The prevention of infection post-transplant: the role of prophylaxis, preemptive and empiric therapy

Invasive Aspergillosis in the Intensive Care Unit

Invasive pulmonary aspergillosis (IPA) is a serious condition resulting in significant mortality and morbidity among patients in intensive care units (ICUs). There is a growing number of at-risk patients for this condition with the increasing use of immunosuppressive therapies. The diagnosis of IPA can be difficult in ICUs, and relies on integration of clinical, radiological, and microbiological features. In this review, we discuss patient populations at risk for IPA, as well as the diagnostic criteria employed. We review the fungal biomarkers used, as well as the challenges in distinguishing colonization with Aspergillus from invasive disease. We also address the growing concern of multidrug-resistant Aspergillosis and review the new and novel therapeutics which are in development to combat this.

Incidences of infectious events in a renal transplant cohort of the German Center of Infectious Diseases (DZIF)

Background

Infectious complications are a major cause of morbidity and mortality after kidney transplantation.

Methods

In this transplant cohort study at the German Center of Infectious Diseases (DZIF), we evaluated all infections occurring during the first year after renal transplantation. We assessed microbial etiology, incidence rates, and temporal occurrence of these infections.

Results

Of 804 renal transplant recipients (65.2% male, 51 ± 14 years), 439 (54.6%) had 972 infections within the first year after transplantation. Almost half of these infections (47.8%) occurred within the first three months. Bacteria were responsible for 66.4% (645/972) of all infections, followed by viral (28.9%[281/972]) and fungal (4.7%[46/972]) pathogens. The urinary tract was the most common site of infection (42.4%). Enterococcus was most frequently isolated bacteria (20.9%), followed by E.coli (17.6%) and Klebsiella (12.5%). E.coli was the leading pathogen in recipients <50 years of age, whereas Enterococcus predominated in older recipients. Resistant bacteria were responsible for at least one infection in 9.5% (76/804) of all recipients. Viral infections occurred in 201 recipients (25.0%). Of these, herpes viruses predominated (140/281[49.8%]) and cytomegalovirus had the highest incidence rate (12.3%). In the 46 fungal infections, Candida albicans (40.8%) was most commonly isolated. Other fungal opportunistic pathogens, including Aspergillus fumigatus and Pneumocystis, were rare.

Conclusions

Renal allograft recipients in Germany experience a high burden of infectious complications in the first year after transplantation. Bacteria were the predominating pathogen, followed by opportunistic infections such as cytomegalovirus. Microbial etiology varied between age groups and resistant bacteria were identified in 10% of recipients.

How I treat CMV reactivation after allogeneic hematopoietic stem cell transplantation

Cytomegalovirus (CMV) reactivation remains one of the most common and life-threatening infectious complications following allogeneic hematopoietic stem cell transplantation, despite novel diagnostic technologies, several novel prophylactic agents, and further improvements in preemptive therapy and treatment of established CMV disease. Treatment decisions for CMV reactivation are becoming increasingly difficult and must take into account whether the patient has received antiviral prophylaxis, the patient's individual risk profile for CMV disease, CMV-specific T-cell reconstitution, CMV viral load, and the potential drug resistance detected at the time of initiation of antiviral therapy. Thus, we increasingly use personalized treatment strategies for the recipient of an allograft with CMV reactivation based on prior use of anti-CMV prophylaxis, viral load, the assessment of CMV-specific T-cell immunity, and the molecular assessment of resistance to antiviral drugs.

Adherence to guidelines across different specialties to prevent infections in patients undergoing immunosuppressive therapies

BACKGROUND

Substantial numbers of patients are now receiving either immunosuppressive therapies or chemotherapy. There are significant risks in such patients of developing opportunistic infections or re-activation of latent infections, with higher associated morbidity and mortality. The aim of this quality improvement project was to determine how effective 5 different specialties were in assessing and mitigating risks of developing opportunistic infections or re-activation of latent infections in patients undergoing immunosuppressive therapies.

METHODS

This was a single centre audit where records of patients attending clinics providing immunosuppressive therapies were reviewed for the following: evidence of screening for blood-borne virus [BBV] infections, varicella and measles immunity, latent/active TB or hypogammaglobulinaemia, and whether appropriate vaccines had been advised or various infection risks discussed. These assessments were audited against both national and international guidelines, or a cross-specialty consensus guideline where specific recommendations were lacking. Two sub-populations were also analysed separately: patients receiving more potent immunosuppression and black and minority ethnic [BME] patients,.

RESULTS

For the 204 patients fulfilling the inclusion criteria, BBV, varicella/measles and latent TB screening was inconsistent, as was advice for vaccinations, with few areas complying with specialty or consensus guidelines. Less than 10% of patients in one specialty were tested for HIV. In BME patients screening for HIV [60%], measles [0%] and varicella [40%] immunity and latent [30%] or active [20%] TB was low. Only 38% of patients receiving potent immunosuppression received Pneumocystis prophylaxis, with 3 of 4 specialties providing less than 15% of patients in this category with prophylaxis.

CONCLUSIONS

Compliance with guidelines to mitigate risks of infection from immunosuppressive therapies was either inconsistent or poor for most specialties. New approaches to highlight such risks and assist appropriate pre-immunosuppression screening are needed.

Immunosuppression following organ transplantation. Part 2: complications and their management

Advances in the care of patients who have had a solid organ transplant has led to a growing population of post-transplant patients, who are also living for longer. As a result of their longer life expectancy, transplant recipients often face a multitude of challenges, including optimising their immunosuppressive regimens and managing potential complications. Life-threatening infections, malignancies, and organ-specific toxicities are the complications post-transplant patients commonly encounter and these complications are often associated with increased morbidity and mortality, adverse graft functioning and survival, profound impairment in the patient's quality of life, and significant healthcare burden. This article, the second of two parts, gives an overview of the issues involved in the care of patients who are receiving immunosuppressants. The common complications encountered by post-transplant patients are discussed and their assessment, management, prevention and treatment explored.

Antiviral prophylaxis for cytomegalovirus infection in allogeneic hematopoietic cell transplantation

Patients treated with allogeneic hematopoietic cell transplantation (HCT) are at risk of cytomegalovirus (CMV) reactivation and disease, which results in increased morbidity and mortality. Although universal antiviral prophylaxis against CMV improves outcomes in solid organ transplant recipients, data have been conflicting regarding such prophylaxis in patients undergoing allogeneic HCT. We conducted a systematic review of randomized trials of prophylactic antivirals against CMV after allogeneic HCT to summarize the evolution of the field over the last 35 years and evaluate the prophylactic potential of antiviral agents against CMV after allogeneic HCT. Electronic databases were queried from database inception through 31 December 2017. For included studies, incidence of CMV infection and all-cause mortality were collected as primary outcomes; CMV disease incidence, use of preemptive therapy, and drug toxicities were collected as secondary outcomes. Nineteen clinical trials conducted between 1981 and 2017 involving a total of 4173 patients were included for review. Prophylactic strategies included use of acyclovir, valacyclovir, ganciclovir, maribavir, brincidofovir, and letermovir compared with placebo or a comparator antiviral. Fourteen trials that compared antiviral prophylaxis with placebo demonstrated overall effectiveness in reducing incidence of CMV infection (odds ratio [OR], 0.49; 95% confidence interval [CI], 0.42-0.58), CMV disease (OR, 0.56; 95% CI, 0.40-0.80), and use of preemptive therapy (OR, 0.51; 95% CI, 0.42-0.62; 6 trials); however, none demonstrated reduction in all-cause mortality (OR, 0.96; 95% CI, 0.78-1.18) except the phase 3 trial of letermovir (week-24 OR, 0.59; 95% CI, 0.38-0.98). Additional research is warranted to determine patient groups most likely to benefit from antiviral prophylaxis and its optimal deployment after allogeneic HCT.

A Randomized, Double-Blind, Placebo-Controlled Phase 3 Trial of Oral Brincidofovir for Cytomegalovirus Prophylaxis in Allogeneic Hematopoietic Cell Transplantation

Cytomegalovirus (CMV) infection is a common complication of allogeneic hematopoietic cell transplantation (HCT). In this trial, we randomized adult CMV-seropositive HCT recipients without CMV viremia at screening 2:1 to receive brincidofovir or placebo until week 14 post-HCT. Randomization was stratified by center and risk of CMV infection. Patients were assessed weekly through week 15 and every third week thereafter through week 24 post-HCT. Patients who developed clinically significant CMV infection (CS-CMVi; CMV viremia requiring preemptive therapy or CMV disease) discontinued the study drug and began anti-CMV treatment. The primary endpoint was the proportion of patients with CS-CMVi through week 24 post-HCT; patients who discontinued the trial or with missing data were imputed as primary endpoint events. Between August 2013 and June 2015, 452 patients were randomized at a median of 15 days after HCT and received study drug. The proportion of patients who developed CS-CMVi or were imputed as having a primary endpoint event through week 24 was similar between brincidofovir-treated patients and placebo recipients (155 of 303 [51.2%] versus 78 of 149 [52.3%]; odds ratio, .95 [95% confidence interval, .64 to 1.41]; P = .805); fewer brincidofovir recipients developed CMV viremia through week 14 compared with placebo recipients (41.6%; P < .001). Serious adverse events were more frequent among brincidofovir recipients (57.1% versus 37.6%), driven by acute graft-versus-host disease (32.3% versus 6.0%) and diarrhea (6.9% versus 2.7%). Week 24 all-cause mortality was 15.5% among brincidofovir recipients and 10.1% among placebo recipients. Brincidofovir did not reduce CS-CMVi by week 24 post-HCT and was associated with gastrointestinal toxicity.

Letermovir Prophylaxis for Cytomegalovirus in Hematopoietic-Cell Transplantation

BACKGROUND

Cytomegalovirus (CMV) infection remains a common complication after allogeneic hematopoietic-cell transplantation. Letermovir is an antiviral drug that inhibits the CMV-terminase complex.

METHODS

In this phase 3, double-blind trial, we randomly assigned CMV-seropositive transplant recipients, 18 years of age or older, in a 2:1 ratio to receive letermovir or placebo, administered orally or intravenously, through week 14 after transplantation; randomization was stratified according to trial site and CMV disease risk. Letermovir was administered at a dose of 480 mg per day (or 240 mg per day in patients taking cyclosporine). Patients in whom clinically significant CMV infection (CMV disease or CMV viremia leading to preemptive treatment) developed discontinued the trial regimen and received anti-CMV treatment. The primary end point was the proportion of patients, among patients without detectable CMV DNA at randomization, who had clinically significant CMV infection through week 24 after transplantation. Patients who discontinued the trial or had missing end-point data at week 24 were imputed as having a primary end-point event. Patients were followed through week 48 after transplantation.

RESULTS

From June 2014 to March 2016, a total of 565 patients underwent randomization and received letermovir or placebo beginning a median of 9 days after transplantation. Among 495 patients with undetectable CMV DNA at randomization, fewer patients in the letermovir group than in the placebo group had clinically significant CMV infection or were imputed as having a primary end-point event by week 24 after transplantation (122 of 325 patients [37.5%] vs. 103 of 170 [60.6%], P<0.001). The frequency and severity of adverse events were similar in the two groups overall. Vomiting was reported in 18.5% of the patients who received letermovir and in 13.5% of those who received placebo; edema in 14.5% and 9.4%, respectively; and atrial fibrillation or flutter in 4.6% and 1.0%, respectively. The rates of myelotoxic and nephrotoxic events were similar in the letermovir group and the placebo group. All-cause mortality at week 48 after transplantation was 20.9% among letermovir recipients and 25.5% among placebo recipients.

CONCLUSIONS

Letermovir prophylaxis resulted in a significantly lower risk of clinically significant CMV infection than placebo. Adverse events with letermovir were mainly of low grade. (Funded by Merck; ClinicalTrials.gov number, NCT02137772 ; EudraCT number, 2013-003831-31 .).

Identification of distinct subgroups of EBV-positive post-transplant diffuse large B-cell lymphoma

Post-transplantation lymphoproliferative disorder is an aggressive complication of transplantation, most frequently of diffuse large B-cell lymphoma morphology and associated with Epstein-Barr virus (EBV) infection/reactivation. In this study the microenvironment of EBV⁺ (n=23) and EBV^- (n=9) post-transplant non-germinal center B-cell diffuse large B-cell lymphoma was characterized. Of EBV⁺ cases somatic hypermutation analysis, gene expression profiling, and extensive phenotyping were performed. Our results demonstrated variable cytotoxic T-cell infiltration and significantly increased CD163⁺ M2 macrophage infiltration in EBV⁺ compared with EBV^- post-transplant diffuse large B-cell lymphoma. On the basis of IgM staining and hypermutation analysis, two EBV⁺ post-transplant diffuse large B-cell lymphoma subgroups were identified: IgM⁺ tumors lacking somatic hypermutations and IgM^- tumors harboring somatic hypermutations. IgM^- tumors arose late following transplantation (median interval: 16 months), mainly in kidney recipients. IgM⁺ tumors on the other hand arose early (median interval: 3 months, P-value=0.0032), almost exclusively following stem cell transplantation and were associated with worse outcome (median survival 1 month for IgM⁺ versus 41 months for IgM^- tumors, log-rank/Wilcoxon P-value 0.07/0.04). Notably, IgM⁺ tumors were characterized by plasma cell features (monotypic kappa/lambda expression, high MUM1 expression, and partial CD138 expression) and a high proliferation index. Consistent with the plasma cell phenotype, unfolded protein response signaling was upregulated. In contrast, IgM^- EBV⁺ post-transplant diffuse large B-cell lymphoma did not express kappa, lambda, IgD, or CD138 and expressed limited MUM1. In these tumors T-cell signaling was enhanced associated with increased T-cell infiltration compared with IgM⁺ cases. Overall, our results allow further molecular classification of EBV⁺ post-transplant diffuse large B-cell lymphoma and provide a rationale for the use of subtype-specific-targeted therapies (eg, bortezomib in IgM⁺ tumors). Our findings also provide a biological basis for the clinical differences between post-transplant lymphoproliferative disorder following solid organ and stem cell transplantation, which are regarded as different disorders.

Gastrointestinal Infections

Gastrointestinal infections in the immunocompromised host are caused by the common bacterial, viral, fungal, and parasitic agents that also cause infections in the immunocompetent host. Of special consideration is that immunocompromised patients may be at increased risk for infection or disease severity and by pathogens not seen in the competent host. This chapter reviews the various agents, risk factors, and diagnostic approaches to detect gastrointestinal infections in this patient population.

Genotyping of Nocardia farcinica with multilocus sequence typing

Nocardia are aerobic Gram-positive saprophytes that are widely distributed in nature, but some species cause nocardiosis, especially opportunistic infections that affect immunocompromised patients mostly. In this study, we developed a multilocus sequence typing (MLST) scheme using seven housekeeping genes (gyrB, hsp65, secA1, rpoB, rpoA, recA, and trpB) for genotyping the most common clinical species, Nocardia farcinica (37 clinical isolates from the patients with nocardiosis and seven from animals in China and 15 reference strains). The results showed that using these loci could perform accurate identification among different species, and high discriminative power within the N. farcinica species. Of the 59 N. farcinica isolates, 44 sequence types have been identified; 32 STs covering 46 isolates could be assigned to six clonal complexes that encompassed most of the collected strains. The results showed that these strains displayed a sufficiently informative population structure using this method. Our study also provided a suitable approach for epidemiological studies of N. farcinica. A large clonal complex comprising 16 strains was identified, and was notable for its wide distribution and host adaptation. This complex should be monitored closely and merits further study.

Aspergillus and aspergilloses in wild and domestic animals: a global health concern with parallels to human disease

The importance of aspergillosis in humans and various animal species has increased over the last decades. Aspergillus species are found worldwide in humans and in almost all domestic animals and birds as well as in many wild species, causing a wide range of diseases from localized infections to fatal disseminated diseases, as well as allergic responses to inhaled conidia. Some prevalent forms of animal aspergillosis are invasive fatal infections in sea fan corals, stonebrood mummification in honey bees, pulmonary and air sac infection in birds, mycotic abortion and mammary gland infections in cattle, guttural pouch mycoses in horses, sinonasal infections in dogs and cats, and invasive pulmonary and cerebral infections in marine mammals and nonhuman primates. This article represents a comprehensive overview of the most common infections reported by Aspergillus species and the corresponding diseases in various types of animals.

Triple opportunistic pulmonary cavitary disease after cord blood transplantation

Opportunistic infectious diseases in patients are variable and depend on the host as well as the type of immunosuppression. Cord blood transplant recipients appear to be particularly vulnerable to infectious complications. Sequential or concurrent opportunistic infectious diseases can be particularly difficult to manage and have increased mortality. We present a young patient, status post cord blood transplantation for acute myelogenous leukemia, who developed a large pulmonary mass-like infection with Aspergillus, cytomegalovirus, and Mycobacterium avium complex. Radiological, surgical, and pathological features are described.

Prevention of infection in cancer patients

Patients with cancer vary regarding the nature and level of immunocompromise. Both the underlying malignancy and therapy can influence risk of infectious complications. Therefore, decisions about antimicrobial prophylaxis must be guided by a number of factors: (1) the risk of infection; (2) the potential severity of infection and the likelihood of response to therapy; and (3) the safety and efficacy of antimicrobial prophylaxis. The potential for selection for antibiotic-resistant pathogens should also inform decisions about prophylaxis. When assessing clinical trial data on antimicrobial prophylaxis, two major criteria should be considered: the quality of studies supporting prophylaxis (randomized, blinded studies are optimal) and the expected benefit of prophylaxis, measured in terms of prevention of morbidity and potentially mortality. This chapter reviews the epidemiology and clinical trial data on prophylaxis against the major bacterial, viral, and fungal diseases in patients with cancer. Gaps in knowledge and alternative approaches, such as the use of newer diagnostics, are discussed.

Diagnostic utility of human cytomegalovirus-specific T-cell response monitoring in predicting viremia in pediatric allogeneic stem-cell transplant patients

BACKGROUND

Several studies proved that virus-specific T-cells play a pivotal role in controlling cytomegalovirus (CMV) infection in adult allogeneic hematopoietic stem-cell transplant (HSCT) patients. Fewer data are available in pediatric HSCT settings, when immature and inexperienced immune system may affect antiviral immune reconstitution.

METHODS

We analyzed prospectively the CMV-specific T-cell reconstitution in a cohort of 31 pediatric allogeneic HSCT recipients at 30, 60, 90, 120, 180, and 360 days after HSCT.

RESULTS

Depending on donor-recipient CMV serostatus, we observed distinct patterns and kinetics of CMV-specific T-cell immune reconstitution: during the early time-points, patients displayed a severe reduction in CMV-specific T-cell recovery in both CMV seropositive donor (D+) group and CMV seronegative donor (D-) on CMV seropositive recipients (R+). From day 90 onward, statistical significant differences in the profile of T-cell immune reconstitution emerged between D+ and D-. The pattern of immune reconstitution was characterized by heterogeneous kinetics and efficiencies: we report cases of: (1) spontaneous antiviral T-cell recovery with no previous viremia, (2) immune T-cell recovery anticipated by CMV viremia, and (3) no T-cell immune reconstitution despite previous viremia episodes.

CONCLUSIONS

Given the heterogeneous scenarios of antiviral T-cell immune recovery in pediatric allogeneic HSCT, we conclude that the evaluation of the antiviral immune reconstitution is a promising and appealing system for identifying patients at higher risk of CMV infection. The use of interferon-γ ELISPOT test is a valid tool for immunological monitoring and predicting CMV viremia in pediatric HSCT.

The occurrence and prevention of foodborne disease in vulnerable people

In developed countries, such as the United Kingdom and the United States, between 15% and 20% of the population show greater susceptibility than the general population to foodborne disease. This proportion includes people with primary immunodeficiency, patients treated with radiation or with immunosuppressive drugs for cancer and diseases of the immune system, those with acquired immune-deficiency syndrome and diabetics, people suffering from liver or kidney disease or with excessive iron in the blood, pregnant women, infants, and the elderly. Malnutrition and use of antacids, particularly proton-pump inhibitors, also increase susceptibility. We review the occurrence of infection by foodborne pathogens in these groups of people and measures to prevent infection. The nature and use of low microbial diets to reduce the risk of foodborne disease in immunocompromised patients are very variable. Diets for vulnerable people in care should exclude higher-risk foods, and vulnerable people in the community should receive clear advice about food safety, in particular avoidance of higher-risk foods and substitution of safer, nutritious foods.

Past, present, and future prospects for inducing donor-specific transplantation tolerance for composite tissue allotransplantation

Composite tissue allotransplantation (CTA) is among the most immunologically complex and newest transplant fields. Although the field has made considerable advances, there are still concerns that these procedures are performed to enhance quality-of-life issues and are not lifesaving procedures that restore physiologic function. Two challenges limit the widespread application of CTA; the first is chronic rejection, the most prevailing cause of organ allograft failure after transplantation; the second barrier is the numerous health complications associated with lifelong immunosuppressive therapy. Several tolerance-inducing strategies, including costimulatory blockade, T-cell depletion, mixed chimerism, and gene targeting of transplanted organs, have the potential to induce lifelong tolerance to organ allografts without chronic immunosuppression. Effective clinical tolerance protocols that improve CTA acceptance and offer an alternative to the requirement for chronic immunosuppressive therapy could be a major advance in the field. Tolerance would allow allotransplantation to provide a currently unmet need for reconstruction of large tissue defects. This article reviews the history of CTA, current challenges and complications, and offers future directions for CTA research in strategies to induce tolerance.

Impaired pulmonary immunity post-bone marrow transplant

Infectious complications are a serious cause of morbidity and mortality following hematopoietic stem cell transplantation (HSCT), and the lung is a particular target organ post-transplant. Our laboratory has used a murine bone marrow transplant model to study alterations in immunity that occur as a result of transplantation. Our studies focus on immune responses that occur following immune cell reconstitution in the absence of immunosuppressive drug therapy or graft-versus-host disease. We have found that impaired clearance of both bacterial and viral pulmonary infections is related to specific alterations in immune cell function and cytokine production. Our data offer insight into mechanisms that contribute to opportunistic infections in HSCT recipients.

Pulmonary aspergillosis: clinical presentation, diagnostic tests, management and complications

PURPOSE OF REVIEW

When functioning properly, the immune system recognizes inhaled fungi and controls their growth, while avoiding injurious inflammation and allergy. 'Aspergillosis' represents a spectrum of clinical diseases resulting from impaired or excessive immune responses. Invasive aspergillosis is principally disease of severely immunocompromised patients, whereas allergic forms of aspergillosis result from an excessive inflammatory response to hyphae colonizing the sinopulmonary tract. We will review insights gained in host defense against Aspergillus species and the immunopathogenesis of Aspergillus-related diseases as well as important advances made in fungal diagnostics and antifungal therapy.

RECENT FINDINGS

Important advances have been made in diagnosis of invasive aspergillosis and in antifungal agents. Voriconazole was superior to amphotericin B deoxycholate as primary therapy for invasive aspergillosis. There is significant interest in combination antifungal therapy for invasive aspergillosis. Fungal genomics offers a powerful opportunity to gain knowledge about fungal virulence factors that can be targets for drug development. In addition, new insights have been gained regarding host defense against Aspergillus species that may be exploited therapeutically.

SUMMARY

We have gained substantial knowledge regarding how the immune system recognizes inhaled fungi and calibrates the inflammatory response. There has also been substantial progress in tools to diagnose aspergillosis and in antifungal therapeutics. Future progress will likely involve the development of more refined diagnostic tools, new classes of antifungal agents, and greater knowledge of pathogen and host factors that predispose to aspergillosis.

Incidence and clinical predictors of primary opportunistic deep cutaneous mycoses in solid organ transplant recipients: a multicenter cohort study

BACKGROUND

Primary opportunistic deep cutaneous fungal infections may cause significant morbidity and mortality in solid organ transplant recipients (OTR), but no data exist about their incidence, timing, and clinical predictors in a long-term follow-up.

PATIENTS AND METHODS

A series of 3293 consecutive OTR including 1991 kidney, 929 heart, and 373 liver transplant recipients were enrolled. Patients were regularly followed up since time at transplantation (mean 5.5 yr +/-5.9 SD) and primary opportunistic fungal infections registered. Persons-year at risk (PYs), incidence rates (IR), incidence rate ratios (IRR), and 95% confidence intervals were computed.

RESULTS

Twenty-two cases of deep cutaneous mycoses were detected, (IR 1.2 cases per 1000 PYs) after a mean follow-up time since transplantation of 2.5 yr +/- 2.0 SD (median 1.8 yr). Six patients had subsequent systemic involvement and three patients died of systemic dissemination. A higher risk for mycoses was observed in the first two yr after transplantation, (IRR 35.9, p < 0.0001), in renal transplant recipients (IRR 5.1 p = 0.030), and in patients transplanted after the age of 50 (IRR 11.5 p = 0.020).

CONCLUSIONS

Primary deep cutaneous opportunistic mycoses in OTR occur mainly in the first two yr after transplantation, in renal transplant recipients, and in older patients.

Valganciclovir as pre-emptive therapy for cytomegalovirus infection post-allogenic stem cell transplantation: implications for the emergence of drug-resistant cytomegalovirus

OBJECTIVES

Valganciclovir is a well established drug for the management of cytomegalovirus (CMV) infection in haematopoietic stem cell transplantation (HSCT). Data concerning its safety regarding the development of drug resistance are required. The aim of the present study was to retrospectively investigate CMV drug resistance in a group of HSCT patients experiencing relapses of CMV infection after a first-line pre-emptive antiviral therapy.

METHODS

Thirteen adult HSCT patients out of 26 with asymptomatic CMV infection, experiencing relapsing infections 45-155 days after either intravenous (iv) ganciclovir (2 patients) or valganciclovir (11 patients), were studied. Genotypic assays for mutations in the viral phosphotransferase (UL97) and DNA-polymerase (UL54) genes were directly applied on patient specimens. Baseline CMV sequences were compared with those at the time of relapses to identify drug-resistant strains.

RESULTS

UL97 mutations A594V and M460V known to confer drug resistance developed in one relapsing patient who received iv ganciclovir as first-line therapy, corresponding to a rate of 7.7% of relapses due to drug-resistant strains and an overall 3.8% rate of infections due to CMV drug-resistant strains. UL54 drug resistance mutations were absent. No evidence of drug resistance was found in patients on valganciclovir either as first-line therapy or as treatment for relapses.

CONCLUSIONS

The safety profile of valganciclovir as anti-CMV pre-emptive therapy was confirmed, as well as that monitoring CMV drug resistance with genotypic tests on sequential isolates over the time-course of therapy offers guidance to tailor antiviral treatment in a clinically relevant time frame.

Tacrolimus monotherapy in liver transplantation: one-year results of a prospective, randomized, double-blind, placebo-controlled study

BACKGROUND

Minimal immunosuppression (IS) is desirable in organ transplantation to reduce side effects and to promote the process of tolerance induction.

MATERIAL AND METHODS

Between February 2000 and September 2004, 156 adults (>15 years old) receiving a primary liver graft were enrolled in a prospective, randomized, double-blind, placebo-controlled, investigator-driven single-center study comparing tacrolimus (TAC)-placebo (PL) and TAC-low-dose, short-term (64 days) steroid (ST) IS. There were no exclusion criteria at moment of randomization. All patients had a 12-month follow-up (range, 12-84).

RESULTS

Three- and 12-month patient survival rates were 93.6% and 87.2% in the TAC-PL group and 98.7% and 94.7% in TAC-ST group (P = 0.096 and P = 0.093, respectively). Three- and 12-month graft survival rates were 92.3% and 85.9% versus 97.4% and 92.3% (P = 0.14 and 0.13, respectively). By 3 and 12 months, rejection treatment had been given in 20.5% (16 pts) and 23% (18 pts) of TAC-PL patients and in 12.7% (10 pts) and 20.5% (16 pts) of TAC-ST patients (P = 0.20 and 0.54). Corticosteroid-resistant rejection (CRR) at 3 and 12 months was recorded in 12.8% (10 pts) of TAC-PL patients and 3.8% (3 pts) of TAC-ST patients (P = 0.04). When considering the 145 patients transplanted without artificial organ support (n = 145), CRR at 3 and 12 months was recorded in 8.8% (6/68 pts) of TAC-PL patients and in 3.9% (3/77 pts) of TAC-ST patients (P = 0.22). Vanishing bile duct syndrome was diagnosed in 1 (1.2%) TAC-PL patient and 4 (5.1%) TAC-ST patients (P = 0.17). By 1 year, 78.2% (61/78) of TAC-PL patients and 82% (64/78) of TAC-ST patients were on TAC monotherapy (P = 0.54). When considering 67 TAC-PL and 74 TAC-ST survivors, rates of monotherapy were 91% (61 pts) and 86.5% (64 pts) (P = 0.39). At 1 year, 62.5% (42 pts) of TAC-PL survivors and 64.9% (48 pts) of TAC-ST survivors were on low-dosage (<6 ng/mL) TAC monotherapy (P 0.79).

CONCLUSION

TAC monotherapy can be achieved safely without compromising graft nor patient survival in a primary, even unselected, adult liver transplant population. The higher incidence of early CRR in the TAC-PL group related to the significantly higher number of patients transplanted while being on artificial organ support. In such condition, this monodrug immunosuppressive strategy needs to be adapted. TAC monotherapy strategy should lay the basis for further large scale minimization studies in liver transplantation.

Nonhuman primate infections after organ transplantation

Nonhuman primates, primarily rhesus macaques (Macaca mulatta), cynomolgus macaques (Macaca fascicularis), and baboons (Papio spp.), have been used extensively in research models of solid organ transplantation, mainly because the nonhuman primate (NHP) immune system closely resembles that of the human. Nonhuman primates are also frequently the model of choice for preclinical testing of new immunosuppressive strategies. But the management of post-transplant nonhuman primates is complex, because it often involves multiple immunosuppressive agents, many of which are new and have unknown effects. Additionally, the resulting immunosuppression carries a risk of infectious complications, which are challenging to diagnose. Last, because of the natural tendency of animals to hide signs of weakness, infectious complications may not be obvious until the animal becomes severely ill. For these reasons the diagnosis of infectious complications is difficult among post-transplant NHPs. Because most nonhuman primate studies in organ transplantation are quite small, there are only a few published reports concerning infections after transplantation in nonhuman primates. Based on our survey of these reports, the incidence of infection in NHP transplant models is 14%. The majority of reports suggest that many of these infections are due to reactivation of viruses endemic to the primate species, such as cytomegalovirus (CMV), polyomavirus, and Epstein-Barr virus (EBV)-related infections. In this review, we address the epidemiology, pathogenesis, role of prophylaxis, clinical presentation, and treatment of infectious complications after solid organ transplantation in nonhuman primates.

Rotavirus enteritis in solid organ transplant recipients: an underestimated problem?

BACKGROUND

Diarrhea in solid organ transplantation can be a complication with a high morbidity and mortality. Rotavirus (RV) infection normally occurs in children up to 3 years of age and often presents with severe diarrhea; however, it can also affect adults. We investigated the prevalence and outcome of RV infections in both adult and pediatric patients after solid organ transplantation.

PATIENTS AND METHODS

Retrospective analysis of RV-related enteritis in solid organ transplant recipients with a minimum of a 1-year follow-up from a single center between 2000 and 2004.

RESULTS

Within our cohort of 1303 solid organ transplants, RV infection was observed in 19 patients (1.5%); 14 of these were liver recipients. Infection was most prevalent among pediatric liver recipients, with 52% (11/21) of the children affected. Five adults acquired the infection during their initial hospitalization. Two adult patients had to be readmitted following late-onset RV infection. In all cases, infection was self-limiting, but led to prolonged hospitalization because of significant loss of fluids and electrolytes.

CONCLUSIONS

RV enteritis is a common infection in pediatric solid organ recipients but may also affect adult patients.

Early and late onset Clostridium difficile-associated colitis following liver transplantation

Clostridium difficile colitis (CDC) remains a serious and common complication after liver transplantation (LT). Four hundred and sixty-seven consecutive LTs in 402 individuals were performed between 1998 and 2001 at our center. Standard immunosuppression consisted of tacrolimus, mycophenolate, and steroids. CD toxins A and B were detected by using a rapid immunoassay or enzyme immunoassay. CDC was diagnosed in 32 patients (5-1999 days post-LT), with 93.8% (30/32) of patients developing CDC during the first year post-LT; three individuals had CDC more than 3 years post-LT, one of which also had early CDC. All patients presented with abdominal pain and watery diarrhea. Patients who developed CDC within 1-year post-LT were significantly more likely to have a hemorrhagic, biliary, or infectious complication. Patients who developed CDC within 28 days post-LT had a significantly higher model end-stage liver disease score. Treatment consisted of fluid and electrolyte replacement and metronidazole and no patients developed toxic megacolon, required colonic resection, or died from CDC. CDC represents a potentially severe complication following LT. Most cases occur early post-LT. Development of a hemorrhagic, biliary, or infectious complication is associated with the development of CDC.

Sarcoidal granulomatous tenosynovitis of the hands occurring in an organ transplant patient

Six years after kidney-pancreas transplant, a 47-year-old white man developed multiple subcutaneous and tenosynovial nodules of hands and wrists, limiting mobility. Biopsy of multiple nodules showed fibrosing, sarcoidal granulomas, some of which contained pigmented material. Microbiology, immunohistochemistry, scanning electron microscopy with backscattered electron imaging and energy dispersive X-ray analysis and polymerase chain reaction assays failed to show any infectious agents or foreign material. There was no historical, clinical or laboratory evidence of systemic sarcoidosis. It is not known whether the donor had sarcoidosis. Despite empiric antimycobacterial therapy and ongoing immunosuppressive therapy (corticosteroids, mycophenolate, cyclosporine), the man has progressively developed more nodules, limiting hand function. Sarcoidosis occurring in non-donor tissue post-transplantation is an exceedingly rare complication of transplantation. We discuss this case and review the literature on sarcoidal tenosynovitis and sarcoidosis occurring post-transplantation.

Infectious complications after kidney transplantation: a single-center experience

Infectious complications after renal transplantation are associated with significant morbidity and mortality. The prevalence of infections in transplant recipients varies from country to country. This study sought to assess the overall incidence of post-transplant infectious complications at our research center in Iran, compared with other centers in the world. Between 2002 and 2004, 179 renal transplantations were performed in our center. Of these, 142 were studied and followed for 1 year. Immunosuppressive regimens were cyclosporine, mycophenolate mofetil, and prednisolone. The overall incidence of infections was 54.2%. The most common sites of infections were the urinary tract (41.5%) and the respiratory tract (6.3%). The most frequent causes of infections were Klebsiella (24%) and cytomegalovirus (CMV) (17.6%). Wound infection occurred in 4.9% of the patients. Three (2.1%) patients developed hepatitis C and 2 (1.4%) had mycobacterial infections. There was no case of Pneumocystis pneumonia. Overall mortality was 7.7%. Infection-related mortality was 3.5%. In conclusion, this study identifies infections as the cause of morbidity and mortality in the post-transplant period. There was a low incidence of tuberculosis (<2% yearly) and a high incidence of CMV disease in our recipients.

Polyomavirus nephropathy in native kidneys and renal allografts: an update on an escalating threat

Polyomavirus nephropathy, also termed BK-virus nephropathy (BKN) after the main causative agent, the polyoma-BK-virus strain, is a significant complication after kidney transplantation. BKN is the most common viral infection that affects renal allografts with a prevalence of 1-9% on average 8-13 months post surgery. It can also occur sporadically in native kidneys. Viral nephropathy is caused by the (re)activation of latent BK viruses that enter into a replicative cycle under sustained and intensive immunosuppression. Pure productive kidney infections with JC- and SV-40 polyomaviruses are exceptionally rare. BKN is morphologically defined by the presence of intranuclear viral inclusion bodies in epithelial cells and tubular injury, which is the morphological correlate for renal dysfunction. Renal disease can progress through different histologic stages (from early BKN stage A to late fibrotic stage C) that carry prognostic significance; disease stages B and C often result in chronic kidney (allograft) dysfunction and end-stage renal disease. The clinical goal is to diagnose viral nephropathy in disease stage A and to limit chronic renal injury. Strategies to recognize, classify, and manage BKN are critically discussed including ancillary techniques for risk assessment and patient monitoring: (i) urine cytology and the search for so-called 'decoy cells'; (ii) PCR analyses for viral load measurements in the plasma and urine; and (iii) negative staining urine electron microscopy to identify viral particles.

[Intensive care treatment following transplant surgery]

Transplant-related intensive care treatment after transplantation of visceral organs, in Germany traditionally headed by transplant surgeons, is an integral part of postoperative therapy after liver, pancreas, intestinal, and combined organ transplantation, i.e. pancreas-kidney, liver-kidney, and multivisceral transplantation. Apart from adjustment and monitoring of immunosuppressive therapy, as well as common intensive care issues such as cardiopulmonary disease and complications, the avoidance, early detection, and rigorous treatment of transplant-related problems are the focus of surgical intensive care treatment of transplant patients. In the following article, its role after visceral organ transplantation is described regarding the most frequent transplant-related complications such as technical failure, various kinds of infection, and graft failure with different etiologies.

Polymorphisms at exon 4 of p53 and the susceptibility to herpesvirus types 6 and 1 infection in renal transplant recipients

In order to replicate their own genome in the host nucleus, herpesviruses have to overcome the barrier presented by p53 gene. Variants of codon 72 and codon 47 of exon four decrease the ability of p53 to induce apoptosis. In order to investigate the influence of this germline inheritance on the susceptibility to herpesvirus type 6 (HHV6) and 1 (HHV1) infection, we examined 78 renal transplant recipients and 151 controls. HHV6 infection was more frequent among the renal transplant patients (35.89%) than in the control population (11.25%) (P < 0.001). HHV1 infection rate was similar in renal transplant patients (7.28%) and controls (2.56%). HHV6-positive cases were more frequent among patients with codon 72 of p53 variants (60.71%) than among wild-type p53 patients (28.20%) (P = 0.001) despite the higher frequency of codon 72 of p53 wild-type variant in renal transplant patients compared with controls (64.1% vs. 36.4%; P < 0.001). The presence of a codon 72 of p53 germline variant genotype increased the risk for HHV6 infection more than five times (OR = 5.479; 95% CI = 1.992-15.069). Our data suggest that codon 72 of p53 polymorphism genotyping may be useful to screen for patients at higher risk for post-transplant infections hence identifying individuals that could benefit from preventive treatment.

Infectious complications following 72 consecutive enteric-drained pancreas transplants

New immunosuppressive protocols and advanced surgical technique resulted in an improved outcome of pancreatic transplantation (PTx) with infection remaining the most common complication. Seventy-two enteric-drained whole PTxs performed at the Innsbruck University Hospital between September 2002 and October 2004 were retrospectively analyzed. Prophylactic immunosuppression consisted of either the standard protocol consisting of single bolus antithymocyteglobulin (ATG) (Thymoglobulin, Sangstat or ATG Fresenius) induction (9 mg/kg), tacrolimus (TAC), mycophenylate mofetil (MMF) and steroids (38 patients) or a 4-day course of ATG (4 mg/kg) tacrolimus and steroids with MMF (n = 19), or Sirolimus (n = 15). Perioperative antimicrobial prophylaxis consisted of Piperacillin/Tazobactam (4.5 g q 8 h) in combination with ciprofloxacin (200 mg q 12 h) and fluconazole (400 mg daily). Ganciclovir was used for cytomegalovirus (CMV) prophylaxis if donor was positive and recipient-negative. Patient, pancreas, and kidney graft survival at 1 year were 97.2%, 88.8%, and 93%, respectively, with no difference between the groups. All retransplants (n = 8) and single transplants (n = 8) as well as all type II diabetics and nine of 11 patients older 55 years received standard immunosuppression (IS). The rejection rate was 14% and infection rate 46% with no difference in terms of incidence or type according to the three groups. Severe infectious complications included intra-abdominal infection (n = 12), wound infection (n = 7), sepsis (n = 13), respiratory tract infection (n = 4), urinary tract infection (n = 12), herpes simplex/human herpes virus 6 infection (n = 5), CMV infection/disease (n = 7), post-transplant lymphoproliferative disorder (PTLD, n = 3), invasive filamentous fungal infection (n = 4), Clostridial/Rotavirus colitis (n = 1), and endocarditis (n = 1). All four patients in this series died of infectious complications (invasive aspergillosis n = 2) (one with Candida glabrata superinfection), invasive zygomycosis (n = 1), PTLD (n = 1). Five grafts were lost (vascular thrombosis n = 3, pancreatitis n = 1, noncompliance n = 1). Infection represented the most frequent complication in this series and all four deaths were of infectious origin. Better prophylaxis and management of infections now should be the primary target to be addressed in the field of pancreas transplantation.