Dinnes, Laura M.

Abstract Background Revaccination is required for patients who receive a hematopoietic cell transplant (HCT) to reduce vaccine preventable illness. Revaccination requires an individualized plan due to differences in immunosuppressive therapy, immune reconstitution, age, and other challenges such as graft versus host disease. A structured approach is required to ensure prompt initiation of re-vaccinations and completion of the re-vaccination schedule. This study sought to evaluate the re-vaccination process at our center as a baseline for quality improvement. Methods We conducted a retrospective chart review of pediatric patients who received an autologous or allogeneic HCT between January 2019 and March 2024 to assess time to starting re-vaccination after post-HCT medical clearance and percentage of patients up to date within each series of vaccinations per internal protocol. Results A total of 64 patients were evaluated, of whom 23 were female and 35 underwent allogeneic stem cell transplant. For analysis, 13 were excluded due to death prior to clearance for vaccination. Among those included, 42 patients were cleared for restarting vaccines, and 37 (88%) of those have received at least one vaccine, while only 25 (59%) have completed the first series of recommended vaccines. The average time from transplant to administration of the first vaccine was 431 days for autologous HCT and 459 days for allogeneic HCT. The average time from medical clearance to the first vaccine was 66 days. The mean interval between the first and second vaccine doses was 97 days. Conclusion The majority of eligible patients initiated re-vaccination after transplant, but rates for the receipt of full recommended initial series remained suboptimal, with notable delays with notable delays between transplant and the day of clearance as well as clearance and the first vaccine administered. These findings highlight significant gaps in post-transplant immunization practices and underscore the need for targeted interventions to optimize protection for this vulnerable population. Disclosures All Authors: No reported disclosures

OBJECTIVE The optimal dose for triazoles in pediatric patients may substantially vary given the dynamic changes in pharmacokinetics and pharmacodynamics, based on disease severity. Therapeutic drug monitoring has been a valuable tool to help guide management and avoid potential toxicities associated with treatment of invasive fungal infections (IFIs). Goal azole serum concentrations are based on specific drug, indication, and minimum inhibitory concentration when known. This study aimed to determine the optimal pediatric azole doses needed to achieve targeted serum concentrations of isavuconazole, itraconazole, posaconazole, and voriconazole. METHODS This is a single center, retrospective chart review of pediatric patients who received isavuconazole, itraconazole, posaconazole, or voriconazole between January 1, 2011, and August 31, 2021. RESULTS A total of 273 pediatric patients received isavuconazole, itraconazole, posaconazole, or voriconazole in the inpatient or outpatient setting during the study period. Of the 273 patients, only 122 met criteria for inclusion in the analysis. Eighty-three percent of patients reached a goal serum concentration. Patients younger than 12 years required a higher dose (mg/kg/day) to achieve goal serum concentrations. Patients who received an azole in the form of an oral tablet or intravenously were more likely to reach a goal concentration than those not receiving these formulations. Median time to goal concentration occurred at 20 days for isavuconazole, 34 days for itraconazole, 11 days for posaconazole, and 10 days for voriconazole. CONCLUSIONS Higher starting azole doses are needed to obtain goal concentrations quickly, especially for children younger than 12 years.

ABSTRACT Background Patients at high risk for cytomegalovirus (CMV) infection after allogeneic hematopoietic stem cell transplant (HCT) should receive CMV prophylaxis. Historically, ganciclovir has been the preferred agent. However, its side effect profile, particularly myelosuppression, is undesirable. Letermovir is a newer agent that is not myelosuppressive and has replaced ganciclovir as the preferred agent for CMV prophylaxis in high‐risk adult patients. Methods The primary objective was to compare the incidence of dose modifications or discontinuation of CMV prophylaxis between pediatric patients who received ganciclovir versus letermovir. Secondary objectives included comparing the use of granulocyte colony‐stimulating factor (G‐CSF) support and the incidence of CMV DNAemia. We reviewed records of all pediatric patients who received an HCT at our institution between 2000 and 2024 and received either ganciclovir/valganciclovir or letermovir for CMV prophylaxis. Results Between 2000 and 2024, 65 pediatric patients receiving prophylactic ganciclovir, valganciclovir, or letermovir were evaluated. The median age at transplant was 12.2 years. No patients receiving letermovir required dose modification or discontinuation as opposed to 14 (29.2%) patients receiving ganciclovir ( p = 0.014). After engraftment, 12 (25%) patients receiving ganciclovir required G‐CSF support compared to seven (41.2%) patients receiving letermovir ( p = 0.23). In the ganciclovir group, 10 (20.8%) patients experienced CMV infection versus one (5.9%) patient receiving letermovir ( p = 0.26). Conclusion Compared with those receiving letermovir, a significantly higher proportion of patients in the ganciclovir/valganciclovir group experienced dose modifications or discontinuation of CMV prophylaxis due to adverse effects. Letermovir shows great promise as a CMV prophylactic agent in pediatric HCT patients due to its favorable side effect profile.

Abstract Background Acute hematogenous osteomyelitis (AHO) is a relatively infrequent but significant infection in pediatric patients. As Staphylococcus aureus is the most common cause of AHO, intravenous and oral first-generation cephalosporins are common therapies. Cephalexin is a commonly prescribed oral therapy for pediatric AHO, although it requires frequent dosing that may affect adherence. Cefadroxil is a comparable oral first-generation cephalosporin with a more desirable dosing schedule. Methods We reviewed pediatric patients admitted to Mayo Clinic between March 2002 and September 2020 for management of AHO who received treatment with a first-generation cephalosporin. We reviewed timing of oral therapy transition, therapy-associated adverse effects, and recurrence of disease after completion of therapy. Results There were 59 patients included in the study. There was similar occurrence of adverse effects in patients receiving cefadroxil and cephalexin, although use of cefadroxil coincided with more gastrointestinal adverse effects and leukopenia and use of cephalexin with more rash and neutropenia. One secondary treatment failure occurred in our study, in a patient receiving cephalexin for treatment of septic arthritis. Conclusions Cefadroxil may be a reasonable alternative oral therapy for methicillin-susceptible S aureus or culture-negative AHO in pediatric patients, particularly when a less frequent dosing schedule is desired. Future study with a larger sample size is warranted.

AbstractHuman antimicrobial consumption largely occurs in the ambulatory setting, with inappropriate or unnecessary antimicrobial prescribing well documented in the literature. In 2020, The Joint Commission implemented a regulatory standard requiring the development and implementation of antimicrobial stewardship programs (ASP) in those institutions surveyed under the ambulatory accreditation standard. While experience with inpatient antimicrobial stewardship has continued to increase, ambulatory ASPs are programmatically distinct and can present unique challenges with regards to operationalizing regulatory components. Herein, we lay a framework for addressing the task of developing an ambulatory ASP for a large health system by reviewing the regulatory requirements, examining relevant recent publications, and describing our institutional experience.