Summary Objectives The incidence of haematogenous periprosthetic joint infections (PJI) among patients with remote infections has been reported to be less than 1%. This incidence may be much higher ...in cases after documented Staphylococcus aureus bacteremia (SAB). We evaluated the incidence of haematogenous PJI following SAB in patients with previously uninfected arthroplasties. Methods A retrospective analysis of our cohort including patients with SAB and prosthetic joints at the Basel University Medical Clinic Liestal from 1998 to 2008. Results We identified 31 patients with 45 uninfected prosthetic joints in situ at the time of SAB. In 12 patients (39%) and 13 arthroplasties (29%), SAB caused PJI. In comparison to nosocomial SAB, infections occurred only in cases with community-acquired SAB ( p = 0.002). PJI was diagnosed within a median time of 2.5 days (IQR 1–3.5) after admission. The comparison between patients with and without PJI revealed no significant difference in gender, age, comorbidities and number of prostheses per patient and age of the prosthesis. Conclusions The rate of PJI after SAB is high, ranging from 30% to 40%, and clearly higher than rates reported for bacteremia with other pathogens. PJIs were observed in community-onset bacteremia, in which there is a typically delay from symptoms to antimicrobial treatment.
Background. Small colony variants of Staphylococcus aureus tend to persist despite antimicrobial therapy, especially when involved in implant-associated infections. Methods. We analyzed 5 cases of ...hip prosthesis-associated infections due to small colony variants, including their course prior to identification of the pathogen. Biopsy investigations included microbiological examination and, in 1 case, transmission electron microscopy to detect intracellular bacteria in nonprofessional phagocytes. A treatment concept was elaborated on the basis of a published algorithm and patients were managed accordingly. Results. The patients' mean age was 62.2 years. All patients experienced treatment failures prior to isolation of small colony variants, despite as many as 3 surgical revisions and up to 22 months of antibiotics. Transmission electron microscopy performed on biopsy specimens from periprosthetic tissue revealed intracellular cocci in fibroblasts. All prostheses were removed without implanting a spacer, and antimicrobial agents were administered for 5.5–7 weeks. Reimplantation of the prosthesis was performed for 4 patients. Follow-ups were uneventful in all 5 cases. Conclusions. In the case of a poor response to adequate antimicrobial and surgical treatment in implant-associated staphylococcal infections, small colony variants should be considered and actively sought. In our case series, a 2-stage exchange without implantation of a spacer combined with antimicrobial therapy for an implant-free interval of 6–8 weeks was associated with successful outcome, with a mean follow-up of 24 months.
Background and purpose - The use of uncemented revision stems is an established option in 2-stage procedures in patients with periprosthetic joint infection (PJI) after total hip arthroplasty (THA). ...However, in 1-stage procedures, they are still rarely used. There are still no detailed data on radiological outcome after uncemented 1-stage revisions. We assessed (1) the clinical outcome, including reoperation due to persistent infection and any other reoperation, and (2) the radiological outcome after 1- and 2-stage revision, using an uncemented stem.
Patients and methods - Between January 1993 and December 2012, an uncemented revision stem was used in 81 THAs revised for PJI. Patients were treated with 1- or 2-stage procedures according to a well-defined algorithm (1-stage: n = 28; 2-stage: n = 53). All hips had a clinical and radiological follow-up. Outcome parameters were eradication of infection, re-revision of the stem, and radiological changes. Survival was calculated using Kaplan-Meier analysis. Radiographs were analyzed for bone restoration and signs of loosening. The mean clinical follow-up time was 7 (2-15) years.
Results - The 7-year infection-free survival was 96% (95% CI: 92-100), 100% for 1-stage revision and 94% for 2-stage revision (95% CI: 87-100) (p = 0.2). The 7-year survival for aseptic loosening of the stem was 97% (95% CI: 93-100), 97% for 1-stage revision (95% CI: 90-100) and 97% for 2-stage revision (95% CI: 92-100) (p = 0.3). No further infection or aseptic loosening occurred later than 7 years postoperatively. The radiographic results were similar for 1- and 2-stage procedures.
Interpretation - Surgical management of PJI with stratification to 1- or 2-stage exchange according to a well-defined algorithm combined with antibiotic treatment allows the safe use of uncemented revision stems. Eradication of infection can be achieved in most cases, and medium- and long-term results appear to be comparable to those for revisions for aseptic loosening.
Interprofessional education and culture are often taught independently. Students are not afforded the opportunity to practice these competencies before engaging in clinical practice.
Graduate family ...nurse practitioner (FNPs), athletic training, and physical therapy students (N = 108) participated in uniquely developed advanced practice, culturally competent interprofessional simulations.
The Cultural Awareness Scale revealed that FNPs became more comfortable interacting with diverse patients. Critical reflection essays and clinical case analysis supported that FNPs are becoming culturally competent. On the Attitudes Toward Health Care Teams Scale athletic training, and physical therapy students felt team collaborations were poor but shared leadership was valued; the FNP data was just the opposite.
This initiative was successful in simultaneously incorporating interprofessional education and culture in simulation; however, the students' varying experiences influenced outcomes.
The thermodynamic H+/ATP ratio of the H+–ATP synthase from chloroplasts was measured in proteoliposomes after energization of the membrane by an acid base transition (Turina et al. 2003 13, 418–422). ...The method is discussed, and all published data obtained with this system are combined and analyzed as a single dataset. This meta-analysis led to the following results. 1) At equilibrium, the transmembrane ΔpH is energetically equivalent to the transmembrane electric potential difference. 2) The standard free energy for ATP synthesis (reference reaction) is ΔG°ref=33.8±1.3kJ/mol. 3) The thermodynamic H+/ATP ratio, as obtained from the shift of the ATP synthesis equilibrium induced by changing the transmembrane ΔpH (varying either pHin or pHout) is 4.0±0.1. The structural H+/ATP ratio, calculated from the ratio of proton binding sites on the c-subunit-ring in F0 to the catalytic nucleotide binding sites on the β-subunits in F1, is c/β=14/3=4.7. We infer that the energy of 0.7 protons per ATP that flow through the enzyme, but do not contribute to shifting the ATP/(ADP·Pi) ratio, is used for additional processes within the enzyme, such as activation, and/or energy dissipation, due e.g. to internal uncoupling. The ratio between the thermodynamic and the structural H+/ATP values is 0.85, and we conclude that this value represents the efficiency of the chemiosmotic energy conversion within the chloroplast H+–ATP synthase.
•The thermodynamic H+/ATP ratio in the chloroplast ATP synthase is 4.0±0.1.•ΔpH and Δφ are equivalent in shifting the ATP synthesis equilibrium.•H+/ATP=4.7 from structure points to energy losses within the enzyme.
Synthesis of ATP from ADP and phosphate, catalyzed by F(0)F(1)-ATP synthases, is the most abundant physiological reaction in almost any cell. F(0)F(1)-ATP synthases are membrane-bound enzymes that ...use the energy derived from an electrochemical proton gradient for ATP formation. We incorporated double-labeled F(0)F(1)-ATP synthases from Escherichia coli into liposomes and measured single-molecule fluorescence resonance energy transfer (FRET) during ATP synthesis and hydrolysis. The gamma subunit rotates stepwise during proton transport-powered ATP synthesis, showing three distinct distances to the b subunits in repeating sequences. The average durations of these steps correspond to catalytic turnover times upon ATP synthesis as well as ATP hydrolysis. The direction of rotation during ATP synthesis is opposite to that of ATP hydrolysis.
Periprosthetic ankle joint infection is a feared complication of total ankle arthroplasty because the implant fails in the majority of cases. However, risk factors for developing these infections are ...unknown.
We aimed to determine risk factors for infection in a matched case-control study that included twenty-six patients with periprosthetic ankle joint infection and two control groups, each consisting of fifty-two patients.
The prevalence of periprosthetic ankle joint infection within our cohort was 4.7%. Four infections (15%) had a hematogenous origin and twenty-two (85%), an exogenous origin. Staphylococcus aureus was the most common pathogen, followed by coagulase-negative staphylococci. Preoperative predisposing factors associated with infection included prior surgery at the site of infection (odds ratio OR = 4.56, 95% confidence interval CI = 0.98 to 21.35, and OR = 4.78, 95% CI = 1.53 to 14.91, in comparison with the two control groups) and a low American Orthopaedic Foot & Ankle Society (AOFAS) hindfoot score (35.8 versus 49.8 and 47.6 in the two control groups, p ≤ 0.02). The mean duration of the index surgery was significantly longer in the case group than in both control groups (119 versus eighty-four and ninety-three minutes, p ≤ 0.02). After surgery, persistent wound dehiscence (OR = 15.38, 95% CI = 2.91 to 81.34, p = 0.01, in comparison with both control groups) and secondary wound drainage (OR = 7.00, 95% CI = 1.45 to 33.70, and OR = 5.31, 95% CI = 1.01 to 26.78, in comparison with the two control groups, p ≤ 0.04) were associated with the development of a periprosthetic ankle joint infection.
Patients at risk for periprosthetic ankle joint infection following total ankle arthroplasty include those with a history of surgery on the ankle, a low preoperative AOFAS hindfoot score, and a long operative time. Postoperatively, patients with a prolonged wound dehiscence or a secondary wound-healing problem are also at risk for infection.
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