Septic arthritis in the era of immunosuppressive treatments

Autoimmune Connective Tissue Diseases: Systemic Lupus Erythematosus and Rheumatoid Arthritis

Systemic lupus erythematosus and rheumatoid arthritis are just 2 of several autoimmune connective tissue diseases that are primarily chronic in nature but can present to the emergency department by virtue of an acute exacerbation of disease. Beyond an acute exacerbation of disease, their predilection for invading multiple organ systems lends itself to the potential for patients presenting to the emergency department with either a single or isolated symptom or a myriad of signs and/or symptoms indicative of a degree of disease complexity and severity that warrant timely recognition and resuscitation.

Total Knee Arthroplasty in Unrecognized Septic Arthritis-A Descriptive Case Series Study

BACKGROUND

Synovitis, like that associated with chronic bacterial arthritis, is a very rare finding during the implantation of knee endoprostheses. In such cases, we fix the knee prostheses with cement containing two antibiotics and carry out a course of systemic antibiotic administration. The aim was to analyze these cases for incidence, detection of bacteria, risk factors, and outcome.

METHODS

Out of 7534 knee replacements between January 2013 and December 2020, 25 cases were suspected during the surgical procedure to have suffered from bacterial arthritis and were treated accordingly. Total synovectomy was carried out, whereby five intraoperative synovial samples were examined bacteriologically, and the complete synovitis was analyzed histologically. The mean follow-up was 65.3 ± 27.1 (24-85) months.

RESULTS

In nine cases (0.12%), the diagnosis of bacterial arthritis was made histologically and by clinical chemistry (elevated CRP), and in two of these cases, pathogen verification was performed. Eight of these nine patients had previously had injections or surgery associated with the corresponding knee joint or had an underlying immunomodulatory disease. None of the patients developed a periprosthetic infection at a later stage.

CONCLUSION

With an incidence of 0.12%, it is rare to unexpectedly detect bacterial synovitis during surgery. Total synovectomy, use of bone cement with two antibiotics, and immediate systemic antibiotic therapy seem to keep the risk of periprosthetic infection low.

Autoimmune Connective Tissue Diseases: Systemic Lupus Erythematosus and Rheumatoid Arthritis

Systemic lupus erythematosus and rheumatoid arthritis are just 2 of several autoimmune connective tissue diseases that are primarily chronic in nature but can present to the emergency department by virtue of an acute exacerbation of disease. Beyond an acute exacerbation of disease, their predilection for invading multiple organ systems lends itself to the potential for patients presenting to the emergency department with either a single or isolated symptom or a myriad of signs and/or symptoms indicative of a degree of disease complexity and severity that warrant timely recognition and resuscitation.

Evaluation for septic arthritis of the native adult knee is aided by multivariable assessment

INTRODUCTION

Evaluation of suspected septic arthritis of the native adult knee is a common diagnostic dilemma. Pre-aspirate criteria predictive of septic arthritis do not exist for the adult knee and investigations of aspiration results (cell count, differential, gram stain and crystal analysis) have been limited to univariate analyses. Given numerous clinical variables inform the risk of septic arthritis, multivariable analysis that incorporates all clinically available information is critical to allowing accurate decision-making.

METHODS

We retrospectively identified 455 cases of potential septic arthritis of a native adult knee at a tertiary health system from 2012 to 2017, of which 281 underwent aspiration. We recorded demographics, comorbidities, history, exam, laboratory, and radiographic data. Among aspirated cases, we performed univariate analyses of all variables for association with septic arthritis followed by multivariable logistic regression analysis.

RESULTS

Septic arthritis was confirmed in 61 of 281 patients who underwent aspiration. Independent associations of risk for septic arthritis included synovial fluid WBC ≥ 30,000 (Odds Ratio 90.8, 95% Confidence Interval 26.6-310.1, p < 0.001), bacteria reported on synovial fluid gram stain (OR 21.5, 95% CI 3.9-119.2, p < 0.001), duration of pain >2 days (OR 6.9, 95% CI. 2.3-20.9, p < 0.001), history of septic arthritis at any joint (OR 5.0, 95% CI 1.1-23.4, p = 0.039), clinical effusion (OR 4.8, 95% CI 1.2-20.0, p = 0.030). Independent associations protective against septic arthritis included presence of synovial fluid crystals (OR 0.1, 95% CI 0.1-0.4, p < 0.001). The multivariable model was highly accurate in discriminating between septic and aseptic cases (AUC = 0.942). A web-based tool was created to aid clinical decision-making.

CONCLUSION

When evaluating for septic arthritis of a native adult knee, several independent associations were identified for variables related and unrelated to joint aspiration. The associated multivariable model discriminated very well between patients with and without septic arthritis, outperforming previous univariate assessments. A web-based tool was created that estimates the probability of septic arthritis based on this model. This may aid decision-making in complex clinical scenarios.

Diagnosis of Culture-Negative Septic Arthritis with Polymerase Chain Reaction in an Immunosuppressed Patient: A Case Report

CASE

We present a 23-year-old woman on immunosuppressive therapy with polyarticular, culture-negative septic arthritis. She underwent irrigation and debridement with empiric antibiotic therapy but had recurrence of septic arthritis despite treatment. Polymerase chain reaction testing eventually identified Ureaplasma as the causative organism. She was successfully treated with an extended course of organism-specific antibiotics.

CONCLUSION

More patients are being treated with immune modulating therapies. Immunosuppressed patients are at risk for atypical infections and may have different presentations than immunocompetent patients. Newer diagnostic modalities can help identify causative organisms and direct treatment in the case of negative cultures.

Septic Arthritis in Immunosuppressed Patients: Do Laboratory Values Help?

Previous studies have recommended synovial fluid cell count thresholds of 50,000 cells/mm^-3 to diagnose septic arthritis; however, data to support this are limited. It is also unknown if this value is valid in immunosuppressed patients.

Methods

We retrospectively reviewed 33 immunosuppressed patients treated at our institution from 2008 to 2018. We compared culture-positive patients with culture-negative patients.

Results

We found no statistically significant differences in synovial fluid cell count, percent synovial fluid neutrophils, erythrocyte sedimentation rate, or C-reactive protein between the groups (all P = 0.081). The median synovial fluid cell count in the culture-positive cohort was 29,000 cells/mm^-3, with only 31.2% having >50,000 cells/mm^-3.

Conclusion

Traditional synovial fluid cell thresholds are not a reliable method of diagnosing septic arthritis in immunosuppressed patients.

Synovial Fluid Mediated Aggregation of Clinical Strains of Four Enterobacterial Species

Septic arthritis and prosthetic joint infection (PJI) are conditions commonly associated with Gram-positive cocci, however, a drastic increase in cases derived from enterobacterial species has been observed. Recently it has been reported by multiple groups that staphylococci rapidly form free-floating aggregates in the presence of synovial fluid. These aggregates are comparatively more resistant to antimicrobial challenge than their planktonic counterparts, and thus may play a role in the pathogenesis of joint infection. While staphylococcal aggregates have been the primary focus of interest in the field, it is unclear just how widespread synovial fluid mediated aggregation (SFMA) is in Gram negative enterobacteria (GNE). Through this work we have evaluated SFMA in clinical GNE isolated from PJIs. Two PJI clinical strains each of Enterobacter cloacae, Escherichia coli, Klebsiella pneumonia and Proteus mirabilis strains representing a range of antibiotic susceptibilities were exposed to 10% bovine synovial fluid supernatant (BSF) using a relatively simple, quick semi-quantitative method using an imaging plate reader. BSF stimulated aggregation within 0.5 h both strains of E. cloacae and P. mirabilis and one strain of E.coli. In one strain of P. mirabilis and E.coli, the size of the aggregates significantly increased from 0.5 to 2 h exposure. In contrast, neither K. pneumoniae strain aggregated in BSF. These preliminary findings show that aggregation can occur quickly in GNE, but the extent appears strain and species specific. Further work is required to assess the impact of SFMA on antibiotic tolerance, host innate immunity and the establishment of biofilms.

Neutrophils: Beneficial and Harmful Cells in Septic Arthritis

Septic arthritis is an inflammatory joint disease that is induced by pathogens such as Staphylococcus aureus. Infection of the joint triggers an acute inflammatory response directed by inflammatory mediators including microbial danger signals and cytokines and is accompanied by an influx of leukocytes. The recruitment of these inflammatory cells depends on gradients of chemoattractants including formylated peptides from the infectious agent or dying cells, host-derived leukotrienes, complement proteins and chemokines. Neutrophils are of major importance and play a dual role in the pathogenesis of septic arthritis. On the one hand, these leukocytes are indispensable in the first-line defense to kill invading pathogens in the early stage of disease. However, on the other hand, neutrophils act as mediators of tissue destruction. Since the elimination of inflammatory neutrophils from the site of inflammation is a prerequisite for resolution of the acute inflammatory response, the prolonged stay of these leukocytes at the inflammatory site can lead to irreversible damage to the infected joint, which is known as an important complication in septic arthritis patients. Thus, timely reduction of the recruitment of inflammatory neutrophils to infected joints may be an efficient therapy to reduce tissue damage in septic arthritis.

Arthroscopic Management of Septic Arthritis of the Native Shoulder: A Systematic Review

PURPOSE

To investigate arthroscopic management of native shoulder joint septic arthritis-specifically, indications, patient outcomes, and complications.

METHODS

PubMed, MEDLINE, and Embase were used to search the literature, and data abstraction was performed independently and in duplicate. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) checklist guided reporting and data abstraction. The quality of all included studies was assessed with the Methodological Index for Non-randomized Studies (MINORS) criteria. The results are presented in a narrative summary fashion using descriptive statistics including means, proportions, ranges, κ values, and intraclass correlation coefficient values.

RESULTS

Overall, 27 studies (19 case reports and 8 case series) were identified, including 115 patients (121 shoulders). The mean follow-up period was 29.1 months (range, 1-199 months). The indications for shoulder arthroscopy owing to infection included pain; limited range of motion; swelling, erythema, and tenderness; fever; elevated leukocyte count, erythrocyte sedimentation rate, and/or C-reactive protein level; synovial aspirate findings; and/or imaging findings. Overall, 46 patients (40%) achieved infection eradication and functional improvement after a single arthroscopic procedure. However, 43 patients (37%) had ongoing symptoms or complications, including 32 (30%) who required revision arthroscopic procedures, 7 (6%) who underwent open arthrotomy for septic arthritis management, 2 (2%) in whom avascular necrosis of the humeral head developed, 1 (1%) in whom adhesive capsulitis developed, and 1 (1%) in whom an irregular profile of the humeral epiphysis developed on plain radiographs.

CONCLUSIONS

Arthroscopic management of native shoulder septic arthritis can yield alleviation of pain and a return to full range of motion, daily activities, and sports. However, there is a high reoperation rate, which may correlate with poor patient prognostic factors. This systematic review did not show the superiority of either arthroscopic surgery or open arthrotomy for the management of shoulder septic arthritis.

LEVEL OF EVIDENCE

Level IV, systematic review of Level IV studies.

Primary Meningococcal Type C Arthritis: A Case Report and Literature Review

Acute septic arthritis is a common clinical problem in emergency departments. Primary meningococcal arthritis (PMA) is very rare and few cases are reported in literature. D. B. M. consulted the emergency department for knee pain and fever; analysis showed that the cause was a Neisseria meningitidis type C infection. He received a treatment consisting of 2 arthroscopies and 5 weeks of antibiotics. At five weeks he returned to work and at 2 months he resumed sports (jogging and soccer) without complaints. Primary arthritis of the knee caused by Neisseria meningitidis is very rare. It has a very good response to antibiotics and arthroscopy procedure. Short-term follow-up and functional results are often good or excellent.

Staphylococcus aureus-Associated Musculoskeletal Infections

Musculoskeletal infections caused by Staphylococcus aureus are among the most difficult-to-treat infections. S. aureus osteomyelitis is associated with a tremendous disease burden through potential for long-term relapses and functional deficits. Although considerable advances have been achieved in diagnosis and treatment of osteomyelitis, the management remains challenging and impact on quality of life is still enormous. S. aureus acute arthritis is relatively seldom in general population, but the incidence is considerably higher in patients with predisposing conditions, particularly those with rheumatoid arthritis. Rapidly destructive course with high mortality and disability rates makes urgent diagnosis and treatment of acute arthritis essential. S. aureus pyomyositis is a common disease in tropical countries, but it is very seldom in temperate regions. Nevertheless, the cases have been increasingly reported also in non-tropical countries, and the physicians should be able to timely recognize this uncommon condition and initiate appropriate treatment. The optimal management of S. aureus-associated musculoskeletal infections requires a strong interdisciplinary collaboration between all involved specialists.