Invasive aspergillosis in liver transplant recipients: association with candidemia and consumption coagulopathy and failure of prophylaxis with low-dose amphotericin B

Antifungal prophylaxis in liver transplantation: a systematic review and network meta-analysis

Invasive fungal infections (IFIs) cause significant morbidity and mortality in liver transplant recipients, but the need and best agent for prophylaxis is uncertain. A comprehensive literature search was performed to identify randomized controlled trials comparing regimens for antifungal prophylaxis in liver transplant recipients. Direct comparisons were made between treatments using random-effects meta-analysis and a Bayesian network meta-analysis was performed for the primary end point of proven IFI. Fourteen studies met inclusion criteria, reporting comparisons of fluconazole, liposomal amphotericin B (L-AmB), itraconazole, micafungin and placebo. Overall, antifungal prophylaxis reduced the rate of proven IFI (odds ratio [OR] 0.37, confidence interval [CI] 0.19-0.72, p = 0.003), suspected or proven IFI (OR 0.40, CI 0.25-0.66, p = 0.0003) and mortality due to IFI (OR 0.32, CI 0.10-0.83, p = 0.02) when compared to placebo. All-cause mortality was not significantly affected. There was no difference in risk of adverse events requiring cessation of prophylaxis (OR 1.11, 95% CI 0.48-2.55, p = 0.81). In the network meta-analysis an equivalent reduction in the rate of IFI was seen with fluconazole (OR 0.21, CI 0.06-0.57) and L-AmB (OR 0.21, CI 0.05-0.71) compared with placebo. Routine prophylaxis with fluconazole or L-AmB reduces the incidence of IFI following liver transplantation, and the available evidence suggests that the two are equivalent in efficacy.

Antifungal prophylaxis in liver transplant recipients

Although the overall incidence of fungal infections in liver transplant recipients has declined, these infections still contribute significantly to the morbidity and mortality of patients with risk factors for infection. Although antifungal prophylaxis has been widely studied and practiced, no consensus exists on which patients should receive prophylaxis, with which agent, and for what duration. Numerous studies have attempted to ascertain independent risk factors for invasive fungal infections in liver transplant patients, and these data, in addition to clinical trials, identify several patient groups at exceedingly high risk of fungal infection. These include retransplant patients, patients with renal failure requiring hemodialysis or renal replacement therapy, and those requiring reoperations after transplant. Because the majority of infections occur in the first month after transplantation, prophylaxis should be continued for 4-6 weeks. However, local epidemiology and research should guide decisions regarding choice of agent as well as overall development of interinstitutional guidelines, because the incidence and spectrum of infection may differ dramatically among institutions. Liver Transpl 15:842-858, 2009. (c) 2009 AASLD.

A risk profile for invasive aspergillosis in liver transplant recipients

BACKGROUND

Given the high incidence (1.5%-10%) of invasive aspergillosis (IA) after liver transplantation and the associated mortality, prophylaxis according to the patients' circumstances is a reasonable approach. The purpose of this investigation was to determine the effect and significance of risk factors for IA in a specialized transplantation center.

METHODS

We collected data from patients who underwent liver transplantation at the Transplantation Center of the University Hospital Heidelberg (Germany) between December 2001 and December 2004 in a specifically designed database for retrospective analysis. Invasive aspergillosis was defined according to the European Organization for Research and Treatment of Cancer classifications. Univariate analysis and logistic regression were performed to assess the influence of each assumed risk factor.

RESULTS

A total of 195 liver transplantations were performed in 170 patients, with two patients (1.2%) developing a proven IA, seven (4.1%) developing a probable IA, and five developing a possible IA (2.9%). All patients received oral itraconazole prophylaxis. Of these 14 patients with proven, probable or possible IA, 13 died within 4 weeks after the initial diagnosis; this represents 33.3% of all patients with a fatal outcome. Univariate significant factors were retransplantation (p = 0.004), cytomegalovirus (CMV) infection (p = 0.024), dialysis (p < 0.001), renal insufficiency (p = 0.05), thrombocytopenia (p = 0.001), and leukocytopenia (p = 0.002). Multivariate analysis showed an independent influence of CMV infection (OR 6.032, 95% CI 1.446-25.163) and dialysis (OR 14.985, 95%CI 2.936-76.486).

CONCLUSION

The rate of IA found in this investigation is within the range reported in published studies. Based on our data, extended antifungal prophylaxis should be given to liver transplant patients with specific risk factors, such as renal insufficiency, requirement for dialysis, CMV infection, or thrombocytopenia. Additional focus should be on the prevention of CMV infections.

Infecciones en los pacientes trasplantados de hígado

Infection is the main cause of morbidity and mortality in liver transplant patients. Infections appear in three different periods following transplantation and are related to surgical factors, the degree of immunosuppression, environmental exposure and the type of prophylaxis used. Bacterial infections occur in the first two months after transplantation as bacteremia, surgical wound and intra-abdominal infection, or pneumonia. Tuberculosis in the liver transplant recipient is more aggressive than in immunocompetent persons. Viruses produce direct infection in these patients; moreover, some viruses (e.g., cytomegalovirus and human herpes virus 6) are immunomodulators and can facilitate other infections and graft rejection. Polymerase chain reaction and antigenemia techniques have made possible prompt diagnosis of cytomegalovirus infection and the implementation of prophylactic strategies. Fungal infections still have a high associated mortality rate, despite new diagnostic techniques and new antifungal drugs.

Invasive Pilzinfektionen bei Patienten nach Lebertransplantation. Invasive fungal infections in patients after liver transplantation

Advances in surgical technique, immunosuppression, and medical management have greatly improved clinical results after liver transplantation (LTx). Fungal infections in LTx-patients still represent serious complications and are associated with a significant decrease in survival. The majority of fungal infections in LTx-patients are caused by Candida species, which is explained by the major abdominal surgery. Aspergillus infections are second common, whereas other fungal infections such as pneumocystosis, cryptococcosis, or zygomycosis represent rare events. The high mortality of invasive fungal infections in LTx-recipients is explained by the severity of the underlying medical condition and by difficulties in diagnosis and medical therapy. Currently available diagnostic tests do not allow a timely and reliable diagnosis of invasive fungal infections in LTx-patients. Amphotericin B has been the standard treatment for invasive candidiasis and aspergillosis for many years but the high frequency of side effects limits its application. Fluconazole is widely used due to better tolerability and fewer drug interactions. Disadvantages are the lack of activity against Aspergillus species and the selection of resistant Candida strains. Progress is to be expected from new antimycotic agents belonging to azoles (voriconazole) and echinocandins (caspofungin) as these are less toxic and have a broad range of antimycotic activity. Analysis of prognostic factors allows identifying LTx-patients at high risk for invasive fungal infection. Antimycotic prophylaxis or pre-emptive therapy may improve clinical outcome in this patient subgroup.

Prise en charge diagnostique et thérapeutique des infections à Aspergillus sp. chez le patient immunodéprimé. Recommandations du CHRU de Lille — version 4 — novembre 2004

Invasive aspergillosis is a severe complication in immunocompromised patients. The arrival of new antifungal agents motivated the redaction of guidelines, regularly updated, by a Lille University hospital multidisciplinary task force. These guidelines assess diagnostic and therapeutic issues. The main recommended diagnosis tool is the chest CT scan, ordered at the smallest suspicion and, also, measure of the blood and broncho alveolar lavage fluid galactomannan. Treatment guidelines assess prophylaxis, empirical and documented therapy. Primary prophylaxis is warranted in only two cases, pulmonary graft or stem cell transplant in patients with chronic GVH and receiving corticosteroids. Empirical therapy should use one of the available amphotericin B formulations, chosen according to the patient history. Caspofungin is another choice. Documented therapy, depending on presentation, can be a single drug or a combination. First line therapy for single drug is i.v. voriconazole. Lipid formulations of amphotericin B are another choice. A combination therapy can be used as a first line treatment, for multiple lesions, or as salvage therapy. It must include caspofungin, associated with liposomal amphotericin B or voriconazole. A tight cooperation with thoracic surgeons is recommended.

Antifungal Prophylaxis in Solid-Organ Transplant Recipients: Considerations for Clinical Trial Design

BACKGROUND

There are several key issues regarding clinical trial design for antifungal prophylaxis in organ transplant recipients.

METHODS

The existing and emerging data on the epidemiology and risk factors for invasive mycoses in organ transplant recipients formed the basis for discerning the subgroups that may be targeted for prophylaxis, the unique end points to be considered, and the attributes of currently available drugs that may be suitable candidates for antifungal prophylaxis.

RESULTS

Epidemiological characteristics of invasive mycoses in organ transplant recipients have evolved sufficiently to warrant thoughtful reconsideration of the subsets of patients and the fungal pathogens to be targeted for antifungal prophylactic trials in the current era. Safety and tolerability of antifungal agents and outcome stratified by severity of illness are important end points given the potential for drug interactions with immunosuppressive agents and the fact that a beneficial effect of prophylaxis on outcome has been difficult to document in organ transplant recipients.

CONCLUSIONS

Clinical trial design for antifungal prophylaxis must carefully consider the unique issues pertaining to the selection of patients most likely to benefit, as well as the tolerability and drug interactions of antifungal agents in organ transplant recipients.

Prophylaxis of invasive mycoses in solid organ transplantation

PURPOSE OF REVIEW

Solid organ transplantation is emerging as a life-saving procedure for increasing numbers of patients and invasive fungal infections are a significant cause of mortality and morbidity for patients undergoing these procedures. This paper will review the latest data pertinent to the development of effective regimens aimed at preventing invasive mycoses in the solid organ transplantation population.

RECENT FINDINGS

Risks for developing invasive fungal infections are continuing to evolve, leading to shifts in the epidemiology of invasive mycoses occurring after transplantation. For instance, risks for the development of invasive candidiasis in the immediate postoperative period following orthotopic liver transplantation have decreased dramatically while the incidence of invasive aspergillosis appears to be on the rise. New agents have recently been approved for use in the United States and may have a role in prophylactic strategies aimed at preventing these fungal infections.

SUMMARY

An understanding of these issues is crucial to the development of targeted prophylactic regimens for the successful prevention of invasive fungal infections in the solid organ transplant recipient.

Risk factors for invasive aspergillosis in liver transplant recipients

Aspergillosis is a potential, severe, and usually early complication of liver transplantation. New promising strategies, such as detecting Aspergillus antigenemia, have been used for the diagnosis of aspergillosis in immunosuppressed patients, but the impact in solid organ transplantation is not well known. A case-control study in 260 adults who underwent liver transplantation from January 1994 to June 2000 was performed. A case was defined as any liver transplant recipient with a proven or probable diagnosis of invasive aspergillosis. Controls were defined as a liver transplant recipient without aspergillosis infection with a survival longer than two months after transplantation. Clinical and analytical variables, including Aspergillus antigenemia, were compared. A special analysis was performed in patients in whom late aspergillosis developed (after day 100 posttransplantation). Among 260 patients, invasive aspergillosis developed in 15 (5.6%). Median time from transplantation to aspergillosis in 13 patients with sufficient data for analysis was 126 days (range, 22 to 1117). Seven (54%) developed the infection after day 100 posttransplantation. Thirty-eight patients were used as controls. Antigenemia was available in nine of 13 cases and in 33 of 38 controls. By multivariate analysis, retransplantation (OR, 29.9 [95% CI, 2.1 to 425.1]), dialysis requirements after transplantation (OR, 24.5 [95% CI, 1.25 to 354]), and the presence of Aspergillus antigenemia in serum at any time point after transplantation (OR, 50.0 [95% CI, 3.56 to 650]) were independently associated to aspergillosis. In the subgroup of patients that developed late aspergillosis, cytomegalovirus infection (OR, 6.7 [95% CI, 1.0 to 42.5]) was the only independent factor associated. Hepatic and renal dysfunction predispose to Aspergillus infection in liver transplant recipients. Cytomegalovirus infection and increased immunosuppression favor invasive aspergillosis during the late posttransplantation period. Aspergillus antigenemia seems to be a good predictor of invasive aspergillosis.

Epidemiology and Prevention of Invasive Aspergillosis

Aspergillus species are the most common causes of invasive mold infections in immunocompromised persons. This review examines the available information regarding the rising incidence of invasive aspergillosis in different high-risk groups, including persons with acute leukemia, hematopoietic stem cell transplant recipients, and liver and lung transplant recipients. The risk factors for infection in these groups are discussed. Because Aspergillus species are widespread in the environment, it is difficult to link specific sources and exposures to the development of human infections. However, molecular strain typing and other studies indicate that a significant number of Aspergillus infections are now being acquired outside the health care setting, either before patients are admitted to hospital, or after they have been discharged. The role of environmental control measures and antifungal drug prophylaxis in the prevention of hospital- and community-acquired aspergillosis is discussed.

Infectious complications of solid organ transplantations

The rate of infectious complications in SOT recipients has declined dramatically. As improvements in immunosuppressive therapy, surgical techniques, and diagnostics and antimicrobial treatment continue, further declines in infectious complications are expected. Refinements to preemptive therapy for high-risk patients are likely to contribute further to this decrease. Further investigation is required to define what role various infectious agents play in chronic allograft injury and rejection.

Identification of genes of Aspergillus fumigatus up-regulated during growth on endothelial cells

Aspergillus fumigatus is an important opportunistic fungal pathogen that can cause acute invasive disease in neutropenic hosts. Invasive aspergillosis is being diagnosed with increasing frequency, and morbidity and mortality remain high despite prompt antifungal therapy. Because little is known about the virulence factors used by A. fumigatus, a tissue culture model was developed to mimic the interaction of the fungus with the endothelium. Differential display was used to compare gene expression in fungal cells grown on endothelial cells with that of cells grown in the absence of endothelial cell contact, and genes that were up-regulated were selected for analysis as putatively virulence-related genes. Two of these up-regulated genes were chosen for further study and were identified as genes encoding the regulatory subunit of cyclic adenosine monophosphate (cAMP)-dependent protein kinase and a member of the ras gene family, both of which are involved in cAMP-mediated signaling in fungi. This model system provides a new approach to the identification of potentially virulence-related genes induced in A. fumigatus by the interaction with host cells.

PREEMPTIVE PROPHYLAXIS WITH A LIPID PREPARATION OF AMPHOTERICIN B FOR INVASIVE FUNGAL INFECTIONS IN LIVER TRANSPLANT RECIPIENTS REQUIRING RENAL REPLACEMENT THERAPY1

BACKGROUND

Posttransplant renal replacement therapy has been shown to be an independently significant risk factor for invasive fungal infections after liver transplantation. We assessed the efficacy of a lipid preparation of amphotericin B as prophylaxis for invasive fungal infections, directed toward liver transplant recipients requiring renal replacement therapy.

METHODS

A total of 148 patients transplanted between 1990 and 1997 received no antifungal prophylaxis. Since 1997, 38 patients underwent liver transplantation; antifungal prophylaxis with a lipid preparation of amphotericin B was used in patients requiring renal replacement therapy.

RESULTS

Fifteen percent (22 of 148) of the patients transplanted before 1997 required renal replacement therapy. In this cohort, the incidence of invasive fungal infections (36% vs. 7%, P=0.0007) and invasive aspergillosis (14% vs. 2%, P=0.02) was significantly higher in patients who required renal replacement therapy compared with those who did not. Since 1997, 29% (11 of 38) of the patients required renal replacement therapy and received antifungal prophylaxis. Invasive fungal infections occurred in 36% (8 of 22) of the patients who received no prophylaxis (patients before 1997), and 0% (0 of 11, P=0.03) in those who received antifungal prophylaxis (since 1997). Antifungal prophylaxis was independently associated with protection from fungal infection (P=0.017). No reduction in mortality with antifungal prophylaxis was documented.

CONCLUSION

Prophylaxis with a lipid preparation of amphotericin B was associated with a significant reduction in invasive fungal infections in high-risk liver transplant recipients, i.e., those requiring renal replacement therapy. However, no beneficial effect on survival could be documented.

Recent Advances in the Management of Infections in Liver Transplant Recipients

Antimicrobial-resistant bacteria (vancomycin-resistant enterococci and Staphylococcus aureus) have emerged as leading pathogens in liver transplant recipients. Liver transplant recipients have also been shown to be uniquely more susceptible to harboring extended-spectrum beta-lactamase-producing Enterobacteriaceae. The frequency of mycelial fungal infections has increased; however, effective prophylaxis and management of these infections remains suboptimal. Emerging reports have highlighted the morbidity due to novel herpesviruses in these patients. Finally, the emergence of ganciclovir resistance in cytomegalovirus has implications relevant for all solid organ transplant recipients.

The current management of infectious diseases in the liver transplant recipient

The spectrum of major infections after transplantation has undergone a striking evolution. The epidemiologic trends in infectious diseases through the last decade have been most notable for a dramatic decrease in the incidence of several opportunistic infections, largely because of advances in prophylaxis against these pathogens. Paralleling these trends has been an exponential rise in the proportion of infections caused by antimicrobial-resistant bacteria. These multiresistant organisms have now emerged as leading pathogens at many transplant centers, and their management is a daunting challenge.

Association of fungal infection and increased mortality in liver transplant recipients

BACKGROUND

Invasive fungal infection is associated with increased morbidity and mortality following orthotopic liver transplantation (OLTx). Understanding the risk factors associated with fungal infection may facilitate identification of high-risk patients and guide appropriate initiation of antifungal therapy.

OBJECTIVES

The aim of this study was to determine the incidence of fungal infections, identify the most common fungal pathogens, and determine the risk factors associated with fungal infections and mortality in OLTx recipients.

METHODS

Medical records from 96 consecutive OLTx in 90 American veterans (88 males, 2 females; mean age 48 years, range 32 to 67) performed from January 1994 to December 1997 were retrospectively reviewed for fungal infection in the first 120 days after transplantation. Infection was defined by positive cultures from either blood, urine (<105 CFU/mL), cerebrospinal or peritoneal fluid, and/or deep tissue specimens. Superficial fungal infection and asymptomatic colonization were excluded from study. All patients received cyclosporine, azathioprine, and prednisone as maintenance immunosuppressive therapy. Fungal prophylaxis consisted of oral clotrimazole (10 mg) troches, five times per day during the study period.

RESULTS

Thirty-five patients (38%) had documented infection with one or more fungal pathogens, including Candida albicans (25 of 35; 71%), C torulopsis (7 of 35; 20%), C tropicalis (2 of 35; 6%), non-C albicans (2 of 35; 6%), Aspergillus fumigatus (4 of 35; 11%), and Cryptococcus neoformans (1 of 35; 3%). The crude survival for cases with or without fungal infection was 68% and 87%, respectively (P <0.0001). The median intensive care unit stay and overall duration of hospitalization were significantly longer for patients with fungal infection (P <0.01). The mean time interval from transplantation to the development of fungal infection was 15 days (range 4 to 77) with a mean survival time from fungal infection to death of 21 days (range 3 to 64). Fungal infections occurred significantly more often in patients with renal insufficiency (serum creatinine >2.5 mg/dL), biliary/vascular complications, and retransplantation.

CONCLUSIONS

Fungal infections were associated with increased morbidity and mortality following OLTx, with Candida albicans being the most common pathogen. Treatment strategies involving antifungal prophylaxis for high-risk patients and earlier initiation of antifungal therapy in cases of presumed infection are warranted.

Prophylactic fluconazole in liver transplant recipients. A randomized, double-blind, placebo-controlled trial

BACKGROUND

Among persons who receive solid organ transplants, liver transplant recipients have the highest incidence of invasive fungal infection; however, no antifungal prophylaxis has been proven to be effective.

OBJECTIVE

To evaluate the efficacy and safety of prophylactic fluconazole in liver transplant recipients.

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

University-affiliated transplantation center.

PATIENTS

212 liver transplant recipients who received fluconazole (400 mg/d) or placebo until 10 weeks after transplantation.

MEASUREMENTS

Fungal colonization, proven superficial or invasive fungal infection, drug-related side effects, and death.

RESULTS

Fungal colonization increased in patients who received placebo (from 60% to 90%) but decreased in patients who received fluconazole (from 70% to 28%). Proven fungal infection occurred in 45 of 104 placebo recipients (43%) but in only 10 of 108 fluconazole recipients (9%) (P < 0.001). Fluconazole prevented both superficial infection (29 of 104 placebo recipients became infected [28%] compared with 4 of 108 fluconazole recipients [4%]; P < 0.001) and invasive infection (24 of 104 placebo recipients became infected [23%] compared with 6 of 108 fluconazole recipients [6%]; P < 0.001). Fluconazole prevented infection by most Candida species, except C. glabrata. However, infection and colonization by organisms intrinsically resistant to fluconazole did not seem to increase. Fluconazole was not associated with any hepatotoxicity. Patients receiving fluconazole had higher serum cyclosporine levels and more adverse neurologic events (headaches, tremors, or seizures in 13 fluconazole recipients compared with 3 placebo recipients; P = 0.01). Although the overall mortality rate was similar in both groups (12 of 108 [11%] in the fluconazole group compared with 15 of 104 [14%] in the placebo group; P > 0.2), fewer deaths related to invasive fungal infection were seen in the fluconazole group (2 of 108 patients [2%]) than in the placebo group (13 of 104 patients [13%]) (P = 0.003).

CONCLUSIONS

Prophylactic fluconazole after liver transplantation decreases fungal colonization, prevents superficial and invasive fungal infections, and has no appreciable hepatotoxicity. Although fluconazole prophylaxis is associated with fewer deaths from fungal infection, it does not improve overall survival. Patients receiving prophylactic fluconazole require close monitoring of serum cyclosporine levels to avoid neurologic toxicity.

Fungal infection and liposomal amphotericin B (AmBisome) therapy in liver transplantation: a 2 year review

We reviewed the use of liposomal amphotericin B in 30 patients receiving therapy following liver transplantation over a 2 year period. Five of these patients were treated for presumed invasive aspergillosis: four of them died despite therapy, each having combined renal and respiratory failure at the time of diagnosis of presumed aspergillosis. Post-mortem examination of three of these patients confirmed the diagnosis of aspergillosis. Twenty-five patients were treated empirically; 11 died and supportive evidence for invasive fungal infection following commencement of therapy was found in only one case. Following liver transplantation, the use of liposomal amphotericin B following confirmation of aspergillus infection or for empirical therapy is of uncertain value, and strategies based on selective prophylaxis for high-risk cases may be preferable.

Systemic mycoses during prophylactical use of liposomal amphotericin B (Ambisome) after liver transplantation

We investigated the prophylactical administration of liposomal amphotericin B (Ambisome) in the early phase after liver transplantation (LTx). Fifty-eight patients received Ambisome prophylactically after LTx. Ambisome (1 mg kg-1 day-1) was given intravenously for 7 days after LTx. Immunosuppressive prophylaxis was cyclosporin A (CsA) based in 11 patients. Forty-seven patients had a tacrolimus-based immunosuppressive regimen. CsA and tacrolimus dosages were adjusted to trough levels of 150-250 ng ml-1 (EMIT) and 5-15 ng ml-1 (MEIA II) respectively. Three patients died from sepsis due to Aspergillus fumigatus infection. Reasons for a fatal outcome were foudroyant Aspergillus pneumonia in a patient transplanted for fulminant hepatic failure on post-operative day (pod) 8; Aspergillus sepsis with severe endocardidtis in a patient with two retransplantations for graft non/dysfunction on pod 24; and disseminated aspergillosis due to Aspergillus fumigatus in a patient retransplanted for primary non-function (pod 19). All three patients underwent haemofiltration for renal failure. One patient with Candida albicans sepsis (pod 4) recovered under increased dosage of Ambisome (3 mg kg-1 per day). Ambisome (1 mg kg-1 per day) seems to be beneficial against systemic Candida infections. However, the onset of systemic Aspergillus infections could not be prevented. Obviously, higher Ambisome doses appear to be necessary against Aspergillus. We recommend the use of Ambisome (3 mg kg-1 per day) for patients with risk factors such as graft dys-/non-function, retransplantation, haemofiltration and complicated acute liver failure to prevent invasive aspergillosis.

Combination antifungal therapy for invasive aspergillosis infection in liver transplant recipients: report of two patients

Invasive aspergillosis in solid organ transplant recipients is associated with mortality of approximately 100%. The search for optimal therapy has led clinicians to administer antifungal combinations. Two orthotopic liver transplant recipients developed invasive aspergillosis (pulmonary and perivertebral) after transplantation and were treated with combination antifungal therapy consisting of liposomal amphotericin B and itraconazole. Although both patients were initially stabilized, they died after 94 and 138 days of antifungal therapy, respectively. Presumably, aspergillosis was the principal cause of death. Antifungal serum concentrations and fungicidal titers in both patients indicated that the drugs may have been antagonistic and thus detrimental.

Epidemiology, diagnosis and treatment of systemic Candida infection in surgical patients under intensive care

The incidence of systemic Candida infections in patients requiring intensive care has increased substantially in recent years as a result of a combination of factors. More patients with severe underlying disease or immunosuppression from anti-neoplastic or anti-rejection chemotherapy and at risk from fungal infection are now admitted to the ICU. Improvements in supportive medical and surgical care have led to many patients who would previously have died as a result of trauma or disease surviving to receive intensive care. Moreover, some therapeutic interventions used in the ICU, most notably broad-spectrum antibiotics and intravascular catheters, are also associated with increased risks of candidiasis. Systemic Candida infections are associated with a high morbidity and mortality, but remain difficult to diagnose and ICU staff need to be acutely aware of this often insidious pathogen. A number of studies have identified risk factors for systemic Candida infection which may be used to identify those at highest risk. Such patients may be potential candidates for early, presumptive therapy. Here we review the epidemiology, pathogenesis, morbidity and mortality of systemic Candida infections in the ICU setting, and examine predisposing risk factors. Antifungal treatment, including the use of amphotericin B, flucytosine and fluconazole, and the roles of early presumptive therapy and prophylaxis, is also reviewed.

Efficacy of deoxycholate amphotericin B and unilamellar liposomal amphotericin B in prophylaxis of experimental Aspergillus fumigatus endocarditis

OBJECTIVE

To evaluate and compare in vivo the protective efficacy of unilamellar liposomal amphotericin B (L-AmB) with that of deoxycholate amphotericin B (D-AmB) in experimental endocarditis.

MATERIAL AND METHODS

In the rabbit model of experimental Aspergillus fumigatus endocarditis, two doses of each antifungal agent (1.5 mg/kg each) were administered intravenously at 4 hours and at 30 minutes before challenge with an inoculum of A. fumigatus. Three days later, the animals were sacrificed, and the aortic vegetations were analyzed.

RESULTS

All 19 animals that did not receive chemoprophylaxis acquired endocarditis. In contrast, endocarditis developed in 2 of 10 animals pretreated with D-AmB (P < 0.01) and 3 of 8 animals pretreated with L-AmB (P < 0.01). Both D-AmB and L-AmB prevented the development of endocarditis due to A. fumigatus and decreased the concentration of fungi in the aortic vegetations by more than 1 log10.

CONCLUSION

In the rabbit experimental model of Aspergillus endocarditis, D-AmB and L-AmB were equally effective in reducing the incidence of the infection and the tissue burden of fungi.

Antifungal prophylaxis during neutropenia and immunodeficiency

Fungal infections represent a major source of morbidity and mortality in patients with almost all types of immunodeficiencies. These infections may be nosocomial (aspergillosis) or community acquired (cryptococcosis), or both (candidiasis). Endemic mycoses such as histoplasmosis, coccidioidomycosis, and penicilliosis may infect many immunocompromised hosts in some geographic areas and thereby create major public health problems. With the wide availability of oral azoles, antifungal prophylactic strategies have been extensively developed. However, only a few well-designed studies involving strict criteria have been performed, mostly in patients with hematological malignancies or AIDS. In these situations, the best dose and duration of administration of the antifungal drug often remain to be determined. In high-risk neutropenic or bone marrow transplant patients, fluconazole is effective for the prevention of superficial and/or systemic candidal infections but is not always able to prolong overall survival and potentially selects less susceptible or resistant Candida spp. Primary prophylaxis against aspergillosis remains investigative. At present, no standard general recommendation for primary antifungal prophylaxis can be proposed for AIDS patients or transplant recipients. However, for persistently immunocompromised patients who previously experienced a noncandidal systemic fungal infection, prolonged suppressive antifungal therapy is often indicated to prevent a relapse. Better strategies for controlling immune deficiencies should also help to avoid some potentially life-threatening deep mycoses. When prescribing antifungal prophylaxis, physicians should be aware of the potential emergence of resistant strains, drug-drug interactions, and the cost. Well-designed, randomized, multicenter clinical trials in high-risk immunocompromised hosts are urgently needed to better define how to prevent severe invasive mycoses.

Infections in solid-organ transplant recipients

Solid-organ transplantation is a therapeutic option for many human diseases. Infections are a major complication of solid-organ transplantation. All candidates should undergo a thorough infectious-disease screening prior to transplantation. There are three time frames, influenced by surgical factors, the level of immunosuppression, and environmental exposures, during which infections of specific types most frequently occur posttransplantation. Most infections during the first month are related to surgical complications. Opportunistic infections typically occur from the second to the sixth month. During the late posttransplant period (beyond 6 months), transplantation recipients suffer from the same infections seen in the general community. Opportunistic bacterial infections seen in transplant recipients include those caused by Legionella spp., Nocardia spp., Salmonella spp., and Listeria monocytogenes. Cytomegalovirus is the most common cause of viral infections. Herpes simplex virus, varicella-zoster virus, Epstein-Barr virus and others are also significant pathogens. Fungal infections, caused by both yeasts and mycelial fungi, are associated with the highest mortality rates. Mycobacterial, pneumocystis, and parasitic diseases may also occur.

Risk factors of invasive Candida and non-Candida fungal infections after liver transplantation

Fungal infections are associated with a high mortality rate after liver transplantation. To describe risk factors for fungal infections, 405 consecutive liver transplant recipients were analyzed. Forty-five patients (11%) developed invasive fungal infection. Median posttransplantation time to the first episode was 60 days. Pathogens were Candida species (spp) (n=24, 53%), Cryptococcus neoformans (n=10, 22%), Aspergillus spp (n=6, 13%), Rhizopus spp (n=l), and others (n=4). Presentations of infection included disseminated (n=9), intra-abdominal (n=9), esophageal (n=9), lung (n=8), blood (n=6), and central nervous system infections (n=3), and sinusitis with esophagitis (n=1). Eighteen patients (40%) with invasive fungal infection died, and 13 (72%) of these deaths were attributable to fungi. Mortality in the nonfungal infection group was 12%. Univariate analysis identified separate risk factors for Candida (intra-abdominal bleeding), Aspergillus (fulminant hepatitis), and cryptococcal (symptomatic cytomegalovirus infection) infections. In both univariate and multivariate analyses, a high intratransplant transfusion requirement and posttransplant bacterial infection were identified as significant risk factors for all types of fungal infection. The risk factor analysis reported here suggests that different pathogenic processes lead to Candida and non-Candida infection in liver transplant recipients. Their identification should prompt specific prophylactic measures to reduce morbidity and mortality in this population.

Aspergillus endophthalmitis. An unrecognized endemic disease in orthotopic liver transplantation

PURPOSE

The authors discovered an unusually high incidence of Aspergillus endophthalmitis in an autopsy series of orthotopic liver transplantation recipients. This study was conducted to discern the frequency, topographic distribution, and potential significance of the infections.

METHODS

Autopsy reports from liver transplant patients were reviewed. All patients with Aspergillus endophthalmitis were studied by gross and histologic examination. Histologic sections were stained with Grocott-Gomori methenamine-silver nitrate and periodic acid-Schiff stains. Some Grocott-Gomori methenamine-silver nitrate stained sections were counterstained with hematoxylin-eosin. The distribution of ocular infections in the eye was determined for each patient. The organs infected were determined at autopsy.

RESULTS

The authors found seven patients with Aspergillus endophthalmitis. Six of these seven patients were from a group of 85 (7.1%) orthotopic liver transplantation recipients. Fourteen (16.5%) orthotopic liver transplantation recipients had invasive pulmonary aspergillosis and ten (11.8%) had disseminated disease. The eyes were the second most common site of infection. Two patients had ocular involvement as the only nonpulmonary site of infection. Aspergillus endophthalmitis was diagnosed in only one patient before death. Infection was located posterior to the equator in all patients; three patients were anterior to the equator as well. The retina (5/7), vitreous (5/7), and choroid (3/7) were common sites of infection.

CONCLUSIONS

This is the first report of Aspergillus endophthalmitis associated with orthotopic liver transplantation recipients. Patients with orthotopic liver transplants are unusually susceptible to invasive aspergillosis and Aspergillus endophthalmitis. Aspergillus infection is frequently bilateral, begins posteriorly in the retina or choroid, and has vitreous involvement. Recognition of this entity is important because many patients die of disseminated Aspergillus infection that may be detected early with bedside funduscopic examination.

Incidence and significance of Aspergillus cultures following liver and kidney transplantation

Aspergillus infection is a rare but devastating complication following solid organ transplantation, with mortality rates that approach 100%. Aspergillus species (sp) are also ubiquitous in our environment and may contaminate culture plates. To determine the significance of positive Aspergillus cultures, we analyzed all positive cultures from the liver and kidney transplant services at our center for the treatments used and clinical outcomes. Aspergillus sp. were cultured from 4.5% of liver and 2.2% of kidney transplant recipients. A. fumigatus was the most common isolate, followed by A. niger and A. flavus. The lung was the most common site of positive cultures. Body fluids (ascites, pleural fluid) were common sources of positive cultures but were never associated with clinical disease. Positive brain biopsies occurred in 10% of patients. Analysis of risk factors for significant infection revealed that cultures with >2 colonies or more than one site of infection were predictive of significant infection and portended a poor prognosis even with aggressive therapy. Two or fewer colonies from a single site likely represented contamination and may be followed with repeat cultures. The high mortality rate associated with Aspergillus sp. infections in transplant recipients highlights the need for better anti-fungal prophylaxis and treatment.