Anti-Gentamicin monoclonal antibody, clone A103

Background: Scottish Antimicrobial Prescribing Group (SAPG) recommendations to reduce broad-spectrum antimicrobial use led to an increase in gentamicin and vancomycin prescribing. In 2009, SAPG introduced national guidance to standardize dosage regimens, reduce calculation errors and improve the monitoring of these antibiotics. Studies conducted in 2010 and 2011 identified limitations in guideline implementation. Objectives: To develop, implement and assess the long-term impact of quality improvement (QI) resources to support gentamicin and vancomycin prescribing, administration and monitoring. Methods: New resources, comprising revised guidelines, online and mobile app dose calculators, educational material and specialized prescribing and monitoring charts were developed in collaboration with antimicrobial specialists and implemented throughout Scotland during 2013-16. An online survey in 2017 evaluated the use of these resources and a before (2011) and after (2018) point prevalence study assessed their impact. Results: All 12 boards who responded to the survey (80%) were using the guidance, electronic calculators and gentamicin prescription chart; 8 used a vancomycin chart. The percentage of patients who received the recommended gentamicin dose increased from 44% to 89% (OR 10.99, 95% CI=6.37-18.95) between 2011 and 2018. For vancomycin, the correct loading dose increased from 50% to 85% (OR=5.69, CI=2.76-11.71) and the correct maintenance dose from 55% to 90% (OR=7.17, CI=3.01-17.07). Conclusions: This study demonstrated improvements in the national prescribing of gentamicin and vancomycin through the development and coordinated implementation of a range of QI resources and engagement with local and national multidisciplinary teams.

Aims The aim of this study was to determine if the local delivery of vancomycin and tobramycin in primary total knee arthroplasty (TKA) can achieve intra-articular concentrations exceeding the minimum inhibitory concentration thresholds for bacteria causing acute prosthetic joint infection (PJI). Methods Using a retrospective single-institution database of all primary TKAs performed between January 1 2014 and May 7 2019, we identified patients with acute PJI that were managed surgically within 90 days of the initial procedure. The organisms from positive cultures obtained at the time of revision were tested for susceptibility to gentamicin, tobramycin, and vancomycin. A prospective study was then performed to determine the intra-articular antibiotic concentration on postoperative day one after primary TKA using one of five local antibiotic delivery strategies with tobramycin and/or vancomycin mixed into the polyme-thylmethacrylate (PMMA) or vancomycin powder. Results A total of 19 patients with acute PJI after TKA were identified and 29 unique bacterial isolates were recovered. The mean time to revision was 37 days (6 to 84). Nine isolates (31%) were resistant to gentamicin, ten (34%) were resistant to tobramycin, and seven (24%) were resistant to vancomycin. Excluding one Fusobacterium nucleatum, which was resistant to all three antibiotics, all isolates resistant to tobramycin or gentamicin were susceptible to vancomycin and vice versa. Overall, 2.4 g of tobramycin hand-mixed into 80 g of PMMA and 1 g of intra-articular vancomycin powder consistently achieved concentrations above the minimum inhibitory concentrations of susceptible organisms. Conclusion One-third of bacteria causing acute PJI after primary TKA were resistant to the aminogly-cosides commonly mixed into PMMA, and one-quarter were resistant to vancomycin. With one exception, all bacteria resistant to tobramycin were susceptible to vancomycin and vice versa. Based on these results, the optimal cover for organisms causing most cases of acute PJI after TKA can be achieved with a combination of tobramycin mixed in antibiotic cement, and vancomycin powder.