Purpose of review Infections can result in serious complications in solid organ transplant (SOT) patients. The need to remain up to date on recommendations on screening, vaccinations, and chemoprophylaxis is paramount in the management of SOT patients. The goal of this review is to provide an overview of current recommendations for the prevention of infections and optimization of vaccinations from the pretransplant through posttransplant periods. Recent findings There is an emphasis on thorough pretransplant evaluation to guide clinicians and pretransplant testing based on epidemiological and endemic risk factors. Additionally, recent studies on vaccine safety and efficacy of newer vaccine formulations in SOT recipients are addressed. Summary This review provides insight on updated recommendations for pretransplant screening, new data on vaccine optimization in SOT recipients and posttransplant prophylaxis. Further research is needed in order to improve preventive measures including screening tests, vaccines, and chemoprophylaxis.

Background Coagulase-negative Staphylococci (CoNS), including mecA-positive Staphylococcus epidermidis (MRSE), are among the bacteria identified by BioFire blood culture identification (BCID2). After transition to BCID2 on 31 March 2021, our institution began providing a suggested empiric antimicrobial therapy (EAT) comment with rapid diagnostic results, whereas no suggestions were given with the prior platform. Limited data exist on the impact of EAT suggestions on antibiotic use when likely contaminants such as CoNS are identified. Methods This was a single center, observational, pre- and post-intervention study of patients aged ≥ 18 years with CoNS in the blood between 1 April 2020 and 30 September 2021. Patients with compromised immunity, intravenous drug use, polymicrobial cultures, or MRSE-active therapy use for a documented infection were excluded. Primary outcome was the rate of initiation or discontinuation of MRSE-active agent in response to the rapid diagnostic result. Secondary outcome was healthcare resource utilization such as Infectious Diseases consultation and delayed discharge. Results A total of 174 patients were included (pre-BCID2, n=93; post-BCID2, n=81). For all CoNS rapid diagnostic results, no significant difference was noted in MRSE-active agent initiation (33.3% vs. 37.0%, p=.90) and discontinuation (61.3% vs. 48.4%, p=.31). A subgroup analysis of S. epidermidis was performed with 64 and 46 patients in pre- and post-BCID2 groups, respectively; in the latter, BCID2 identified 31/46 (67.4%) as MRSE. In this subgroup, empiric MRSE-active agent was significantly less likely to be discontinued if EAT suggestion was reported with results (68.4% vs. 31.2%, p=.03). This change was not seen if Staphylococcus species were identified as the suggestion was to withhold EAT. There was no difference in healthcare resource utilization. Conclusion Providing EAT suggestion with BCID2 result for S. epidermidis unexpectedly encouraged continuing empiric MRSE-active agent for likely contaminants. In contrast, suggestion to withhold treatment had no impact on EAT use for other CoNS. The reason for this difference is unclear, but may be a result of the highlighted methicillin resistance in the BCID2 result reporting which is specific to S. epidermidis. Disclosures James S. Lewis, PharmD, FIDSA, Cidara: Advisor/Consultant|Merck: Advisor/Consultant|SeLux Diagnostics: Advisor/Consultant.

Background Letermovir (LMV) is indicated for cytomegalovirus (CMV) prophylaxis in seropositive adults after allogeneic hematopoietic stem cell transplants (alloSCT). LMV is well tolerated compared to its alternatives. Our institution restricts LMV use to high-risk patient groups to maximize the cost/benefit of LMV. Despite these restrictions, LMV was in our institution’s top 50 drug expenditures, prompting a formal evaluation of its use. We describe a real-world experience with LMV at a 576-bed academic transplant center. Methods This was a single center, retrospective, descriptive study of LMV use at a transplant center. Any hospitalized patient who received ≥ 1 dose of LMV between August 2021 and January 2022 was eligible for analysis. Data collection included age, LMV administration data, length of stay, transplant status, Infectious Diseases (ID) consultation, documented rationale for non-criteria uses, and drug cost. The primary outcome was incidence of use not aligning with restriction criteria. The secondary outcome was institutional drug expenditure for non-criteria uses compared to approved uses. Results Over 6 months, 388 doses of LMV were administered to 31 unique patients during 41 admissions. LMV use during 12/41 admissions (31.7%) fell outside the institutional criteria. ID consult occurred in 58.3% (7/12) of cases. 27/31 (87%) were alloSCT patients, including 1 pediatric patient. There was also 1 liver and 1 heart transplant recipient. Reasons for non-criteria use were: primary prophylaxis in the heart transplant patient to avoid ganciclovir toxicity and in 2 alloSCT patients without high risk for CMV, pre-emptive therapy due to CMV reactivation (n=2), and step-down therapy for CMV viremia (n=4). LMV was used for extended periods ( > 100 days from transplant) in 2 cases. Non-criteria use of LMV accounted for $20 414 in drug cost over 6 months, 29% of total expenditure. Conclusion Our data suggest real world use of LMV often differs from the patient types enrolled in the phase 3 trials. Use of LMV as an alternative to available CMV therapies to avoid drug toxicities appears to drive much of this use. In addition, use outside of criteria was frequent and incurred a nontrivial cost. Modification of our criteria, such as requiring an ID consultation for off-label use, should be considered. Disclosures James S. Lewis, PharmD, FIDSA, Cidara: Advisor/Consultant|Merck: Advisor/Consultant|SeLux Diagnostics: Advisor/Consultant.