Bacterial septic arthritis in adults

Clinical effects of staged joint replacement in patients with septic arthritic knee

OBJECTIVE

To assess the clinical effect of staged joint replacement for the treatment of septic arthritic knee and the therapeutic differences between antibiotic cement beads and the tibial plateau spacer.

METHODS

Twenty-three patients (24 knee joints) treated with a staged joint replacement for septic arthritis knee were retrospectively reviewed between March 2014 and April 2018. At the first stage, thorough debridement and irrigation with self-made antibiotic cement beads or tibial plateau spacer were performed. After that, systemic antibiotic treatment was followed; when the infection was surely eliminated, the second-stage TKA was performed. Knee mobility (range of motion, abbreviated to ROM) and function (HSS scores system) were evaluated before surgery, in the interval period, and after joint replacement.

RESULTS

All patients finished follow-up, and the mean follow-up time was 27.3 months (12-54 months). Each group has one patient replaced with a homotypic spacer, and all patients eventually cleared the infection. None of the patients had a recurrent infection. The mobility and HSS scores of the two groups were significantly improved postoperation (p < 0.05). And there was no significant difference in the post-surgery ROM (p = 0.153) and the HSS score (p = 0.054) between the two groups.

CONCLUSION

Staged joint replacement is an efficacious way for septic arthritic knees, whether tibial plateau spacer or antibiotic cement beads were used, which can effectively control infection and improve knee function.

Septic arthritis post anterior cruciate ligament reconstruction due to Clostridioides difficile

Clostridioides difficile is an obligate anaerobe ubiquitous in the environment and is of particular interest in the healthcare setting as a cause of healthcare associated infection usually presenting with colitis. Extracolonic manifestations of C. difficile infection are less common with only rare reports of septic arthritis primarily in the setting of relative or overt immunocompromise. This report details the case of a 31-year-old immunocompetent male presenting with clinical features of septic arthritis, three weeks post right knee anterior cruciate ligament (ACL) reconstruction using a native hamstring tendon graft. C. difficile was isolated from two different samples of the synovial tissue from a subsequent arthroscopic washout and synovectomy. The ACL graft was retained. The isolate underwent whole genome sequencing and was found to be tcdA and tcdB gene deficient. Susceptibility testing showed susceptibility to benzylpenicillin and metronidazole. The patient received a two-week course of intravenous benzylpenicillin and four weeks of oral metronidazole. At one-year post cessation of antibiotics the patient has no clinical evidence of recurrence. This is the first known reported case of C. difficile septic arthritis in an immunocompetent patient. It demonstrates successful treatment of post-ACL septic arthritis with a graft retention strategy.

Inflammatory Joint Disease Is a Risk Factor for Streptococcal Sepsis and Septic Arthritis in Mice

Septic arthritis is a medical emergency associated with high morbidity and mortality, yet hardly any novel advances exist for its clinical management. Despite septic arthritis being a global health burden, experimental data uncovering its etiopathogenesis remain scarce. In particular, any interplay between septic arthritis and preceding joint diseases are unknown as is the contribution of the synovial membrane to the onset of inflammation. Using C57BL/6 mice as a model to study sepsis, we discovered that Group A Streptococcus (GAS) – an important pathogen causing septic arthritis - was able to invade the articular microenvironment. Bacterial invasion resulted in the infiltration of immune cells and detrimental inflammation. In vitro infected fibroblast-like synoviocytes induced the expression of chemokines (Ccl2, Cxcl2), inflammatory cytokines (Tnf, Il6), and integrin ligands (ICAM-1, VCAM-1). Apart from orchestrating immune cell attraction and retention, synoviocytes also upregulated mediators impacting on bone remodeling (Rankl) and cartilage integrity (Mmp13). Using collagen-induced arthritis in DBA/1 × B10.Q F1 mice, we could show that an inflammatory joint disease exacerbated subsequent septic arthritis which was associated with an excessive release of cytokines and eicosanoids. Importantly, the severity of joint inflammation controlled the extent of bone erosions during septic arthritis. In order to ameliorate septic arthritis, our results suggest that targeting synoviocytes might be a promising approach when treating patients with inflammatory joint disease for sepsis.

Optimizing the Composition of Irrigation Fluid to Reduce the Potency of Staphylococcus aureus α-Toxin: Potential Role in the Treatment of Septic Arthritis

OBJECTIVE

Septic arthritis is commonly caused by Staphylococcus aureus and is a medical emergency requiring antibiotics and joint irrigation. The bacteria produce α-toxin causing rapid cartilage cell (chondrocyte) death. Saline (0.9%NaCl) lavage is normally used to remove bacteria and toxins, however, its composition might be suboptimal to suppress the lethal effects of α-toxin. We utilized rabbit erythrocyte hemolysis as a sensitive, biologically relevant assay of α-toxin levels to determine if changes to osmolarity, temperature, pH, and divalent cation (Mg²⁺, Ca²⁺) concentration were protective.

DESIGN

Erythrocytes were incubated in the various conditions and then exposed to α-toxin ("chronic" challenge) or incubated with α-toxin and then exposed to experimental conditions ("acute" challenge).

RESULTS

Raising osmolarity from 300 mOsm (0.9%NaCl) to 400, 600, or 900 mOsm (sucrose addition) when applied chronically, significantly reduced hemolysis linearly. As an acute challenge, osmotic protection was significant and similar over 400 to 900 mOsm. Reducing temperature chronically from 37°C to 25°C and 4°C significantly reduced hemolysis, however, when applied as an acute challenge although significant, was less marked. Divalent cations (Mg²⁺, Ca²⁺ at 5mM) reduced hemolysis. Varying pH (6.5, 7.2, 8.0) applied chronically marginally reduced hemolysis. The optimized saline (0.9% NaCl; 900 mOsm with sucrose, 5 mM MgCl₂ (37°C)) rapidly and significantly reduced hemolysis compared with saline and Hank's buffered saline solution applied either chronically or acutely.

CONCLUSIONS

These results on the effect of S. aureus α-toxin on erythrocytes showed that optimizing saline could markedly reduce the potency of S. aureus α-toxin. Such modifications to saline could be of benefit during joint irrigation for septic arthritis.

Role of preoperative magnetic resonance imaging in patients with quiescent septic arthritis undergoing primary total hip arthroplasty

AIM

to evaluate the role of preoperative magnetic resonance imaging (MRI) in assessing patients with a history of quiescent hip septic arthritis undergoing total hip arthroplasty.

MATERIALS AND METHODS

retrospective consecutive study of patients with previous history of septic arthritis who underwent MRI scans of their hips prior to primary hip arthroplasty surgery and who also had minimum 2 years follow up postoperatively. Detailed radiographic examinations were obtained, demographic and microbiological data collected. The primary outcome measure was whether a preoperative MRI scan had influenced the surgical decision-making and planning. Rate of recurrence of infection and complications was also collected at final follow up.

RESULTS

sixteen patients with quiescent hip septic arthritis were included. There were 4 males and 12 females with average age at time of primary hip arthroplasty 51.7 years (range 22-75). Five patients had childhood septic arthritis with no documented microbiology data. Eleven patients had adult onset septic arthritis. In patients with childhood septic arthritis the MRI findings were similar to those with degenerative joint disease and had no added value to the routine surgical work up. MRIs of patients with adult onset septic arthritis showed persistent findings of effusion, marrow oedema and soft tissue oedema and had no added value to the surgical planning. All but one underwent single stage total hip arthroplasty. At final follow up, with average 4.6 years (range 2-8), none had a recurrence of infection.

CONCLUSION

In our experience, preoperative MRI scans did not influence the surgical decision making and are not recommended for routine practice in the surgical work up of quiescent septic arthritis prior to total hip arthroplasty.

Thiol/disulfide homeostasis as a novel indicator of oxidative stress during the treatment process of patients with septic arthritis

Objectives

This study aims to investigate dynamic thiol/disulfide homeostasis as a novel indicator of oxidative stress and to find out its association with standard inflammatory markers during the treatment of patients with septic arthritis (SA).

Patients and methods

In this prospective study, a new colorimetric method for measuring thiol/disulfide homeostasis was assessed between May 2013 and October 2014 in 24 patients with SA (14 males, 10 females; mean age 14.5±19.1 years; range, 1 to 80 years) at baseline and the end of the third week of the treatment, and in 24 healthy controls (14 males, 10 females; mean age 12.5±18.7 years; range, 1 to 85 years). Also, standard inflammatory markers such as C-reactive protein (CRP), erythrocyte sedimentation rate, and white blood cell count were evaluated.

Results

At baseline, serum disulfide was higher in SA group compared to the control group, whereas native thiol was lower (p<0.05 for all). At the end of the third week of the treatment, serum disulfide level was lower, whereas the native thiol was higher compared to baseline (p<0.05 for all). In addition, serum disulfide level was positively correlated with CRP (r=0.736, p<0.001) and disulfide/native thiol ratio (r=0.779, p<0.001). Furthermore, in multiple regression analyses, the disulfide level was independently associated with CRP (β=0.226, p=0.005).

Conclusion

Our results suggest that the elevated levels of serum disulfide and standard inflammatory markers at baseline in patients with SA and decreased levels of these parameters are related with oxidative stress. This homeostasis shifted towards disulfide formation due to thiol oxidation. Therefore, thiol/ disulfide homeostasis may be a helpful biomarker for the follow- up in patients with SA.

Septic arthritis due to non-tuberculous mycobacterium without effusion

Septic arthritis is an important but difficult to make diagnosis that leads to significant morbidity and mortality. Joint effusion is generally accepted to be a highly sensitive finding in septic arthritis; however, final diagnosis requires synovial fluid studies. Without a significant joint effusion, it is difficult to obtain synovial fluid. In this case report, we describe the presentation and diagnosis of septic arthritis in the first MTP due to mycobacterium chelonae in a 69 year old man with a history of gout and immunosuppression due to a heart transplant. There was notably no significant effusion in the joint on clinical examination or bedside ultrasound. As the patient was immunosuppressed, arthrocentesis was performed under ultrasound guidance. A needle was clearly visualized in the joint; however, minimal synovial fluid was obtained. The fluid grew Mycobacterium chelonae in culture. Subsequent joint washout revealed purulent synovial fluid that grew out the same bacteria. This case emphasizes the importance of obtaining synovial fluid to evaluate for septic arthritis, even when joint effusion is absent. Ultrasound guidance can facilitate this.

[Septic arthritis of the native joint and after ligamentoplasty : Diagnosis and treatment]

BACKGROUND

Septic arthritis is an acute emergency. It occurs more frequently in patients with pre-existing degenerative or chronic inflammatory joint diseases than in the general population. The causative microorganisms can be introduced in various ways.

DIAGNOSTICS

A rapid diagnosis is of great importance for the success of the therapy. In the clinical examination, the typical signs of inflammation are noticeable. The gold standard is the aspiration of synovial fluid and the subsequent laboratory and microbiological investigation.

THERAPY

A prerequisite for successful therapy is the early initiation of an antimicrobial pathogen-specific treatment and the surgical alleviation of the joint.

Synovial fluid leukocyte cell count before versus after administration of antibiotics in patients with septic arthritis of a native joint

BACKGROUND

Antibiotics have been shown to affect the accuracy of cultures; so antibiotics are held prior to obtaining cultures intra-operatively. No study has evaluated the effects of antibiotics on synovial fluid leukocyte cell count. The purpose of the current study is to compare the leukocyte cell count of native joints with septic arthritis when antibiotics have been given before aspiration and when no antibiotics have been given prior to aspiration.

METHODS

This study was performed at a community hospital and a level 1 urban trauma hospital after IRB approval from both institutions from July 2007 to July 2017. Inclusion criteria comprised of a diagnosis of septic arthritis with positive cultures and a recorded arthrocentesis with cell count performed. Patients with septic arthritis were identified using ICD-9 codes 711.00-711.99 and ICD-10 codes M00 - M02. A retrospective chart review was performed and data was collected. Patients were placed into one of two groups. Group 1 received no antibiotics for two weeks prior to arthrocentesis, group 2 received antibiotics within 24 h prior to arthrocentesis. Demographic information, cell count number and differential, and blood lab values were collected. Timing data was also collected on timing of admission, antibiotics, joint irrigation, and discharge from the inpatient setting.

RESULTS

There were 81 patients meeting final inclusion criteria. The average cell count for the group which received antibiotics (n = 30) was 40,408 ± 29,433 while the average cell count for the group receiving no antibiotics (n = 51) was 93,824 ± 73,875 (p < .0001). The average length of stay was not significantly different between the antibiotic group versus no antibiotic group (14.0 days vs 12.1 days p = .4). The time from admission to arthrocentesis and admission to washout was longer for the antibiotic group versus no antibiotic group (p = .004 and p = .002, respectively).

CONCLUSION

When antibiotics are given prior to arthrocentesis of a septic joint, there is an associated lower synovial fluid leukocyte count compared to when no antibiotics are given prior.

LEVEL OF EVIDENCE

Level III.

2020 French recommendations on the management of septic arthritis in an adult native joint

Septic arthritis (SA) in an adult native joint is a rare condition but a diagnostic emergency due to the morbidity and mortality and the functional risk related to structural damage. Current management varies and the recommendations available are dated. The French Rheumatology Society (SFR) Bone and Joint Infection Working Group, together with the French Language Infectious Diseases Society (SPILF) and the French Orthopaedic and Trauma Surgery Society (SOFCOT) have worked according to the HAS methodology to devise clinical practice recommendations to diagnose and treat SA in an adult native joint. One new focus is on the importance of microbiological documentation (blood cultures and joint aspiration) before starting antibiotic treatment, looking for differential diagnoses (microcrystal detection), the relevance of a joint ultrasound to guide aspiration, and the indication to perform a reference X-ray. A cardiac ultrasound is indicated only in cases of SA involving Staphylococcus aureus, oral streptococci, Streptococcus gallolyticus or Enterococcus faecalis, or when infective endocarditis is clinically suspected. Regarding treatment, we stress the importance of medical and surgical collaboration. Antibiotic therapies (drugs and durations) are presented in the form of didactic tables according to the main bacteria in question (staphylococci, streptococci and gram-negative rods). Probabilistic antibiotic therapy should only be used for patients with serious symptoms. Lastly, non-drug treatments such as joint drainage and early physical therapy are the subject of specific recommendations.

Septic Joints: Finger and Wrist

Infections in the joints of the hand and wrist carry the risk of significant morbidity. Common presenting symptoms include joint redness, swelling, and pseudoparalysis that occurs several days following a penetrating trauma. Diagnostic workup should be expedited, including a laboratory evaluation and arthrocentesis. Imaging, including radiographs, ultrasound, computed tomography, and/or MRI, are helpful tools in diagnosis. Once infection is identified, prompt surgical debridement and antibiotics are required. Once the infection has been managed, hand therapy is initiated to decrease the risk of stiffness. Stiffness is the most common complication following infection; additional reported complications include arthritis, ankylosis, and amputation."

Septic arthritis of the acromioclavicular joint: a case series and review of the literature

OBJECTIVE

To report a case series of three patients with septic arthritis of the acromioclavicular joint and a review of the literature for this condition. Additionally, we developed an algorithm for diagnosing and treating septic arthritis of the acromioclavicular joint.

METHODS

A retrospective review of patients treated at our institution for septic arthritis of the acromioclavicular joint during the collection period was performed and three cases were identified. A review of the English literature on this rare condition was also performed with only 28 cases being identified.

RESULTS

A series of three consecutive patients were treated for septic acromioclavicular arthritis with resolution of the infection. Two patients underwent open surgical debridement and one underwent aspiration. All patients were treated with a minimum of six weeks of tailored intravenous antibiotic therapy.

CONCLUSION

Septic arthritis of the acromioclavicular joint can be difficult to diagnose and requires a high index of suspicion. Surgical debridement, open or arthroscopic, with tailored antibiotic therapy is an effective means for the management of septic arthritis of the acromioclavicular joint. In patients who are unable to have surgical debridement, aspiration and tailored antibiotics have been shown to be effective.

Mid- to Long-Term Outcomes After Deep Infections After Arthroscopic Rotator Cuff Repair

Purpose

To review clinical and subjective outcomes in patients with deep infections after arthroscopic rotator cuff repair.

Methods

All patients in whom deep infections developed after arthroscopic rotator cuff repair at a single center between 2002 and 2016 were retrospectively reviewed. Demographic data, clinical and microbiological findings, and treatment were analyzed. Clinical and subjective outcomes included the Constant score, visual analog scale score for pain, American Shoulder and Elbow Surgeons score, and Simple Shoulder Test score.

Results

Thirty patients could be identified and included in the study. The most commonly isolated pathogens were Staphylococcus epidermidis (36.7%) and Cutibacterium acnes (30.0%). In 26 of 30 patients (86.7%), the infection was treated initially with an open surgical approach, whereas 4 patients (13.3%) underwent arthroscopic revision. A transosseous rotator cuff repair could be performed in 20.0% of patients. A single reoperation was sufficient in 80% of patients, whereas 13.3% required 2 revisions and 6.7% required 3. At the final follow-up of 8.3 years (range, 4-14 years), 26 patients (1 woman and 25 men) were available for outcome evaluation. Significant improvement from the initial surgical procedure to final follow-up was detected in the Constant score (25.7 vs 65.7, P < .001), visual analog scale score for pain (7.0 vs 1.7, P < .001), American Shoulder and Elbow Surgeons score (38.0 vs 76.7, P < .001), and Simple Shoulder Test score (4.0 vs 8.3, P < .001).

Conclusions

Patients with deep infections after arthroscopic rotator cuff repair showed moderate mid- to long-term outcomes.

Level of Evidence

Level IV, therapeutic case series.

Case Studies and Literature Review of Pneumococcal Septic Arthritis in Adults

We saw an increase in this condition related to emergence of Streptococcus pneumoniae serotype 23B.

We conducted a retrospective study on all cases of pneumococcal septic arthritis (SA) in patients >18 years of age reported to the Picardie Regional Pneumococcal Network in France during 2005–2016. Among 1,062 cases of invasive pneumococcal disease, we observed 16 (1.5%) SA cases. Although SA is uncommon in adult patients, the prevalence of pneumococcal SA in the Picardie region increased from 0.69% during 2005–2010 to 2.47% during 2011–2016 after introduction of the pneumococcal 13-valent conjugate vaccine. We highlight the emergence of SA cases caused by the 23B serotype, which is not covered in the vaccine.

Tofacitinib treatment aggravates Staphylococcus aureus septic arthritis, but attenuates sepsis and enterotoxin induced shock in mice

Tofacitinib, a janus kinase inhibitor, is a novel immunosuppressive drug for treatment of rheumatoid arthritis (RA). Septic arthritis (SA) and sepsis caused by Staphylococcus aureus (S. aureus), for which RA patients are at risk, are infections with high mortality. The aim of this study was to investigate the effect of tofacitinib on S. aureus infections using mouse models. In vitro tofacitinib treated mouse splenocytes were stimulated with S. aureus derived stimuli. Mice pre-treated with tofacitinib were inoculated intravenously with either arthritogenic- or septic doses of S. aureus. Arthritis severity and mortality were compared between groups. Additionally, pre-treated mice were challenged with staphylococcal toxin TSST-1 to induce shock. Tofacitinib inhibited splenocyte proliferation and IFN-γ production in response to TSST-1 and dead S. aureus. In SA, tofacitinib treatment aggravated arthritis with more severe bone erosions. However, in sepsis, treated mice displayed significantly prolonged survival compared to controls. Similarly, in staphylococcal enterotoxin-induced shock tofacitinib pre-treatment, but not late treatment dramatically reduced mortality, which was accompanied by decreased levels of TNF-α and IFN-γ. Our findings show that tofacitinib treatment increase susceptibility of SA in mice, but has a positive effect on survival in S. aureus-induced sepsis and a strong protective effect in toxin-induced shock.

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.

Hospital Stays and Medical Expenses Increase Nationwide Among Patients With Septic Arthritis of the Shoulder Who Inject Drugs

The authors determined the proportion of patients nationwide with septic arthritis of the shoulder who inject drugs, evaluated differences in hospitalization outcomes and charges between patients with and without injection drug use (IDU), and quantified demographic trends among patients with IDU from 2000 to 2013. Nationally representative data of patients with a principal discharge diagnosis of shoulder septic arthritis were obtained from the Nationwide Inpatient Sample 2000-2013. Using published algorithms, the authors classified septic arthritis of the shoulder as related or unrelated to IDU. They compared length of stay, leaving against medical advice, number of procedures, and mortality rates between the 2 groups, using regression models to control for age, sex, and race. Fifteen percent (95% confidence interval [CI], 13.6%-16.5%) of septic arthritis cases were associated with IDU. From 2000 to 2013, shoulder septic arthritis associated with IDU increased 4-fold. After controlling for age, sex, and race, individuals who inject drugs stayed in the hospital for 3.7 more days (95% CI, 2.4-5.0), incurred an average of $13,250 more charges for medical care (95% CI, $2635-$23,866), and were 5.54 times more likely (95% CI, 3.22-9.55) to leave against medical advice than those without IDU. From 2000 to 2013, there was an increase in the proportion of patients with IDU-related septic arthritis of the shoulder between 35 and 54 years old and 55 and 64 years old, and an increase in the proportion who were white. Injection drug use-related shoulder septic arthritis is linked to suboptimal inpatient outcomes and greater resource use. [Orthopedics. 2020;43(4):e270-e277.].

Treatment Outcomes in Septic Arthritis of the Foot and Ankle in People Who Inject Drugs

Background:

Although injection drug use (IDU) is a known risk factor for septic arthritis (SA) of the foot and ankle (F&A), disease and hospitalization outcomes are poorly characterized. We evaluated national trends, demographic characteristics, and hospitalization outcomes of SA of the F&A in people who inject drugs vs those who do not.

Methods:

Using the Nationwide Inpatient Sample, we identified all patients aged 15-64 with a principal discharge diagnosis of SA of the F&A from 2000 to 2013 and evaluated if they were related or unrelated to IDU. We assessed differences in demographic characteristics and in-hospital outcomes in these groups.

Results:

From 2000 to 2013, there were an estimated 14,198 hospitalizations for SA of the F&A in the United States, and 11% were associated with IDU (SA-IDU). Compared to SA unrelated to IDU, people with SA-IDU were significantly more likely to be younger, black, and have Medicaid or no insurance. People with SA-IDU were significantly more likely to leave against medical advice (9.7% vs 1.4%, P < .001), have a longer length of stay (9.2 vs 6.8 days, P < .001), and incur increased hospital charges ($58 628 vs $38 876, P = .005). People with SA-IDU were significantly less likely to receive an arthroscopy (1.5% vs 6.5%, P < .001) or arthrotomy (2.2% vs 11.0%, P < .001) of the foot.

Conclusion:

People with SA-IDU of the F&A had suboptimal hospitalization outcomes with greater costs. Recognizing risk factors and proactively addressing potential complications of substance use disorder in the hospital should be prioritized by the orthopedic community.

Level of Evidence:

Level III, retrospective cohort study.

The Epidemiology and Outcomes of Septic Arthritis in the Maltese Islands: A Hospital-Based Retrospective Cohort Study

Objective/Aim:

Septic arthritis is an uncommon but important disease with significant morbidity and mortality, especially if inadequately managed. The aim of this epidemiological study was to identify the characteristics and outcomes of patients treated for septic arthritis at Mater Dei Hospital, Malta, over a 10-year period.

Methods:

This was a retrospective observational study. Patients diagnosed with septic arthritis between 2008 and 2018 were recruited. Cases were identified by reviewing all inhospital episodes of patients diagnosed with septic arthritis according to Newman criteria.

Results:

There were 124 cases of native joint septic arthritis and 138 of prosthetic joint infection. Cases were present amongst all age groups, with the highest incidence amongst those aged 61–70 years for both native and prosthetic infections. Fever was present in around 40% of cases. Raised white cell count was prevalent in 66.9% of native joint infections and 52.9% of prosthetic joints. Elevated C-reactive protein was overwhelmingly seen in most cases, present in 93.5% (median=159.5 mg/L; IQR=85.8–291) of native joints and 92.0% of prosthetic joint infections (median=68.7 mg/L; IQR=20.5–186). Over 55% of patients had one or more risk factors for joint sepsis, diabetes mellitus being the most prevalent clinical comorbidity (22.6% and 24.6% for native and prosthetic joint infections respectively). Synovial cultures were positive in 66% and 82% of native and prosthetic joint aspirates respectively. Staphylococcus aureus was the most commonly isolated organism from both native and prosthetic joint infection, followed by streptococcal infections in native joints and coagulase negative staphylococci and gram-negative infections in prosthetic joints. Fifteen deaths were directly attributed to joint sepsis.

Conclusion:

Absence of fever and elevated white cell count does not exclude the diagnosis. The mortality rate due to septic arthritis in this cohort of patients was found to be 5.7%. All deaths occurred in elderly patients with clinical comorbidities suggesting that this group is at highest risk.

Arthrotomy debridement of arthrostic septic arthritis of the knee is more effective than arthroscopic debridement and delays the need for prosthesis despite progression

BACKGROUND AND OBJECTIVE

40%-50% of this septic arthritis occurs in the knee, despite rapid medical surgical treatment, 24%-50% will have a poor clinical outcome. It is not clear which debridement technique, by arthrotomy or arthroscopy, is more effective in controlling infection, or whether or not previous osteoarthritis worsens the outcome. The objective of this study on septic arthritis of the osteoarthritic knee was to analyse which surgical debridement technique, arthroscopy or arthrotomy, is more effective, the clinical and radiographic outcomes of the patients, and how many go on to require a TKR after the infection has healed.

MATERIAL AND METHODS

A retrospective study was performed in 27 patients with native septic arthritis of the knee. Eighteen were men and the mean age was 64.8 years (30-89years). Fifteen patients were debrided by arthrotomy and 12 by arthroscopy. The effectiveness of debridement in controlling infection, the radiographic progression of the osteoarthritis on the Ahlbäch scale, the need for subsequent replacement, and pain and functional status were analysed using the VAS and WOMAC scales at 52.8±11.2-month follow-up.

RESULTS

The infection was controlled in 93% and 92% of the patients, 13% and 42% required 2 or more surgeries for infection control, 18% and 44.4% showed progression of arthritis in the arthrotomy and arthroscopy groups, respectively. One patient in each group required a knee replacement. The VAS score was superior in the arthrotomy group and there were no differences in WOMAC score.

CONCLUSION

Debridement by arthrotomy in the emergency department by non-sub-specialist knee surgeons is more effective than arthroscopic debridement in controlling septic arthritis of the knee. Surgical debridement of septic arthritis in knees with previous osteoarthritis enabled control of the infection with no pain despite the progression of the osteoarthritis.

Patients with surgically treated culture-negative native joint septic arthritis have less severe disease and better outcomes

Background: Patients with culture-negative septic arthritis patients are often treated surgically but might be successfully managed medically. We compared clinical characteristics and outcomes in patients with culture negative and culture positive native joint monoarticular septic arthritis.Methods: This retrospective study included all patients age ≥18 years admitted to a single, tertiary-care hospital between 1998 and 2015 with native joint monoarticular SA and treated with antibiotics and surgery.Results: Of 306 patients, 85 had negative and 221 had positive cultures. Mean C-reactive protein (p < .01) and mean percentage of peripheral polymorphonuclear cells (p = .01) were higher in culture-positive patients who had higher intensive care unit admission rates (16.7% vs. 4.7%, respectively, [p < .01]), longer length of hospital stay (11.4 vs. 7.1 days, respectively, [p < .01]) and higher mortality rates within 30 days (0% vs. 5.5%, respectively,[p = .02]). Of culture-negative patients, 28.6% received an alternative diagnosis within one year. Logistic regression models showed that culture positive patients had an adjusted odds ratio for length of stay of 4.5 (2.69, 7.51), intensive care unit admission of 5.76 (1.31, 25.22), discharge to rehabilitation of 4.7 (2.28, 9.71) and an alternative diagnosis within one year of 0.05 (0.02, 0.15) compared to culture negative patients.Conclusion: Patients with culture-negative native joint septic arthritis had less severe disease, better outcomes and higher rates of alternative diagnosis within one year than patients with positive cultures.

Centrifugation may eliminate false-positive leucocyte esterase strip test results caused by inflammatory arthritis in the diagnosis of knee infection: A pilot study

Aims

The purpose of this study was to validate our hypothesis that centrifugation may eliminate false-positive leucocyte esterase (LE) strip test results caused by autoimmune diseases in the diagnosis of knee infection.

Methods

Between January 2016 and May 2019, 83 cases, including 33 cases of septic arthritis and 50 cases of aseptic arthritis, were enrolled in this study. To further validate our hypothesis, another 34 cases of inflammatory arthritis from the Department of Rheumatology of our institution were also included. After aspiration, one drop of synovial fluid was applied to LE strips before and after centrifugation. The results were recorded after approximately three minutes according to the different colour grades on the colour chart. The differences of LE results between each cohort were analyzed.

Results

Before centrifugation, 46% (23/50) of the LE strip tests in the aseptic arthritis group were false-positives. Most of the false-positive results were due to inflammatory arthritis; after centrifugation, 78.3% (18/23) of the tests yielded negative results. Similar results were observed in cases from the Department of Rheumatology. The sensitivity of the centrifuged LE strip test was 0.818 (0.639 to 0.924), which is still an acceptable level compared with the uncentrifuged results, which yielded a sensitivity of 0.909 (0.745 to 0.976). However, the specificity was increased from 0.540 (0.395 to 0.679) to 0.900 (0.774 to 0.963) after centrifugation.

Conclusion

Although inflammatory arthritis can yield a false-positive LE strip test result in the diagnosis of knee infection, centrifugation may eliminate these false-positive results.

Cite this article: Bone Joint Res. 2020;9(5):236–241.

A Bioinformatic Approach to Utilize a Patient's Antibody-Secreting Cells against Staphylococcus aureus to Detect Challenging Musculoskeletal Infections

Noninvasive diagnostics for Staphylococcus aureus musculoskeletal infections (MSKI) remain challenging. Abs from newly activated, pathogen-specific plasmablasts in human blood, which emerge during an ongoing infection, can be used for diagnosing and tracking treatment response in diabetic foot infections. Using multianalyte immunoassays on medium enriched for newly synthesized Abs (MENSA) from Ab-secreting cells, we assessed anti-S. aureus IgG responses in 101 MSKI patients (63 culture-confirmed S. aureus, 38 S. aureus-negative) and 52 healthy controls. MENSA IgG levels were assessed for their ability to identify the presence and type of S. aureus MSKI using machine learning and multivariate receiver operating characteristic curves. Eleven S. aureus-infected patients were presented with prosthetic joint infections, 15 with fracture-related infections, 5 with native joint septic arthritis, 15 with diabetic foot infections, and 17 with suspected orthopedic infections in the soft tissue. Anti-S. aureus MENSA IgG levels in patients with non-S. aureus infections and healthy controls were 4-fold (***p = 0.0002) and 8-fold (****p < 0.0001) lower, respectively, compared with those with culture-confirmed S. aureus infections. Comparison of MENSA IgG responses among S. aureus culture-positive patients revealed Ags predictive of active MSKI (IsdB, SCIN, Gmd) and Ags predictive of MSKI type (IsdB, IsdH, Amd, Hla). When combined, IsdB, IsdH, Gmd, Amd, SCIN, and Hla were highly discriminatory of S. aureus MSKI (area under the ROC curve = 0.89 [95% confidence interval 0.82-0.93, p < 0.01]). Collectively, these results demonstrate the feasibility of a bioinformatic approach to use a patient's active immune proteome against S. aureus to diagnose challenging MSKI.

A Retrospective Review of Native Septic Arthritis in Patients: Can We Diagnose Based on Laboratory Values?

Introduction The accurate diagnosis of acute septic arthritis is essential to initiating appropriate treatment and minimizing potential cartilage damage. A synovial fluid cell count of 50,000 cells/mm³ has been used as a diagnostic cutoff for acute septic arthritis, although data supporting this is lacking. The purpose of this study was to assess the efficacy of synovial cell counts to predict septic arthritis in patients with symptomatic native joints. Methods A retrospective review was performed of patients who were evaluated for septic arthritis at a single institution with the use of synovial fluid analysis and adjunctive lab tests. Exclusion criteria included history of a total joint arthroplasty of the affected joint or immunocompromised state. A true infection was considered on the basis of positive or negative synovial aspirate cultures. We evaluated the synovial cell count, synovial polymorphonuclear cell percentile (% neutrophils), serum white blood cell (WBC), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) in order to determine their association and predictive power in a true infection. Results Of the 65 patients included in the study, 40 (61.5%) had a positive culture for septic arthritis and 25 (38.5%) had negative cultures. Patients with positive cultures had a larger median % neutrophils than patients with negative cultures (median: 93 vs. median: 86, P=0.041). They also tended to have higher serum CRP levels compared to negative culture patients (median: 142.30 vs. 34.20, P=0.051). No outcomes were independently highly effective in discriminating between patient groups (area under the curve (AUC) ≤ 0.67). There was no significant difference between the synovial cell counts in patients with culture positive septic arthritis and patients with negative cultures (median: 32435 vs 35385, P = 0.94).  Conclusion Patients with culture proven septic arthritis had larger % neutrophils. However, there were no other statistically significant differences between patient groups regarding ESR, CRP, WBC, or cell count aspiration at the time of diagnosis. No synovial cell count level was highly effective in discriminating patients with a positive culture for septic arthritis from patients with negative cultures.

Platelet-rich plasma lysate displays antibiofilm properties and restores antimicrobial activity against synovial fluid biofilms in vitro

Infectious arthritis is difficult to treat in both human and veterinary clinical practice. Recent literature reports Staphylococcus aureus as well as other gram-positive and gram-negative isolates forming free-floating biofilms in both human and equine synovial fluid that are tolerant to traditional antimicrobial therapy. Using an in vitro equine model, we investigated the ability of platelet-rich plasma (PRP) formulations to combat synovial fluid biofilm aggregates. Synovial fluid was infected, and biofilm aggregates allowed to form over a 2-hour period. PRP was collected and processed into different formulations by platelet concentration, leukocyte presence, and activation or lysis. Infected synovial fluid was treated with different PRP formulations with or without aminoglycoside cotreatment. Bacterial load (colony-forming unit/mL) was determined by serial dilutions and plate counting at 8 hours posttreatment. All PRP formulations displayed antimicrobial properties; however, formulations containing higher concentrations of platelets without leukocytes had increased antimicrobial activity. Lysis of PRP and pooling of the PRP lysate (PRP-L) from multiple horses as compared to individual horses further increased antimicrobial activity. This activity was lost with the removal of the plasma component or inhibition of the proteolytic activity within the plasma. Fractionation of pooled PRP-L identified the bioactive components to be cationic and low-molecular weight (<10 kDa). Overall, PRP-L exhibited synergism with amikacin against aminoglycoside tolerant biofilm aggregates with greater activity against gram-positive bacteria. In conclusion, the use of PRP-L has the potential to augment current antimicrobial treatment regimens which could lead to a decrease in morbidity and mortality associated with infectious arthritis.

Clinical features, risk factors, and outcomes of septic arthritis in patients on maintenance hemodialysis

The aim of this study was to investigate the clinical features, risk factors, and outcomes of septic arthritis in patients on maintenance hemodialysis (HD). We systematically reviewed medical records of 16 HD patients with septic arthritis admitted to our hospital from April 2008 to April 2018. A total of 16 HD in patients with bloodstream infection but without septic arthritis were randomly selected as controls. The incidence of septic arthritis in our patient group was 0.2% per year. Organisms isolated were Staphylococcus aureus in 11 (68.7%), Gram-negative bacilli in 3, streptococci in 1, and fungi in 1. Patients with septic arthritis were significantly older (72.7 ± 9.4 vs 63.5 ± 8.7 years, p = 0.035) and had more joint diseases (62.5% vs 12.5%, p = 0.003) and a longer duration of hospitalization (35.2 ± 5.7 vs 22.1 ± 3.5 days, p = 0.021) than the control group. In a logistic regression analysis, patients with older age and more joint diseases were more likely to have septic arthritis compared with controls (OR = 1.39, p = 0.024 and OR = 3.24, p = 0.003, respectively). These findings indicate that old age and joint diseases (osteoarthritis or inflammatory arthritis) were independent risk factors for septic arthritis in patients on HD when bloodstream infection occurred. Key Points • Patients with septic arthritis were significantly older and had more joint diseases than the control group. • Old age and joint diseases are independent risk factors for septic arthritis in patients on HD when bloodstream infection occurs.

Medical versus surgical treatment in native hip and knee septic arthritis

OBJECTIVE

Antibiotic treatment and arthroscopic or open drainage is the gold standard for septic arthritis. Full recovery takes time after surgery and hospital stay is longer than for arthrocentesis at the bedside. We aimed to evaluate the effectiveness of arthrocentesis (medical approach) versus a surgical approach.

METHOD

We retrospectively included 97 cases of native joint arthritis (hip and knee) between 2010 and 2017. The primary outcome was treatment failure of medical and surgical approaches (defined as surgical intervention within 7 days following diagnosis). Risk factors of failure were identified by univariable and multivariable logistic regression.

RESULTS

We included 72 cases of knee arthritis, of which 43 and 29 were treated medically and surgically, respectively; 25 cases of hip arthritis, of which 8 and 17 were treated medically and surgically, respectively. Failure was observed in 39.2% of cases in the medical group and in 30.4% in the surgical group (P=0.2) (37.5% vs. 52.9% and 39.5% vs. 17.2% for hip and knee, respectively). The univariate analysis identified age and male sex as risk factors for failure (P=0.048 and P=0.02, respectively), but only age was independently associated with failure (P=0.04). Hospital length of stay was 12 days shorter in the medical group (21 vs. 33 days, P=0.02), sequelae were less frequent and less important in the medical group (31.7% vs. 60%).

CONCLUSION

The medical treatment seems to be as effective as the surgical treatment for native joint septic arthritis with a shorter hospital stay and better functional outcome. Further prospective studies are warranted.

Synovial Cell Count Poorly Predicts Septic Arthritis in the Presence of Crystalline Arthropathy

Introduction: A synovial cell count greater than 50,000/mm³ is the threshold most commonly used to diagnose septic arthritis. This lab value may be nonspecific in the setting of crystalline arthropathy. The purpose of this study was to evaluate the accuracy of diagnosing septic arthritis using a synovial cell count cut-off of 50,000/mm³ in the setting of crystalline arthropathy.

Methods: This was a retrospective review of joint aspirations performed between July 1^st, 2013 and June 30^th, 2016. Synovial fluid samples were evaluated for cell count, crystals, Gram stain, and culture. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the synovial markers were calculated.

Results: During the study period, 738 joint aspirations were sent for testing, of which 358 aspirations in 348 patients met inclusion criteria. There were 49 (13.7%) cases of culture-positive septic arthritis, and 47 patients underwent surgical irrigation and debridement. Gout and pseudogout crystals were present in 163 aspirates (45.5%). Three joints (0.8% overall rate) had concomitant crystalline arthropathy and septic arthritis, each of which had a synovial WBC ≥85,000/mm³. Increasing the WBC count cutoff to 85,000/mm³ demonstrated a specificity of 100%, but a PPV of 12.0%.

Conclusions: A cut-off of 85,000/mm³ may be more appropriate to diagnose concomitant septic arthritis and crystalline arthropathy. We recommend medical management and observation in patients with crystal-positive joint aspirations unless the synovial cell count is elevated above 85,000/mm³. Prospective studies using this treatment guideline are needed to evaluate its validity and accuracy.

The difference between native septic arthritis and prosthetic joint infections: A review of literature

Current literature occasionally considers septic arthritis in native joints and prosthetic joint infections as equal pathologies. However, significant differences can be identified. The aim of this review of literature is to describe these differences in definitions, pathology, diagnostic workups, treatment strategies, and prognosis.

Boron doped silver-copper alloy nanoparticle targeting intracellular S. aureus in bone cells

OBJECTIVES

Alloyed metallic nanoparticles of silver and copper are effective against intracellular infection. However, systemic toxicity may arise due to the non-specific delivery of the nanoparticles. In addressing the issue, this study deals with the targeting of silver-copper-boron (ACB) nanoparticles to infected osteoblasts, which could decrease systemic toxicity and form the basis of targeting specific markers expressed in bone infections.

METHODS

ACB nanoparticles were synthesized and conjugated to the Cadherin-11 antibody (OBAb). The effect of targeting nanoparticles against extracellular and intracellular S. aureus was determined by enumeration of bacterial growth. The binding of the targeting nanoparticles to infected osteoblasts as well as the visualization of live/dead bacteria due to treatment was carried out using fluorescence microscopy. MTT assay was used to determine the viability of osteoblasts with different concentrations of the nanoparticles.

RESULTS

The ACB nanoparticles conjugated to OBAb (ACB-OBAb) were effective against extracellular S. aureus. The ACB-OBAb nanoparticles showed a 1.32 log reduction of intracellular S. aureus at a concentration of 1mg/L. The ACB-OBAb nanoparticles were able to bind to the infected osteoblast and showed toxicity to osteoblasts at levels ≥20mg/L. Also, the percentage of silver, copper, and boron in the nanoparticles determined the effectiveness of their antibacterial activity.

CONCLUSION

The ACB-OBAb nanoparticles were able to target the osteoblasts and demonstrated significant antibacterial activity against intracellular S. aureus. Targeting shows promise as a strategy to target specific markers expressed on infected osteoblasts for efficient nanoparticle delivery, and further animal studies are recommended to test its efficacy in vivo.

Septic Arthritis of the Hip in Children: A Critical Analysis Review

Septic arthritis of the hip is a common and potentially devastating condition in children. Septic arthritis is most commonly caused by Staphylococcus aureus, but other pathogens should be considered on the basis of patient age and presence of risk factors. Diagnosis of septic arthritis is based on history and physical examination, laboratory tests, radiographs, ultrasound, and arthrocentesis. Treatment comprises empiric antibiotics and joint debridement, and antibiotics are subsequently tailored on the basis of culture data, local resistance patterns, and clinical response. Late sequelae of septic arthritis include osteonecrosis, chondrolysis, growth disturbance, subluxation or dislocation, and progressive ankylosis. Surgical treatments to address these issues have been described.

Performance of a new rapid diagnostic test the lactate/glucose ratio of synovial fluid for the diagnosis of septic arthritis

OBJECTIVE

To evaluate the diagnostic performance of the synovial lactate, glucose and lactate/glucose ratio assay for the diagnosis of septic arthritis.

METHODS

In this monocentric cross-sectional study, synovial fluids were prospectively obtained from patients with acute joint effusion (<30 days) on native joint. Septic arthritis was defined using Newman's criteria. To evaluate diagnostic performance, Receiver Operating Characteristic (ROC) curves with Area under the curve (AUC), Sensitivities (Se), Specificities (Sp), LR+ their 95% confidence intervals were calculated. Synovial fluid cultures with gram staining, crystal analyses, synovial fluid white blood cell counts (WBC), lactate and glucose assays were performed.

RESULTS

A total of 233 synovial fluids were included. 25 patients had septic arthritis and 208 had non-septic arthritis (104 crystal-induced arthritis, 15 RA, 8 SpA, 6 reactive arthritis, and 75 acute arthritis of undifferentiated origin). Synovial lactate/glucose ratio performed higher than the synovial lactate or glucose assay separately (AUC: 0.859 [0.772-0.945]). Best synovial lactate/glucose ratio threshold to differentiate septic arthritis from non-septic arthritis was 5 Se 52% [0.34-0.7], Sp 98.1% [0.95-0.99], LR+ 27.0[9.50-76.00]).

CONCLUSION

The diagnostic performance of synovial lactate/glucose allows septic arthritis to be effectively and very quickly distinguished from other types of arthritis.

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.

Review on calcium- and magnesium-based silicates for bone tissue engineering applications

Bone is a self-engineered structural component of the human body with multifaceted mechanical strength, which provides indomitable support to the effective functioning of the human body. It is indispensable to find a suitable biomaterial for substituting the bone as the bone substitute material requirement is very high due to the rate of bone fracture and infection lead to osteoporosis in human beings increases rapidly. It is not an easy task to design a material with good apatite deposition ability, a faster rate of dissolution, superior resorbability, high mechanical strength, and significant bactericidal activity. Since the synthetic hydroxyapatite was not able to achieve the dahlite phase of hydroxyapatite (natural bone mineral phase), silicates emerged as an alternate biomaterial to meet the need for bone graft substitutes. All silicates do not exhibit the properties required for bone graft substitutes, as their composition and methodology adopted for the synthesis are different. Calcium, magnesium, and silicon play a major role in the formation of bone mineral and their metabolism during bone formation. In this review, the relationship between composition and activity of calcium, magnesium-based silicates have been discussed along with the future scope of these materials for hard tissue engineering applications.

Persistent candida arthritis successfully treated with micafungin instillation and surgery. A case report

We report a rare case of C. krusei knee arthritis treated with instillation of micafungin and arthroscopy. A 49-year-old man hospitalized for treatment of Acute Myeloid Leukemia developed knee arthritis with C. krusei. He was treated with a combination of arthroscopic debridement, intravenous as well as intra-articular micafungin. Serum and intra-articular concentrations of micafungin were determined. After instillation of micafungin in the knee and arthroscopic debridement, the patient completely recovered.

Risk factors for failure of eradicating infection in a single arthroscopic surgical procedure for septic arthritis of the adult native shoulder with a focus on the volume of irrigation

BACKGROUND

Septic arthritis of a native joint is relatively rare but is still a challenging and important orthopedic emergency. Most previous reports have focused on the clinical outcomes rather than the risk factors for failure in arthroscopic surgery.

METHODS

We retrospectively reviewed the records of patients with septic monoarthritis of the shoulder who underwent arthroscopic irrigation and débridement between January 2007 and January 2019. All patients were divided into 2 groups according to recurrence after a single arthroscopic surgical procedure: eradicated group or recurred group. To identify risk factors affecting the recurrence of septic arthritis of the shoulder after arthroscopic surgery, the following parameters were considered: age; sex; involved side; presentation of rotator cuff tear; volume of irrigation; bacterial organism involved; preoperative erythrocyte sedimentation rate, C-reactive protein level, and white blood cell count in blood and joint fluid; diabetes mellitus; and hypertension. We compared the eradicated and recurred groups regarding the presence of potential risk factors.

RESULTS

The study included 97 patients with a mean age of 61 years. Septic arthritis of the shoulder was eradicated completely with a single arthroscopic surgical procedure in 85 patients. However, a second arthroscopic surgical procedure was necessary in 12 patients (12.4%) because of infection recurrence. No significant differences were found between groups except in the volume of irrigation (P < .001).

CONCLUSIONS

Most patients with septic arthritis (87.6%) of native shoulders were effectively treated with a single arthroscopic irrigation and débridement. The amount of irrigation may be the most important factor for preventing the need for additional surgical management.

Septic Arthritis and the Opioid Epidemic: 1465 Cases of Culture-Positive Native Joint Septic Arthritis From 1990-2018

BACKGROUND

The clinical spectrum of septic arthritis in the era of the opioid crisis is ill-defined.

METHODS

This is a retrospective chart review of 1465 cases of culture-positive native joint septic arthritis at Boston teaching hospitals between 1990 and 2018.

RESULTS

Between 1990-2008 and 2009-2018, the proportion of septic arthritis cases involving people who inject drugs (PWID) rose from 10.3% to 20% (P < .0000005). Overall, methicillin-sensitive Staphylococcus aureus (MSSA) caused 41.5% of cases, and methicillin-resistant Staphylococcus aureus (MRSA) caused 17.9%. Gram-negative rods caused only 6.2% of cases. Predictors of MRSA septic arthritis included injection drug use (P < .001), bacteremia (P < .001), health care exposure (P < .001), and advancing age (P = .01). Infections with MSSA were more common in PWID (56.3% vs 38.8%; P < .00001), as were infections with MRSA (24% vs 16.8%; P = .01) and Serratia sp. (4% vs 0.4%; P = .002). Septic arthritis in the setting of injection drug use was significantly more likely to involve the sacroiliac, acromioclavicular, and facet joints; 36.8% of patients had initial synovial fluid cell counts of <50 000 cells/mm³.

CONCLUSIONS

Injection drug use has become the most common risk factor for septic arthritis in our patient population. Septic arthritis in PWID is more often caused by MRSA, MSSA, and Serratia sp., and is more prone to involve the sacroiliac, acromioclavicular, sternoclavicular, and facet joints. Synovial fluid cell counts of <50000 cells/mm³ are common in culture-positive septic arthritis.

[Native joint infections]

Joint infections are a great challenge for the treating physicians. Infection of a native joint can result in the rapid destruction of the joint if treatment is inadequate or delayed and is associated with severe life-threatening diseases, such as sepsis. This article presents a detailed overview of the treatment of joint infections of native joints with a focus on the diagnostic approach and treatment decisions. Infections in native joints are caused either endogenously by hematogenic spreading or are caused by exogenous factors. A relevant proportion of joint infections in native joints occur in connection with iatrogenic measures, such as operations, synovial punctures and joint infiltrations. Fundamentally, acute infections represent an orthopedic surgical emergency, which is associated with the necessity for immediate operative measures. The best possible success can only be achieved by an interaction between early diagnosis, an adequate surgical approach and a tailor-made anti-infectious treatment. This is also the case with periprosthetic infections, which will be dealt with in detail in a second article.

Secondary purulent infections of the elbow joint: a retrospective, single-center study

Background

Septic arthritis of the elbow joint is a rare condition. Limited data is available on infections of the elbow joint following trauma or prior surgery on this joint. The aim of this study was to describe the etiology, comorbidities, bacterial spectrum and therapy of secondary purulent elbow infections.

Methods

Patients treated in our hospital were selected through retrospective chart review between 2006 and 2015. We included all patients with an empyema of the elbow after a trauma or surgical intervention on this joint. 30 patients between 26 and 82 years (mean: 52.47) were included.

Results

Seven patients (23.3%) were female, 23 (76.7%) male. 22 patients (73.3%) had a history of trauma, eight (26.7%) had prior elective surgeries on their elbow. Between one and 25 surgeries (mean: 5.77) were necessary for treatment. In nine patients, debridement and synovectomy were sufficient, eight patients (26.7%) received resection of the elbow joint. One patient was treated with a chronic fistula. In 18 patients (60%), cultures of aspiration/intraoperative swabs were positive for Staphylococcus aureus, four of these were methicillin-resistant. Four patients (13.3%) had positive cultures for Staphylococcus epidermidis, in five patients (16.7%) no bacteria could be cultured.

Conclusions

Secondary infections of the elbow joint are a rare disease with potentially severe courses, requiring aggressive surgical treatment and possibly severely impacting elbow function. Staphylococcus aureus was the most common bacteria in secondary infections and should be addressed by empiric antibiotic treatment when no suspicion for other participating organisms is present.