The Impact of Pharmacist-Led Antimicrobial Stewardship Review of Cultures in the Ambulatory Setting at a Comprehensive Cancer Center.

Background: Several antimicrobial stewardship interventions have demonstrated improved clinical outcomes. Though the impact of a pharmacist-led antimicrobial stewardship review of cultures has been described, studies have not evaluated such an intervention in institutions that primarily serve cancer patients. Aim: To describe the impact of the antimicrobial stewardship pharmacist's review of microbiological cultures from adult cancer patients in the ambulatory setting. Method: A retrospective study at a comprehensive cancer center that included adult cancer patients with positive microbiological cultures treated in the ambulatory setting, between August 2020 and February 2021. The cultures were reviewed in real time by the antimicrobial stewardship pharmacist, and were assessed for appropriateness of treatment. The number of antimicrobial modifications made, type of modifications, and physicians' acceptance rate were recorded. Results: A total of 661 cultures from 504 patients were reviewed by the pharmacist. The mean age of patients was 58 years ± 16 (SD); most had solid tumors (95%), and 34% were recent recipients of chemotherapy. Among the reviewed cultures, 175 (26%) required antimicrobial therapy modification, with an acceptance rate of 86%. The modifications consisted of changing from non-susceptible to susceptible antimicrobials (n = 95, 54%), initiation (n = 61, 35%), discontinuation (n = 10, 6%), de-escalation (n = 7, 4%), and dose modification (n = 2, 1%) of antimicrobials. Conclusion: Around one fourth of the cultures reviewed by the antimicrobial stewardship pharmacist in the ambulatory setting required interventions to optimize therapy. Future studies should evaluate the impact of these interventions on clinical outcomes.

Vancomycin therapeutic monitoring by measured trough concentration versus Bayesian-derived area under the curve in critically ill patients with cancer.

The updated vancomycin guideline and recent studies suggested that trough concentrations may result in underestimation of the actual area under the curve (AUC), leading to excessive dosing and nephrotoxicity. With limited data available on critically ill cancer patients, this study aimed to compare the two methods in this patient population. This was a 5-year retrospective study on patients treated with vancomycin in the intensive care unit (ICU) of a comprehensive cancer center. The measured trough concentration was compared to Bayesian-derived AUC/minimum-inhibitory-concentration (MIC), considering MIC as 1. Trough concentrations of 15-20 mg/L and AUC of 400-600 mg h/L were considered the targeted goal. Multivariate analysis was performed to identify factors associated with an AUC below the targeted goal. During the study period, 316 patients were included. The mean age was 54 years ±16 (SD); most patients had solid tumors (75%), and 11% had neutropenia. A targeted goal AUC and trough were recorded in 128 (41%) patients and in 64 (20%) patients, respectively. Of the 128 patients with targeted goal AUC, 31 (24%) had targeted goal trough concentrations and 91 (71%) had trough concentrations below 15 mg/L. Furthermore, among the patients with targeted goal trough concentration (n = 64), 33 (52%) had higher than targeted goal AUC. Augmented renal clearance (ARC), defined as a calculated creatinine-clearance ≥130 ml/min, was associated with an AUC below the targeted goal. In a cohort of critically ill patients with cancer, over two-thirds of the patients with a targeted goal Bayesian AUC/MIC had trough concentrations below the targeted goal. ARC was associated with AUC below the targeted goal.