Multidrug-resistant organisms in liver transplant: Mitigating risk and managing infections

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.

Comparative phenotypic and genotypic analysis of community-acquired and hospital-acquired intra-abdominal infections among liver transplanted patients

AIM

During liver transplantation, both hospital-acquired (HA) and community-acquired (CA) intra-abdominal infections (IAIs) are involved causing life-threatening diseases. Therefore, comparative studies of aerobic and facultative anaerobic HA-IAIs and CA-IAIs after liver transplantation surgery are necessary.

METHODS AND RESULTS

The species of detected isolates (310) from intra-abdominal fluid were identified and classified into hospital-acquired intra-abdominal infections (HA-IAIs) and community-acquired intra-abdominal infections (CA-IAIs). Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii were the most commonly detected species. The resistant phenotypes were commonly detected among the HA-IAIs; however, the virulent phenotypes were the predominant strains of CA-IAIs. Regrettably, the resistance profiles were shocking, indicating the inefficacy of monotherapy in treating these isolates. Therefore, we confirmed the use of empirical combination therapies of amikacin and meropenem for treating all IAIs (FICI ≤ 0.5). Unfortunately, the high diversity and low clonality of all identified HA and CA-IAIs were announced with D-value in the range of 0.992-1.

CONCLUSION

This diversity proves that there are infinite numbers of infection sources inside and outside healthcare centers.

New Antibiotics Against Multidrug-Resistant Gram-Negative Bacteria in Liver Transplantation: Clinical Perspectives, Toxicity, and PK/PD Properties

Antimicrobial resistance is a growing global health problem, and it is especially relevant among liver transplant recipients where infections, particularly when caused by microorganisms with a difficult-to-treat profile, are a significant cause of morbidity and mortality. We provide here a complete dissection of the antibiotics active against multidrug-resistant Gram-negative bacteria approved over the last years, focusing on their activity spectrum, toxicity profile and PK/PD properties, including therapeutic drug monitoring, in the setting of liver transplantation. Specifically, the following drugs are presented: ceftolozane/tazobactam, ceftazidime/avibactam, meropenem/vaborbactam, imipenem/relebactam, cefiderocol, and eravacycline. Overall, studies on the safety and optimal employment of these drugs in liver transplant recipients are limited and especially needed. Nevertheless, these pharmaceuticals have undeniably enhanced therapeutic options for infected liver transplant recipients.

Colonization of extended-spectrum β-lactamase-producing Enterobacteriaceae does not affect subsequent infection and liver transplant outcomes: a retrospective observational cohort study

Objective

To investigate the colonization rate of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E), subsequent infections by ESBL-E and ESBL-producing gram-negative bacilli (ESBL-GNB), and the effect of ESBL-E colonization on clinical outcomes in liver transplantation (LT) recipients.

Methods

This is a retrospective cohort study that included patients who underwent LT at Shanghai Renji Hospital between July 2016 and December 2017. Rectal swabs from LT patients at the postoperative ICU enrollment were screened anonymously for ESBL-E carriage. Demographics data, laboratory indexes, operative complications, and clinical course information were also obtained. The extent of ESBL-E colonization, the subsequent infection rates of ESBL-E and ESBL-GNB, and the clinical outcomes were compared between ESBL-E colonized and non-colonized patients.

Results

In total, 496 liver transplant recipients (387 males) were included in this study. ESBL-E colonization was detected in 240 patients (48.4%). There was no significant difference between the rates of ESBL-E infection (5.8 vs. 3.1%, p = 0.143), Ischemia-reperfusion ≥ 3 (27.9 vs. 24.6%, p = 0.403), acute kidney injury (39.6 vs. 38.7%, p = 0.835), acute rejection (2.1 vs. 1.6%, p = 0.664), graft versus host reaction (1.3 vs. 1.2%, p = 0.937), duration of hospitalization (22 vs. 23 days, p = 0.568), 90-day mortality (7.1 vs. 4.7%, p = 0.262) and 1-year mortality (12.9 vs. 9.3%, p = 0.265) in patients with and without ESBL-E colonization. Though the ESBL-GNB infection rate was higher in ESBL-E colonized patients (12.1 vs. 6.6%, p = 0.037), multivariate analysis showed that ESBL-E colonization did not increase the risk of ESBL-GNB infection (Model 1: aOR 1.755, 95% CI: 0.911-3.380, p = 0.093; Model 2: aOR 1.556, 95% CI: 0.761-3.181, p = 0.226). The ESBL-producing bacteria spectrum of colonization was significantly different from that of infections occurring after LT, with only three colonization events leading to infection by the same pathogen identified.

Conclusion

ESBL-E colonization in liver transplant patients is not associated with ESBL-E infection, nor is it a risk factor for post-transplant ESBL-GNB infection. Additionally, ESBL-E colonization does not lead to worse prognoses when compared with non-colonized patients.

Clinical trial registration

Chinese Clinical Trial Registry, Identifier [ChiCTR2100043034].

Impact of bacterial infections prior to liver transplantation on post-transplant outcomes in patients with cirrhosis

Background & Aims

Bacterial infections are frequent in patients with cirrhosis and increase the risk of death and drop-out from liver transplant (LT) waiting list. In patients with bacterial infections, LT is frequently delayed because of the fear of poor outcomes. We evaluated the impact of pre-LT infections on post-LT complications and survival.

Methods

From 2012 to 2018, consecutive patients transplanted at the Hospital of Padua were identified and classified in two groups: patients surviving an episode of bacterial infection within 3 months before LT (study group) and patients without infections before LT (control group). Post-LT outcomes (complications, new infections, survival) were collected.

Results

A total of 466 LT recipients were identified (study group n = 108; control group n = 358). After LT, the study group had a higher incidence of new bacterial (57% vs. 20%, p <0.001) and fungal infections (14% vs. 5%, p = 0.001) and of septic shock (8% vs. 2%, p = 0.004) than the control group. Along with the model for end-stage liver disease (MELD) score and alcohol-related cirrhosis, bacterial infection pre-LT was an independent predictor of post-LT infections (odds ratio = 3.92; p <0.001). Nevertheless, no significant difference was found in 1-year (88% vs. 89%, p = 0.579) and 5-year survival rates (76% vs. 75%, p = 0.829) between the study group and control group. Within the study group, no association was found between the time elapsed from infection improvement/resolution to LT and post-LT outcomes.

Conclusions

Patients with pre-LT infections have a higher risk of new bacterial and fungal infections and of septic shock after LT. However, post-LT survival is excellent. Therefore, as soon as the bacterial infection is improving/resolving, transplant should not be delayed, but patients with pre-transplant bacterial infections require active surveillance for infections after LT.

Impact and Implications

Bacterial infections increase mortality and delay transplant in patients with cirrhosis awaiting liver transplantation (LT). Little is known about the impact of adequately treated infections before LT on post-transplant complications and outcomes. The study highlights that pre-LT infections increase the risk of post-LT infections, but post-LT survival rates are excellent despite the risk. These findings suggest that physicians should not delay LT because of concerns about pre-LT infections, but instead should actively monitor these patients for infections after surgery.

Risk factors of early bacterial infection and analysis of bacterial composition, distribution and drug susceptibility after cadaveric liver transplantation

BACKGROUND

This study provided a theoretical basis for the clinical diagnosis and treatment of bacterial infection after liver transplantation through analyzing the pathogenic distribution, drug sensitivity and risk factors of bacterial infection after liver transplantation.

METHODS

We collected clinical data from 207 recipients undergoing liver transplantation of graft from donation after citizens' death donors in the Third Xiangya Hospital of Central South University from January 2019 to December 2021 and analyzed the composition and distribution of bacterial pathogens, drug resistance and risk factors of infection.

RESULTS

A total of 90 bacterial infections occurred in 55 recipients within two months after liver transplantation, and the incidence of bacterial infection was 26.6% (55/207). The gram-negative bacteria (46/90, 51.1%) were more prevalent than gram-positive bacteria (44/90, 48.9%). Common sites of infection were the abdominal/biliary tract (26/90, 28.9%), lung (22/90, 22.4%) and urinary tract (22/90, 22.4%). Fourteen cases (6.8%) died after liver transplantation. Klebsiella pneumoniae (17/90, 18.9%) was the most frequent gram-negative bacteria causing infection in liver transplant recipients and 58.7%, 50%, 80.4% and 89.1% of gram-negative bacteria were sensitive to amikacin, minocycline, tigecycline and polymyxin B, respectively. The most common gram-positive bacteria was Enterococcus faecium (30/90, 33.3%) and 97.7%, 100%, 86.4%, 100% and 100% of gram-positive bacteria were sensitive to vancomycin, teicoplanin, daptomycin, tigecycline and linezolid, respectively. Univariate analysis revealed that bacterial infection was associated with female, age (≥ 50 years old), preoperative albumin (≤ 30 g/L), operation duration (≥ 400 min), intraoperative blood loss (≥ 3000 ml) and postoperative ventilator support. Binary Logistic regression analysis showed that female (OR = 3.149, 95% CI: 1.418-6.993, P = 0.005), operation duration (≥ 400 min) (OR = 2.393, 95% CI: 1.202-4.765, P = 0.013) and intraoperative blood loss (≥ 3000 ml) (OR = 2.052, 95% CI: 1.007-4.183, P = 0.048) were independent risk factors for bacterial infection after liver transplantation.

CONCLUSION

The incidence of early bacterial infection after liver transplantation was high, and the infection sites were mainly abdominal/biliary tract, respiratory tract and urinary tract. The most common pathogenic bacterium was gram-negative bacterium. Our study also identified several independent risk factors for bacterial infection after liver transplantation, including female gender, operation duration of 400 min or more, and intraoperative blood loss of 3000 ml or more. By addressing these risk factors, such as implementing strategies to optimize surgical procedures and minimize blood loss, healthcare professionals can work towards reducing the incidence of bacterial infections following liver transplantation.

Infections after organ transplantation and immune response

Organ transplantation has provided another chance of survival for end-stage organ failure patients. Yet, transplant rejection is still a main challenging factor. Immunosuppressive drugs have been used to avoid rejection and suppress the immune response against allografts. Thus, immunosuppressants increase the risk of infection in immunocompromised organ transplant recipients. The infection risk reflects the relationship between the nature and severity of immunosuppression and infectious diseases. Furthermore, immunosuppressants show an immunological impact on the genetics of innate and adaptive immune responses. This effect usually reactivates the post-transplant infection in the donor and recipient tissues since T-cell activation has a substantial role in allograft rejection. Meanwhile, different infections have been found to activate the T-cells into CD₄⁺ helper T-cell subset and CD₈⁺ cytotoxic T-lymphocyte that affect the infection and the allograft. Therefore, the best management and preventive strategies of immunosuppression, antimicrobial prophylaxis, and intensive medical care are required for successful organ transplantation. This review addresses the activation of immune responses against different infections in immunocompromised individuals after organ transplantation.

Pharmacokinetic and pharmacodynamic considerations of antibiotics and antifungals in liver transplantation recipients

The liver plays a major role in drug metabolism. Liver transplantation impacts the intrinsic metabolic capability and extrahepatic mechanisms of drug disposition and elimination. Different levels of inflammation and oxidative stress during transplantation, the process of liver regeneration, and the characteristics of the graft alter the amount of functional hepatocytes and activity of liver enzymes. Binding of drugs to plasma proteins is affected by the hyperbilirubinemia status and abnormal synthesis of albumin and alpha-1-acid glycoproteins. Postoperative intensive care complications such as biliary, circulatory, and cardiac also impact drug distribution. Renally eliminated antimicrobials commonly present reduced clearance due to hepatorenal syndrome and the use of nephrotoxic immunosuppressants. In addition, liver transplantation recipients are particularly susceptible to multidrug-resistant infections due to frequent manipulation, multiple hospitalizations, invasive devices, and frequent use of empiric broad-spectrum therapy. The selection of appropriate anti-infective therapy must consider the pathophysiological changes after transplantation that impact the pharmacokinetics and pharmacodynamics of antibiotics and antifungal drugs.

ESCMID/EUCIC clinical practice guidelines on perioperative antibiotic prophylaxis in patients colonized by multidrug-resistant Gram-negative bacteria before surgery

SCOPE

The aim of the guidelines is to provide recommendations on perioperative antibiotic prophylaxis (PAP) in adult inpatients who are carriers of multidrug-resistant Gram-negative bacteria (MDR-GNB) before surgery.

METHODS

These evidence-based guidelines were developed after a systematic review of published studies on PAP targeting the following MDR-GNB: extended-spectrum cephalosporin-resistant Enterobacterales, carbapenem-resistant Enterobacterales (CRE), aminoglycoside-resistant Enterobacterales, fluoroquinolone-resistant Enterobacterales, cotrimoxazole-resistant Stenotrophomonas maltophilia, carbapenem-resistant Acinetobacter baumannii (CRAB), extremely drug-resistant Pseudomonas aeruginosa, colistin-resistant Gram-negative bacteria, and pan-drug-resistant Gram-negative bacteria. The critical outcomes were the occurrence of surgical site infections (SSIs) caused by any bacteria and/or by the colonizing MDR-GNB, and SSI-attributable mortality. Important outcomes included the occurrence of any type of postsurgical infectious complication, all-cause mortality, and adverse events of PAP, including development of resistance to targeted (culture-based) PAP after surgery and incidence of Clostridioides difficile infections. The last search of all databases was performed until April 30, 2022. The level of evidence and strength of each recommendation were defined according to the Grading of Recommendations Assessment, Development and Evaluation approach. Consensus of a multidisciplinary expert panel was reached for the final list of recommendations. Antimicrobial stewardship considerations were included in the recommendation development.

RECOMMENDATIONS

The guideline panel reviewed the evidence, per bacteria, of the risk of SSIs in patients colonized with MDR-GNB before surgery and critically appraised the existing studies. Significant knowledge gaps were identified, and most questions were addressed by observational studies. Moderate to high risk of bias was identified in the retrieved studies, and the majority of the recommendations were supported by low level of evidence. The panel conditionally recommends rectal screening and targeted PAP for fluoroquinolone-resistant Enterobacterales before transrectal ultrasound-guided prostate biopsy and for extended-spectrum cephalosporin-resistant Enterobacterales in patients undergoing colorectal surgery and solid organ transplantation. Screening for CRE and CRAB is suggested before transplant surgery after assessment of the local epidemiology. Careful consideration of the laboratory workload and involvement of antimicrobial stewardship teams before implementing the screening procedures or performing changes in PAP are warranted. High-quality prospective studies to assess the impact of PAP among CRE and CRAB carriers performing high-risk surgeries are advocated. Future well-designed clinical trials should assess the effectiveness of targeted PAP, including the monitoring of MDR-GNB colonization through postoperative cultures using European Committee on Antimicrobial Susceptibility Testing clinical breakpoints.

Epidemic, risk factors of carbapenem-resistant Klebsiella pneumoniae infection and its effect on the early prognosis of liver transplantation

Background

Carbapenem-resistant Klebsiella pneumoniae (CRKP) infection remains a major cause of morbidity and mortality in early-stage post-liver transplantation (LT).

Methods

We retrospectively analyzed the demographic and clinical infections characteristics of all LT recipients in our hospital between January 2019 and December 2021.

Results

Among the 272 LT recipients who received LT between January 2019 and December 2021, sixty-two patients had at least one infection within 3-months post-LT, with a prevalence of 22.8% (62/272). The prevalence of CRKP infections was 7.0% (19/272), and the 3-months post-LT mortality was 19.4% (12/62). The risk factors independently related to 3-months mortality were age (Odds ratio (OR)= 1.126, 95% Confidence interval (CI): 1.009~1.257; P=0.034), mechanical ventilation (MV) (OR=1.206, 95% CI: 1.039~1.401; P =0.014), and CRKP infection (OR=18.240, 95% CI: 2.206~150.842; P =0.007). In CRKP infection, the length of ICU stay (OR=1.067, 95% CI: 1.015~1.122; P=0.011), pre-operation infection (POI) (OR=6.733, 95% CI: 1.160~39.088; P=0.034), and hepatocellular carcinoma (HCC) (OR=26.772, 95% CI: 1.747~410.187; P=0.018) were the independent risk factors. With COX multivariate regression analysis, the 3-months survival rate of CRKP infected patients was significantly lower than that without CRKP infection post-LT.

Conclusions

CRKP infection is closely correlated with poor prognosis in 3-months post-LT.

Bacterial and Viral Infections in Liver Transplantation: New Insights from Clinical and Surgical Perspectives

End-stage liver disease patients undergoing liver transplantation are prone to develop numerous infectious complications because of immunosuppression, surgical interventions, and malnutrition. Infections in transplant recipients account for the main cause of mortality and morbidity with rates of up to 80%. The challenges faced in the early post-transplant period tend to be linked to transplant procedures and nosocomial infections commonly in bloodstream, surgical, and intra-abdominal sites. Viral infections represent an additional complication of immunosuppression; they can be donor-derived, reactivated from a latent virus, nosocomial or community-acquired. Bacterial and viral infections in solid organ transplantation are managed by prophylaxis, multi-drug resistant screening, risk assessment, vaccination, infection control and antimicrobial stewardship. The aim of this review was to discuss the epidemiology of bacterial and viral infections in liver transplants, infection control issues, as well as surgical frontiers of ex situ liver perfusion.

Infection with Two Multi-Drug-Resistant Organisms in Solid Organ Transplant Patients Is Associated with Increased Mortality and Prolonged Hospitalization

Background: Solid organ transplant recipients have several risk factors for peri-operative multi-drug-resistant infection: their immune system is dampened as a result of critical illness and surgical stress that may be further impaired by induction immunotherapy and broad-spectrum antibiotic prophylaxis promotes selection for resistant pathogens. Infection with multi-drug-resistant organisms (MDRO) results in morbidity and mortality for solid organ transplant recipients. Patients and Methods: To assess in-hospital mortality and hospitalization duration associated with these infections, we analyzed cross-sectional, retrospective data from the 2016 Agency for Healthcare and Quality, Healthcare Cost and Utilization Project's National Inpatient Sample. Our analysis included 31,105 index admissions records for liver, kidney, heart, lung, and pancreas transplant recipients in the United States. Outcomes were assessed by multivariable regression analysis adjusting for covariables. Results: One percent (355/29,451) of patients with diagnosis of no MDRO infections died, 3% (40/1491) with diagnosis of one MDRO infection died, and 15% (25/166) with diagnosis of two MDRO infections died. Diagnosis of one MDRO infection was associated with a 20-day increase in hospitalization duration (95% confidence interval [CI], 17-22) but not increased odds of death (odds ratio [OR], 1.2; 95% CI, 0.5-2.5). Diagnosis of two MDRO infections was associated with an increased odds of death (OR, 9.6' 95% CI, 3.3-27.9) and a 41-day increase in hospitalization duration (95% CI, 34-49). Conclusions: Strategies to decrease peri-operative MDRO infection may improve survival and decrease duration of hospitalization for solid organ transplant patients.

Epidemiology, Risk Factors and Outcome Due to Multidrug Resistant Organisms in Paediatric Liver Transplant Patients in the Era of Antimicrobial Stewardship and Screening

(1) Background: Multidrug-resistant organisms (MDRO) are a growing problem in liver transplant recipients (LTR), associated with high morbidity and mortality. We reviewed the impact of antimicrobial stewardship (AMS) and active screening of MDRO on the epidemiology and outcomes in paediatric LTR. (2) Methods: Single-centre retrospective review of paediatric LTR from January 2017 to December 2018. (3) Results: Ninety-six children were included; 32 (33%) patients were colonised with ≥1 MDRO and 22 (23%) patients had MDRO infections. Median (IQR) duration for start of infection was 9.5 (1.8−16.0) days. Colonisation rate with Gram-positive MDRO was 15.6%, with infection rate of 6.2%; majority due to Vancomycin-Resistant Enterococcus faecium (VRE). Colonisation with Gram-negative MDRO was 27.0%, with infection rate of 16.6%; majority due to extended-spectrum β-lactamase producing Enterobacteriaceae. Colonisation and infection rate due to Carbapenem-resistant Enterobacteriaceae was 6% and 3%, respectively, during screening and AMS, compared to historical control of 25% and 30%, respectively, without screening and AMS. There was significant reduction in VRE and CRE infection during AMS period in comparison to historical control. Pre-transplant risk factors including bacterial infections pre-transplant (p < 0.01), diagnosis of biliary atresia (p = 0.03), exposure to antibiotics (p < 0.01), EBV viraemia (p = 0.01), and auxiliary transplantation (p < 0.01) were associated with post-transplant MDRO infections. Patients with MDRO infections had longer length of hospital and paediatric intensive care unit stay days (p < 0.01) but associated with no mortality. (4) Conclusions: Our results demonstrate low incidence of colonisation and infections with MDRO, which were associated with high morbidity but no mortality in paediatric LTR. There was significant reduction in MRSA, VRE, and CRE during AMS period compared to pre-AMS era. Some risk factors are unavoidable but antibiotic overuse, early initiation of appropriate antibiotic therapy and effective infection prevention strategies can be monitored with multifaceted approach of AMS and screening of MDRO. With limited therapeutic options for MDRO and efficacy data of newer antibiotics in paediatric LTR, robust infection control practices are of paramount importance.

Ceftazidime-Avibactam as Salvage Treatment for Infections Due to Carbapenem-Resistant Klebsiella pneumoniae in Liver Transplantation Recipients

Background

Ceftazidime-avibactam (CZA) has been approved in vitro activity against carbapenem-resistant K. pneumoniae (CRKP), but the experience for the treatment of CRKP in liver transplantation (LT) recipients was limited, and previous data on its efficacy in this setting are lacking.

Methods

LT recipients with CRKP infection who received CZA treatment were reviewed retrospectively, microbiological and clinical response, adverse events were also assessed. The primary outcome was 30-day mortality after CZA administration.

Results

CZA was used in 21 LT recipients (including 4 pediatric patients) with CRKP infections after failure with other antimicrobials. CZA was administered as monotherapy in 4 patients. Median time from the onset of CRKP infection until the initiation of CZA treatment was 2 days (IQR, 1–6.5), and the median treatment duration was 12 days (IQR, 8.5–18.5). The mortality at 14 days, 30 days and all-cause was 28.6%, 38.1% and 42.9%, respectively. In adult patients, clinical response of 14 days and 30 days was 70.6% (12/17) and 58.8% (10/17), respectively, while in pediatric patients the 14-day and 30-day clinical response were both 75%, respectively. The relapse rate during the treatment developed in 3 patients after 30 days with the cessation of CZA monotherapy. CZA resistance was not detected in any case and 3 (3/21, 14.3%) patients developed acute kidney injury related to uncontrolled infection.

Conclusion

CZA shows promising results, even in monotherapy, for the treatment of patients with severe infections due to carbapenem-resistant K. pneumoniae among LT recipients. The emergence of resistance to CZA was not observed.

Impact of Two Antibiotic Therapies on Clinical Outcome and Gut Microbiota Profile in Liver Transplant Paediatric Candidates Colonized by Carbapenem-Resistant Klebsiella pneumoniae CR-KP

Colonization by multidrug-resistant (MDR) organisms in liver transplant (LT) candidates significantly affects the LT outcome. To date, consensus about patient management is lacking, including microbiological screening indications. This pilot study aimed to evaluate the impact of carbapenem-resistant Klebsiella pneumoniae (CR-KP) colonization in LT paediatric candidates to enable optimal prevention and therapeutic strategies that exploit both clinical and microbiological approaches. Seven paediatric patients colonized by CR-KP were evaluated before and until one-year post LT. At the time of the transplant, patients were stratified based on antibiotic (ATB) prophylaxis into two groups: ‘standard ATB’ (standard ATB prophylaxis), and ‘targeted ATB’ (MDR antibiogram-based ATB prophylaxis). Twenty-eight faecal samples were collected during follow-up and used for MDR screening and gut microbiota 16S rRNA-based profiling. Post-transplant hospitalization duration was comparable for both groups. With the exception of one patient, no serious infections and/or complications, nor deaths were recorded. A progressive MDR decontamination was registered. In the ‘standard ATB’ group, overall bacterial richness increased. Moreover, 6 months after LT, Lactobacillus and Bulleidia were increased and Enterobacteriaceae and Klebsiella spp. were reduced. In the ‘targeted ATB’ group Klebsiella spp., Ruminococcus gnavus, Erysipelotrichaceae, and Bifidobacterium spp. were increased 12 months after LT. In conclusion, both antibiotics prophylaxis do not affect nor LT outcomes or the risk of intestinal bacterial translocation. However, in the ‘standard ATB’ group, gut microbiota richness after LT was increased, with an increase of beneficial lactic acid- and short-chain fatty acids (SCFA)-producing bacteria and the reduction of harmful Enterobacteriaceae and Klebsiella spp. It could therefore be appropriate to administer standard prophylaxis, reserving the use of ATB-based molecules only in case of complications.

Multidrug-resistant organisms: A significant cause of severe sepsis in pediatric intestinal and multi-visceral transplantation

Severe sepsis in immunocompromised children is associated with increased mortality. This paper describes the epidemiology landscape, clinical acuity, and outcomes for severe sepsis in pediatric intestinal (ITx) and multi-visceral (MVTx) transplant recipients requiring admission to the pediatric intensive care unit (PICU). Severe sepsis episodes were retrospectively reviewed in 51 ITx and MVTx patients receiving organs between 2009 and 2015. Twenty-nine (56.8%) patients had at least one sepsis episode (total of 63 episodes) through December 2016. Bacterial etiologies accounted for 66.7% of all episodes (n = 42), occurring a median of 122.5 days following transplant (IQR 59-211.8 days). Multidrug-resistant organisms (MDROs) accounted for 73.8% of bacterial infections; extended spectrum beta-lactamase producers, vancomycin-resistant enterococcus, and highly-resistant Pseudomonas aeruginosa were the most commonly identified. Increased mechanical ventilation and vasoactive requirements were noted in MDRO episodes (OR 3.03, 95% CI 1.09-8.46 and OR 3.07, 95% CI 1.09-8.61, respectively; p < .05) compared to non-MDRO episodes. PICU length of stay was significantly increased for MDRO episodes (7 vs. 3 days, p = .02). Graft loss was 24.1% (n = 7) and mortality was 24.1% (n = 7) in patients who experienced severe sepsis. Further attention is needed for MDRO risk mitigation and modification of sepsis treatment guidelines to ensure MDRO coverage for this population.

The Interplay between Gut Microbiota and the Immune System in Liver Transplant Recipients and Its Role in Infections

Liver transplantation (LT) is a life-saving strategy for patients with end-stage liver disease, hepatocellular carcinoma, and acute liver failure. LT success can be hampered by several short-term and long-term complications. Among them, bacterial infections, especially those due to multidrug-resistant germs, are particularly frequent, with a prevalence between 19 and 33% in the first 100 days after transplantation. In the last decades, a number of studies have highlighted how the gut microbiota (GM) is involved in several essential functions to ensure intestinal homeostasis, becoming one of the most important virtual metabolic organs. The GM works through different axes with other organs, and the gut-liver axis is among the most relevant and investigated ones. Any alteration or disruption of the GM is defined as dysbiosis. Peculiar phenotypes of GM dysbiosis have been associated with several liver conditions and complications, such as chronic hepatitis, fatty liver disease, cirrhosis, and hepatocellular carcinoma. Moreover, there is growing evidence of the crucial role of the GM in shaping the immune response, both locally and systemically, against pathogens. This paves the way to the manipulation of the GM as a therapeutic instrument to modulate infectious risk and outcome. In this minireview, we provide an overview of the current understanding of the interplay between the gut microbiota and the immune system in liver transplant recipients and the role of the former in infections.

Clinical Outcome of Vancomycin-Resistant Enterococcus Colonization Among Liver Transplant Recipients at Shiraz Organ Transplant Center

OBJECTIVES

Liver transplant recipients are more susceptible to vancomycin-resistant enterococci colonization than healthy individuals. We investigated the prevalence of vancomycin-resistant enterococci colonization and its effect on the outcomes of liver transplant recipients.

MATERIALS AND METHODS

Patients who had undergone primary liver transplant at the Shiraz Organ Transplant Center from 2015 to 2017 were enrolled in this study. Demographic characteristics, laboratory test results, duration of stay in the intensive care unit, total duration of hospital stay, and clinical outcome data were extracted from the Shiraz Organ Transplant Center database. Posttransplant outcomes such as graft rejection, mortality, hospital stay, and kidney function tests were included for the first 90 days after transplant.

RESULTS

A total of 753 liver transplant recipients (470 males and 283 females) were included in this study. Vancomycin-resistant enterococci colonization was identified in 51 patients (6.8%) after transplant at the time of intensive care unit admission. Our study found no significant difference between outcomes for patients with vancomycin-resistant enterococci colonization and outcomes for patients without colonization, including graft rejection, mortality, hospital stay, and kidney function tests.

CONCLUSIONS

Our study revealed that asymptomatic vancomycin-resistant enterococci colonization in liver transplant patients has no adverse effect on the duration of posttransplant hospital stay, early mortality rate, graft rejection rate, or kidney function compared with noncolonized patients.

High mortality associated with gram-negative bacterial bloodstream infection in liver transplant recipients undergoing immunosuppression reduction

BACKGROUND

Immunosuppression is an important factor in the incidence of infections in transplant recipient. Few studies are available on the management of immunosuppression (IS) treatment in the liver transplant (LT) recipients complicated with infection. The aim of this study is to describe our experience in the management of IS treatment during bacterial bloodstream infection (BSI) in LT recipients and assess the effect of temporary IS withdrawal on 30 d mortality of recipients presenting with severe infection.

AIM

To assess the effect of temporary IS withdrawal on 30 d mortality of LT recipients presenting with severe infection.

METHODS

A retrospective study was conducted with patients diagnosed with BSI after LT in the Department of Liver Surgery, Renji Hospital from January 1, 2016 through December 31, 2017. All recipients diagnosed with BSI after LT were included. Univariate and multivariate Cox regression analysis of risk factors for 30 d mortality was conducted in the LT recipients with Gram-negative bacterial (GNB) infection.

RESULTS

Seventy-four episodes of BSI were identified in 70 LT recipients, including 45 episodes of Gram-positive bacterial (GPB) infections in 42 patients and 29 episodes of GNB infections in 28 patients. Overall, IS reduction (at least 50% dose reduction or cessation of one or more immunosuppressive agent) was made in 28 (41.2%) cases, specifically, in 5 (11.9%) cases with GPB infections and 23 (82.1%) cases with GNB infections. The 180 d all-cause mortality rate was 18.5% (13/70). The mortality rate in GNB group (39.3%, 11/28) was significantly higher than that in GPB group (4.8%, 2/42) (P = 0.001). All the deaths in GNB group were attributed to worsening infection secondary to IS withdrawal, but the deaths in GPB group were all due to graft-versus-host disease. GNB group was associated with significantly higher incidence of intra-abdominal infection, IS reduction, and complete IS withdrawal than GPB group (P < 0.05). Cox regression showed that rejection (adjusted hazard ratio 7.021, P = 0.001) and complete IS withdrawal (adjusted hazard ratio 12.65, P = 0.019) were independent risk factors for 30 d mortality in patients with GNB infections after LT.

CONCLUSION

IS reduction is more frequently associated with GNB infection than GPB infection in LT recipients. Complete IS withdrawal should be cautious due to increased risk of mortality in LT recipients complicated with BSI.

IS

High prevalence of multidrug-resistant gram-negative bacterial infection following pediatric liver transplantation

Bacterial infection has been identified as one of the most significant complications of liver transplantation (LT). Multidrug-resistant (MDR) gram-negative bacteria (GNB) infection remains problematic issue following LT in the adults. However, data in children are scarce. We aimed to examine the prevalence and associated factors of MDR-GNB infection among pediatric LT recipients.We performed a single-center retrospectively study of 118 children who underwent LT between January 2010 and December 2018. Data on the prevalence, clinical characteristics, types, and sites of MDR-GNB infection within 3 months after LT as well as the treatment outcomes were collected. Multidrug resistance was defined as acquired non-susceptibility to at least 1 agent in 3 or more antibiotic classes.In total, 64 (53.7%) patients developed 96 episodes of culture-proven bacterial infection with 93 GNB isolates. Moreover, there were 58 (62.4%) MDR-GNB isolates, with a predominance of Klebsiella pneumoniae (32.7%), Escherichia coli (31%), and Pseudomonas aeruginosa (10.3%). Interestingly, 10 (17.2%) isolates were determined to be carbapenem-resistant Enterobacteriaceae. The median time to MDR-GNB infection was 9 (interquartile range: 5-33) days. The most common type of infection was intra-abdominal infection (47.9%). In the multivariate analysis, the significant variables associated with post-LT MDR-GNB infection include exposure to third-generation cephalosporins (hazard ratio [HR]: 2.16, P = .023), operative time (hazard ratio [HR] 1.20, P = .009), and length of intensive care unit stay (HR 1.03, P = .049). With a focus on carbapenem-resistant Enterobacteriaceae infection, a pediatric end-stage liver disease score >21 was the only significant 6 variable in the multivariate analysis (HR 11.48, P = .024). The overall 3-month mortality rate was 6.8%.This study has highlighted the high prevalence rate of MDR-GNB infection after pediatric LT. Therefore, caution on the emergence of MDR-GNB infection should be paid in at-risk children. Moreover, knowledge regarding the prevalence of MDR-GNB infection and resistant patterns is essential for guideline development to prevent and minimize the risk of MDR-GNB infection in this group of patients.

Intra-abdominal infections among adult intestinal and multivisceral transplant recipients in the 2-year post-operative period

BACKGROUND

Intestinal and multivisceral transplantations are treatment options for patients with intestinal failure. Transplantation is often complicated by abdominal and/or bloodstream infections in the post-operative period.

METHODS

A retrospective chart review of all adults who underwent intestinal or multivisceral transplantation at our institution from 2003 to 2015 was performed. Data were collected for 2 years post transplant.

RESULTS

A total of 106 intestinal or multivisceral transplants were performed in 103 patients. The median age at the time of transplant was 44 (IQR: 34-52) with 55% (n = 58) male and 45% (n = 48) female. There were 46 (43%) intra-abdominal infections post transplant among the 103 patients, and six transplant recipients (13%) developed concurrent bloodstream infections. The median time to first intra-abdominal infection was 23 days (IQR: 10-48). For those with organisms isolated in culture, forty-seven percent of the isolates were gram negative, 39% gram positive, 7% anaerobes, and 7% yeast. The most common isolates were enterococci at 28%, E. coli at 14%, and Klebsiella spp at 13%. Sixty-three percent of the enterococci were vancomycin-resistant enterococci (VRE), and 22% of the gram-negative isolates were extended spectrum beta-lactamases (ESBLs). Patients with intra-abdominal infections had longer hospital post-transplant length of stays at a median of 35 days (IQR: 25-48) vs 23 days (IQR: 17-33) for those without infections, P = .0012. There was no difference in all-cause mortality in patients with or without intra-abdominal infections, P = .654.

CONCLUSIONS

Intra-abdominal infections are common in intestinal or multivisceral transplant recipients, but despite this complication, we found no increased risk of mortality. These transplant recipients are also at risk for infection with drug-resistant organisms.

Infections due to multidrug-resistant organisms following heart transplantation: Epidemiology, microbiology, and outcomes

BACKGROUND

Infections secondary to multidrug-resistant organisms (MDRO) have emerged as a growing problem in solid organ transplantation (SOT). Most of the published data on MDRO infections in SOT pertains to abdominal organ transplantation and data specific to heart transplantation (HT) are limited.

METHODS

This is a retrospective review of HT recipients at our institution from 2011 to 2016; with the aim to investigate the epidemiology, microbiologic spectrum, and outcomes in patients with post-HT MDRO infections, classified as multidrug-resistant (MDR), extensively drug-resistant (XDR), and pandrug-resistant (PDR) using standardized definitions.

RESULTS

Of the 149 HT recipients, 82 episodes of bacterial infection were seen in 46 patients (31%) in the year following HT. Thirty (37%) were due to MDR pathogens and 13 (16%) were XDR. The most common gram-negative MDR pathogens were extended-spectrum beta-lactamase (ESBL) Escherichia coli and Klebsiella pneumoniae; while XDR pathogens were most commonly Pseudomonas aeruginosa followed by carbapenem-resistant Klebsiella pneumoniae. Majority of infection episodes were bloodstream (54, 66%) followed by pulmonary infection (20, 24%). Within a year after transplant, HT recipients with any bacterial infection had significantly higher mortality versus those without infection; and XDR infections were associated with a 26-fold greater hazard of death on average compared to those without infection (adjusted HR, 26.1; 95% CI, 6.4-107.0; P < .001). There were no PDR infections.

CONCLUSION

Bacterial infections were a significant predictor of 1-year post-HT mortality, which was highest among those with XDR infections. This study highlights the burden of MDRO infections in HT recipients and identifies an area of future research.

Graft Hepatic Artery Rupture Due to Carbapenem-Resistant Klebsiella pneumoniae Infection After Liver Transplant

Carbapenem-resistant Klebsiella pneumoniae infection is a major cause of morbidity and mortality after solid-organ transplant and hematopoietic stem cell transplant. Here, we report a 57-year-old man with hepatitis B virus-related decompensated liver cirrhosis, huge splenic artery aneurysm, and hypersplenism who underwent liver transplant from a deceased brain-dead donor. Recipient sputum surveillance showed carbapenem-resistant Klebsiella pneumoniae when he entered the intensive care unit, and combined tigecycline, meropenem, and fosfomycin were administered. At 1 week posttransplant, the recipient's hepatic artery was eroded by disseminated carbapenem-resistant Klebsiella pneumoniae infection, and the patient developed acute kidney injury. Our experience suggests that colonization of carbapenem-producing organisms may be included during surveillance posttransplant and that the infected graft artery must be removed instead of noninfected vessels.

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.

Severe Sepsis in Pediatric Liver Transplant Patients: The Emergence of Multidrug-Resistant Organisms

OBJECTIVES

To describe characteristics of liver transplant patients with severe sepsis in the PICU.

DESIGN

Retrospective descriptive analysis.

SETTING

Tertiary children's hospital PICU.

PATIENTS

Liver transplant recipients admitted January 2010 to July 2016 for pediatric severe sepsis.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Between January 2010 and July 2016, 173 liver transplants were performed, and 36 of these patients (21%) were admitted with severe sepsis (54 episodes total). Median age at admission was 2 years (1-6.5 yr), 47.2% were male. Bacterial infections were the most common (77.8%), followed by culture negative (12.9%) and viral infections (7.4%). Fungal infections accounted for only 1.9%. Median time from transplant for viral and culture negative infections was 18 days (8.25-39.75 d) and 25 days (9-41 d), whereas 54.5 days (17-131.25 d) for bacterial infections. Bloodstream and intra-abdominal were the most common bacterial sites (45% and 22.5%, respectively). Multidrug-resistant organisms accounted for 47.6% of bacterial sepsis. Vancomycin-resistant Enterococcus and extended-spectrum beta-lactamase producers were the most frequently identified multidrug-resistant organisms. Patients with multidrug-resistant organism sepsis demonstrated higher admission Pediatric Logistic Organ Dysfunction scores (p = 0.043) and were noted to have an odds ratio of 3.8 and 3.6 for mechanical ventilation and multiple organ dysfunction syndrome, respectively (p = 0.047 and p = 0.044). Overall mortality was 5.5% (n = 2 patients), with both deaths occurring in multidrug-resistant organism episodes.

CONCLUSIONS

We report that multidrug-resistant organisms are increasingly being identified as causative pathogens for sepsis in pediatric liver transplant recipients and are associated with significantly higher odds for mechanical ventilation and higher organ failure. The emergence of multidrug-resistant organism infections in pediatric liver transplant patients has implications for patient outcomes, antibiotic stewardship, and infection prevention strategies.

Lessons learnt from living donor liver transplantation with ABO-incompatibility: A single-centre experience from southern India

BACKGROUND

Although, ABO-incompatible (ABOi) liver transplantation is considered a high-risk procedure, using newer and more effective preoperative B cell desensitisation techniques, many transplant centres are routinely performing ABOi living donor liver transplantation (LDLT).

METHODS

This was a retrospective study of 12 patients (adult:pediatric = 10:2; M:F = 9:3; median age, 45.5 years [range 1 to 56 years]) who underwent ABOi LDLT at a tertiary care centre.

RESULTS

The median model for end-stage liver disease (MELD)/pediatric end-stage liver disease (PELD) scores were 28 (range 18 to 35) and 30.5 (range 24 to 37), respectively. For desensitisation, we initially used two doses of rituximab and two sessions of plasmapheresis preoperatively. We faced high mortality in the initial seven patients (five deaths) due to overwhelming sepsis from multidrug-resistant (MDR) pathogens. Subsequently, we restricted the rituximab to one dose and performed plasmapheresis only when isoagglutinin titre value was more than 1:64. With this regimen, out of the last five patients, four did well. For the whole cohort, the incidence of antibody-mediated rejection, acute cellular rejection, biliary complications, hepatic artery thrombosis, infection, and 5-year patient survival were 16.7%, 16.7%, 16.7%, 8.3%, 75%, and 40%, respectively. The risk factors for mortality were high MELD score, O blood group, and more intense desensitisation protocol.

CONCLUSIONS

Careful selection of patients and less intense desensitisation protocol are probably important in improving the outcomes in ABOi LDLT.

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.

Carbapenem-Resistant Klebsiella Pneumoniae Infections Early After Liver Transplantation: A Single-Center Experience

The aims of this study were to define in a cohort of 310 liver transplant recipients, the incidence of post-liver transplantation (LT) non-carbapenem-resistant Klebsiella pneumoniae (CRKP) and CRKP infections, pre- and post-LT CRKP colonization, CRKP-associated mortality, and risk factors for non-CRKP and CRKP infections. Every patient was screened for CRKP immediately before and after LT. The 6-month survival rate was 95%. Fifty-two patients became infected (16.5%): 8 by CRKP (2.5%) and 44 (14%) by a non-CRKP micro-organism. Median onset of CRKP infections occurred at postoperative (POD) 12 (range, 4-70). CRKP colonization occurred in 20 patients (6%): 10 before LT (3 infected and died) and 10 after (5 infected, 3 died). CRKP- versus non-CRKP-infected patients had higher rates of intensive care unit (ICU) and hospital mortality (50% vs 20% and 62.5% vs 36%; P ≤ .001), septic shock (87% vs 34%; P = .0057; confidence interval [CI], 9.8-71.5), prolonged mechanical ventilation (100% vs 64%; P = .043, CI, 3.5-51.9), and renal replacement therapy (87% vs 41%; P = .0177; CI, 2.8-65). The small number of CRKP-infected patients did not allow the definition of specific risk factors for CRKP infection. At univariate analysis, pre- and post-LT colonization (odds ratio [OR], 10.76; CI, 2.6-44; OR, 14.99; CI, 3.83-58.66, respectively), relaparotomy (OR, 9.09; CI, 4.01-20.6), retransplantation (OR, 7.45; CI, 3.45-16), bile leakage (OR, 61.28; CI, 9.23-80), and early allograft dysfunction (EAD; OR, 5.7; CI, 3-10.7) were significantly associated with infections, making CRKP colonization (any time) and post-LT surgical and medical complications critical factors for post-LT CRKP infections.

Infections in pediatric solid-organ transplant recipients

Solid-organ transplantation in pediatrics can be a life-saving procedure, but it cannot be accomplished without risk of infection-related morbidity and mortality. Evaluation of the recipient during candidacy and donor during evaluation can assist with identification of risk. Further, risk of infection from the surgical procedure can be mitigated through careful planning and attention to infection prevention processes. Finally, early recognition of infection posttransplant can limit the impact of these events.

Management of multidrug resistant Gram-negative bacilli infections in solid organ transplant recipients: SET/GESITRA-SEIMC/REIPI recommendations

Solid organ transplant (SOT) recipients are especially at risk of developing infections by multidrug resistant (MDR) Gram-negative bacilli (GNB), as they are frequently exposed to antibiotics and the healthcare setting, and are regulary subject to invasive procedures. Nevertheless, no recommendations concerning prevention and treatment are available. A panel of experts revised the available evidence; this document summarizes their recommendations: (1) it is important to characterize the isolate's phenotypic and genotypic resistance profile; (2) overall, donor colonization should not constitute a contraindication to transplantation, although active infected kidney and lung grafts should be avoided; (3) recipient colonization is associated with an increased risk of infection, but is not a contraindication to transplantation; (4) different surgical prophylaxis regimens are not recommended for patients colonized with carbapenem-resistant GNB; (5) timely detection of carriers, contact isolation precautions, hand hygiene compliance and antibiotic control policies are important preventive measures; (6) there is not sufficient data to recommend intestinal decolonization; (7) colonized lung transplant recipients could benefit from prophylactic inhaled antibiotics, specially for Pseudomonas aeruginosa; (8) colonized SOT recipients should receive an empirical treatment which includes active antibiotics, and directed therapy should be adjusted according to susceptibility study results and the severity of the infection.

Infectious agents after liver transplant: etiology, timeline and patients' cell-mediated immunity responses

Infections continue to be one of the leading causes of morbidity and mortality in liver transplant recipients. We retrospectively reviewed the symptomatic infectious episodes that occurred during the first year post-transplant to determine time of onset, causative pathogens and cell-mediated immunity response patterns. Ninety-eight of the 202 (48.5%) recipients enrolled developed at least one infectious episode. The total number of infectious episodes was 135: 77 (57.1%) bacterial, 45 (33.3%) viral and 13 (9.6%) fungal. The most frequently isolated bacteria were Escherichia coli (21 isolates) and Klebsiella pneumoniae (19 isolates). Overall, extended-spectrum beta lactamase-producing and methicillin-resistant organisms were responsible for 29 (29/77; 37.7%) infectious episodes. Members of the herpes virus group, in particular cytomegalovirus (34/45 viral infections, 75.5%), were detected. Candida species (9 isolates) followed by Aspergillus species (4 isolates) were isolated. The majority of infections (63%) occurred during the early post-transplant phase (<1 month), whereas only 8/135 episodes (5.9%) were detected after the sixth month (late phase). Significantly lower median ImmuKnow^® intracellular ATP values in patients who developed bacterial and fungal infections compared to infection-free patients were observed (P < 0.0001 and P = 0.0016, respectively), whereas patients who developed a viral infection had a median intracellular ATP level not statistically different compared to uninfected patients (P = 0.4). Our findings confirm that bacteria are responsible for the majority of symptomatic infections and occur more frequently during the first month post-transplant. The ImmuKnow^® measurements can be a useful tool for identifying patients at high risk of developing infection, particularly of fungal and bacterial etiology.