for administrations during CytoSorb w use than for the adjacent peak levels. Finally, the meropenem peak level during the second period of CytoSorb w use was substantially lower than the peak level before use. The observed substantially lower linezolid peak levels during CytoSorb w use might be due to adsorption by the cytokine filter. Indeed, different endogenous substances, apart from cytokines, are reported to be adsorbed by cytokine filters. 6 Adsorption would also explain the lower peak level of meropenem during the second use of CytoSorb w. However, blood samples were not collected at optimal timepoints for meropenem; hence, the information for this antibiotic is limited. It should be mentioned that the high intra-individual variability observed for both antibiotics might also be due to the effects of critical illness. 4,7 However, because of the possible adsorption of antibiotics by cytokine filters, therapeutic drug monitoring (TDM) might be especially important for patients using such systems. Indeed, first guidelines already recommended the use of TDM in critically ill patients. 8,9 If TDM is not available, high loading doses or shorter intervals between antibiotic administrations could be used to achieve adequate antibiotic levels. The results suggest that further studies are needed to understand the impact of cytokine filters on the concentrations of different antimicrobials.

ObjectivesSophisticated scientific methods have facilitated dose individualisation with substantial advancements in therapeutic drug monitoring (TDM) practice. It is unclear whether these methods have translated to the clinical setting. This study aimed to determine current TDM practice for tobramycin monitoring in cystic fibrosis (CF) centres in the USA and Canada, UK and Ireland, and Australia and New Zealand due to a high prevalence of CF.MethodsA web-based survey was developed and circulated via CF specialist groups within the targeted geographical regions. Themes included centre demographics, tobramycin usage, dosing and infusion practices, TDM practices, and blood sampling methods.ResultsIn total 77 responses were received from 75 different CF centres over the 3-month evaluation period (October 2019–January 2020). Respondents were from the USA and Canada (60%), Australia and New Zealand (25%), and the UK and Ireland (15%). Tobramycin was used in 97% of sites, with an international variation in practice across all survey aspects including dosing and infusion practice. TDM-based dose adjustment in the UK and Ireland was most commonly based only on trough sample collection for avoidance of toxicity, where use of computer programs for targeting both efficacy and toxicity endpoints were most common in Australia and New Zealand. The underlying pharmacokinetic basis of that program was not known by 33% of sites who utilised a computer program for tobramycin dose individualisation.ConclusionThere remains substantial heterogeneity in tobramycin management worldwide. Despite two decades of research into TDM of tobramycin, there has been a slow uptake of new technologies and evolution of practice. An improved understanding of TDM processes is required for translation of evidence-based research into clinical practice. International guidelines require updating due to the advances in research to support confidence in the changes in clinical practice.

Background: Antimicrobial stewardship (AMS) programs are increasingly implemented in intensive care units (ICU) to combat the emerging threat of antimicrobial-resistance. To optimise AMS programs, interventions need to be tailored to target problem areas. Aim: To provide an overview of the current antimicrobial prescribing patterns in a 32-bed ICU and thereby identify areas requiring improvement. Method: A 10-week prospective observational audit was conducted in the ICU of a public tertiary hospital. Patients on antimicrobial treatment or surgical prophylaxis antibiotics were audited. The primary outcomes were: duration of surgical antibiotic prophylaxis; duration of therapy for pneumonia, urosepsis and peritonitis; de-escalation within 24-h of microbiological results returning for empirical therapy; appropriate prescribing in penicillin allergy. Adherence to guidelines was also assessed. Results: A total of 277 cases were included. The mean duration of surgical antibiotic prophylaxis and adherence to maximum guideline duration were: cardiothoracic 21.6 h (83.9% adherence), vascular 14.9 h (81.8%), neurosurgery 20.4 h (40.0%) and general surgery 11.1 h (79.6%). The mean duration of therapy was 8.8 AE 4.7 days (62.5% adherence) for community-acquired pneumonia, 8.5 AE 4.6 days (28.6%) for hospital-acquired pneumonia and 11.9 AE 4.6 days (46.2%) for ventilator-associated pneumonia. Urosepsis and peritonitis were underpowered and complex. De-escalation occurred 63.2% of the time, with 75% occurring within 24-h of microbiological result availability. Antibiotic selection in 68.0% of patients with a documented penicillin allergy was appropriate. Conclusion: This study successfully identified baseline prescribing patterns and areas requiring improvement. With this information, tailored stewardship programs can be developed to improve antimicrobial utilisation in the critical care setting.

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