Joint aspiration, including culture of reaspirated saline after a 'dry tap', is sensitive and specific for the diagnosis of hip and knee prosthetic joint infection.

Aims: The aim of this study was to establish the diagnostic accuracy of culture of joint aspirate with and without saline injection-reaspiration. Patients and Methods: This is a retrospective analysis of 580 hip and knee aspirations in patients who were deemed to have a moderate to high risk of infection, and who subsequently proceeded to revision arthroplasty over a period of 12 years. It was carried out at a large quaternary referral centre where preoperative aspiration is routine. Results: Fluid was aspirated primarily in 313 (54%) cases and after saline injection-reaspiration of a 'dry tap' in 267 (46%) cases. Overall sensitivity and specificity of the diagnostic aspirate were 84% (78% to 89%) and 85% (81% to 88%), respectively. Sensitivity and specificity of saline injection-reaspiration after 'dry tap' were 87% (79% to 92%) and 79% (72% to 84%) compared with 81% (71% to 88%) and 90% (85% to 93%) for direct aspiration. Conclusion: Preoperative joint aspiration and culture is a sensitive and specific test for the confirmation of diagnosis in patients at a moderate to high risk of prosthetic joint infection. Culture of saline injection-reaspiration also provides accurate diagnostic information in the event of a 'dry tap'. Both methods allow susceptibility testing of relevant organisms and are therefore able to guide perioperative antibiotic therapy. Cite this article: Bone Joint J 2018;100-B:749-54.

Antibiotic stewardship and early discharge from hospital: impact of a structured approach to antimicrobial management.

OBJECTIVES: To assess the impact of an infection team review of patients receiving antibiotics in six hospitals across the UK and to establish the suitability of these patients for continued care in the community. METHODS: An evaluation audit tool was used to assess all patients on antibiotic treatment on acute wards on a given day. Clinical and antibiotic use data were collected by an infection team (doctor, nurse and antibiotic pharmacist). Assessments were made of the requirement for continuing antibiotic treatment, route and duration [including intravenous (iv)/oral switch] and of the suitability of the patients for discharge from hospital and their requirement for community support. RESULTS: Of 1356 patients reviewed, 429 (32%) were on systemic antibiotics, comprising 165 (38%) on iv ±â€Šoral antibiotics and 264 (62%) on oral antibiotics alone. Ninety-nine (23%) patients (including 26 on iv antibiotics) had their antibiotics stopped immediately on clinical grounds. The other 330 (77%) patients (including 139 on iv antibiotics) needed to continue antibiotics, although 47 (34%) could be switched to oral. Eighty-nine (21%) patients were considered eligible for discharge, comprising 10 who would have required outpatient parenteral antibiotic therapy (OPAT), 55 who were suitable for oral outpatient treatment and 24 who had their antibiotics stopped. CONCLUSIONS: Infection team review had a significant impact on antimicrobial use, facilitating iv to oral switch and a reduction in the volume of antibiotic use, possibly reducing the risk of healthcare-associated complications and infections. It identified many patients who could potentially have been managed in the community with appropriate resources, saving 481 bed-days. The health economics are reported in a companion paper.

Method comparison--a different approach.

The commonly accepted method of analysing data from method comparison studies is regression analysis, a method which has limitations. This study illustrates the use of a graphical presentation of data, the difference plot, which can be used as an alternative to least squares regression analysis. The data from comparison studies performed on five methods were analysed both by Deming's regression analysis, with calculation of the correlation coefficient, and by the difference plot. The results show that in most cases much more relevant information was obtained from the difference plot.