Synovial calprotectin in prosthetic joint infection. A systematic review and meta-analysis of the literature.

INTRODUCTION: Calprotectin is a protein endowed with antimicrobial properties, rendering it a distinctive marker for infection. Two methods are currently available for the assay of calprotectin: the enzyme-linked immunosorbent assay (ELISA) and the lateral flow test (LFT). We aimed to assess the diagnostic accuracy of synovial fluid calprotectin and to compare the accuracy of the laboratory-based test and the qualitative assessment for the diagnosis of hip and knee prosthetic infection. MATERIALS AND METHODS: We searched (from inception to November 2023) MEDLINE, Scopus, EMBASE, Web of Science, and Cochrane for studies on calprotectin in the diagnosis of periprosthetic joint infection (PJI). Sensitivity, specificity, positive and negative likelihood ratio (LR), and diagnostic odds ratio were analyzed. The receiver-operating curve for each method was calculated. RESULTS: We included 14 articles in our meta-analysis, including 902 patients who underwent total hip and knee arthroplasties revision; 331 (37%) had a joint infection according to MSIS, MSIS-modified criteria, ICM 2018 and EBJIS 2021. Considering the false-positive result rate of 6% and false-negative result rate of 7%, pooled sensitivity and specificity were 0.92 (95% CI 0.89-0.94) and 0.93 (0.91-0.95), respectively. The area under the curve (AUC) was 0.93 (95% CI 0.91-0.94). No statistical differences in terms of sensitivity and specificity were found between ELISA and LFT. The pooled sensitivity and specificity of the two calprotectin assessment methods were: LFT 0.90 (95% CI 0.869-0.935) and 0.92 (95% CI 0.894-0.941), respectively; ELISA 0.96 (95% CI 0.914-0.986) and 0.97 (95% CI 0.934-0.988), respectively. The diagnostic odds ratio of the ELISA was superior to that of the LFT (906.6667, 95% CI 271.2686-3030.3712 versus 113.8886, 95% CI 70.4001-184.2414; p < 0.001). The AUC for ELISA and LFT was 0.968 (95% CI 0.944-0.984) and 0.915 (95% CI 0.895-0.933), respectively. CONCLUSIONS: Detection of synovial calprotectin is an accurate test for diagnosis of hip and knee prosthetic infections. The diagnostic accuracy of the two calprotectin assessment methods is almost comparable. The LFT is a valid, rapid, and more available diagnostic tool, particularly to rule out PJI.

Articulating spacers in elderly patients affected by periprosthetic knee infection: clinical findings and outcome.

OBJECTIVE: Although the two-stage technique is a validated strategy in periprosthetic joint infections, there is a lack of data on the patients' clinical outcomes after the spacer placement. This study aims at evaluating the quality of life, joint function, and pain in patients over 70 years affected by periprosthetic joint infection treated with a two-stage exchange using metal on polyethylene spacers. PATIENTS AND METHODS: We conducted a follow-up study to evaluate the quality of life and functionality of consecutive patients over 70 years treated for PJI at our institution using a validated assessment set including the Western Ontario and Mac Master University (WOMAC) score, Knee Society Score (KSS), numerical rating scale (NRS). Knee Range of Movement (ROM) before and after the surgery was also analyzed. RESULTS: Forty-five patients with a mean age of 76 ± 5.3 years were included. Coagulase-negative staphylococci were the most isolated microorganisms. In the preoperative study group, the WOMAC score was 48.4 ± 18.9, and the KSS objective and functional scores were 37.6 ± 17.3 and 27.6 ± 22.3, respectively. NRS was 7.3 ± 1.8. After three months of follow-up, we found better results than preoperative clinical evaluation. We retrieved similar results comparing our post-operative PROMS (WOMAC and KSS scores) with published thresholds for treatment success two months after primary total knee arthroplasty. The infection eradication rate was 87%. CONCLUSIONS: The two-stage technique confirmed its efficacy in the treatment of PJI. Patients over 70 years who had undergone the first stage of the two-stage technique for PJI showed a good quality of life and knee function.

Characteristics of viral pneumonia in the COVID-19 era: an update.

Influenza virus, rhinovirus, and adenovirus frequently cause viral pneumonia, an important cause of morbidity and mortality especially in the extreme ages of life. During the last two decades, three outbreaks of coronavirus-associated pneumonia, namely Severe Acute Respiratory Syndrome, Middle-East Respiratory Syndrome, and the ongoing Coronavirus Infectious Disease-2019 (COVID-19) were reported. The rate of diagnosis of viral pneumonia is increasingly approaching 60% among children identified as having community-acquired pneumonia (CAP). Clinical presentation ranges from mild to severe pneumonitis complicated by respiratory failure in severe cases. The most vulnerable patients, the elderly and those living with cancer, report a relevant mortality rate. No clinical characteristics can be useful to conclusively distinguish the different etiology of viral pneumonia. However, accessory symptoms, such as anosmia or ageusia together with respiratory symptoms suggest COVID-19. An etiologic-based treatment of viral pneumonia is possible in a small percentage of cases only. Neuraminidase inhibitors have been proven to reduce the need for ventilatory support and mortality rate while only a few data support the large-scale use of other antivirals. A low-middle dose of dexamethasone and heparin seems to be effective in COVID-19 patients, but data regarding their possible efficacy in viral pneumonia caused by other viruses are conflicting. In conclusion, viral pneumonia is a relevant cause of CAP, whose interest is increasing due to the current COVID-19 outbreak. To set up a therapeutic approach is difficult because of the low number of active molecules and the conflicting data bearing supportive treatments such as steroids.

Post-arthroscopic septic arthritis of the knee. Analysis of the outcome after treatment in a case series and systematic literature review.

OBJECTIVE: The aim of this study was to review the characteristics of patients with septic arthritis after ACL reconstruction comparing our results with those deriving from the literature review. PATIENTS AND METHODS: Patients with suspected post arthroscopic septic arthritis of the knee occurring within 6 months after surgery were evaluated to be included in the investigation. Septic arthritis was defined by i) clinical evidence; ii) laboratory investigations; iii) synovial fluid leukocyte count of more than 2,5 x 104/µL or positive cultures obtained by synovial fluid aspirate. RESULTS: Thirty-nine patients (median age 25 years, range 17-42) with septic arthritis following ACL reconstruction were enrolled. Staphylococci were the main bacteria identified. Resolution within 4 weeks of local signs was observed more frequently in those receiving arthroscopic debridement and synovectomy coupled with antibiotic therapy (18/21 vs. 9/18, p<0.05). Fever was present in 33 (85%) cases. Fever disappearance and CRP normalization within 4 weeks were reported more frequently in patients receiving intravenous antibiotics (17/20 vs. 9/19, p<0.05). Similar findings were retrieved by literature analysis. CONCLUSIONS: An intravenous antibiotic therapy with surgical debridement is the first-line treatment for septic arthritis. Staphylococci are the main causative agents, justifying an empiric therapeutic approach with an anti-MRSA agent and cephalosporin.

Knee Septic Arthritis after Arthroscopy: Incidence, Risk Factors, Functional Outcome, and Infection Eradication Rate.

Purpose Septic knee arthritis following arthroscopy is a rare but dreaded complication. Definition and management of knee deep infections are quite discussed in literature. In this review, literature regarding infections after knee arthroscopy is analyzed highlighting the incidence, causative bacteria, risk factors as well as clinical outcomes. Methods We performed a review of the literature matching the following key words: "septic arthritis" OR "infection" AND "arthroscopy" AND "knee." Knee arthroscopic procedures, such as debridement, meniscectomy, meniscus repair, synovectomy, microfracture, and lateral release, were considered. Complex procedures, such as ligament reconstruction, fractures, or complex cartilage repair techniques, were not included. Results Thirteen studies were included in this review. Incidence of infection ranged from 0.009 to 1.1% in patients undergoing simple arthroscopic procedures. Staphylococci are the most commonly isolated organisms from postarthroscopy infection. Use of intraoperative intra-articular steroids, smoking, obesity, male sex, diabetes, number of procedures performed during surgery, time of surgery, and tourniquet time of more than 60 minutes have been certified as risk factors for knee infection. Conclusion Postarthroscopy septic arthritis of the knee causes significant morbidity, usually requiring readmission to the hospital, at least one additional operation, and prolonged antibiotic therapy, both intravenous and oral. Prompt diagnosis and treatment are associated with a high success rate. Level of Evidence Level IV, systematic review of I-IV studies.

RELEASE OF GENTAMICIN FROM CEMENT SPACERS IN TWO-STAGE PROCEDURES FOR HIP AND KNEE PROSTHETIC INFECTION: AN IN VIVO PHARMACOKINETIC STUDY WITH CLINICAL FOLLOW-UP.

Eighteen patients undergoing two-stage exchange arthroplasty for infected total hip or knee arthroplasty using gentamicin-loaded bone cement spacers (80g bone cement, 2 g gentamicin and 2 g clindamycin) were studied. The concentration of gentamicin eluted from the spacers was assessed on samples of blood, urine, and drainage fluid that were collected from each patient at set intervals during the 48 hours following the first-stage surgery. The hip and knee cement spacers showed similar curve of release over the first postoperative hours (early peak followed by slow release), but the mean gentamicin concentration in the drainage fluid was higher in patients with hip spacers compared to patients with knee spacers (30.61±19.47 mg/L vs 17.43±13,63 mg/L, p less than 0.05). In patients with hip spacers, the mean, maximum, and minimum concentration of gentamicin was higher with respect to the minimum inhibitory concentration (MIC) break point for Staphylococcus spp, Pseudomonas Aeruginosa and Enterobacteriaceae throughout the first postoperative 48 h. Conversely, in 25% of patients with a knee spacer a drug concentration below the MIC break point for Gram negative bacteria was found in the drainage fluid after 12 h. Gentamicin levels in the blood samples were negligible over the entire time interval and were steadily well below the renal toxicity reference. The highest urinary concentration of gentamicin was observed between 4 and 9 h postoperatively. Subsequently, it gradually declined until 48 h. Clinically, the rate of cure was 100% at a mean follow-up of 113 weeks (range 90-182). Gentamicin-loaded cement spacers offer the advantage of achieving early high concentrations of the antibiotic directly at the site of infection but especially in the knee a systemic antibiotic therapy must be given as a complement to the spacer implantation to eradicate periprosthetic joint infection (PJI).

Factors related to outcome of early and delayed prosthetic joint infections.

UNLABELLED: In this prospective study, we evaluate the impact of adherence to a diagnostic and therapeutic protocol on prosthetic joint infections (PJI) diagnostic accuracy and outcome. PATIENTS AND METHODS: Patients with early or delayed PJI referred over a 5-year period were included. Diagnosis was based on characteristic clinical signs, radiographic findings and microbiological evidence. Antibiotics were chosen on the basis of microbiological findings, and drugs active against methicillin-resistant staphylococci were administered if no microbiological evidence had been obtained. RESULTS: Inclusion criteria were met in 159 cases (median age 64 years, males 45%). 56 were early infections and 103 delayed infections. Comorbidities were reported in 99 (62%) cases. Positive cultures were obtained in 122/159 (77%), coagulase-negative staphylococci were cultured in 20%, Staphylococcus aureus in 28%, and Pseudomonas aeruginosa in 7%. In early infections, cure rate after debridement and antibiotic therapy was 80%. In delayed infections, cure rate after two-stage exchange was 85%. Of 28 patients with delayed infection treated with antibiotics without surgery, only 8 (29%) infections were suppressed 48 weeks after treatment discontinuation. Rifampin afforded a better outcome. CONCLUSION: Appropriate diagnostic and surgical procedures and microbiologically driven antibiotic therapy including rifampin are recommended to improve diagnostic accuracy and outcome.