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Background: The aim of this study was to investigate the prevalence of positive microbiology samples after osteosynthesis of proximal humerus fractures at the time of revision surgery and evaluate clinical characteristics of patients with positive culture results.Methods: All patients, who underwent revision surgery after locked platting, medullary nailing or screw osteosynthesis of proximal humeral fractures between April 2013 and July 2018 were retrospectively evaluated. Patients with acute postoperative infections, those with apparent clinical signs of infection and those with ≤1 tissue or only sonication sample obtained at the time of implant removal were excluded. Positive culture results of revision surgery and its correlation with postoperative shoulder stiffness was analyzed in patients with an interval of ≥6 months between the index osteosynthesis and revision surgery.Results: Intraoperatively obtained cultures were positive in 31 patients (50%). Cutibacterium acnes was the most commonly isolated microorganism, observed in 21 patients (67.7%), followed by coagulase negative staphylococci in 12 patients (38.7%). There were significantly more stiff patients in the culture positive group compared to the culture-negative group (19/21, 91% vs. 15/26, 58%, p = 0.02). Furthermore, 11 of 12 (91.7%) patients with growth of the same microorganism in at least two samples had a stiff shoulder compared to 23 of 35 (65.7%) patients with only one positive culture or negative culture results (p = 0.14).Conclusion: Infection must always be considered as a possibility in the setting of revision surgery after proximal humerus osteosynthesis, especially in patients with postoperative stiffness. [ABSTRACT FROM AUTHOR]

Introduction: Reinfection after two-stage exchange arthroplasty is a difficult clinical scenario with limited data on adequate treatment algorithms. Beside the possibility of treatment failure and a new intraoperative infection at the time of reimplantation, hematogenous seeding could play an up to date underestimated crucial role as another cause of an infection after two-stage exchange. The aim of this study was to evaluate its incidence and treatment possibilities in a prospectively followed case series.Methods: All consecutive hip and knee periprosthetic joint infection cases (93 hips and 89 knees) treated according to a standardized diagnostic and therapeutic algorithm at our institution with a two-stage exchange arthroplasty from 2013 to 2015 were included and followed prospectively to identify recurrent infections due to hematogenous seeding.Results: Six percent from our septic revision hip and knee arthroplasties (11 of 182, including 5 hips and 6 knees) were identified with a hematogenous reinfection after a mean follow-up of 31.8 months (range 14-48 months). The mean time to reinfection after reimplantation was 12.2 months (range 3.1-35.1). In all but two cases was the causative microorganism different than isolated at the time of initial two-stage exchange. In 5 of 11 patients, the primary focus of infection was identified.Conclusion: Hematogenous infection after a successful two-stage exchange arthroplasty is a rare but very important cause of a reinfection. With our work, we aim at raising the awareness for this entity and recommend consideration of irrigation and debridement with implant retention in these cases, as well as possibly the identification of a primary infection source. [ABSTRACT FROM AUTHOR]

Background: Periprosthetic joint infections (PJI) caused by pathogens, for which no biofilm-active antibiotics are available, are often referred to as difficult-to-treat (DTT). However, it is unclear whether the outcome of DTT PJI is worse than those of non-DTT PJI. We evaluated the outcome of DTT and non-DTT PJI in a prospective cohort treated with a two-stage exchange according to a standardized algorithm.Methods: Patients with hip and knee PJI from 2013 to 2015 were prospectively included and followed up for ≥ 2 years. DTT PJI was defined as growth of microorganism(s) resistant to all available biofilm-active antibiotics. The Kaplan-Meier survival analysis was used to compare the probability of infection-free survival between DTT and non-DTT PJI and the 95% confidence interval (95% CI) was calculated.Results: Among 163 PJI, 30 (18.4%) were classified as DTT and 133 (81.6%) as non-DTT. At a mean follow-up of 33 months (range 24-48 months), the overall treatment success was 82.8%. The infection-free survival rate at 2 years was 80% (95% CI 61-90%) for DTT PJI and 84% (95% CI 76-89%) for non-DTT PJI (p = 0.61). The following mean values were longer in DTT PJI than in non-DTT PJI: hospital stay (45 vs. 28 days; p < 0.001), prosthesis-free interval (89 vs. 58 days; p < 0.001) and duration of antimicrobial treatment (151 vs. 117 days; p = 0.003).Conclusions: The outcome of DTT and non-DTT PJI was similar (80-84%), however, at the cost of longer hospital stay, longer prosthesis-free interval and longer antimicrobial treatment. It remains unclear whether patients undergoing two-stage exchange with a long interval need biofilm-active antibiotics. Further studies need to evaluate the outcome in patients treated with biofilm-active antibiotics undergoing short vs. long interval. [ABSTRACT FROM AUTHOR]

Background: Two-stage exchange arthroplasty is still the preferred treatment choice for chronic PJI. However, the results remain unpredictable. We analyzed the treatment success of patients with an infected hip prosthesis, who were treated according to a standardized algorithm with a multidisciplinary team approach and evaluated with a strict definition of failure. Methods: In this single-center prospective cohort study, all hip PJI episodes from March 2013 to May 2015 were included. Treatment failure was assessed according to the Delphi-based consensus definition. The Kaplan-Meier survival method was used to estimate the probability of infection-free survival. Patients were dichotomized into two groups depending on the number of previous septic revisions, duration of prosthesis-free interval, positive culture with difficult-to-treat microorganisms, microbiology at explantation, and microbiology at reimplantation. Results: Eighty-four patients with hip PJI were the subject of this study. The most common isolated microorganisms were coagulase-negative staphylococci (CNS) followed by Staphylococcus aureus and Propionibacterium. Almost half of the study cohort (46%) had at least one previous septic revision before admission. The Kaplan-Meier estimated infection-free survival after 3 years was 89.3% (95% CI, 80% to 94%) with 30 patients at risk. The mean follow-up was 33.1 months (range, 24–48 months) with successful treatment of PJI. There were no statistical differences in infect eradication rate among the dichotomized groups. Conclusions: High infect eradication rates were achieved in a challenging cohort using a standardized two-stage exchange supported by a multidisciplinary approach. [ABSTRACT FROM AUTHOR]