Can pre-analytical procedures improve microbiological culture yield in patients with periprosthetic infections?

BACKGROUND: The detection of causative pathogens plays a crucial role in the diagnosis and targeted treatment of periprosthetic joint infections (PJI). While there have been improvements in analytic methods in the past, pre-analytical procedures have not yet been sufficiently investigated. The objective of this study was to compare the culture yield of four different pre-analytical procedures. METHODS: Patients with perioperative diagnosis of PJI were included in a single center cross-sectional study (2021-2022). Tissue samples (n = 20) of each patient were randomly and equally distributed to each of the four study arms. Tissue samples were either send to the laboratory without culture medium (group A) or were transported in thioglycolate medium immediately after sampling at three different temperatures (room temperature, 4 °C, 37° for 24 h; group B-D). Culture media were investigated for growth on days 1, 3, 7, 12, 14. All organisms, the number of positive samples and the time to positivity were recorded and compared between the study arms. Single positive cultures were considered as contamination. RESULTS: In total, 71 patients were included. The proportions of culture negative samples (10-15%) and polymicrobial infections (51-54%) were comparable between the four arms. Seven patients (10%) were culture-negative in group A, but showed growth in thioglycolate media (group B-D). Furthermore, 13% of patients showed growth in all groups, but additional organisms were cultured in thioglycolate. There was growth beyond day 7 of culturing only in thioglycolate, but not in group A. A storage temperature of 4 °C showed a longer time to positivity compared to the other groups (p < 0.001). CONCLUSIONS: Pre-analytical storage of tissue samples in thioglycolate broth did not improve the culture yield and did not detect additional cases of infection compared to the standard (pre-analytical storage in sterile containers). However, including a thioglycolate medium to the sampling algorithm reduced the rate of culture-negative infections and helped to identify additional organisms.

Clinical use of linezolid in periprosthetic joint infections - a systematic review.

Introduction: The most common causative organism in periprosthetic joint infections (PJIs) is Gram-positive bacteria that are increasingly drug resistant. In these cases the use of linezolid may be warranted. However, there are conflicting reports regarding its role in antibiotic treatment of PJIs. The aim of this review is to gather and analyze clinical results and treatment details on linezolid in patients with PJIs. Methods: In August 2019, a comprehensive literature search using MEDLINE (Pubmed and Ovid) and Cochrane Library was performed. A total of 504 records were screened, and a total of 16 studies including 372 patients treated with linezolid for a PJI were included in this review based on the PRISMA criteria and after quality analysis using the MINOR score and Newcastle-Ottawa scale, as well as assessing level of evidence. Pooling analysis as well as descriptive analysis was performed. Results: Based on the results from the studies included, infection control was achieved in 80 % (range 30 %-100 %) of patients after a mean follow-up period of 25 (range 2-66) months. The mean duration of treatment was 58 d intravenous and orally at a median dose of 600 mg bis in die (b.i.d.) (range 400-900 b.i.d.). A combination therapy with rifampicin was used in 53 % of patients. MRSA (methicillin-resistant Staphylococcus aureus) infections were present in 29 % and resistant CoNS (coagulase-negative Staphylococcus) in 46 %. Adverse effects occurred in 33 % of cases, mostly anemia, thrombocytopenia and gastrointestinal complaints leading to treatment discontinuation in 9 %. However, great heterogeneity was found with respect to surgical treatment, diagnosis of infection and indication for linezolid. Discussion: Linezolid is an appropriate option for treatment of resistant Gram-positive organisms in PJIs. Most commonly 600 mg b.i.d. is used, and a combination with rifampicin appears feasible although one must consider individual increases in doses in these cases. However, adverse effects are common and there are limited data for long-term use and optimal antibiotic combinations or individual doses.

Comparing the Diagnostic Value of Serum D-Dimer to CRP and IL-6 in the Diagnosis of Chronic Prosthetic Joint Infection.

Introduction: D-dimer is a diagnostic criterion for periprosthetic joint infection (PJI) of the Musculoskeletal Infection Society (MSIS) in 2018. The aim of this study was to evaluate the serum D-dimer values in comparison to C-reactive protein (CRP) and interleukin-6 (IL-6) for the diagnosis of PJI. Materials and Methods: We included 119 patients (50 women, 69 men; 71 knees, 48 hips) undergoing revision arthroplasty with preoperative assessment of CRP, IL-6, and serum D-dimer. Cases were classified as infected or aseptic based on the MSIS criteria of 2018. Receiver operating curves and Youden's index were used to define an ideal cut-off value and sensitivity and specificity for the individual parameters, and respective combinations were calculated using cross-tables. Results: The median D-dimer level (2320 vs. 1105 ng/mL; p < 0.001), the median CRP level (4.0 vs. 0.5 mg/dL; p < 0.001), and the median IL-6 level (21.0 vs. 5.0 pg/mL; p < 0.001) were significantly higher in the group of PJI compared to the group with aseptic failure. The calculated optimal cut-off values were 2750 ng/mL (AUC 0.767) for D-dimer, 1.2 mg/dL (AUC 0.914) for CRP, and 10.0 pg/mL (AUC 0.849) for IL-6. D-dimer showed a sensitivity of 38% and specificity of 94%, whereas the CRP and IL-6 had sensitivities of 88% and 76%, and specificities of 87% and 92%, respectively. Conclusion: In comparison with CRP and IL-6, serum D-dimer showed low sensitivity and specificity in our cohort. While CRP and IL-6 combination had the highest sensitivity, a combination of Il-6 and D-dimer or CRP and IL-6 had the highest specificity.

Acetabular Erosion After Bipolar Hemiarthroplasty in Proximal Femoral Replacement for Malignant Bone Tumors.

BACKGROUND: Hemiarthroplasty megaprosthetic proximal femur reconstruction after tumor resection is a widespread procedure in orthopedic oncology. One potential complication is acetabular wear requiring secondary acetabular revision. The study's purpose is to investigate prevalence of acetabular erosion, secondary revisions, and potential risk factors. METHODS: We retrospectively identified 112 patients who underwent proximal femur replacement after resection of a malignant bone tumor and had radiological follow-up longer than 12 months. Patient demographic, surgical, and oncologic factors were recorded, acetabular wear was measured using the classification proposed by Baker, and prosthetic failure was classified using the International Society on Limb Salvage classification. Functional assessment was performed using the Musculoskeletal Tumor Society Score and Harris Hip Score. RESULTS: Prevalence of acetabular wear was 28.6%. Secondary conversion to total hip arthroplasty was required in 5 patients (4.6%), all treated for primary bone tumors. No patient treated for metastatic tumor had higher grade acetabular wear or required revision. Significant risk factors for the development of acetabular wear were age under 40 (P = .035) and longer follow-up (63 vs 43 months, P = .004). Other patient, surgical, or adjuvant treatment-related factors were not associated with acetabular revision or acetabular wear. The dislocation rate in the patient cohort was 0.9%. CONCLUSION: Bipolar hemiarthroplasty proximal femoral replacement represents a durable reconstruction after tumor resection. Hip instability is rare. Acetabular erosion is rare and can be successfully treated with conversion to total hip arthroplasty. Young patients with long-term survival over 10 years are at risk. In reconstruction for metastases, instability and acetabular wear are rare.