Infection in Organ Transplantation: Risk Factors and Evolving Patterns of Infection

Hospitalizations for opportunistic infections following transplantation and associated risk factors: A national cohort study of Medicare beneficiaries

BACKGROUND

Opportunistic infections (OIs) are a significant cause of morbidity and mortality after organ transplantation, though data in the liver transplant (LT) population are limited.

METHODS

We performed a retrospective cohort study of LT recipients between January 1, 2007 and Deceber 31, 2016 using Medicare claims data linked to the Organ Procurement and Transplantation Network database. Multivariable Cox regression models evaluated factors independently associated with hospitalizations for early (≤1 year post transplant) and late (>1 year) OIs, with a particular focus on immunosuppression.

RESULTS

There were 11 320 LT recipients included in the study, of which 13.2% had at least one OI hospitalization during follow-up. Of the 2638 OI hospitalizations, 61.9% were early post-LT. Cytomegalovirus was the most common OI (45.4% overall), although relative frequency decreased after the first year (25.3%). Neither induction or maintenance immunosuppression were associated with early OI hospitalization (all p > .05). The highest risk of early OI was seen with primary sclerosing cholangitis (aHR 1.74; p = .003 overall). Steroid-based and mechanistic target of rapamycin inhibitor-based immunosuppression at 1 year post LT were independently associated with increased late OI (p < .001 overall).

CONCLUSION

This study found OI hospitalizations to be relatively common among LT recipients and frequently occur later than previously reported. Immunosuppression regimen may be an important modifiable risk factor for late OIs.

Diagnosing and Managing Urinary Tract Infections in Kidney Transplant Recipients

In the article, the authors review antibiotic treatment options for both acute uncomplicated UTI and complicated UTI. In addition, they review alternative regimens which are needed in the setting of drug-resistant pathogens including vancomycin-resistant Enterococcus, -extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-E), carbapenem-resistant Enterobacterales, and carbapenem-resistant Pseudomonas, which are encountered with more frequency.

Epidemiology and Management of Infections in Liver Transplant Recipients

Background: Improvements in liver transplant (LT) outcomes are attributed to advances in surgical techniques, use of potent immunosuppressants, and rigorous pre-LT testing. Despite these improvements, post-LT infections remain the most common complication in this population. Bacteria constitute the most common infectious agents, while fungal and viral infections are also frequently encountered. Multi-drug-resistant bacterial infections develop because of polymicrobial overuse and prolonged hospital stays. Immediate post-LT infections are commonly caused by viruses. Conclusions: Appropriate vaccination, screening of both donor and recipients before LT and antiviral prophylaxis in high-risk individuals are recommended. Antimicrobial drug resistance is common in high-risk LT and associated with poor outcomes; epidemiology and management of these cases is discussed. Additionally, we also discuss the effect of coronavirus disease 2019 (COVID-19) infection and monkeypox in the LT population.

The Predictors and Risk Factors of 2-Year Rejection in Renal Transplant Patients: A Multicenter Case-Control Study

INTRODUCTION

Kidney transplantation is a definitive treatment for end-stage renal disease. It is associated with improved life expectancy and quality of life. One of the most common complications following kidney transplantation is graft rejection. To our knowledge, no previous study has identified rejection risk factors in kidney transplant recipients in Saudi Arabia. Therefore, this study aimed to determine the specific risk factors of graft rejection.

METHODS

A multicenter case-control study was conducted at four transplant centers in Saudi Arabia. All adult patients who underwent a renal transplant between January 1, 2015 and December 31, 2021 were screened for eligibility. Included patients were categorized into two groups (cases and control) based on the occurrence of biopsy-proven rejection within 2 years. The primary outcome was to determine the risk factors for rejection within the 2 years of transplant. Exact matching was utilized using a 1:4 ratio based on patients' age, gender, and transplant year.

RESULTS

Out of 1,320 screened renal transplant recipients, 816 patients were included. The overall prevalence of 2-year rejection was 13.9%. In bivariate analysis, deceased donor status, the presence of donor-specific antibody (DSA), intraoperative hypotension, Pseudomonas aeruginosa, Candida, and any infection within 2 years were linked with an increased risk of 2-year rejection. However, in the logistic regression analysis, the presence of DSA was identified as a significant risk for 2-year rejection (adjusted OR: 2.68; 95% CI: 1.10, 6.49, p = 0.03). Furthermore, blood infection, infected with Pseudomonas aeruginosa or BK virus within 2 years of transplant, were associated with higher odds of 2-year rejection (adjusted OR: 3.10; 95% CI: 1.48, 6.48, p = 0.003, adjusted OR: 3.23; 95% CI: 0.87, 11.97, p = 0.08 and adjusted OR: 2.76; 95% CI: 0.89, 8.48, p = 0.07, respectively).

CONCLUSION

Our findings emphasize the need for appropriate prevention and management of infections following kidney transplantation to avoid more serious problems, such as rejection, which could significantly raise the likelihood of allograft failure and probably death. Further studies with larger sample sizes are needed to investigate the impact of serum chloride levels prior to transplant and intraoperative hypotension on the risk of graft rejection and failure.

The impact of colonization by multidrug resistant bacteria on graft survival, risk of infection, and mortality in recipients of solid organ transplant: systematic review and meta-analysis

BACKGROUND

The Global increase in colonization by multidrug-resistant (MDR) bacteria poses a significant concern. The precise impact of MDR colonization in solid organ transplant recipients (SOTR) remains not well established.

OBJECTIVES

To assess the impact of MDR colonization on SOTR's mortality, infection, or graft loss.

METHODS AND DATA SOURCES

Data from PROSPERO, OVID Medline, OVID EMBASE, Wiley Cochrane Library, ProQuest Dissertations, Theses Global, and SCOPUS were systematically reviewed, spanning from inception until 20 March 2023. The study protocol was registered with PROSPERO (CRD42022290011) and followed the PRISMA guidelines. STUDY ELIGIBILITY CRITERIA, PARTICIPANTS, INTERVENTIONS, AND ASSESSMENT OF RISK OF BIAS: Cohorts and case-control studies that reported on adult SOTR colonized by Methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), extended-spectrum β-lactamase (ESBL) or carbapenem-resistant Enterobacteriaceae. (CRE), or MDR-pseudomonas, and compared to noncolonized, were included. Two reviewers assessed eligibility, conducted a risk of bias evaluation using the Newcastle-Ottawa Scale, and rated certainty of evidence using the GRADE approach.

METHODS OF DATA SYNTHESIS

We employed RevMan for a meta-analysis, using random-effects models to compute pooled odds ratios (OR) and 95% confidence intervals (CI). Statistical heterogeneity was determined using the I2 statistic.

RESULTS

15,202 SOTR (33 cohort, six case-control studies) were included, where liver transplant and VRE colonization (25 and 14 studies) were predominant. MDR colonization significantly increased posttransplant 1-year mortality (OR, 2.35; 95% CI, 1.63-3.38) and mixed infections (OR, 10.74; 95% CI, 7.56-12.26) across transplant types (p < 0.001 and I2 = 58%), but no detected impact on graft loss (p 0.41, I2 = 0). Subgroup analysis indicated a higher association between CRE or ESBL colonization with outcomes (CRE: death OR, 3.94; mixed infections OR, 24.8; ESBL: mixed infections OR, 10.3; no mortality data) compared to MRSA (Death: OR, 2.25; mixed infection: OR, 7.75) or VRE colonization (Death: p 0.20, mixed infections: OR, 5.71).

CONCLUSIONS

MDR colonization in SOTR, particularly CRE, is associated with increased mortality. Despite the low certainty of the evidence, actions to prevent MDR colonization in transplant candidates are warranted.

Infections in the first year of living related kidney transplantation in a young transplant cohort

BACKGROUND

Infection after a kidney transplant is a serious cause of morbidity and mortality. Weighing the risks and benefits of immunosuppression is of paramount importance for patient wellbeing and transplant survival.

METHODS

This is a prospective observational study exploring the variety of bacterial, viral and fungal infections occurring within the first year of living related kidney transplantation in a young transplant cohort. Fifty-one kidney transplant recipients (KTR) between the age of 18 and 45 who had a kidney transplant between Jan 2020 and Jan 2022 were enrolled and followed up for one year. Primary outcome was the occurrence of infection.

RESULTS

Twenty-four patients (47%) recorded a collective 33 episodes of infection. Seven patients had repeated infections and 17 had single infections. Twenty-seven patients had an uneventful year with no infections recorded. Commonest infection was lower urinary tract infection (UTI) (27.3%) followed by SARS-COV2 and Herpes Zoster (15.2%). The commonest pathogens causing lower UTI were Escherichia coli (E coli) (21.2%) and Klebsiella (18.2%). Median Tacrolimus level was (7.8) ng/ml in KTR with infection and (8.95) ng/ml in KTR without infection, p = 0.21. Median Haemoglobin (IQR) was (10.2) g/dl (7.8-14) gm/dl in KTR with infection compared to (10.8) g/dl (7.3-15.3) in KTR without infection odds ratio (OR) = 0.78, confidence interval (CI) (0.5-1.1); p = 0.16.In KTR with infection 25% had donors above the age of 60 compared to 11% in KTR without infection ( OR 2.6,CI (0.5-12), p = 0.2). Post transplant diabetes (PTDM) occurred in (25%) in KTR with infection compared to those without, but that was not statistically significant p = 0. 365.In KTR without infection, 59.3% had a preemptive transplant compared to 20.8% in the group with infection (OR = 0.18; 95% CI: 0.052-0.631; p = 0.007). Median tacrolimus was 7.8 ng/ml in KTR with single infection compared to 7.7 ng/ml in KTR with repeated infections.

CONCLUSION

This study shows that the commonest infection occurring in the first-year post kidney transplant was lower urinary tract infection followed by SARS-COV2 and Herpes Zoster. There was no difference in trough tacrolimus or haemoglobin levels between KTR who developed infection with those who did not.

Long Term Complications of Immunosuppression Post Liver Transplant

Improvement in immunosuppression has led to a remarkable improvement in short-term and long-term outcomes post-liver transplant (LT). However, with improvements in long-term survival, complications related to immunosuppressive drugs, either directly or indirectly, have also increased. The adverse events could be drug-specific, class-specific, or generic. Calcineurin inhibitors (cyclosporine and tacrolimus) are the backbone of the immunosuppression after LT and the main culprit associated with most of the complications, including renal failure, post-transplant diabetes mellitus (PTDM), and metabolic syndrome. Steroids are also implicated in the development of diabetes, osteoporosis, and metabolic syndrome post-LT. The development of infections and de novo malignancies (DNMs) is a generic effect linked to the overall cumulative immunosuppression. The development of these complications significantly hampers the quality of life and leads to increased morbidity and mortality post-LT. Thus, it is important to minimize the cumulative immunosuppression dose while simultaneously preventing allograft rejection. This review provides up-to-date, comprehensive knowledge of the complications of long-term immunosuppression post-LT along with associated risk factors and strategies to minimize the risk of complications.

South Asian Transplant Infectious Disease Guidelines for Solid Organ Transplant Candidates, Recipients, and Donors

These guidelines discuss the epidemiology, screening, diagnosis, posttransplant prophylaxis, monitoring, and management of endemic infections in solid organ transplant (SOT) candidates, recipients, and donors in South Asia. The guidelines also provide recommendations for SOT recipients traveling to this region. These guidelines are based on literature review and expert opinion by transplant physicians, surgeons, and infectious diseases specialists, mostly from South Asian countries (India, Pakistan, Bangladesh, Nepal, and Sri Lanka) as well as transplant experts from other countries. These guidelines cover relevant endemic bacterial infections (tuberculosis, leptospirosis, melioidosis, typhoid, scrub typhus), viral infections (hepatitis A, B, C, D, and E; rabies; and the arboviruses including dengue, chikungunya, Zika, Japanese encephalitis), endemic fungal infections (mucormycosis, histoplasmosis, talaromycosis, sporotrichosis), and endemic parasitic infections (malaria, leishmaniasis, toxoplasmosis, cryptosporidiosis, strongyloidiasis, and filariasis) as well as travelers' diarrhea and vaccination for SOT candidates and recipients including travelers visiting this region. These guidelines are intended to be an overview of each topic; more detailed reviews are being published as a special supplement in the Indian Journal of Transplantation .

Biofire pneumonia panel in lung donors: faster detection but limited pathogens

BACKGROUND

Culture of bronchoalveolar lavage (BAL) specimens takes time to report. We tested whether a molecular diagnostic test could accelerate donor lung assessment and treatment.

METHODS

We compared BioFire Film Array Pneumonia Panel (BFPP) with standard of care (SOC) tests on lung allograft samples at three time points: (1) donor BAL at organ recovery, (2) donor bronchial tissue and airway swab at implantation, and (3) first recipient BAL following lung implantation. Primary outcomes were the difference in time to result (Wilcoxon signed-ranked tests) and the agreement in results between BFPP and SOC assays (Gwet's agreement coefficient).

RESULTS

We enrolled 50 subjects. In donor lung BAL specimens, BFPP detected 52 infections (14 out of 26 pathogens in the panel). Viral and bacterial BFPP results were reported 2.4 h (interquartile range, IQR 2.0-6.4) following BAL versus 4.6 h (IQR 1.9-6.0, p = 0.625) for OPO BAL viral SOC results and 66 h (IQR 47-87, p < .0001) for OPO BAL bacterial SOC results. Although there was high overall agreement of results between BAL-BFPP versus OPO BAL-SOC tests (Gwet's AC p < .001 for all), the level of agreement differed among 26 pathogens designed in BFPP and differed by types of specimens. BFPP could not detect many infections identified by SOC assays.

CONCLUSIONS

BFPP decreased time to detection of lung pathogens among donated lungs, but it cannot replace SOC tests due to the limited number of pathogens in the panel.

Adult spinal cord tissue transplantation combined with local tacrolimus sustained-release collagen hydrogel promotes complete spinal cord injury repair

The strategy of replacing a completely damaged spinal cord with allogenic adult spinal cord tissues (aSCs) can potentially repair complete spinal cord injury (SCI) in combination with immunosuppressive drugs, such as tacrolimus (Tac), which suppress transplant rejection and improve graft survival. However, daily systemic administration of immunosuppressive agents may cause harsh side effects. Herein, a localized, sustained Tac-release collagen hydrogel (Col/Tac) was developed to maximize the immune regulatory efficacy but minimize the side effects of Tac after aSC transplantation in complete SCI recipients. Thoracic aSCs of rat donors were transplanted into the complete thoracic spinal cord transection rat recipients, after which Col/Tac hydrogel was implanted. The Tac-encapsulated collagen hydrogel exhibited suitable mechanical properties and long-term sustained Tac release behaviour. After Col/Tac hydrogel implantation in SCI rats with aSC transplantation, the recipients' survival rate significantly improved and the side effects on tissues were reduced compared with those with conventional Tac medication. Moreover, treatment with the Col/Tac hydrogel exhibited similarly reduced immune rejection levels by regulating immune responses and promoted neurogenesis compared to daily Tac injections, and thus improved functional restoration. Localized delivery of immunosuppressive agents by the Col/Tac hydrogel may be a promising strategy for overcoming immune rejection of transplants, with significant potential for clinical application in the future.

Infections following rejection therapies in kidney and liver transplant recipients

INTRODUCTION

Infections are known complications of solid-organ transplant. Treatment for rejection may increase risk of infection. We aimed to study frequency of infection and identify the risk factors for infections in solid organ transplant (SOT) (liver and kidney) recipients treated for rejection.

METHODS

This is a retrospective chart review of all liver and kidney transplant recipients treated for rejection at our institution from 2014 to 2020. We collected information on episodes of acute rejection in the first year of transplant and infections within 6 months following rejection treatment.

RESULTS

We identified 257 transplant patients treated for rejection. One hundred twelve (43.6%) developed infections, with a total of 226 infections. Urinary tracts infections were the most common, 72 (31.9%), followed by cytomegalovirus viremia in 37 (16.4%), bacteremia in 24 (10.6%), and BK virus in 14 (6.2%). Female sex (p = .047), elevated neutrophil count at rejection (p = .002), and increased number of rejection episodes (p = .022) were predictors of infection in kidney and simultaneous liver-kidney recipients. No specific type of induction or rejection therapy was identified as a risk factor for infection, likely due to the prophylaxis protocols at our institution. Infection post rejection treatment was associated with higher graft loss (p = .021) and mortality (p = .031) in kidney transplant recipients.

CONCLUSIONS

Infections are common complications after treatment of SOT rejection. Female gender, higher neutrophil at time of rejection, and increased numbers of rejection episodes were predictors of infections after rejection in simultaneous liver-kidney and kidney transplant patients. Infections were predictors of graft loss at 6 months and mortality at any point in follow-up in kidney transplant patients.

Individualized surgical antibiotic prophylaxis – why, when, and how?

"Surgical site infections (SSI) greatly concern clinicians, as they are associated with significant morbidity and mortality, prolonged hospitalization, and costs. Antibiotic prophylaxis plays a pivotal role among the procedures that are usually employed for the prevention of surgical-related infections. This narrative review aims to cover some of the particular situations when the clinician might consider individualizing antibiotic prophylaxis for a patient. With the rising incidence of multi-drug resistant bacteria carriage among not only hospitalized or institutionalized patients but also patients from the community, there might be a tendency to use extended-spectrum antibiotics for longer periods for surgical infection prevention. However, the inappropriate use of antibiotics increases the selection pressure, thus favoring the spreading of resistant bacteria. Moreover, specific patient characteristics or pathologies might need to be considered to customize the type, dose, or length of administration of an antibiotic as surgical prophylaxis. Using prosthetic material or prolonged surgeries with large fluid shifts are other situations when individualized antibiotic prophylaxis might be thought of. Keeping in mind that it is of utmost importance that everyone adheres to the current guidelines for surgical antibiotic prophylaxis, customization of local protocols according to well-thought-out strategies might prove beneficial in SSI prevention."

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.

Infectious Complications in Lung Transplant Recipients

Infection remains a common cause of death throughout the lifespan of a lung transplant recipient. The increased susceptibility of lung transplant recipients is multifactorial including exposure of the graft to the external environment, impaired mucociliary clearance, and high levels of immunosuppression. Long-term outcomes in lung transplant recipients remain poor compared with other solid organ transplants largely due to deaths from infections and chronic allograft dysfunction. Antibacterial, antifungal, and antiviral prophylaxis may be used after lung transplantation to target a number of different opportunistic infections for varying durations of time. The first-month posttransplant is most commonly characterized by nosocomial infections and donor-derived infections. Following the first month to the first 6 months after transplant-a period of intense immunosuppression-is associated with opportunistic infections. While immunosuppression is reduced after the first year posttransplant, infection remains a risk with community-acquired and rarer infectious agents. Clinicians should be vigilant for infection at all time points after transplant. The use of patient-tailored prophylaxis and treatments help ensure graft and patient survival.

Urinary Tract Infections Caused by K. pneumoniae in Kidney Transplant Recipients – Epidemiology, Virulence and Antibiotic Resistance

Urinary tract infections are the most common complication in kidney transplant recipients, possibly resulting in the deterioration of a long-term kidney allograft function and an increased risk of recipient’s death. K. pneumoniae has emerged as one of the most prevalent etiologic agents in the context of recurrent urinary tract infections, especially with multidrug resistant strains. This paper discusses the epidemiology and risk factors associated with urinary tract infections in kidney transplant recipients, multi-drug resistance of K. pneumoniae (ESBL, KPC, NDM), treatment and pathogenesis of K. pneumoniae infections, and possible causes of recurrent UTIs. It also addresses the issue of colonization/becoming a carrier of K. pneumoniae in the gastrointestinal tract and asymptomatic bacteriuria in relation to a symptomatic UTI development and epidemiology.

Bacterial infections in lung transplantation

Lung transplantation has lower survival rates compared to other than other solid organ transplants (SOT) due to higher rates of infection and rejection-related complications, and bacterial infections (BI) are the most frequent infectious complications. Excess morbidity and mortality are not only a direct consequence of these BI, but so are subsequent loss of allograft tolerance, rejection, and chronic lung allograft dysfunction due to bronchiolitis obliterans syndrome (BOS). A wide variety of pathogens can cause infections in lung transplant recipients (LTRs), including a number of nosocomial pathogens and other multidrug-resistant (MDR) pathogens. Although pneumonia and intrathoracic infections predominate, LTRs are at risk of a number of types of infections. Risk factors include altered anatomy and function of airways, impaired immunity, the microbial flora of the donor and recipient, underlying medical conditions, and genetic factors. Further work on immune monitoring has the potential to improve outcomes. The infecting agents can be derived from the donor lung, pre-existing recipient flora, or acquired from the environment over time. Certain infections may preclude lung transplantation, but this varies from center to center, and more recent studies suggest fewer patients should be disqualified. New molecular methods allow microbiome studies of the lung, gut, and other sites that may further our knowledge of how airway colonization can result in infection and allograft loss. Surveillance, early diagnosis, and aggressive antimicrobial therapy of BI is critical in LTRs. Antibiotic resistance is a major barrier to successful management of these infections. The availability of new agents for MDR Gram-negatives may improve outcomes. Other new therapies, such as bacteriophage therapy, show promise for the future. Finally, it is important to prevent infections through peri-transplant prophylaxis, vaccination, and infection control measures.

The Magnitude and Functionality of SARS-CoV-2 Reactive Cellular and Humoral Immunity in Transplant Population Is Similar to the General Population Despite Immunosuppression

BACKGROUND

The ability of transplant (Tx) patients to generate a protective antiviral response under immunosuppression is pivotal in COVID-19 infection. However, analysis of immunity against SARS-CoV-2 is currently lacking.

METHODS

Here, we analyzed T cell immunity directed against SARS-CoV-2 spike-, membrane-, and nucleocapsid-protein by flow cytometry and spike-specific neutralizing antibodies in 10 Tx in comparison to 26 nonimmunosuppressed (non-Tx) COVID-19 patients.

RESULTS

Tx patients (7 renal, 1 lung, and 2 combined pancreas-kidney Txs) were recruited in this study during the acute phase of COVID-19 with a median time after SARS-CoV-2-positivity of 3 and 4 d for non-Tx and Tx patients, respectively. Despite immunosuppression, we detected antiviral CD4+ T cell-response in 90% of Tx patients. SARS-CoV-2-reactive CD4+ T cells produced multiple proinflammatory cytokines, indicating their potential protective capacity. Neutralizing antibody titers did not differ between groups. SARS-CoV-2-reactive CD8+ T cells targeting membrane- and spike-protein were lower in Tx patients, albeit without statistical significance. However, frequencies of anti-nucleocapsid-protein-reactive, and anti-SARS-CoV-2 polyfunctional CD8+ T cells, were similar between patient cohorts. Tx patients showed features of a prematurely aged adaptive immune system, but equal frequencies of SARS-CoV-2-reactive memory T cells.

CONCLUSIONS

In conclusion, a polyfunctional T cell immunity directed against SARS-CoV-2 proteins as well as neutralizing antibodies can be generated in Tx patients despite immunosuppression. In comparison to nonimmunosuppressed patients, no differences in humoral and cellular antiviral-immunity were found. Our data presenting the ability to generate SARS-CoV-2-specific immunity in immunosuppressed patients have implications for the handling of SARS-CoV-2-infected Tx patients and raise hopes for effective vaccination in this cohort.

Next generation sequencing for diagnosis of central nervous system aspergillosis in liver transplant recipients

Background

Fungal encephalitis is uncommon and sometimes fatal in liver transplant (LT) recipients. Early diagnosis of central nervous system (CNS) fungal infections, especially aspergillosis, is difficult based on routine tests of cerebrospinal fluid (CSF) alone. Next-generation sequencing (NGS) as a new tool may help in this respect.

Methods

Shotgun metagenomics was used to detect pathogens in CSF of patients, who were clinically suspected of CNS infection. Sequencing was performed at BGIseq-50 platform (BGI, Shenzhen).

Results

NGS technique identified Aspergillus in CSF of 5 patients, who were suspected of CNS infection, although clinical symptoms of these patients varied dramatically. The resulting sequence reads corresponding to Aspergillus species ranged from 2 to 25, with genomic coverage ranging from 0.0003% to 0.0036%. Rapid identification of Aspergillus enabled early appropriate antifungal therapy, although 4 patients eventually died of severe infection.

Conclusions

This is the first study to highlight the utility of NGS in early diagnosis of CNS aspergillosis in LT recipients. This new tool may be helpful in improving the diagnosis of CNS aspergillosis.

Cytomegalovirus skin disease in a kidney transplant patient

A 44-year-old man with a history of renal transplantation presented with right lower abdominal wall swelling, redness and pain. A bacterial abscess was drained, and he was discharged home with oral antibiotics. After failing to improve, he returned to the hospital, where he was briefly treated with intravenous antibiotics and discharged home again. The patient returned 5 days later, reporting worsening right groin swelling that extended into the ipsilateral scrotum. Imaging revealed a persistent fluid collection in the region, and he was taken for surgical debridement. Tissue immunochemistry and histopathological evaluation identified cytomegalovirus infection. Plasma quantitative PCR for cytomegalovirus demonstrated high viraemia. The patient was successfully treated with intravenous ganciclovir, followed by oral valganciclovir, with resolution of the skin changes. Persistent hydrocele with epididymitis on imaging suggests that this process may have been the source of the cutaneous cytomegalovirus infection.

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.

Role of serum CXCL9 and CXCL13 in predicting infection after kidney transplant: A STROBE study

Chemokines are majorly involved in inflammatory and immune responses. The interferon-γ-inducible chemokines C-X-C motif chemokines 9 and 10 (CXCL9 and CXCL10) are considerably associated with Th1 cells and monocytes, and their expression levels rapidly increase during the early episodes of renal allograft rejection and various infectious diseases. CXCL13 is one of the most potent B-cell and T follicular helper-cell chemoattractants. The expression of CXCL13 in the presence of infection indicates an important chemotactic activity in multiple infectious diseases. C-C motif chemokine ligand 2 (CCL2) can attract monocytes and macrophages during inflammatory responses. However, there are no studies on the role of these chemokines in posttransplant infection in kidney transplant recipients.In this study, CXCL9, CXCL10, CXCL13, and CCL2 were analyzed using the Bio-Plex suspension array system before transplant and 30 days after transplant.The serum levels of CXCL9 and CXCL13 30 days after kidney transplant were associated with infection within 1 year after transplant (P = .021 and P = .002, respectively). The serum levels of CXCL9 and CXCL13 before surgery and those of CCL2 and CXCL10 before and after surgery were not associated with infection within 1 year after transplant (P > .05). The combination of postoperative day (POD) 30 CXCL9 and postoperative day 30 CXCL13 provided the best results with an area under the curve of 0.721 (95% confidence interval, 0.591-0.852), with a sensitivity of 71.4% and specificity of 68.5% at the optimal cutoff value of 52.72 pg/mL.As important chemokines, CXCL9 and CXCL13 could be used to predict the occurrence of infection after kidney transplant.

Intravital Imaging Allows Organ-Specific Insights Into Immune Functions

Leukocytes are among the most mobile and versatile cells that have many essential functions in homeostasis and survival. Especially cells from the innate immune system, i.e., neutrophils and macrophages, play an important role as rapid first responders against invading microorganisms. With the advent of novel imaging techniques, new ways of visualizing innate immune cells have become available in recent years, thereby enabling more and more detailed discoveries about their nature, function and interaction partners. Besides intravital spinning-disc and 2-photon microscopy, clearing and 3D-imaging techniques provide new insights into the mechanism of innate immune cell behavior in their natural environment. This mini review focuses on the contributions of novel-imaging techniques to provide insight into the functions of neutrophils and macrophages under homeostasis and in infections. Imaging setups for different organs like the liver, kidney, heart, lung, and the peritoneal cavity are discussed as well as the current limitations of these imaging techniques.

A primer for managing cardiac transplant patients in the emergency department setting

BACKGROUND

Cardiac transplant is an effective long-term management option for several severe cardiac diseases. These cardiac transplant patients may present to the emergency department with a range of issues involving the cardiac transplantation, including complications due to their transplant as well as altered presentations of disease resulting from their transplant.

OBJECTIVE

This narrative review provides a focused guide to the evaluation and management of patients with cardiac transplantation and its complications.

DISCUSSION

Cardiac transplant is an effective therapy for end-stage heart failure. A transplanted heart varies both anatomically and physiologically from a native heart. Several significant complications may occur. Graft failure, rejection, and infection are common causes of morbidity and mortality within the first year of transplant. As these patients are on significant immunosuppressive medication regimens, they are at risk of infection, but inadequate immunosuppression increases the risk of acute rejection. A variety of dysrhythmias such as atrial fibrillation and ventricular dysrhythmias may occur. These patients are also at risk of acute coronary syndrome, cardiac allograft vasculopathy, and medication adverse events. Importantly, patients with acute coronary syndrome can have an altered presentation with the so-called "painless" myocardial infarction. Consultation with the transplant physician is recommended, if available, for these patients to assist in evaluation and management.

CONCLUSIONS

An understanding of the presentations and various complications that may affect patients with cardiac transplant will assist emergency clinicians in the care of these patients.

Epidemiology, risk factors, and clinical impact of early post-transplant infection in older kidney transplant recipients: the Korean organ transplantation registry study

Background

As in younger recipients, post-transplant infection is a frequent and devastating complication after kidney transplantation (KT) in older recipients. However, few studies have analyzed characteristics of post-transplant infection in older kidney recipients. In this study of a nation-wide cohort of older kidney recipients, we investigated the current epidemiology, risk factors, and clinical impacts of early post-transplant infection, which was defined as infectious complications requiring hospitalization within the first 6 months after KT.

Methods

Three thousand seven hundred thirty-eight kidney recipients registered in the Korean Organ Transplantation Registry between 2014 and 2017 were enrolled. Recipients were divided into two groups, younger (n = 3081) and older (n = 657), with a cutoff age of 60 years. We observed characteristics of early post-transplant infection, and investigated risk factors for the development of infection. We also analyzed the association of early post-transplant infection with clinical outcomes including cardiac events, rejection, graft loss, and all-cause mortality.

Results

The incidence of early post-transplant infection was more frequent in older recipients (16.9% in younger group and 22.7% in older group). Bacteria were the most common causative pathogens of early post-transplant infection, and the most frequent site of infection was the urinary tract in both older and younger recipients. Older recipients experienced more mycobacterial infections, co-infections, and multiple site infections compared with younger recipients. In older recipients, female sex (HR 1.398, 95% CI 1.199–1.631), older donor age (HR 1.010, 95% CI 1.004–1.016), longer hospitalization after KT (HR 1.010, 95% CI 1.006–1.014), and experience of acute rejection (HR 2.907, 95% CI 2.471–3.419) were independent risk factors for the development of early post-transplant infection. Experiencing infection significantly increases the incidence of rejection, graft loss, and all-cause mortality.

Conclusion

Our results illustrate current trends, risk factors, and clinical impacts of early post-transplant infection after KT in older recipients. Considering the poor outcomes associated with early post-transplant infection, careful screening of recipients at high risk for infection and monitoring of recipients who experience infection are advised. In addition, since older recipients exhibit different clinical characteristics than younger recipients, further studies are needed to establish effective strategies for treating older recipients.

Supplementary Information

Supplementary information accompanies this paper at 10.1186/s12877-020-01859-3.

Infectious disease considerations in immunocompromised patients

Immunocompromised patients account for about 3% of the US population. Complications arising from infection are common in these patients and can present diagnostic and therapeutic challenges. This article describes the pathophysiology of immunosuppression in five common immunocompromised states-asplenia, HIV infection, solid organ transplant, biologic use, and cancer-as well as specific infectious risks and considerations for affected patients and how to manage them.

Interrelationship between Toll-like receptors and infection after orthotopic liver transplantation

Early microbial recognition by the innate immune system is accomplished by Toll-like receptors (TLRs), with resultant initiation of a pro-inflammatory response against infecting organisms. In spite of presence of an abundance of Toll-like receptors on the surface of the liver, gut bacteria does not elicit an inflammatory reaction in healthy individuals due to tolerance to these TLRs, suggesting that the inflammatory responses seen in the liver are the result of breakdown of this tolerance. While orthotopic liver transplantation is often life saving in many instances, death following this procedure is most commonly due to infection that occurs in up to 80% of transplant recipients, most commonly due to microbial causes in up to 70% of cases and viral infections in 20%, while fungal infections affect only 8% of cases. The probability of acquiring infection following hepatic transplantation is heightened due to affection of the innate immune defense mechanisms of the host following this procedure. Single nucleotide polymorphisms of TLRs have been associated with increased likelihood of either development of post-transplant infection or eradication of infecting organism. However, conflicting reports from other studies reveal that prevalence of this single nucleotide polymorphism is not increased in infected patients.

Derivation and external validation of the SIMPLICITY score as a simple immune-based risk score to predict infection in kidney transplant recipients

Existing approaches for infection risk stratification in kidney transplant recipients are suboptimal. Here, we aimed to develop and validate a weighted score integrating non-pathogen-specific immune parameters and clinical variables to predict the occurrence of post-transplant infectious complications. To this end, we retrospectively analyzed a single-center derivation cohort of 410 patients undergoing kidney transplantation in 2008-2013 in Madrid. Peripheral blood lymphocyte subpopulations, serum immunoglobulin and complement levels were measured at one-month post-transplant. The primary and secondary outcomes were overall and bacterial infection through month six. A point score was derived from a logistic regression model and prospectively applied on a validation cohort of 522 patients undergoing kidney transplantation at 16 centers throughout Spain in 2014-2015. The SIMPLICITY score consisted of the following variables measured at month one after transplantation: C3 level, CD4⁺ T-cell count, CD8⁺ T-cell count, IgG level, glomerular filtration rate, recipient age, and infection within the first month. The discrimination capacity in the derivation and validation cohorts was good for overall (areas under the receiver operating curve of 0.774 and 0.730) and bacterial infection (0.767 and 0.734, respectively). The cumulative incidence of overall infection significantly increased across risk categories in the derivation (low-risk 13.7%; intermediate-risk, 35.9%; high-risk 77.6%) and validation datasets (10.2%, 28.9% and 50.4%, respectively). Thus, the SIMPLICITY score, based on easily available immune parameters, allows for stratification of kidney transplant recipients at month one according to their expected risk of subsequent infection.

Comparison of Ceftizoxime Plus Ampicillin-Sulbactam versus Gentamicin Plus Ampicillin-Sulbactam in the Prevention of Post-Transplant Early Bacterial Infections in Liver Transplant Recipients: A Randomized Controlled Trial

Purpose

In this study, we aimed to compare the efficacy of combined ceftizoxime with ampicillin-sulbactam versus combined gentamicin with ampicillin-sulbactam as prophylactic antibiotic regimen in preventing early bacterial PTIs in liver TX recipients at a referral center.

Patients and methods

All patients older than 18 years who had undergone liver TX at Abu-Ali Sina transplantation center in Shiraz, Iran from July 2018 to April 2019 were included in this study. In a single-blinded manner, the participants randomly received either combined intravenous ceftizoxime plus ampicillin-sulbactam (ceftizoxime group) or gentamicin plus ampicillin-sulbactam (gentamicin group) as prophylactic antibiotic regimen before the incision of the surgery, which was continued for 48 hrs after liver Tx. The rate and type of bacterial infections, length of hospital and intensive care unit (ICU) stay, mortality rate, and kidney function were assessed during 1 month following liver TX in the two groups.

Results

Two hundred and thirty patients were divided into two groups. One patient in the gentamicin group and five in the ceftizoxime group were excluded due to emergency exploratory laparotomy within the first 3 days after transplantation. The rate of bacterial infections during the first month after transplantation was 25.4%. This rate was significantly lower in the gentamicin group (13.16%) in comparison to the ceftizoxime group (38.18%) (P value<0.01), based on the univariate logistic regression analysis. Length of ICU and hospital stay and also mortality rate were significantly lower in the gentamicin group (P value <0.01). There was no significant difference regarding kidney function between the two groups (P value = 0.16).

Conclusion

Our results suggested that gentamicin can be considered as a promising agent in prophylactic antibiotic regimen for patients undergoing liver TX.

Trial registration

The study was registered at the Iranian Registry of Clinical Trials (IRCT20120731010453N2; http://www.irct.ir/).

Machine learning for the prediction of severe pneumonia during posttransplant hospitalization in recipients of a deceased-donor kidney transplant

Background

Pneumonia accounts for the majority of infection-related deaths after kidney transplantation. We aimed to build a predictive model based on machine learning for severe pneumonia in recipients of deceased-donor transplants within the perioperative period after surgery.

Methods

We collected the features of kidney transplant recipients and used a tree-based ensemble classification algorithm (Random Forest or AdaBoost) and a nonensemble classifier (support vector machine, Naïve Bayes, or logistic regression) to build the predictive models. We used the area under the precision-recall curve (AUPRC) and the area under the receiver operating characteristic curve (AUROC) to evaluate the predictive performance via ten-fold cross validation.

Results

Five hundred nineteen patients who underwent transplantation from January 2015 to December 2018 were included. Forty-three severe pneumonia episodes (8.3%) occurred during hospitalization after surgery. Significant differences in the recipients' age, diabetes status, HBsAg level, operation time, reoperation, usage of anti-fungal drugs, preoperative albumin and immunoglobulin levels, preoperative pulmonary lesions, and delayed graft function, as well as donor age, were observed between patients with and without severe pneumonia (P<0.05). We screened eight important features correlated with severe pneumonia using the recursive feature elimination method and then constructed a predictive model based on these features. The top three features were preoperative pulmonary lesions, reoperation and recipient age (with importance scores of 0.194, 0.124 and 0.078, respectively). Among the machine learning algorithms described above, the Random Forest algorithm displayed better predictive performance, with a sensitivity of 0.67, specificity of 0.97, positive likelihood ratio of 22.33, negative likelihood ratio of 0.34, AUROC of 0.91, and AUPRC of 0.72.

Conclusions

The Random Forest model is potentially useful for predicting severe pneumonia in kidney transplant recipients. Recipients with a potential preoperative potential pulmonary infection, who are of older age and who require reoperation should be monitored carefully to prevent the occurrence of severe pneumonia.

Urinary tract infections in renal transplant recipients at a quaternary care centre in Australia

Background

Urinary tract infections (UTI) are the most common of infections after renal transplantation. The consequences of UTIs in this population are serious, with increased morbidity and hospitalisation rates as well as acute allograft dysfunction. UTIs may impair overall graft and patient survival. We aimed to identify the prevalence and risk factors for post-transplant UTIs and assess UTIs’ effect on renal function during a UTI episode and if they result in declining allograft function at 2 years post-transplant. Additionally, the causative organism, the class of antibacterial drug employed for each UTI episode and utilisation rates of trimethoprim/sulfamethoxazole (TMP/SMX) prophylaxis were also quantified.

Methods

This was a retrospective study of 72 renal transplant patients over a 5-year period who were managed at the Royal Brisbane and Women’s Hospital. Patient charts, pathology records and dispensing histories were reviewed as part of this study and all UTIs from 2 years post transplantation were captured.

Results

Of these patients, 20 (27.8%) had at least one UTI. Older age (p = 0.015), female gender (p < 0.001), hyperglycaemia (p = 0.037) and acute rejection episodes (p = 0.046) were risk factors for developing a UTI on unadjusted analysis. Female gender (OR 4.93) and age (OR 1.03) were statistically significant risk factors for a UTI on adjusted analysis. On average, there was a 14.4% (SEM 5.20) increase in serum creatinine during a UTI episode, which was statistically significant (p = 0.027), and a 9.1% (SEM 6.23) reduction in serum creatinine after the UTI episode trending toward statistical significance.

(p = 0.076). Common organisms (Escherichia coli and Klebsiella pneumoniae) accounted for 82% of UTI episodes with 70% of UTI cases requiring only a single course of antibiotic treatment. Furthermore, the antibiotic class used was either a penicillin (49%) or cephalosporin (36%) in the majority of UTIs. The use of TMP/SMX prophylaxis for Pneumocystis carinii pneumonia prophylaxis did not influence the rate of UTI, with > 90% of the cohort using this treatment.

Conclusions

There was no significant change in serum creatinine and estimated glomerular filtrate rate from baseline to 2 years post-transplant between those with and without a UTI.

Secondary Hypogammaglobulinemia: An Increasingly Recognized Complication of Treatment with Immunomodulators and After Solid Organ Transplantation

Secondary hypogammaglobulinemia is a common development in patients treated with immunomodulatory agents for autoimmune, connective tissue, and malignant diseases. It has been observed in the medical management of patients undergoing hematopoietic stem cell and solid organ transplantation. Some patients have preexisting immunodeficiency associated with these illnesses; immunosuppressive treatment magnifies their immune defect. This article reviews immunosuppressive medications, including biological treatments that cause secondary hypogammaglobulinemia. It summarizes risk factors for rituximab-induced hypogammaglobulinemia, such as preexisting low immunoglobulin G levels, CD19 levels, host factors, and additive effect of all immunomodulatory drugs used. The evaluation and management of secondary hypogammaglobulinemia are discussed.

Risk factors and etiology of repeat infection in kidney transplant recipients

Kidney transplantation (KT) is the best therapy available for patients with end-stage renal disease, but postoperative infections are a significant cause of mortality.In this retrospective study the frequency, risk factors, causative pathogens, and clinical manifestations of infection in KT recipients from Beijing Chao-Yang Hospital, Capital Medical University were investigated. Ninety-seven KT recipients who were hospitalized with infection between January 2010 and December 2016 were included. Clinical characteristics, surgery details, laboratory results, and etiology were compared in patients who developed single infection and patients who developed repeated infection (2 or more) after KT.A total of 161 infections were adequately documented in a total of 97 patients, of which 57 patients (58.8%) had 1 infection, 24 (24.7%) had 2, 11 (11.3%) had 3; 3 (3.1%) had 4, and 2 (2.1%) had 5 or more. The most common infection site was the urinary tract (90 infections; 56%), both overall and in the repeated infection group. The most frequently isolated pathogen was Pseudomonas aeruginosa. In the repeated infection patients, in most cases of P. aeruginosa infection (54%) it was cultured from urine. For first infections, a time between KT and infection of ≤ 21 days (area under receiver operating characteristic curve [AUC] 0.636) and a tacrolimus level ≥ 8 ng/mL (AUC 0.663) independently predicted repeat infection. The combination of these two predictive factors yielded an AUC of 0.716, which did not differ statistically significantly from either predictor alone.With regard to first infections after KT, a time between KT and infection of ≤ 21 days, and a tacrolimus level ≥ 8 ng/mL each independently predicted repeated infection in KT recipients.

Infection is the chief cause of mortality and non-death censored graft loss in the first year after renal transplantation in a resource limited population: A single centre study

AIM

Few studies have assessed the impact of infections after renal transplantation (RTX) in low and middle income countries. This single centre study aimed to delineate the profile and impact of infections requiring hospitalization (IRH) occurring in the first year after RTX in India.

METHOD

Patients who underwent RTX between July 2012 and June 2015 were followed up for 12 months after transplantation.

RESULTS

60.2% of the 387 patients studied had at least one IRH and total 492 infections were diagnosed. The most common were urinary tract (30.3%), gastrointestinal (17.1%) and pulmonary (11.2%) infections. Viral aetiology (33.3%) was most frequent, followed by bacterial (23.6%), parasitic (5.1%), tuberculosis (4.5%), and fungal infections (3.9%). 86.4% deaths were due to infections. One year patient and graft survival were inferior among recipients with IRH compared to those with no IRH: 91.8% vs. 98.1% (log rank = 0.010) and 90.1% vs. 97.4% (log rank = 0.006) respectively. Average monthly income per family member <5000 Rupees (75 USD), NODAT, and acute rejection were independent risk factors for IRH.

CONCLUSION

The profile of IRH is unique involving opportunistic, community-acquired and endemic infections seen in this country. It is the predominant cause of mortality and graft loss in the first year after RTX. Poor economic status is an important determinant of IRH in our population.

Fluoroquinolones for the treatment of latent Mycobacterium tuberculosis infection in liver transplantation

Solid organ transplantation (SOT) is the best treatment option for end-stage organ disease. Newer immunosuppressive agents have reduced the incidence of graft rejection but have increased the risk of infection, particularly due to the reactivation of latent infections due to opportunistic agents such as Mycobacterium tuberculosis. Active tuberculosis (TB) after SOT is a significant cause of morbidity and mortality. Most cases of posttransplant TB are secondary to reactivation of latent tuberculosis infection (LTBI) due to the effects of long-term immunosuppressive therapy. Risk minimization strategies have been developed to diagnose LTBI and initiate treatment prior to transplantation. Isoniazid with vitamin B6 supplementation is the treatment of choice. However, liver transplantation (LT) candidates and recipients have an increased risk of isoniazid-induced liver toxicity, leading to lower treatment completion rates than in other SOT populations. Fluoroquinolones (FQs) exhibit good in vitro antimycobacterial activity and a lower risk of drug-induced liver injury than isoniazid. In the present review, we highlight the disease burden posed by posttransplant TB and summarize the emerging clinical evidence supporting the use of FQs for the treatment of LTBI in LT recipients and candidates.

Characteristics of community-acquired respiratory viruses infections except seasonal influenza in transplant recipients and non-transplant critically ill patients

Background/Purpose

Transplant recipients are vulnerable to life-threatening community-acquired respiratory viruses (CA-RVs) infection (CA-RVI). Even if non-transplant critically ill patients in intensive care unit (ICU) have serious CA-RVI, comparison between these groups remains unclear. We aimed to evaluate clinical characteristics and mortality of CA-RVI except seasonal influenza A/B in transplant recipients and non-transplant critically ill patients in ICU.

Methods

We collected 37,777 CA-RVs multiplex real-time reverse transcription-polymerase chain reaction test results of individuals aged ≥18 years from November 2012 to November 2017. The CA-RVs tests included adenovirus, coronavirus 229E/NL63/OC43, human bocavirus, human metapneumovirus, parainfluenza virus 1/2/3, rhinovirus, and respiratory syncytial virus A/B.

Results

We found 286 CA-RVI cases, including 85 solid organ transplantation recipients (G1), 61 hematopoietic stem cell transplantation recipients (G2), and 140 non-transplant critically ill patients in ICU (G3), excluding those with repeated isolation within 30 days. Adenovirus positive rate and infection cases were most prominent in G2 (p < 0.001). The median time interval between transplantation and CA-RVI was 30 and 20 months in G1 and G2, respectively. All-cause in-hospital mortality was significantly higher in G3 than in G1 or G2 (51.4% vs. 28.2% or 39.3%, p = 0.002, respectively). The mechanical ventilation (MV) was the independent risk factor associated with all-cause in-hospital mortality in all three groups (hazard ratio, 3.37, 95% confidence interval, 2.04–5.56, p < 0.001).

Conclusions

This study highlights the importance of CA-RVs diagnosis in transplant recipients even in long-term posttransplant period, and in non-transplant critically ill patients in ICU with MV.

Early post-operative intravenous tacrolimus in pediatric liver transplant recipients is not superior to oral tacrolimus

We aimed to compare the early results of i.v. with p.o. TAC as a primary immunosuppressant in pediatric patients undergoing LT. This retrospective study enrolled 75 children who underwent LT and received TAC-steroid regimens as a primary immunosuppressant between September 2011 and October 2015 at our institution. Thirty-five recipients received TAC i.v. and 40 received TAC p.o. Early results were evaluated and compared, including ACR, EBV, or CMV infection; renal adverse effects; and hospital stay. Comparisons of 90-day post-transplant results showed that the rates of overall viral (74% vs 40% P < 0.002), EBV (46% vs 17.5% P < 0.008), and CMV (51% vs 30% P = 0.05) infections were significantly higher in the i.v. than in the p.o. group. Neither regimen has any adverse effects on renal function. There were no between-group differences in ACR incidence and severity, serum creatinine concentration, and hospital stay. Patient and graft survival rates at 3 months and 1 year did not differ significantly between the two groups. Compared with p.o. treatment, i.v. administration of high TAC concentration did not have beneficial post-transplant effects on ACR incidence and severity, while increasing the incidence of viral infections in pediatric LT.

Prevention and Treatment of Yeast and Endemic Fungal Infections

Invasive fungal infections (IFIs) remain an important complication of solid organ transplantation owing to their significant morbidity and mortality and include infections due to Candida, Cryptococcus, endemic mycosis, and other rare yeasts and molds. IFIs occur in different intervals posttransplantation and depend on a number of extrinsic and intrinsic risk factors, some of which are specific to the type of organs transplanted, surgical techniques, and type of immunosuppressive medications. Donor-derived IFIs and emergence of new multidrug-resistant yeasts have been reported in various healthcare settings. Clinical manifestations of yeast and endemic fungal infections vary in different types of organ transplants. Diagnosis of IFIs in SOT recipients is challenging due to their nonspecific signs and symptoms owing to the impaired inflammatory responses as a result of immunosuppression and the lack of highly sensitive and specific diagnostic modalities. Early diagnosis is key to successful therapy, and physicians should have a high index of suspicion based on risk factors and epidemiology of these pathogens. Antifungal treatment strategies for yeast infections have been outlined in various society guidelines. Management of complications that arise before or during antifungal therapy is critical for optimizing clinical response.

Graft Dysfunction and Management in Liver Transplantation

Graft dysfunction of the liver allograft manifests across a spectrum in both timing posttransplantation and clinical presentation. This can range from mild transient abnormalities of liver tests to acute liver failure potentially leading to graft failure. The causes of graft dysfunction can be divided into those resulting in early and late graft dysfunction. Although nonspecific, liver biochemistry abnormalities are still the mainstay investigation used in monitoring for dysfunction. This article provides a summary of the main causes and management strategies for liver graft dysfunction in the early through late posttransplant stages.

Management of bacterial and fungal infections in end stage liver disease and liver transplantation: Current options and future directions

Patients with liver cirrhosis are susceptible to infections due to various mechanisms, including abnormalities of humoral and cell-mediated immunity and occurrence of bacterial translocation from the intestine. Bacterial infections are common and represent a reason for progression to liver failure and increased mortality. Fungal infections, mainly caused by Candida spp., are often associated to delayed diagnosis and high mortality rates. High level of suspicion along with prompt diagnosis and treatment of infections are warranted. Bacterial and fungal infections negatively affect the outcomes of liver transplant candidates and recipients, causing disease progression among patients on the waiting list and increasing mortality, especially in the early post-transplant period. Abdominal, biliary tract, and bloodstream infections caused by Gram-negative bacteria [e.g., Enterobacteriaceae and Pseudomonas aeruginosa (P. aeruginosa)] and Staphylococcus spp. are commonly encountered in liver transplant recipients. Due to frequent exposure to broad-spectrum antibiotics, invasive procedures, and prolonged hospitalizations, these patients are especially at risk of developing infections caused by multidrug resistant bacteria. The increase in antimicrobial resistance hampers the choice of an adequate empiric therapy and warrants the knowledge of the local microbial epidemiology and the implementation of infection control measures. The main characteristics and the management of bacterial and fungal infections in patients with liver cirrhosis and liver transplant recipients are presented.

The Role of mTOR Inhibitors in the Management of Viral Infections: A Review of Current Literature

Viruses are the leading cause of infections after solid organ transplant. The antiviral properties of mammalian target of rapamycin inhibitors (mTORis) have been ascribed to a variety of mechanisms and historical data have supported their use over other immunosuppressants for a myriad of viruses. Herein, we summarize the most current data to highlight the role of mTORis in the management of viral infections after solid organ transplant. The mTORis play a clear role in the management of cytomegalovirus, and have data supporting their potential use for BK virus and human herpesvirus 8-related Kaposi sarcoma. No data definitively supports mTORis for use in Epstein-Barr virus-mediated posttransplant lymphoproliferative disorder or hepatitis C virus viral replication. Although theoretically an advantageous therapy for hepatitis C virus-related liver allograft fibrosis and human immunodeficiency virus, mTORi use specifically for these indications is less attractive with modern treatments currently available. Data surrounding mTORi efficacy in preventing rejection, and their toxicity profile must be balanced with their potential antiviral effects in combination with patient-specific factors.

Donor-derived multiorgan transmission of mixed P. malariae and P. ovale infection: Impact of globalization on post-transplant infections

A 57-year-old man was admitted with fever and thrombocytopenia 1 month after renal transplantation. He had never received a blood transfusion or travelled outside Spain. A peripheral blood smear revealed Plasmodium malariae and P. ovale parasites, diagnosis confirmed later by malaria PCR. The donor, from Equatorial Guinea, had negative thick and thin blood smears and rapid malaria antigen test prior to organ donation. Peripheral blood malaria PCR was not performed during donor screening. The second renal recipient and the liver recipient were evaluated and were found to be asymptomatic. Thick and thin films and rapid malaria diagnostic tests were negative for both patients and blood for malaria PCR was sent to the referral laboratory. The index patient was treated with oral chloroquine diphosphate, with a favorable outcome and was considered cured. Malaria PCR was negative for the other renal recipient and positive for P. malariae and P. ovale curtisi for the liver transplant patient. Both were treated with oral chloroquine and the liver recipient also completed treatment with primaquine phosphate. This reported case of multiorgan transmission of mixed malaria infection highlights the importance of PCR-based tests for Plasmodium in the screening of donors from endemic areas.

Established and potential predictors of blood loss during lung transplant surgery

Lung transplantation is an established therapeutic procedure for end stage lung diseases. Its success may be impaired by perioperative complications. Intraoperative blood loss and the resulting blood transfusion are among the most common complications. The various factors contributing to increased blood loss during lung transplantation are only scarcely investigated and not yet completely understood. This is in sharp contrast to other surgical fields, as in orthopedic surgery, liver transplantation and cardiac surgery the contributors to blood loss are well identified. This narrative review article aims to highlight the acknowledged factors influencing blood loss in lung transplantation (such as double vs. single lung transplant) and to discuss potential factors that may be of interest for further research or helpful to develop strategies targeting risk factors in order to minimize blood loss during lung transplantation and finally improve patient outcome.

Saprochaete capitata (Geotrichum capitatum), an emerging fungal infection in kidney transplant recipients

We are reporting the case of an 82-year-old Yemeni patient, renal transplant recipient who was admitted to our institution and who subsequently developed disseminated infection with Saprochaete capitata. This pathogenic fungus is rarely reported in patients with solid organ trans-plants. Saprochaete capitata is an emerging fungal pathogen, ubiquitously spread in the environment. This is the second case to our knowledge of infection with Saprochaete capitata in a renal transplant patient. Our patient was treated for multiple nosocomial infections with prolonged antibiotic courses. He succumbed to the infection with Saprochaete capitate after several weeks spent in the intensive care unit.

Single-center outbreak of Pneumocystis jirovecii pneumonia in heart transplant recipients

BACKGROUND

Pneumocystis jirovecii pneumonia (PJP) outbreaks are described in solid organ transplant recipients. Few reports suggest interhuman transmission with important infection control implications. We described a large PJP outbreak in heart transplant (HTx) recipients.

METHODS

Six cases of PJP occurred in HTx recipients within 10 months in our hospital. Demographics, clinical characteristics, treatment and outcomes were described. To identify contacts among individuals a review of all dates of out-patient visits and patient hospitalizations was performed. Cross exposure was also investigated using genotyping on PJ isolates.

RESULTS

At the time of PJP-related hospitalization, patients' mean age was 49 ± standard deviation 4 years, median time from HTx was 8 (25%-75% interquartile range [Q1-Q3] 5-12) months and none of the cases were on prophylaxis. At PJP-related admission, 5 patients had CMV reactivation, of whom 4 were on antiviral preemptive treatment. Median in-hospital stay was 30 (Q1-Q3, 28-48) days; and 2 cases required intensive care unit admission. All patients survived beyond 2 years. Transmission map analysis suggested interhuman transmission in all cases (presumed incubation period, median 90 [Q1-Q3, 64-91] days). Genotyping was performed in 4 cases, demonstrating the same PJ strain in 3 cases.

CONCLUSIONS

We described a large PJP cluster among HTx recipients, supporting the nosocomial acquisition of PJP through interhuman transmission. Based on this experience, extended prophylaxis for more than 6 months after HTx could be considered in specific settings. Further work is required to understand its optimal duration and timing based on individual risk factor profiles and to define standardized countermeasures to prevent and limit PJP outbreaks.

Pneumonia in Renal Transplant Recipients: A Single-Center Study

OBJECTIVES

Pulmonary infections are a significant cause of morbidity and mortality in solid-organ transplant recipients despite enhanced facilities for perioperative care. The aim of this study was to evaluate the demographic characteristics, clinical course, and outcomes of renal transplant recipients with pneumonia.

MATERIALS AND METHODS

The medical records of all renal transplant recipients from January 2010 to December 2014 were retrospectively reviewed, and patients diagnosed with pneumonia according to Centers for Disease Control and Prevention criteria were evaluated. Pneumonia was classified as community acquired or nosocomial. Patient demographics, microbiologic findings, need for intensive care/mechanical ventilation over the course of treatment, and information about clinical follow-up and mortality were all recorded.

RESULTS

Eighteen (13.4%) of 134 renal transplant recipients had 25 pneumonia episodes within the study period. More than half (56%) of the pneumonia episodes developed within the first 6 months of transplant, whereas 44% developed after 6 months (all > 1 year). Eight cases (32%) were considered nosocomial pneumonia, and 17 (68%) were considered community-acquired pneumonia. Bacteria were the most common cause of pneumonia (28%), and fungi ranked second (8%). No viral or mycobacterial agents were detected. No patients required prolonged mechanical ventilation. No statistically significant difference was found in the need for intensive care or regarding mortality between patients with nosocomial and community-acquired pneumonia. Two patients (11%) died, and all remaining patients recovered.

CONCLUSIONS

The present study confirmed that pneumonia after renal transplant is not a rare complication but a significant cause of morbidity. Long-term and close follow-up for pneumonia is necessary after renal transplant.