in patients with two culture-negative aspirations in the diagnostic work-up of periprosthetic joint infection.

Different approaches have been proposed for bacterial identification in patients with a suspected periprosthetic joint infection (PJI). If a one-stage procedure is considered, a higher rate of preoperative bacterial identification can be achieved if biopsy is included in the diagnostic work-up. The performance of open biopsy (OB) in the context of PJI has not been clearly determined yet. The purpose of this study was to determine the value of an OB added to two consecutive culture-negative joint aspirations during PJI workup. We retrospectively analyzed the OB data from a single institution. Patients under PJI work-up of the hip or knee with two culture-negative periprosthetic aspirations who underwent OB were included. Sensitivity and specificity were calculated using the musculoskeletal infection society (MSIS) criteria as gold standard. Patients undergoing urgent irrigation and debridement and patients with history of surgery to the affected joint in the prior 6weeks were excluded. 126 patients were included in this study. 62 (49.2%) patients had prior revisions, 48 of them due to PJI. The sensitivity and specificity of OB was 69.4% and 89.1%, respectively. The OB procedure led to the identification of the causative germ in 50 out of 126 (40%) cases so they could undergo one-stage (septic) exchange. The OB is a valuable resource if preoperative synovial fluid cultures are negative, a high suspicion of infection persists and a one-stage procedure is preferred. It intends bacteria identification and allows surgeons to evaluate prosthetic complications for further surgical procedures.

Microbiology of septic arthritis in young Auckland children.

Kingella kingae is an important cause of septic arthritis in young children, with modern laboratory methods leading to increased detection. Prevalence of this pathogen in New Zealand, where there are high rates of childhood infections due to Staphylococcus aureus and Streptococcus pyogenes, is not known. We conducted a retrospective review of children <5 years with septic arthritis (without osteomyelitis) at a tertiary children's hospital in Auckland, over 10 years (2005-2014). Data were collected on demographics, microbiology, clinical presentation, investigations and management. Of the 68 cases of septic arthritis, 57 (83.8%) occurred in children aged <24 months. Among those <3 months, Streptococcus agalactiae (Group B streptococcus) was predominant (45.5% of 11 cases), followed by S. aureus (36.4%). The most common pathogen in those 3 to <12 months was Streptococcus pneumoniae (38.5% of 13 cases). In children aged 12 to <24 months, K. kingae was most common (30.3% of 33 cases). Of the 12 cases of K. kingae, 91.7% were identified from synovial fluid culture. All K. kingae isolates were susceptible to amoxicillin. K. kingae is the leading pathogen in septic arthritis in New Zealand children aged 12 to <24 months. Routine inoculation of synovial fluid into blood culture bottles at time of sample collection, in addition to use of polymerase chain reaction methods, should be encouraged to improve detection rates. For infants and preschool children presenting with single joint septic arthritis, empiric antibiotics should include cover for S. aureus and K. kingae.

Leukocyte Esterase Testing Of Synovial Fluid For Septic Joint In A Community Setting: A Case Series

PURPOSE: Septic arthritis, bacterial infection of the joint space, is an orthopedic emergency and requires prompt antibiotics and joint decompression with irrigation and drainage. Poor sensitivity characterizes current testing available to the Emergency Clinician, including systemic leukocytosis (50%), blood culture (25-50%) gram stain (30% to 70%) and synovial leukocytosis of 50,000 (70%). Recently, orthopedic research has begun to explore utilization of leukocyte esterase assays as an additional investigation for septic arthritis. No previous study has examined the utility and feasibility of leukocyte esterase in a community Emergency Department. METHODS: In this prospective study, patients who underwent joint aspiration with joint fluid culture underwent synovial leukocyte esterase testing. Diagnosis of septic arthritis was confirmed if one of the following is found: 1) a positive synovial fluid culture; 2) pathogen isolated from blood culture and clinical presentation deemed consistent with septic arthritis; or 3) turbid synovial fluid with a negative crystal analysis result. RESULTS: 23 joint aspirations were performed from March through December of 2020, of which 5 were diagnosed with septic arthritis. 4 had readable leukocyte esterase tests and all 4 resulted in positive tests, indicating sensitivity of 100%. The fifth was unreadable due to excess blood in the sample. Of the remaining 18 samples, 16 were readable and 6 had a positive leukocyte esterase, indicating specificity of 63%. Notably, synovial leukocytosis demonstrated sensitivity of 25% and specificity of 86% and Gram stain demonstrated sensitivity of 60% and specificity of 100%. CONCLUSIONS: This study suggests that synovial fluid leukocyte esterase is an effective tool in the hands of the Emergency Clinician that, when readable, has superior sensitivity for septic joint than other testing available based on both results from this study and from existing literature. This case series also demonstrates pathologies besides septic joint that resulted positive leukocyte esterase test and the ease with which this test was implemented in a community emergency department. Given these results and its cost-effectiveness (roughly 50¢), this study demonstrates potential for more widespread use of synovial leukocyte esterase testing.

Sequencing of Circulating Microbial Cell-Free DNA Can Identify Pathogens in Periprosthetic Joint Infections.

Over 1 million Americans undergo joint replacement each year, and approximately 1 in 75 will incur a periprosthetic joint infection. Effective treatment necessitates pathogen identification, yet standard-of-care cultures fail to detect organisms in 10% to 20% of cases and require invasive sampling. We hypothesized that cell-free DNA (cfDNA) fragments from microorganisms in a periprosthetic joint infection can be found in the bloodstream and utilized to accurately identify pathogens via next-generation sequencing. In this prospective observational study performed at a musculoskeletal specialty hospital in the U.S., we enrolled 53 adults with validated hip or knee periprosthetic joint infections. Participants had peripheral blood drawn immediately prior to surgical treatment. Microbial cfDNA from plasma was sequenced and aligned to a genome database with >1,000 microbial species. Intraoperative tissue and synovial fluid cultures were performed per the standard of care. The primary outcome was accuracy in organism identification with use of blood cfDNA sequencing, as measured by agreement with tissue-culture results. Intraoperative and preoperative joint cultures identified an organism in 46 (87%) of 53 patients. Microbial cfDNA sequencing identified the joint pathogen in 35 cases, including 4 of 7 culture-negative cases (57%). Thus, as an adjunct to cultures, cfDNA sequencing increased pathogen detection from 87% to 94%. The median time to species identification for cases with genus-only culture results was 3 days less than standard-of-care methods. Circulating cfDNA sequencing in 14 cases detected additional microorganisms not grown in cultures. At postoperative encounters, cfDNA sequencing demonstrated no detection or reduced levels of the infectious pathogen. Microbial cfDNA from pathogens causing local periprosthetic joint infections can be detected in peripheral blood. These circulating biomarkers can be sequenced from noninvasive venipuncture, providing a novel source for joint pathogen identification. Further development as an adjunct to tissue cultures holds promise to increase the number of cases with accurate pathogen identification and improve time-to-speciation. This test may also offer a novel method to monitor infection clearance during the treatment period. Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Outcomes of patients with unexpected diagnosis of infection at total hip or total knee arthroplasty revisions.

The pre-operative differential diagnosis between periprosthetic joint infections (PJIs) and aseptic failure is challenging particularly in low virulence and biofilm-related infections. This study aimed to assess the incidence and survival of patients with unexpected PJIs in a presumed aseptic revision of total hip (THA) and knee (TKA) arthroplasties. A retrospective analysis of a prospective cohort of patients was performed with 295 patients undergoing THA (n = 241) or TKA (n = 54) revision for presumed aseptic causes. Patients were diagnosed with unexpected PJI taking into account leukocyte count in the synovial fluid, sonicate, synovial culture, and tissue cultures of samples collected during surgery. The primary endpoint was the infection-free implant survival rate at theoneyear follow-up. The unexpected PJIs were 60 out of 295 (20.3%), whereas 235 (79.7%) were aseptic revisions. In the unexpected PJI group, 6 (11.1%) patients underwent knee revision and 54 (22.4%) hip revision. At the oneyear follow-up, one patient (1.6%) in the unexpected PJI group and 3 (1.3%) in the aseptic group (p = 1.0) failed for infection. The infection-free implant survival rate at the oneyear follow-up was 98.3% (C.I. 95%, 94.9-99.9%) for the unexpected PJI group and 98.7% (C.I. 95%, 97.3-99.9%) (p = 0.82) for the aseptic group. The incidence of unexpected PJIs in a presumed aseptic revision of THAs and TKAs has been previously underestimated. The infection-free implant survival rate at the oneyear follow-up in patients with unexpected PJIs was not significantly lower compared with patients undergoing aseptic revision.

Extracellular vesicles derived from mesenchymal stromal cells mediate endogenous cell growth and migration via the CXCL5 and CXCL6/CXCR2 axes and repair menisci

BackgroundMesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) are promising candidates for tissue regeneration therapy. However, the therapeutic efficacy of MSC-EVs for meniscus regeneration is uncertain, and the mechanisms underlying MSC-EV-mediated tissue regeneration have not been fully elucidated. The aims of this study were to evaluate the therapeutic efficacy of intra-articular MSC-EV injection in a meniscus defect model and elucidate the mechanism underlying MSC-EV-mediated tissue regeneration via combined bioinformatic analyses.MethodsMSC-EVs were isolated from human synovial MSC culture supernatants via ultrafiltration. To evaluate the meniscus regeneration ability, MSC-EVs were injected intra-articularly in the mouse meniscus defect model immediately after meniscus resection and weekly thereafter. After 1 and 3 weeks, their knees were excised for histological and immunohistochemical evaluations. To investigate the mechanisms through which MSC-EVs accelerate meniscus regeneration, cell growth, migration, and chondrogenesis assays were performed using treated and untreated chondrocytes and synovial MSCs with or without MSC-EVs. RNA sequencing assessed the gene expression profile of chondrocytes stimulated by MSC-EVs. Antagonists of the human chemokine CXCR2 receptor (SB265610) were used to determine the role of CXCR2 on chondrocyte cell growth and migration induced by MSC-EVs.ResultsIn the meniscus defect model, MSC-EV injection accelerated meniscus regeneration and normalized the morphology and composition of the repaired tissue. MSC-EVs stimulated chondrocyte and synovial MSC cell growth and migration. RNA sequencing revealed that MSC-EVs induced 168 differentially expressed genes in the chondrocytes and significantly upregulated CXCL5 and CXCL6 in chondrocytes and synovial MSCs. Suppression of CXCL5 and CXCL6 and antagonism of the CXCR2 receptor binding CXCL5 and CXCL6 negated the influence of MSC-EVs on chondrocyte cell growth and migration.ConclusionsIntra-articular MSC-EV administration repaired meniscus defects and augmented chondrocyte and synovial MSC cell growth and migration. Comprehensive transcriptome/RNA sequencing data confirmed that MSC-EVs upregulated CXCL5 and CXCL6 in chondrocytes and mediated the cell growth and migration of these cells via the CXCR2 axis.

The impact of sonication cultures when the diagnosis of prosthetic joint infection is inconclusive.

In the absence of a gold standard criterion for diagnosing prosthetic joint infections (PJI), sonication of the removed implant may provide superior microbiological identification to synovial fluid and peri-implant tissue cultures. The aim of this retrospective study was to assess the role of sonication culture compared to tissue cultures for diagnosing PJI, using different consensus and international guidelines for PJI definition. Data of 146 patients undergoing removal of hip or knee arthroplasties between 2010 and 2018 were retrospectively reviewed. The International Consensus Meeting (ICM-2018), Musculoskeletal Infection Society (MSIS), Infectious Diseases Society of America (IDSA), the European Bone and Joint Infection Society (EBJIS), and a modified clinical criterion, were used to compare the performance of microbiological tests. McNemar´s test and proportion comparison were employed to calculate p-value. Overall, 56% (82/146) were diagnosed with PJI using the clinical criteria. Out of these cases, 57% (47/82) tested positive on tissue culture and 93% (76/82) on sonication culture. Applying this clinical criterion, the sensitivity of sonication fluid and tissue cultures was 92.7% (95% CI: 87.1%- 98.3%) and 57.3% (95% CI: 46.6%-68.0%) (p<0.001), respectively. When both methods were combined for diagnosis (sonication and tissue cultures) sensitivity reached 96.3% (95% CI: 91.5%-100%). Sonication culture and the combination of sonication with tissue cultures, showed higher sensitivity rates than tissue cultures alone for all diagnostic criteria (ICM-18, MSIS, IDSA and EBJIS) applied. Conversely, tissue culture provided greater specificity than sonication culture for all the criteria assessed, except for the EBJIS criteria, in which sonication and tissue cultures specificity was 100% and 95.3% (95% CI: 87.8-100%), respectively (p = 0.024). In a context where diagnostic criteria available have shortcomings and tissue cultures remain the gold standard, sonication cultures can aid PJI diagnosis, especially when diagnostic criteria are inconclusive due to some important missing data (joint puncture, histology).

Osteoarticular Infection of the Shoulder Joint Due to Trichophyton Spp. in a Dog

AbstractA 10-year-old Labrador Retriever was referred for persistent lameness due to chronic right shoulder pain, unresponsive to various pain management therapies. Radiographs indicated signs of severe degenerative changes in the joint. Synovial fluid analysis was not diagnostic. Septic arthritis was suspected based on computed tomography and clinical signs. Arthroscopy allowed joint exploration, tissue biopsies, and copious joint lavage. Trichophyton spp. proliferation was identified on antimicrobial culture and histological analysis on samples obtained during arthroscopy. Oral griseofulvin therapy was initiated. Two months later, the referring veterinarian decided to interrupt the treatment after a negative synovial culture despite persistent lameness. Euthanasia was elected upon after pain also appeared on the tarsus; a post-mortem exam was not authorized by the owner. The origin of the infection remains unclear as this patient had no skin lesions and its immunological status was unknown. However, dermatophytosis has been reported in healthy dogs without skin lesions. To the author's knowledge, this is the first report of an osteoarticular infection with a dermatophyte in a dog.