DAIR-treated patients with prosthetic hip joint infections due to S. aureus tended to have worse outcomes than those infected with Streptococcus spp. The specific influence of the infecting pathogen should be considered in future guidelines and recommendations.

During a two-stage revision for prosthetic joint infections (PJI), joint aspirations, open tissue sampling and serum inflammatory markers are performed before re-implantation to exclude ongoing silent infection. We investigated the performance of these diagnostic procedures on the risk of recurrence of PJI among asymptomatic patients undergoing a two-stage revision. A total of 62 PJI were found in 58 patients. All patients had intraoperative surgical exploration during re-implantation, and 48 of them had intra-operative microbiological swabs. Additionally, 18 joint aspirations and one open biopsy were performed before second-stage reimplantation. Recurrence or persistence of PJI occurred in 12 cases with a mean delay of 218 days after re-implantation, but only four pre-or intraoperative invasive joint samples had grown a pathogen in cultures. In at least seven recurrent PJIs (58%), patients had a normal C-reactive protein (CRP, <10 mg/l) level before re-implantation. The sensitivity, specificity, positive predictive and negative predictive values of pre-operative invasive joint aspiration and CRP for the prediction of PJI recurrence was 0. 58, 0.88, 0.5, 0.84 and 0.17, 0.81, 0.13, 0.86, respectively. As a conclusion, pre-operative joint aspiration, intraoperative bacterial sampling, surgical exploration and serum inflammatory markers are poor predictors of PJI recurrence. The onset of reinfection usually occurs far later than reimplantation.

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Clinical experience suggests fluctuation in the occurrence of osteoarticular infections. We performed a single-centre study during 2004-2012, dividing each year into the four seasons according to the Gregorian calendar. A total of 455 episodes of osteoarticular infections were retrieved. There were 91 prosthetic joint infections (45 of haematogenous origin) and 159 cases of septic arthritis. The median period between early symptoms and diagnosis of infection was 27 days. The overall number of infections per season, cumulated over the 8-year study period, was 119 in spring, 129 in summer, 95 in fall, and 112 in winter, which did not reflect any significant seasonal fluctuation. None of the different subgroups of infections, namely arthroplasties (p for trend = 0.755), haematogenous arthroplasty infections (p = 0.493), gram-negative episodes or arthritis (p = 0.290), showed any season-related fluctuation. We conclude that osteoarticular infections, including haematogenous prosthetic joint infections, do not show any significant seasonality.

Vector-based SARS-CoV-2 vaccines have been associated with vaccine-induced thrombosis with thrombocytopenia syndrome (VITT/TTS), but the causative factors are still unresolved. We comprehensively analyzed ChAdOx1 nCov-19 (AstraZeneca) and Ad26.COV2.S (Johnson & Johnson). ChAdOx1 nCoV-19 contains significant amounts of host cell protein impurities, including functionally active proteasomes, and adenoviral proteins. In Ad26.COV2.S much less impurities were found. Platelet-factor 4 (PF4) formed complexes with ChAdOx1 nCoV-19 constituents, but not with purified virions from ChAdOx1 nCoV-19 or with Ad26.COV2.S. Vascular hyperpermeability was induced by ChAdOx nCoV-19 but not by Ad26.COV2.S.These differences in impurities together with EDTA-induced capillary leakage might contribute to the higher incidence rate of VITT associated with ChAdOx1 nCoV-19 compared to Ad26.COV2.S.