Enhancing Kidney Transplantation and the Role of Xenografts: Report of a Scientific Workshop Sponsored by the National Kidney Foundation.

Chronic kidney disease affects an estimated 37 million people in the United States; of these,>800,000 have end-stage renal disease requiring chronic dialysis or a kidney transplant to survive. Despite efforts to increase the donor kidney supply, approximately 100,000 people are registered on the kidney transplant wait-list with no measurable decrease over the past 2 decades. The outcomes of kidney transplantation are significantly better than for chronic dialysis: kidney transplant recipients have lower rates of mortality and cardiovascular events and better quality of life, but wait-list time matters. Time on dialysis waiting for a deceased-donor kidney is a strong independent risk factor for outcomes after a kidney transplant. Deceased-donor recipients with wait-list times on dialysis of<6 months have graft survival rates equivalent to living-donor recipients with waitlist times on dialysis of>2 years. In 2021,>12,000 people had been on the kidney transplant waitlist for ≥5 years. As the gap between the demand for and availability of donor kidneys for allotransplantation continues to widen, alternative strategies are needed to provide a stable, sufficient, and timely supply. A strategy that is gaining momentum toward clinical application is pig-to-human kidney xenotransplantation. This report summarizes the proceedings of a meeting convened on April 11-12, 2022, by the National Kidney Foundation to review and assess the state of pig-to-human kidney xenotransplantation as a potential cure for end-stage renal disease.

Impact of deceased organ donor marijuana use on donor culture positivity and solid organ transplant recipient outcomes.

With the increasing prevalence of marijuana use in the US, many deceased organ donors have a history of marijuana use, raising concerns about infectious risks to transplant recipients. We performed a multicenter retrospective cohort study in which exposed donors were those with recent marijuana use (in the prior 12 months) and unexposed donors were those with no recent marijuana use. Primary outcomes included the following: (1) positive donor cultures for bacteria or fungi, (2) recipient infection due to bacteria or fungi within 3 months posttransplant, and (3) recipient graft failure or death within 12 months posttransplant. Multivariable regression was used to evaluate the relationship between donor marijuana use and each outcome. A total of 658 recipients who received organs from 394 donors were included. Recent marijuana use was not associated with donor culture positivity (aOR: 0.84, 95% CI: 0.39-1.81, P = .65), recipient infection (aHR: 1.02, 95% CI: 0.76-1.38, P = .90), or recipient graft failure or death (aHR: 1.65, 95% CI: 0.90-3.02, P = .11). Our data suggest that organs from donors with a history of recent marijuana use do not pose significant infectious risks in the early posttransplant period.

Management of infectious disease syndromes in thoracic organ transplants and mechanical circulatory device recipients: a Delphi panel.

PURPOSE: Antimicrobial misuse contributes to antimicrobial resistance in thoracic transplant (TTx) and mechanical circulatory support (MCS) recipients. This study uses a modified Delphi method to define the expected appropriate antimicrobial prescribing for the common clinical scenarios encountered in TTx and MCS recipients. METHODS: An online questionnaire on managing 10 common infectious disease syndromes was submitted to a multidisciplinary Delphi panel of 25 experts from various disciplines. Consensus was predefined as 80% agreement for each question. Questions where consensus was not achieved were discussed during live virtual live sessions adapted by an independent process expert. RESULTS: An online survey of 62 questions related to 10 infectious disease syndromes was submitted to the Delphi panel. In the first round of the online questionnaire, consensus on antimicrobial management was reached by 6.5% (4/62). In Round 2 online live discussion, the remaining 58 questions were discussed among the Delphi Panel members using a virtual meeting platform. Consensus was reached among 62% (36/58) of questions. Agreement was not reached regarding the antimicrobial management of the following six clinical syndromes: (1) Burkholderia cepacia pneumonia (duration of therapy); (2) Mycobacterium abscessus (intra-operative antimicrobials); (3) invasive aspergillosis (treatment of culture-negative but positive BAL galactomannan) (duration of therapy); (4) respiratory syncytial virus (duration of antiviral therapy); (5) left ventricular assist device deep infection (initial empirical antimicrobial coverage) and (6) CMV (duration of secondary prophylaxis). CONCLUSION: This Delphi panel developed consensus-based recommendations for 10 infectious clinical syndromes seen in TTx and MCS recipients.

COVID-19 in organ donors: An organ procurement organization perspective.

BACKGROUND: The COVID-19 pandemic presented a significant challenge for Organ Procurement Organizations (OPOs) with the use of SARS-CoV-2 positive donors varying widely. This study used detailed single OPO data to determine the success of using SARS-CoV-2 positive donors. METHODS: We performed a retrospective cohort study including all SARS-CoV-2 positive donors referred to the Gift of Life OPO from January 1, 2021, to June 30, 2023. Descriptive analyses were performed to characterize referral and organ utilization. RESULTS: There were 861 organ referrals with 1 positive SARS-Cov-2 test: 282 were ruled out with telephone evaluation, 431 referrals were ruled out with onsite evaluation ("evaluated nondonors") and 148 became donors. For donors who had both nasopharyngeal and lower respiratory testing completed, there was notable result discordance observed. Median cycle threshold (Ct) values were similar between donors and evaluated nondonors with no change in median donor Ct values over the study period. Transplanted organs from COVID-positive donors included 27 hearts, 88 livers, 5 pancreata, and 107 kidneys; no lung donation occurred. The proportion of COVID-positive donors significantly increased over the study period. CONCLUSION: This large volume donor referral study demonstrates increasing COVID-19 referrals progressing to donation over time, supporting the increased use of these donors for nonlung transplantation.

Wait Time Advantage for Transplant Candidates With HIV Who Accept Kidneys From Donors With HIV Under the HOPE Act.

BACKGROUND: Kidney transplant (KT) candidates with HIV face higher mortality on the waitlist compared with candidates without HIV. Because the HIV Organ Policy Equity (HOPE) Act has expanded the donor pool to allow donors with HIV (D + ), it is crucial to understand whether this has impacted transplant rates for this population. METHODS: Using a linkage between the HOPE in Action trial (NCT03500315) and Scientific Registry of Transplant Recipients, we identified 324 candidates listed for D + kidneys (HOPE) compared with 46 025 candidates not listed for D + kidneys (non-HOPE) at the same centers between April 26, 2018, and May 24, 2022. We characterized KT rate, KT type (D + , false-positive [FP; donor with false-positive HIV testing], D - [donor without HIV], living donor [LD]) and quantified the association between HOPE enrollment and KT rate using multivariable Cox regression with center-level clustering; HOPE was a time-varying exposure. RESULTS: HOPE candidates were more likely male individuals (79% versus 62%), Black (73% versus 35%), and publicly insured (71% versus 52%; P < 0.001). Within 4.5 y, 70% of HOPE candidates received a KT (41% D + , 34% D - , 20% FP, 4% LD) versus 43% of non-HOPE candidates (74% D - , 26% LD). Conversely, 22% of HOPE candidates versus 39% of non-HOPE candidates died or were removed from the waitlist. Median KT wait time was 10.3 mo for HOPE versus 60.8 mo for non-HOPE candidates ( P < 0.001). After adjustment, HOPE candidates had a 3.30-fold higher KT rate (adjusted hazard ratio = 3.30, 95% confidence interval, 2.14-5.10; P < 0.001). CONCLUSIONS: Listing for D + kidneys within HOPE trials was associated with a higher KT rate and shorter wait time, supporting the expansion of this practice for candidates with HIV.

Lung transplantation for COVID-2019 respiratory failure in the United States: Outcomes 1-year posttransplant and the impact of preoperative extracorporeal membrane oxygenation support.

OBJECTIVE: Patients with end-stage respiratory failure after severe coronavirus disease 2019 (COVID-19) infection may benefit from lung transplant; however, data on transplant outcomes and the impact of prolonged circulatory support before transplant in these patients are limited. METHODS: We assessed survival, postoperative complications, and the impact of pretransplant extracorporeal membrane oxygenation (ECMO) in patients undergoing lung transplant in the United States from August 2020 through March 2022 using records validated by United Network for Organ Sharing experts and extracted from the United Network for Organ Sharing database. RESULTS: In 305 patients with COVID-19-related respiratory failure and validated data, survival for up to 1-year posttransplant did not differ between 188 patients with COVID-19-related acute respiratory distress syndrome and 117 patients with post-COVID-19 pulmonary fibrosis (P = .8). Pretransplant ECMO support (median 66 days) was required in 191 patients (63%), and venovenous ECMO was used in 91.2% of patients. One-, 6-, and 12-month survival was not significantly different between patients requiring ECMO and patients without ECMO (95.8% vs 99.1%, 93.1% vs 96.4%, 84.8% vs 90.9%, P = .2) In addition, 1-year survival was similar in recipients requiring ECMO for COVID-19 lung failure and recipients requiring ECMO for non-COVID-19 restrictive lung failure (84.8% vs 78.0%, P = .1). CONCLUSIONS: These findings suggest that lung transplant in patients with COVID-19 respiratory failure yields acceptable 1-year outcomes. Despite an often more complex postoperative course, prolonged ECMO pretransplant in well-selected patients was associated with adequate clinical and functional status.

Into the unknown: The end of the coronavirus disease 2019 public health emergency in the United States and potential impacts on organ transplant recipients.

The public health emergency for coronavirus disease 2019 ended on April 11, 2023, 1 month earlier than its planned termination. The hasty cessation of emergency measures may negatively impact the care of solid organ transplant recipients and other immunosuppressed hosts. Accelerated pathways for drug and vaccine approvals, research funding, and insurance coverage for medical therapies and diagnostic testing are likely to be affected. Health care disparities that characterized the early pandemic may again be intensified. It is imperative that the transplant community promptly anticipate the impact of these changes and prepare accordingly to avoid disruptions in care for the most vulnerable patients.

The SHELTER Trial of Transplanting Hepatitis C Virus-Infected Lungs Into Uninfected Recipients.

SHELTER is a trial of transplanting lungs from deceased donors with hepatitis C virus (HCV) infection into HCV-negative candidates (sponsor: Merck; NCT03724149). Few trials have reported outcomes using thoracic organs from HCV-RNA+ donors and none have reported quality of life (QOL). Methods: This study is a single-arm trial of 10 lung transplants at a single center. Patients were included who were between 18 and 67 y of age and waitlisted for lung-only transplant. Patients were excluded who had evidence of liver disease. Primary outcome was HCV cure (sustained virologic response 12 wk after completing antiviral therapy). Recipients longitudinally reported QOL using the validated RAND-36 instrument. We also applied advanced methods to match HCV-RNA+ lung recipients to HCV-negative lung recipients in a 1:3 ratio at the same center. Results: Between November 2018 and November 2020, 18 patients were consented and opted-in for HCV-RNA+ lung offers in the allocation system. After a median of 37 d (interquartile range [IQR], 6-373) from opt-in, 10 participants received double lung transplants. The median recipient age was 57 y (IQR, 44-67), and 7 recipients (70%) had chronic obstructive pulmonary disease. The median lung allocation score at transplant was 34.3 (IQR, 32.7-86.9). Posttransplant, 5 recipients developed primary graft dysfunction grade 3 on day 2 or 3, although none required extracorporeal membrane oxygenation. Nine patients received elbasvir/grazoprevir, whereas 1 patient received sofosbuvir/velpatasvir. All 10 patients were cured of HCV and survived to 1 y (versus 83% 1-y survival among matched comparators). No serious adverse events were found to be related to HCV or treatment. RAND-36 scores showed substantial improvement in physical QOL and some improvement in mental QOL. We also examined forced expiratory volume in 1 s-the most important lung function parameter after transplantation. We detected no clinically important differences in forced expiratory volume in 1 s between the HCV-RNA+ lung recipients versus matched comparators. Conclusions: SHELTER adds important evidence regarding the safety of transplanting HCV-RNA+ lungs into uninfected recipients and suggests QOL benefits.

Age-related decline in anti-HBV antibodies in vaccinated kidney transplant recipients.

BACKGROUND: Hepatitis B virus (HBV) vaccination is indicated for all end stage kidney disease patients, including all solid organ transplant candidates. Maintenance of adequate immunity is especially important for immunosuppressed solid organ recipients who are at increased risk for donor or community acquired HBV. The impact of age and immunosuppression on long-term maintenance of HBV immunity postvaccination has not been fully investigated. METHODS: We performed a single-center retrospective study of 96 kidney transplant recipients, transplanted between July 2012 and December 2020, who had Hepatitis B surface antibody (HBsAb) levels measured pretransplantation and 1-year posttransplantation. We compared the change in HBsAb levels stratified by patient's age (<45, 45-60, and >60) and by whether or not the patient received lymphocyte depleting induction therapy. RESULTS: Our results demonstrate that HBsAb IgG levels vary by age group, decreased significantly at 1-year posttransplant (p < .0001) and were significantly lower in the older cohort (p = .03). Among recipients who received rabbit anti-thymocyte globulin induction (rATG), the log HbsAb levels were significantly lower in the older age group (2.15 in age <45, 1.75 in age 45-60 and 1.47 in age >60, p = .01). Age group (p = .004), recipient HBcAb status (p = .002), and rATG (p = .048) were independently associated with >20% reduction in log HBsAb levels posttransplant. CONCLUSION: Significant declines in HBsAb levels occur postkidney transplantation, especially in older individuals, thus placing exposed older kidney transplant recipients at greater risk of HBV infection and associated complications.

Infectious complications associated with bronchial anastomotic dehiscence in lung transplant recipients.

INTRODUCTION: Bronchial anastomotic dehiscence (AD) is an uncommon complication following lung transplantation that carries significant morbidity and mortality. The objective of this study was to characterize fungal and bacterial infections in ADs, including whether infections following AD were associated with progression to bronchial stenosis. METHODS: This was a single-center study of 615 lung transplant recipients between 6/1/2015 and 12/31/2021. Airway complications were defined according to ISHLT consensus guidelines. RESULTS: 22 of the 615 recipients (3.6%) developed an AD. Bronchial ischemia or necrosis was common prior to dehiscence (68.1%). Fourteen (63.6%) recipients had bacterial airway infections, most commonly with Gram-negative rods, prior to dehiscence. Thirteen (59.1%) recipients had an associated pleural infection, most commonly with Candida species (30.8%). Post-dehiscence Aspergillus species were isolated in 4 recipients, 3 of which were de novo infections. Eleven had bacterial infections prior to dehiscence resolution, most commonly with Pseudomonas aeruginosa. Eleven recipients developed airway stenosis requiring dilation and/or stenting. Development of secondary infection prior to AD resolution was not associated with progression to stenosis (OR = .41, 95% CI = .05-3.30, p = .41). CONCLUSIONS: Gram-negative bacterial infections are common before and after AD. Pleural infection should be suspected in most cases. Infections prior to healing were not associated with subsequent development of airway stenosis.

Infection and clinical xenotransplantation: Guidance from the Infectious Disease Community of Practice of the American Society of Transplantation.

This guidance was developed to summarize current approaches to the potential transmission of swine-derived organisms to xenograft recipients, health care providers, or the public in clinical xenotransplantation. Limited specific data are available on the zoonotic potential of pig pathogens. It is anticipated that the risk of zoonotic infection in xenograft recipients will be determined by organisms present in source animals and relate to the nature and intensity of the immunosuppression used to maintain xenograft function. Based on experience in allotransplantation and with preclinical models, viral infections are of greatest concern, including porcine cytomegalovirus, porcine lymphotropic herpesvirus, and porcine endogenous retroviruses. Sensitive and specific microbiological assays are required for routine microbiological surveillance of source animals and xenograft recipients. Archiving of blood samples from recipients, contacts, and hospital staff may provide a basis for microbiological investigations if infectious syndromes develop. Carefully implemented infection control practices are required to prevent zoonotic pathogen exposures by clinical care providers. Informed consent practices for recipients and their close contacts must convey the lack of specific data for infectious risk assessment. Available data suggest that infectious risks of xenotransplantation are manageable and that clinical trials can advance with carefully developed protocols for pretransplant assessment, syndrome evaluation, and microbiological monitoring.

Clinical Outcomes and Risk Factors for Carbapenem-resistant Enterobacterales Bloodstream Infection in Solid Organ Transplant Recipients.

BACKGROUND: The clinical outcomes associated with, and risk factors for, carbapenem-resistant Enterobacterales (CRE) bloodstream infections (BSIs) in solid organ transplant (SOT) recipients remain ill-defined. METHODS: A multicenter retrospective cohort study was performed, including SOT recipients with an Enterobacterales BSI between 2005 and 2018. Exposed subjects were those with a CRE BSI. Unexposed subjects were those with a non-CRE BSI. A multivariable survival analysis was performed to determine the association between CRE BSI and risk of all-cause mortality within 60 d. Multivariable logistic regression analysis was performed to determine independent risk factors for CRE BSI. RESULTS: Of 897 cases of Enterobacterales BSI in SOT recipients, 70 (8%) were due to CRE. On multivariable analysis, CRE BSI was associated with a significantly increased hazard of all-cause mortality (adjusted hazard ratio, 2.85; 95% confidence interval [CI], 1.68-4.84; P < 0.001). Independent risk factors for CRE BSI included prior CRE colonization or infection (adjusted odds ratio [aOR] 9.86; 95% CI, 4.88-19.93; P < 0.001)' liver transplantation (aOR, 2.64; 95% CI, 1.23-5.65; P = 0.012)' lung transplantation (aOR, 3.76; 95% CI, 1.40-10.09; P = 0.009)' and exposure to a third-generation cephalosporin (aOR, 2.21; 95% CI, 1.17-4.17; P = 0.015) or carbapenem (aOR, 2.80; 95% CI, 1.54-5.10; P = 0.001) in the prior 6 months. CONCLUSIONS: CRE BSI is associated with significantly worse outcomes than more antibiotic-susceptible Enterobacterales BSI in SOT recipients.

The effect of induction immunosuppression for kidney transplant on the latent HIV reservoir.

The HIV latent viral reservoir (LVR) remains a major challenge in the effort to find a cure for HIV. There is interest in lymphocyte-depleting agents, used in solid organ and bone marrow transplantation to reduce the LVR. This study evaluated the LVR and T cell receptor repertoire in HIV-infected kidney transplant recipients using intact proviral DNA assay and T cell receptor sequencing in patients receiving lymphocyte-depleting or lymphocyte-nondepleting immunosuppression induction therapy. CD4+ T cells and intact and defective provirus frequencies decreased following lymphocyte-depleting induction therapy but rebounded to near baseline levels within 1 year after induction. In contrast, these biomarkers were relatively stable over time in the lymphocyte-nondepleting group. The lymphocyte-depleting group had early TCRß repertoire turnover and newly detected and expanded clones compared with the lymphocyte-nondepleting group. No differences were observed in TCRß clonality and repertoire richness between groups. These findings suggest that, even with significant decreases in the overall size of the circulating LVR, the reservoir can be reconstituted in a relatively short period of time. These results, while from a relatively unique population, suggest that curative strategies aimed at depleting the HIV LVR will need to achieve specific and durable levels of HIV-infected T cell depletion.

Impact of deceased organ donor injection drug use on donor culture positivity and recipient outcomes.

BACKGROUND: Due to the ongoing opioid epidemic in the United States, deceased organ donors increasingly have a history of injection drug use (IDU), raising concerns about infectious risks to solid organ transplant (SOT) recipients. We sought to determine how recent IDU among deceased organ donors impacted donor culture results and recipient outcomes. METHODS: A retrospective cohort study was performed at three transplant centers. Exposed donors were those with "recent IDU" (in the prior 12 months). Primary outcomes included (1) positive donor cultures for bacteria or Candida species, (2) recipient bacterial or Candida infection within 3 months posttransplant, and (3) recipient graft failure or death within 12 months posttransplant. Mixed effects multivariable regression models were used to evaluate the relationship between recent donor IDU and each outcome. RESULTS: A total of 658 SOT recipients who received organs from 394 donors were included. Sixty-six (17%) donors had a history of recent IDU. Recent IDU in donors was associated with a significantly increased odds of donor culture positivity (aOR 3.65, 95% CI 1.06-12.60, p = .04) but was not associated with SOT recipient infection (aHR 0.98, 95% CI 0.71-1.36, p = .92) or graft failure or death (aHR 0.67, 95% CI 0.29-1.51, p = .33). CONCLUSION: Donors with recent IDU are more likely to have positive cultures, but their recipients' outcomes are unaffected, suggesting organs from donors with recent IDU may be safely utilized.

New Perspectives on Antimicrobial Agents: Maribavir.

Maribavir was approved by the U.S. Food and Drug Administration in November 2021 for the treatment of adult and pediatric patients with post-transplant cytomegalovirus (CMV) infection/disease that is refractory to treatment (with or without genotypic resistance) with ganciclovir, valganciclovir, cidofovir, or foscarnet. Maribavir is an oral benzimidazole riboside with potent and selective multimodal anti-CMV activity. It utilizes a novel mechanism of action which confers activity against CMV strains that are resistant to traditional anti-CMV agents, and also offers a more favorable safety profile relative to the dose-limiting side effects of previously available therapies. Maribavir was initially studied as an agent for CMV prophylaxis in solid organ and hematopoietic stem cell recipients, but initial phase III trials failed to meet clinical efficacy endpoints. It has been more recently studied as a therapeutic agent at higher doses for refractory-resistant (R-R) CMV infections with favorable outcomes. After an overview of maribavir's chemistry and clinical pharmacology, this review will summarize clinical efficacy, safety, tolerability, and resistance data associated with maribavir therapy.

A phase I trial of cyclosporine for hospitalized patients with COVID-19.

BACKGROUNDCOVID-19 remains a global health emergency with limited treatment options, lagging vaccine rates, and inadequate healthcare resources in the face of an ongoing calamity. The disease is characterized by immune dysregulation and cytokine storm. Cyclosporine A (CSA) is a calcineurin inhibitor that modulates cytokine production and may have direct antiviral properties against coronaviruses.METHODSTo test whether a short course of CSA was safe in patients with COVID-19, we treated 10 hospitalized, oxygen-requiring, noncritically ill patients with CSA (starting at a dose of 9 mg/kg/d). We evaluated patients for clinical response and adverse events, measured serum cytokines and chemokines associated with COVID-19 hyperinflammation, and conducted gene-expression analyses.RESULTSFive participants experienced adverse events, none of which were serious; transaminitis was most common. No participant required intensive care unit-level care, and all patients were discharged alive. CSA treatment was associated with significant reductions in serum cytokines and chemokines important in COVID-19 hyperinflammation, including CXCL10. Following CSA administration, we also observed a significant reduction in type I IFN gene expression signatures and other transcriptional profiles associated with exacerbated hyperinflammation in the peripheral blood cells of these patients.CONCLUSIONShort courses of CSA appear safe and feasible in patients with COVID-19 who require oxygen and may be a useful adjunct in resource-limited health care settings.TRIAL REGISTRATIONThis trial was registered on ClinicalTrials.gov (Investigational New Drug Application no. 149997; ClinicalTrials.gov NCT04412785).FUNDINGThis study was internally funded by the Center for Cellular Immunotherapies.

Critically important outcomes for infection in trials in kidney transplantation: An international survey of patients, caregivers, and health professionals.

BACKGROUND: Infections are a common complication following kidney transplantation, but are reported inconsistently in clinical trials. This study aimed to identify the infection outcomes of highest priority for patients/caregivers and health professionals to inform a core outcome set to be reported in all kidney transplant clinical trials. METHODS: In an international online survey, participants rated the absolute importance of 16 infections and eight severity dimensions on 9-point Likert Scales, with 7-9 being critically important. Relative importance was determined using a best-worst scale. Means and proportions of the Likert-scale ratings and best-worst preference scores were calculated. RESULTS: 353 healthcare professionals (19 who identified as both patients/caregiver and healthcare professionals) and 220 patients/caregivers (190 patients, 22 caregivers, eight who identified as both) from 55 countries completed the survey. Both healthcare professionals and patients/caregivers rated bloodstream (mean 8.4 and 8.5, respectively; aggregate 8.5), kidney/bladder (mean 7.9 and 8.4; aggregate 8.1), and BK virus (mean 8.1 and 8.6; aggregate 8.3) as the top three most critically important infection outcomes, whilst infectious death (mean 8.8 and 8.6; aggregate 8.7), impaired graft function (mean 8.4 and 8.7; aggregate 8.5) and admission to the intensive care unit (mean 8.2 and 8.3; aggregate 8.2) were the top three severity dimensions. Relative importance (best-worst) scores were consistent. CONCLUSIONS: Healthcare professionals and patients/caregivers consistently identified bloodstream infection, kidney/bladder infections, and BK virus as the three most important infection outcomes, and infectious death, admission to intensive care unit and infection impairing graft function as the three most important infection severity outcomes.

What is the optimal antimicrobial prophylaxis to prevent postoperative infectious complications after liver transplantation? A systematic review of the literature and expert panel recommendations.

BACKGROUND: Antimicrobial prophylaxis is well-accepted in the liver transplant (LT) setting. Nevertheless, optimal regimens to prevent bacterial, viral, and fungal infections are not defined. OBJECTIVES: To identify the optimal antimicrobial prophylaxis to prevent post-LT bacterial, fungal, and cytomegalovirus (CMV) infections, to improve short-term outcomes, and to provide international expert panel recommendations. DATA SOURCES: Ovid MEDLINE, Embase, Scopus, Google Scholar, and Cochrane Central. METHODS: Systematic review following PRISMA guidelines and recommendations using the GRADE approach derived from an international expert panel. PROSPERO ID: CRD42021244976. RESULTS: Of 1853 studies screened, 34 were included for this review. Bacterial, CMV, and fungal antimicrobial prophylaxis were evaluated separately. Pneumocystis jiroveccii pneumonia (PJP) antimicrobial prophylaxis was analyzed separately from other fungal infections. Overall, eight randomized controlled trials, 21 comparative studies, and five observational noncomparative studies were included. CONCLUSIONS: Antimicrobial prophylaxis is recommended to prevent bacterial, CMV, and fungal infection to improve outcomes after LT. Universal antibiotic prophylaxis is recommended to prevent postoperative bacterial infections. The choice of antibiotics should be individualized and length of therapy should not exceed 24 hours (Quality of Evidence; Low | Grade of Recommendation; Strong). Both universal prophylaxis and preemptive therapy are strongly recommended for CMV prevention following LT. The choice of one or the other strategy will depend on individual program resources and experiences, as well as donor and recipient serostatus. (Quality of Evidence; Low | Grade of Recommendation; Strong). Antifungal prophylaxis is strongly recommended for LT recipients at high risk of developing invasive fungal infections. The drug of choice remains controversial. (Quality of Evidence; High | Grade of Recommendation; Strong). PJP prophylaxis is strongly recommended. Length of prophylaxis remains controversial. (Quality of Evidence; Very Low | Grade of Recommendation; Strong).