Rapid bone destruction often leads to permanent joint dysfunction in patients with septic arthritis, which is mainly caused by Staphylococcus aureus ( S . aureus ). Staphylococcal cell wall components are known to induce joint inflammation and bone destruction. Here, we show that a single intra-articular injection of S . aureus lipoproteins (Lpps) into mouse knee joints induced chronic destructive macroscopic arthritis through TLR2. Arthritis was characterized by rapid infiltration of neutrophils and monocytes. The arthritogenic effect was mediated mainly by macrophages/monocytes and partially via TNF-α but not by neutrophils. Surprisingly, a S . aureus mutant lacking Lpp diacylglyceryl transferase ( lgt ) caused more severe joint inflammation, which coincided with higher bacterial loads of the lgt mutant in local joints than those of its parental strain. Coinjection of pathogenic S . aureus LS-1 with staphylococcal Lpps into mouse knee joints caused improved bacterial elimination and diminished bone erosion. The protective effect of the Lpps was mediated by their lipid moiety and was fully dependent on TLR2 and neutrophils. The blocking of CXCR2 on neutrophils resulted in total abrogation of the protective effect of the Lpps. Our data demonstrate that S . aureus Lpps elicit innate immune responses, resulting in a double-edged effect. On the one hand, staphylococcal Lpps boost septic arthritis. On the other hand, Lpps act as adjuvants and activate innate immunity, which could be useful for combating infections with multiple drug-resistant strains.

BackgroundPatient care models have been implemented and documented worldwide. Many studies have focused on features that hinder and facilitate the shift to such models, including the implementation process, staff involvement, resistance to new models and cultural dimensions. However, few studies have identified the potential effects of such new care models from a patient perspective. The aim of the present study was to investigate whether patients did in fact perceive the intentions of partnership in the new care model 1 year after its implementation.MethodsSixteen participants were interviewed, selected from two wards in a medical department where a new care model had been implemented 1 year earlier. A directed deductive content analysis was selected. The aim of the directed approach to content analysis was to investigate to what extent the new care model had been implemented, using patients’ perspectives to describe the level of implementation. A coding framework was developed based on a theoretical paper that described the key features of the new care model.ResultsThe implementation of person-centred care had clearly occurred to a large degree, even if some patients appeared not to have been exposed to the model at all. Aspects of the newly implemented care model were obvious; however, it was also clear that implementation was not complete. The analysis showed that patients felt listened to and that their own perception of the situation had been noted. Patients spontaneously expressed that they felt that the staff saw them as persons and did not solely focus on their disease. It was also stated that not every ailment or aspect of a patient’s illness needed to be addressed or resolved for open listening to be perceived as a positive experience.ConclusionsThe findings indicate that even though some patients were not interested in participating and playing an active role in their own care, this might relate to a lack of understanding on how to invite them to do so and to increase their confidence. To change healthcare from a paternalistic system to care where patients are seen as partners may require pedagogical skills.

CTLA4-Ig therapy significantly increased the susceptibility to S. aureus septic arthritis in mice, whereas anti-TNF therapy deteriorated host bacterial clearance, resulting in more-severe weight loss and kidney abscesses.

The complement system plays an essential role in the innate immune response and protection against bacterial infections. However, detailed knowledge regarding the role of complement in Staphylococcus aureus septic arthritis is still largely missing. In this study, we elucidated the roles of selected complement proteins in S. aureus septic arthritis. Mice lacking the complement component 3 (C3−/−), complement factor B (fB−/−), and receptor for C3-derived anaphylatoxin C3a (C3aR−/−) and wild-type (WT) control mice were intravenously or intra-articularly inoculated with S. aureus strain Newman. The clinical course of septic arthritis, as well as histopathological and radiological changes in joints, was assessed. After intravenous inoculation, arthritis severity and frequency were significantly higher in C3−/− mice than in WT controls, whereas fB−/− mice displayed intermediate arthritis severity and frequency. This was in accordance with both histopathological and radiological findings. C3, but not fB, deficiency was associated with greater weight loss, more frequent kidney abscesses, and higher bacterial burden in kidneys. S. aureus opsonized with C3−/− sera displayed decreased uptake by mouse peritoneal macrophages compared with bacteria opsonized with WT or fB−/− sera. C3aR deficiency had no effect on the course of hematogenous S. aureus septic arthritis. We conclude that C3 deficiency increases susceptibility to hematogenous S. aureus septic arthritis and impairs host bacterial clearance, conceivably due to diminished opsonization and phagocytosis of S. aureus.