Donor-derived bacteremia in liver transplant recipients despite antibiotic prophylaxis

Non-Standard Risk Donors and Risk of Donor-Derived Infections: From Evaluation to Therapeutic Management

Expected and unexpected donor-derived infections are a rare complication of solid organ transplantation, but can result in significant morbidity and mortality. Over the last years, the growing gap existing between patients on the waiting list and available organs has favored the use of organs from donors with suspected or confirmed infections, thanks to the improvement of risk mitigation strategies against transmission of well recognized and emerging infections. Given the recent developments, the particular interest of this review is to summarize data on how to maximize utilization of HIV+ donors in HIV+ recipients, the use of HCV-viremic donors and HBV positive donors. This article also covers the implications for recipient of organs from donors with bacteremia and the challenge of multidrug resistant (MDR) infections. Lastly this review describes emerging risks associated with recent Coronavirus Disease-2019 (COVID-19) pandemics.

Minimizing risk while maximizing opportunity: The infectious disease organ offer process survey

BACKGROUND

The purpose of this study was to understand how transplant infectious disease (TID) physicians assess a potential donor with known or suspected infection and describe posttransplant management.

METHODS

We designed a survey of 10 organ offer scenarios and asked questions pertaining to organ acceptability for transplantation and management posttransplant. The survey was distributed to TID clinicians via transplant society listservs and email. Responses were recorded in REDCap, and descriptive statistics were employed.

RESULTS

One hundred thirteen infectious disease physicians responded to the survey, of whom 85 completed all cases. Respondents were generally in agreement regarding organ acceptability, although some divergence was seen when evaluating lungs from donors with influenza, tuberculosis, or multidrug-resistant Acinetobacter infection. Posttransplant management showed more variation. Areas of optimization were identified: (1) Further understanding of where risk-mitigation strategies within the donor offer process may improve donor acceptability and therefore organ utilization; (2) importance of recipient considerations in assessing degree of infectious risk; and (3) gaps in evidenced-based data regarding optimal posttransplant management of recipients.

CONCLUSION

Evaluation of donor offers by TID clinicians is a complex process. Although the survey does not itself serve to make recommendations regarding best practices, it highlights areas where generation of data to inform acceptance and management practices may allow for improved organ utilization and recipient management.

Infections After Liver Transplant -Timeline, Management and Prevention

Liver transplantation (LT) is the standard treatment for end- stage liver disease. Patient and graft survival have improved significantly in the last three decades owing to improvement in surgical technique, better perioperative management and better immunosuppressive regimens. However, LT recipients are at increased risk of infections, particularly in the first year after transplantation. The risk of infection is directly proportional to immunosuppressive regimen and graft function. In this review, we will briefly discuss the timeline of infections after liver transplant, preventive strategies and management of infectious complications.

Risk of Staphylococcus aureus Bacteremia Before and After Solid Organ Transplantation

BACKGROUND

Solid organ transplant recipients are at high risk for Staphylococcus aureus bacteremia, but the risks before and after transplantation require further research.

METHODS

We performed a population-based retrospective self-controlled study using the State Inpatient Database from 10 states in the United States. Adult and pediatric patients who had solid organ transplantation from 2004 to 2018 were tracked longitudinally for 1 y before and after transplantation outside of the immediate peritransplant periods. The exposure of interest was solid organ transplantation, and the outcome of interest was hospitalization with S. aureus bacteremia.

RESULTS

Of 75 549 patients, 581 (0.77%) and 239 (0.32%) were hospitalized with S. aureus bacteremia in the pretransplant and posttransplant periods, respectively ( P < 0.001). Overall, the odds of hospitalization with S. aureus bacteremia increased from 7 to 12 mo to 1 to 6 mo before transplantation (odds ratio, 1.24; 95% confidence interval, 1.05-1.46) and then decreased following transplantation (odds ratio, 0.35; 95% confidence interval, 0.28-0.45; 7-12 mo after transplantation). The decreased rate after transplantation was driven by the cases associated with central line-associated bloodstream infections and endocarditis among kidney and heart transplant recipients. Odds of hospitalization with S. aureus bacteremia did not change after liver transplantation, whereas they increased after lung transplantation.

CONCLUSIONS

In addition to immunosuppression, the reversal of organ failure and associated requirements for organ support following transplantation may play an important role in the risk of S. aureus bacteremia in solid organ transplant recipients. These results can guide infection prevention approaches and future research on S. aureus infections in transplant patients.

Machine perfusion combined with antibiotics prevents donor-derived infections caused by multidrug-resistant bacteria

Donor infection affects organ utilization, especially the infections by multidrug-resistant bacteria, which may have disastrous outcomes. We established a rat model, inoculated with Escherichia coli or carbapenem-resistant Klebsiella pneumoniae (CRKP), to investigate whether hypothermic machine perfusion (HMP), normothermic machine perfusion (NMP), or static cold storage (SCS) combined with antibiotic (AB) could eliminate the bacteria. E. coli or CRKP-infected kidneys were treated with cefoperazone-sulbactam and tigecycline, respectively. The HMP+AB and NMP+AB treatments had significant therapeutic effects on E. coli or CRKP infection compared with the SCS+AB treatment. The bacterial load of CRKP-infected kidneys in the HMP+AB (22 050 ± 2884 CFU/g vs. 1900 ± 400 CFU/g, p = .007) and NMP+AB groups (25 433 ± 2059 CFU/g vs. 500 ± 458 CFU/g, p = .002) were significantly reduced, with no statistically significant difference between both groups. Subsequently, the CRKP-infected kidneys of the HMP+AB and SCS+AB groups were transplanted. The rats in the SCS+AB group were severe infected and euthanized on day 4 post-transplant. By contrast, the rats in the HMP+AB group were in good condition. In conclusion, HMP and NMP combined with AB seems to be efficient approaches to decrease bacterial load of infected kidneys. This might lead to higher utilization rates of donors with active infection.

Effects of preservative fluid associated possible donor-derived carbapenem-resistant Klebsiella Pneumoniae infection on kidney transplantation recipients

BACKGROUND

Infections remain a major cause of morbidity and mortality in kidney transplant (KT) recipients. This study aimed to investigate the preservation fluid (PF) samples from deceased donors and report the impacts of possible donor-derived carbapenem-resistant Klebsiella pneumoniae (pdd-CRKP) infections on KT recipients.

METHODS

A retrospective study was performed that included all recipients who received kidney transplantation from deceased donors in our hospital between December 2018 and December 2020. A total of 212 patients received kidney transplantation from deceased donors, a total of 206 PF samples were collected, and 20 recipients had a CRKP-positive culture. Both donors and recipients with CRKP-positive PF cultures were divided into two groups, and continuous variables between the two groups were compared using independent-sample t tests and Mann-Whitney tests. Categorical variables were compared using the chi-square test or Fisher's exact test. The significance level of p values was set at 0.05.

RESULTS

A total of 337 recipients underwent kidney transplantation, including 212 recipients of organs from deceased donors and 110 corresponding deceased donors. A total of 206 PF samples were collected, and 20 recipients had CRKP-positive PF cultures. The donors' length of ICU stay was a potential risk factor for CRKP positivity in the PF culture (P < 0.05). Fifteen recipients were infected with pdd-CRKP, and the incidence of pdd-CRKP infection was 7.3% (15/206). The use of antibiotics, including ceftazidime-avibactam (CAZ-AVI), was a potential protective factor against death and graft loss in recipients with a CRKP-positive PF culture (P < 0.05).

CONCLUSIONS

This study shows that the incidence of pdd-CRKP is high in our centre, recipients with pdd-CRKP infection can still achieve a good prognosis with the use of antimicrobial agents including CAZ-AVI.

Candida Contamination in Kidney and Liver Organ Preservation Solution: Does It Matter?

INTRODUCTION

Fungal infections remain a major challenge affecting outcomes after kidney (KT) and liver transplantation (LT).

METHODS

In this retrospective single center study, the incidence of Candida contamination in renal and hepatic graft preservation solution (PS) was evaluated. In addition, Candida associated infections in recipients and related complications were analyzed.

RESULTS

Overall, the PS of 1248 hepatic and 1273 renal grafts were evaluated. The incidence of fungal contamination in the PS of hepatic and renal grafts was 1.2% and 0.86%, respectively. Additionally, the hepatic PS of one patient who underwent a combined liver-kidney transplant had Candida contamination. Candida albicans was the most common organism (70.4%) and 65.4% of the patients received antifungal treatment. Candida-associated complications in the recipients was 19%. Complications in LT patients included Candida peritonitis and Candida sepsis. Two KT recipients with contaminated PS developed a mycotic aneurysm at the anastomotic site resulting in severe bleeding. The 1-year mortality in patients with PS contamination for LT and KT recipients was 33% and 18%, respectively. Although the incidence of fungal contamination of PS was low, contaminated PS was associated with a high mortality.

CONCLUSION

The results of the study suggest that PS should be evaluated for fungal growth.

Tacrolimus Impairs Kupffer Cell Capacity to Control Bacteremia: Why Transplant Recipients Are Susceptible to Infection

BACKGROUND AND AIMS

Kupffer cells (KCs) are the resident intravascular phagocyte population of the liver and critical to the capture and killing of bacteria. Calcineurin/nuclear factor of activated T cells (NFAT) inhibitors (CNIs) such as tacrolimus are used to prevent rejection in solid organ transplant recipients. Although their effect on lymphocytes has been studied extensively, there are limited experimental data about if and how CNIs shape innate immunity, and whether this contributes to the higher rates of infection observed in patients taking CNIs.

APPROACH AND RESULTS

Here, we investigated the impact of tacrolimus treatment on innate immunity and, more specifically, on the capability of Kupffer cells (KCs) to fight infections. Retrospective analysis of data of >2,700 liver transplant recipients showed that taking calcineurin inhibitors such as tacrolimus significantly increased the likelihood of Staphylococcus aureus infection. Using a mouse model of acute methicillin-resistant S. aureus (MRSA) bacteremia, most bacteria were sequestered in the liver and we found that bacteria were more likely to disseminate and kill the host in tacrolimus-treated mice. Using imaging, we unveiled the mechanism underlying this observation: the reduced capability of KCs to capture, phagocytose, and destroy bacteria in tacrolimus-treated animals. Furthermore, in a gene expression analysis of infected KCs, the triggering receptor expressed on myeloid cells 1 (TREM1) pathway was the one with the most significant down-regulation after tacrolimus treatment. TREM1 inhibition likewise inhibited KC bacteria capture. TREM1 levels on neutrophils as well as the overall neutrophil response after infection were unaffected by tacrolimus treatment.

CONCLUSIONS

Our results indicate that tacrolimus treatment has a significant impact directly on KCs and on TREM1, thereby compromising their capacity to fend off infections.

Severe Sepsis Mimicking Primary Nonfunction Following Liver Transplantation: Normothermic Machine Perfusion Is a Potential Environment for Bacterial Overgrowth and Transmission From Donor to Recipient. A Case Report

Primary nonfunction (PNF) in the early postoperative period following liver transplantation is fatal if not managed appropriately with early retransplantation. Severe early allograft dysfunction can mimic PNF. The identification of treatable causative factors such as sepsis, hepatic artery, or portal vein thrombosis is essential to distinguish it from PNF, and their early management may avoid the need for retransplantation. In this article, we describe a case of sepsis-induced severe liver dysfunction from a contaminated graft perfused with normothermic machine perfusion (NMP), which presented in a manner similar to PNF. The implications of graft contamination are poorly described. To our knowledge, this is the first report of bacterial contamination of a graft that underwent NMP and subsequently caused severe sepsis in the recipient. The conditions created with NMP may be optimal for certain micro-organisms to thrive. The role of the liver in the immune system is complex as it provides an essential barrier to enterically derived portal venous pathogens and produces numerous acute phase proteins that augment the systemic immune response. Additionally, the liver is also known to restrain harmful and excessive systemic immune responses such as those that occur with the sepsis syndrome. The relationship between bacterial graft contamination, sepsis, and graft dysfunction may be multidirectional.

Deceased Donor Predictors for Pediatric Liver Allograft Utilization

BACKGROUND

The number of pediatric deceased organ donors has recently declined, and the nonutilization of pediatric liver allografts has limited the development of liver transplantation. We determined the utilization rate of pediatric livers and identified risk factors for graft discard.

METHODS

We used data from the Scientific Registry of Transplant Recipients database from January 1, 2000, to December 31, 2012. The trends of pediatric liver donors and utilization rates were analyzed. Donor risk factors that impacted the graft use of pediatric livers were measured. Logistic regression modelling was performed to evaluate graft utilization and risk factors.

RESULTS

A total of 11,934 eligible pediatric liver donors were identified during this period. A total of 1191 authorized liver grafts did not recover or recovered without transplantation. Factors including pediatric donors >1 year of age (odds ratio [OR] = 2.956, 95% confidence interval [CI] 2.494-3.503, P < .001), nonhead trauma (OR = 2.243, 95% CI 1.903-2.642, P < .001), lack of heartbeat (OR = 7.534, 95% CI 5.899-9.623, P < .001), hepatitis B surface antigen positivity (OR = 4.588, 95% CI 1.021-20.625, P = .047), anti-hepatitis C virus positivity (OR = 4.691, 95% CI 1.352-16.280, P = .015), total bilirubin >1 mg/dL (OR = 1.743, 95% CI 1.469-2.068, P < .001), and blood urea nitrogen >21 mg/dL (OR = 1.941, 95% CI 1.546-2.436, P < .001) were significantly related to graft nonutilization. Steroids or diuretics administered prerecovery were significantly related to graft utilization (OR = 0.684, 95% CI 0.581-0.806, P < .001; OR = 0.744, 95% CI 0.634-0.874, P < .001; respectively).

CONCLUSIONS

The pediatric liver allograft utilization rate and risk factors for nonutilization of grafts were determined.

Impact of Donor Positive Blood Culture in Deceased Donor Liver Transplantation

INTRODUCTION

In the era of shortage of organs for donation, transplantation from suboptimal donors is an expanding alternative to minimize waitlist mortality. In that sense, the safety of using organs from bacteremic donors has been a recurrent matter of discussion. We aimed to evaluate the influence of donor positive blood culture in the recipient and graft outcomes after liver transplantation from deceased donors.

MATERIAL AND METHODS

Blood culture results from 255 deceased liver donors were retrospectively reviewed. Patients were categorized into 2 groups based on the recipients who obtained a graft from a donor with negative or positive blood culture. Graft and recipient outcomes were compared between the 2 groups using univariate survival analysis and multivariate regression models. Transmission of bloodstream infection from donor to recipient was assessed by reviewing recipients' microbiologic status when there was evidence of infection.

RESULTS

Positive blood culture in donors was not associated with negative outcomes after transplantation. Death within 30 days after transplantation and overall recipient and graft survival did not differ between the 2 groups. Only Child-Pugh score ≥10 and retransplantation status were considered independent predictors of recipient death and graft failure. We identified 1 potential case of bacteremia transmission from donor to recipient.

CONCLUSION

Donor positive blood culture was not associated with negative outcomes after liver transplantation. Transmission of infection from donor to recipient is possible, but rare. The results support the usage of bacteremic donors as a safe alternative to the scarcity of optimal donors.

Screening of donors and recipients for infections prior to solid organ transplantation

PURPOSE OF REVIEW

This review is a brief overview of current guidelines on screening donors and candidates for bacterial, fungal, parasitic and viral infections prior to solid organ transplantation. The pretransplant period is an important time to evaluate infection exposure risk based on social history as well as to offer vaccinations.

RECENT FINDINGS

One of the major changes in the past few years has been increased utilization of increased Public Health Service risk, HIV positive, and hepatitis C-positive donors. There has also been increased attention to donor and recipient risks for geographically associated infections, such as endemic fungal infections and flaviviruses.

SUMMARY

Screening for donors and candidates prior to organ transplantation can identify and address infection risks. Diagnosing infections in a timely manner can help guide treatment and additional testing. Use of necessary prophylactic treatment in organ recipients can prevent reactivation of latent infections and improve posttransplant outcomes.

Multidrug-resistant Gram-negative bacterial infections in solid organ transplant recipients-Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of infections due to multidrug-resistant (MDR) Gram-negative bacilli in the pre- and post-transplant period. MDR Gram-negative bacilli, including carbapenem-resistant Enterobacteriaceae, MDR Pseudomonas aeruginosa, and carbapenem-resistant Acinetobacter baumannii, remain a threat to successful organ transplantation. Clinicians now have access to at least five novel agents with activity against some of these organisms, with others in the advanced stages of clinical development. No agent, however, provides universal and predictable activity against any of these pathogens, and very little is available to treat infections with MDR nonfermenting Gram-negative bacilli including A baumannii. Despite advances, empiric antibiotics should be tailored to local microbiology and targeted regimens should be tailored to susceptibilities. Source control remains an important part of the therapeutic armamentarium. Morbidity and mortality associated with infections due to MDR Gram-negative organisms remain unacceptably high. Heightened infection control and antimicrobial stewardship initiatives are needed to prevent these infections, curtail their transmission, and limit the evolution of MDR Gram-negative pathogens, especially in the setting of organ transplantation.

Infections in Liver Transplantation

Liver transplantation has become an important treatment modality for patients with end-stage liver disease/cirrhosis, acute liver failure, and hepatocellular carcinoma. Although surgical techniques and immunosuppressive regimens for liver transplantation have improved significantly over the past 20 years, infectious complications continue to contribute to the morbidity and mortality in this patient population. The use of standardized screening protocols for both donors and recipients, coupled with targeted prophylaxis against specific pathogens, has helped to mitigate the risk of infection in liver transplant recipients. Patients with chronic liver disease and cirrhosis have immunological deficits that place them at increased risk for infection while awaiting liver transplantation. The patient undergoing liver transplantation is prone to develop healthcare-acquired infections due to multidrug-resistant organisms that could potentially affect patient outcomes after transplantation. The complex nature of liver transplant surgery that involves multiple vascular and hepatobiliary anastomoses further increases the risk of infection after liver transplantation. During the early post-transplantation period, healthcare-acquired bacterial and fungal infections are the most common types of infection encountered in liver transplant recipients. The period of maximal immunosuppression that occurs at 1–6 months after transplantation can be complicated by opportunistic infections due to both primary infection and reactivation of latent infection. Severe community-acquired infections can complicate the course of liver transplantation beyond 12 months after transplant surgery. This chapter provides an overview of liver transplantation including indications, donor-recipient selection criteria, surgical procedures, and immunosuppressive therapies. A focus on infections in patients with chronic liver disease/cirrhosis and an overview of the specific infectious complications in liver transplant recipients are presented.

Methicillin-resistant Staphylococcus aureus bacteremia among liver transplant recipients: epidemiology and associated risk factors for morbidity and mortality

Bacteremia due to Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA), complicates the clinical course of liver transplantation and is associated with high morbidity and mortality. Intravascular catheters had been reported to be the most frequent source of MRSA bacteremia. Among bacteremic liver recipients, 26.3%-100% of S. aureus were MRSA. Previous studies identified pre-transplant and post-transplant acquired S. aureus carriage, greater severity of liver disease, hepatocellular carcinoma and infection with immuno-modulatory viruses as predictors of S. aureus bacteremia in liver recipients. MRSA bacteremia accompanied by pneumonia and abdominal infections was related to mortality. Vancomycin, as well as daptomycin, is a first-line antibiotic for MRSA bacteremia. The purpose of this review is to better understand the characteristics of MRSA bacteremia by summarizing the epidemiology and antimicrobial resistance of S. aureus, the primary source, and related risk factors for morbidity and mortality of MRSA bacteremia. We have also explored the diagnostic, therapeutic and preventive measures for MRSA bacteremia to improve the outcomes of liver recipients.

Donor-derived infections among Chinese donation after cardiac death liver recipients

AIM

To investigate blood cultures of deceased donors and report the confirmed transmission of bacterial infection from donors to liver recipients.

METHODS

We retrospectively studied the results of blood cultures among our donation after cardiac death (DCD) donors and calculated the donor-derived bacterial infection rates among liver recipients. Study participants underwent liver transplantation between January 1, 2010 and February 1, 2017. The study involved a total of 67 recipients of liver grafts from 67 DCD donors. We extracted the data of donors’ and patients’ characteristics, culture results and clinical outcomes, especially the post-transplant complications in liver recipients, from electronic medical records. We analyzed the characteristics of the donors and the corresponding liver recipients with emphasis put on donor-derived infections.

RESULTS

Head trauma was the most common origin of death among our 67 DCD donors (46.3%). Blood taken prior to the procurement operation was cultured for 53 of the donors, with 17 episodes of bloodstream infections developing from 13 donors. The predominant organism isolated from the blood of donors was Gram-positive bacteria (70.6%). Only three (4.5%) of 67 liver recipients developed confirmed donor-derived bacterial infections, with two isolates of multidrug-resistant Klebsiella pneumoniae and one isolate of multidrug-resistant Enterobacter aerogenes. The liver recipients with donor-derived infections showed relation to higher crude mortality and graft loss rates (33.3% each) within 3 mo post transplantation, as compared to those without donor-derived infections (9.4% and 4.7%, respectively). All three liver recipients received appropriate antimicrobial therapy.

CONCLUSION

Liver recipients have high occurrence of donor-derived infections. The liver recipients with donor-derived multidrug-resistant Enterobacteriaceae infections can have good outcome if appropriate antimicrobial therapy is given.

Confirmed Transmission of Bacterial or Fungal Infection to Kidney Transplant Recipients from Donated After Cardiac Death (DCD) Donors in China: A Single-Center Analysis

Background

We aimed to investigate blood and urine cultures of donated after cardiac death (DCD) donors and report the cases of confirmed (proven/probable) transmission of bacterial or fungal infection from donors to kidney recipients.

Material/Methods

Seventy-eight DCD donors between 2010 and 2016 were included. Sixty-one DCD donors underwent blood cultures and 22 episodes of bacteremias developed in 18 donors. Forty-three donors underwent urine cultures and 14 donors experienced 17 episodes of urinary infections.

Results

Seven of 154 (4.5%) kidney recipients developed confirmed donor-derived bacterial or fungal infections. Inappropriate use of antibiotics in donor was a risk factor for donor-derived infection (p=0.048). The use of FK506 was more frequent in recipients without donor-derived infection than those with donor-derived infection (p=0.033). Recipients with donor-derived infection were associated with higher mortality and graft loss (42.9% and 28.6%, respectively), when compared with those without donor-derived infection (4.8% each). Three kidney recipients with donor-derived infection died; one death was due to multi-organ failure caused by Candida albicans, and two were related to rupture of the renal artery; two of them did not receive appropriate antimicrobial therapy after infection.

Conclusions

Our kidney recipients showed high occurrence rates of donor-derived infection. Recipients with donor-derived infection were associated with higher mortality and graft loss than those without donor-derived infection. The majority of recipients with donor-derived infection who died did not receive appropriate antimicrobial therapy after infection.

Successful liver transplantation despite donor-transmitted ESBL-producing Klebsiella pneumoniae infection: Case report and review of the literature

Donor-derived bacterial infection is a recognized complication of solid organ transplantation. Patients admitted to the intensive care unit are increasingly exposed to infection with multidrug-resistant microorganisms. However, no specific recommendations are available about their suitability as donors. We report a case of donor-transmitted extended-spectrum beta-lactamase-producing Klebsiella pneumoniae infection in a liver recipient, and review the related literature.

Decreased graft survival in liver transplant recipients of donors with positive blood cultures: a review of the United Network for Organ Sharing dataset

Liver transplantation using blood culture positive donors (BCPD) has allowed a significant expansion of the donor pool. We aimed to characterize BCPD and assess the outcomes of BCPD liver transplant recipients. We retrieved data from the United Network for Organ Sharing (UNOS) registry on all adults who underwent primary, single-organ deceased-donor liver transplantation in the USA between 2008 and 2013. Patients were classified into two cohorts: the BCPD cohort and the non-BCPD cohort. One-year graft and patient survival were compared between cohorts using Kaplan-Meier estimates and Cox models. A total of 28 961 patients were included. There were 2316 (8.0%) recipients of BCPD. BCPD were more likely to be older, female, black, diabetic, hypertensive, and obese compared to non-BCPD. Graft survival was significantly lower in BCPD recipients compared to non-BCPD recipients (Kaplan-Meier, 0.85 vs. 0.87; P = 0.009). Results remained significant in propensity-matched analysis (P = 0.038). BCPD was independently associated with decreased graft survival (adjusted HR; 1.10, 95% CI 1.01-1.20; P = 0.04). There were no significant differences in patient survival between study groups. BCPD was associated with decreased graft survival in liver transplant recipients. Studies are needed to identify subgroups of BCPD with the highest risk of graft failure and characterize the underlying pathogenic mechanisms.

DCD liver transplant infection: experience from a single centre in China

AIM

The purpose of our study was to evaluate the incidence, timing, location and risk factors for bacterial and fungal infections after donation after cardiac death (DCD) liver transplant and clearly delineate any relationship between infection and survival in DCD liver transplant recipients.

METHODS

We retrospectively reviewed 257 consecutive patients undergoing DCD liver transplant between October 2010 and May 2015 at our centre.

RESULTS

A total of 133 patients (51.8%) developed at least one bacterial or fungal infection episode. The predominant infection site was the respiratory tract, followed by the blood stream. Most of the infections occurred within the first week after liver transplant (61.9%). A recipient respiratory support time greater than 7 days (p = 0.041), post-transplant hospital time greater than 24 days (p = 0.002) and renal failure after DCD liver transplant (p = 0.039) were independent predictors of bacterial and fungal infection. The area under the receiver operating characteristic (ROC) curve (AUC) of the transplant infection risk assessment model was 0.788. The 1- and 3-year survival rates for recipients without infection were significantly increased compared with recipients with infection (96.1% and 89.0% vs. 81.5% and 75.9%, p = 0.007).

CONCLUSION

This is the first study that offers detailed data revealing the timing and incidence of bacterial and fungal infection among adult DCD liver transplant recipients. Bacterial and fungal infection occurs at a high rate during the first week after DCD liver transplant, especially in patients with prolonged respiratory support time and renal failure, and infection is related to increased hospital stay.

Donor-Derived Infections: Incidence, Prevention, and Management

Organ donors reflect the diverse US population, and there are an increasing number of donors born in, who have resided in, or who have traveled to underdeveloped areas of the world or areas with geographically restricted infections. As such, these donors are exposed to pathogens that can potentially be transmitted to recipients of the donor’s organs. Additionally, there are newer techniques to identify many pathogens that may be transmitted from the donor to the transplant recipients. Finally, high-profile reports of several donor-derived infections have heightened awareness of donor-derived infections and have likely contributed to increased recognition. In this chapter, the incidence, methods of identification and prevention, and management of unexpected donor-derived infections will be reviewed.

From the classic concepts to modern practice

Transplant infectious disease is a field in evolution. For most allograft recipients, immunosuppressive therapies are more potent and have reduced the incidence of acute allograft rejection. At the same time, these therapies have increased susceptibility to many opportunistic infections and virally-mediated malignancies. Immunological tolerance has been achieved in only small numbers of patients who avoid drug toxicities and infection for as long as tolerance persists. The traditional timeline of post-transplant infections remains useful in the development of a differential diagnosis for patients with infectious syndromes. However, patterns of infection in the post-transplant period have changed over the past decade. Recipients are derived from a broader range of socioeconomic and geographical backgrounds. Infections are diagnosed more often, with improved microbiological assays (e.g. nucleic acid testing, NAT) used routinely in the diagnosis and management of common infections and increasingly in the screening of organ donors. Patterns of opportunistic infection have been altered by the increased identification of organisms demonstrating antimicrobial resistance and by the broader use of strategies to prevent viral, bacterial and fungal (including Pneumocystis) infections. Newer techniques are being applied (e.g. HLA-linked tetramer binding, intracellular cytokine staining) to assess pathogen-specific immunity. These are being integrated into clinical practice to assess individual susceptibility to specific infections. Infection, inflammation and the human microbiome are recognized as playing a central role in shaping innate and adaptive immune responses, graft rejection and autoimmunity. The full impact of infection on transplantation is only beginning to be appreciated.

Transmission of infection to liver transplant recipients from donors with infective endocarditis: lessons learned

Donors not meeting standard criteria, such as those with bacteremia, are now being used in response to the increasing need for organs for transplantation. Recommended strategies to prevent the occurrence of donor-derived bacteremia include the use of directed antibiotic prophylaxis. However, this approach does not eliminate the risk of infection transmission. Similarly, the management of organ recipients from donors with infective endocarditis (IE) remains uncharacterized. We report 2 cases of donor-derived bacterial infections in liver transplant recipients despite pathogen-specific antibiotic prophylaxis. In both instances, the donors had documented IE treated with appropriate antimicrobial therapy and clearance of bacteremia. Recipients had very distinctive clinical outcomes likely related to pathogen virulence and the extent of donor infection. Persistent infection in the transplanted liver should be suspected in organ recipients of a liver from donors with IE, despite the absence of bacteremia at the time of death and organ procurement. For eradication, recipients may require prolonged pathogen-directed antimicrobial therapy, such as is used for endovascular infections. Prompt recognition of donors with IE, appropriate notification, and prolonged antibiotic prophylaxis are key to reducing the risk of such donor-derived infections.

Transmission of methicillin-resistant Staphylococcus aureus via deceased donor liver transplantation confirmed by whole genome sequencing

Donor-derived bacterial infection is a recognized complication of solid organ transplantation (SOT). The present report describes the clinical details and successful outcome in a liver transplant recipient despite transmission of methicillin-resistant Staphylococcus aureus (MRSA) from a deceased donor with MRSA endocarditis and bacteremia. We further describe whole genome sequencing (WGS) and complete de novo assembly of the donor and recipient MRSA isolate genomes, which confirms that both isolates are genetically 100% identical. We propose that similar application of WGS techniques to future investigations of donor bacterial transmission would strengthen the definition of proven bacterial transmission in SOT, particularly in the presence of highly clonal bacteria such as MRSA. WGS will further improve our understanding of the epidemiology of bacterial transmission in SOT and the risk of adverse patient outcomes when it occurs.

Bacterial infection after liver transplantation

Infectious complications are major causes of morbidity and mortality after liver transplantation, despite recent advances in the transplant field. Bacteria, fungi, viruses and parasites can cause infection before and after transplantation. Among them, bacterial infections are predominant during the first two months post-transplantation and affect patient and graft survival. They might cause surgical site infections, including deep intra-abdominal infections, bacteremia, pneumonia, catheter-related infections and urinary tract infections. The risk factors for bacterial infections differ between the periods after transplant, and between centers. Recently, the emergence of multi-drug resistant bacteria is great concern in liver transplant (LT) patients. The instructive data about effects of infections with extended-spectrum beta lactamase producing bacteria, carbapenem-resistant gram-negative bacteria, and glycopeptide-resistant gram-positive bacteria were reported on a center-by-center basis. To prevent post-transplant bacterial infections, proper strategies need to be established based upon center-specific data and evidence from well-controlled studies. This article reviewed the recent epidemiological data, risk factors for each type of infections and important clinical issues in bacterial infection after LT.

Changing pattern of donor selection criteria in deceased donor liver transplant: a review of literature

During the last couple of decades, with standardization and progress in surgical techniques, immunosuppression and post liver transplantation patient care, the outcome of liver transplantation has been optimized. However, the principal limitation of transplantation remains access to an allograft. The number of patients who could derive benefit from liver transplantation markedly exceeds the number of available deceased donors. The large gap between the growing list of patients waiting for liver transplantation and the scarcity of donor organs has fueled efforts to maximize existing donor pool and identify new avenues. This article reviews the changing pattern of donor for liver transplantation using grafts from extended criteria donors (elderly donors, steatotic donors, donors with malignancies, donors with viral hepatitis), donation after cardiac death, use of partial grafts (split liver grafts) and other suboptimal donors (hypernatremia, infections, hypotension and inotropic support).