Fungal infections in lung transplant recipients

PURPOSE OF REVIEW: Despite numerous advances in lung transplantation, survival is still significantly compromised by a higher rate of infections. This review intends to provide an overview of the most common fungal infections afflicting lung transplant recipients, focusing on the most recent developments in diagnosis, therapy and prophylaxis. RECENT FINDINGS: Although detection of galactomannan in serum has poor sensitivity for the diagnosis of invasive aspergillosis in lung transplant recipients, detection of galactomannan in the bronchoalveolar lavage of a lung transplant recipient, with a compatible clinical illness, is highly suggestive of invasive disease. New antifungal agents, with a broader spectrum of activity and a more tolerable side effect profile, have become available for the treatment and prophylaxis of fungal infections. Evidence suggests that, at least for voriconazole, monitoring of drug concentrations may be advisable to prevent clinical failure due to underdosing and toxicity due to excessive dosing. SUMMARY: Fungal infections remain a significant cause of morbidity and mortality in lung transplant recipients; however, advances have been made in the recent years, which will allow earlier diagnosis and more effective and tolerated treatment.     

Investigation and control of aspergillosis and other filamentous fungal infections in solid organ transplant recipients

Filamentous fungal infections are associated with high morbidity and mortality in solid organ transplant patients, and prevention is warranted whenever possible. An increase in invasive aspergillosis was detected among solid organ transplant recipients in our institution during 1991–92. Rates of Aspergillus infection (18.2%) and infection or colonization (42%) were particularly high among lung transplant recipients. Epidemiologic investigation revealed cases to be both nosocomial and community‐acquired, and preventative efforts were directed at both sources. Environmental controls were implemented in the hospital, and itraconazole prophylaxis was given in the early period after lung transplantation. The rate of Aspergillus infection in solid organ transplant recipients decreased from 9.4% to 1.5%, and mortality associated with this disease decreased from 8.2% to 1.8%. The rate of Aspergillus infection or colonization among lung transplant recipients decreased from 42% to 22.5%; nosocomial Aspergillus infection decreased from 9% to 3.2%. Cases of aspergillosis in lung transplant recipients were more likely to be early infections in the pre‐intervention period. Early mortality in lung transplant recipients decreased from 15% to 3.2%. Two cases of dematiaceous fungal infection were detected, and no further cases occurred after environmental controls. The use of environmental measures that resulted in a decrease in airborne fungal spores, as well as antifungal prophylaxis, was associated with a decrease in aspergillosis and associated mortality in these patients. Ongoing surveillance and continuing intervention is needed for prevention of infection in high‐risk solid organ transplant patients.     

Infectious complications in heart transplant recipients receiving cyclosporine and corticosteroids

The rate of infectious complications differed significantly in two groups of heart transplant recipients who received different immunosuppressive regimens. Compared with patients who received conventional immunosuppression, patients treated with cyclosporine had a lower rate of infectious complications, and the contribution of infection to observed mortality was lower. Herpes simplex virus caused less morbidity and there were fewer active cytomegalovirus infections in seropositive recipients treated with cyclosporine. The incidence of bacterial pulmonary infections and associated bacteremia also decreased impressively. A decrease in nocardial infections was offset by a rise in those due to Legionella species. The frequency of aspergillosis was decreased by 54% in the cyclosporine-treated group, but half of these infections disseminated beyond the lung and such dissemination was always fatal. Infections with Pneumocystis carinii were significantly less common with cyclosporine-based immunosuppression. Screening serologic tests for toxoplasma should be done routinely and consideration given to prophylaxis in heart transplant recipients at high risk.     

Prevention and treatment of fungal infections in bone marrow transplantation

There has not been as much success in the prevention and treatment of invasive fungal infections, particularly aspergillosis, compared to the prevention and treatment of cytomegalovirus infection and graft-versus-host disease in bone marrow transplant (BMT) recipients. Allogeneic BMT recipients who develop graft-versus-host disease and remain immunosuppressed for long periods are at major risk for development of these infections. Prevention of environmental exposure, antifungal chemoprophylaxis, and attempts at early diagnosis are essential for the reduction of mortality from invasive fungal infections. Chest computerized axial tomography is extremely useful in diagnosing pulmonary aspergillosis. However, microbiologic or histologic identification of infection remains essential. Unfortunately, the response to therapy in BMT recipients remains suboptimal. With the development of the lipid formulations of amphotericin B, the newer azoles, and the echinocandins, safer and more efficacious options have become available. The optimal use of antifungal agents or their combinations remains to be determined.     

Pulmonary fungal infections

PURPOSE OF REVIEW: Invasive fungal infections of the lung have historically been associated with an extremely high mortality. This review aims to disseminate the most recent advances in the diagnosis and management of fungal infections of the lung. RECENT FINDINGS: The number and diversity of immunosuppressed populations are growing rapidly. Transplant immunosuppression is becoming more aggressive early in the posttransplant period, potentially increasing the risk of invasive fungal infections. The galactomannan antigen test and the beta-D-glucan test have emerged as methods of serially monitoring at-risk patients for invasive aspergillosis. Their utility has been established in some neutropenic populations but not in solid organ transplant recipients. In-vitro studies, animal studies, and retrospective human studies support the use of combination antifungal therapy for invasive aspergillosis. Unfortunately no randomized clinical trials exist. SUMMARY: Invasive pulmonary aspergillosis will continue to be a major problem in immunocompromised patients in the future. Immense advances in the last 2-3 years are sure to improve outcome. Well-designed multicenter evaluations are still necessary, however, to optimize management as management options widen.     

Combination antifungal therapy: what can and should we expect?

Invasive fungal infections are associated with significant morbidity and mortality among immunocompromised patients. Recent advances in antifungal development have afforded us more pharmacologic compounds to choose from when managing these fungal infections. The role of combination antifungal therapy has been well established for fungal infections such as cryptococcal meningitis. The availability of new antifungals, increased incidence of mould infections and high mortality among certain affected populations, such as hematopoietic stem cell transplant recipients, has stimulated interest in the clinical use of combination antifungal therapy. In this paper, we review supporting evidence for the use of combination antifungals in the treatment of cryptococcal meningitis, invasive candidiasis, invasive aspergillosis and zygomycosis. Several controlled clinical trials have demonstrated benefits of combination antifungal approaches for patients with cryptococcal meningitis and invasive candidiasis, but variable effects when using different agents in combination have been reported. Randomized prospective studies of combination antifungal therapy in mould infections are lacking but some series provide supportive evidence for this approach. We also describe limitations of the data and these study designs, including the fact that we still need randomized controlled multicenter studies of combination antifungal therapy for mould infections. Trials in this area should be performed with efficiency and economics in mind, and could potentially use surrogate markers as end points. Therefore, we suggest future investigations of combination antifungal therapy should include a randomized, comparative trial of primary therapy for 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.     

Hospitalizations for fungal infections after renal transplantation in the United States

Abstract: Fungal infections in renal transplant recipients have not been studied in a national population. Therefore, 33,420 renal transplant recipients in the United States Renal Data System from 1 July 1994 to 30 June 1997 were analyzed in a retrospective registry study of hospitalized fungal infections (FI). FI were most commonly associated with secondary diagnoses of esophagitis (68, 23.9%), pneumonia (57, 19.8%), meningitis (23, 7.6%), and urinary tract infection (29, 10.3%). Opportunistic organisms accounted for 95.4% of infections, led by candidiasis, aspergillosis, cryptococcosis, and zygomycosis. Most fungal infections (66%) had occurred by six months post-transplant, but only 22% by two months. In logistic regression analysis, end-stage renal disease due to diabetes, duration of pre-transplant dialysis, maintenance tacrolimus and allograft rejection were associated with FI. In Cox regression analysis, recipients with FI had a relative risk of mortality of 2.88 (95% CI=2.22–3.74) compared to all other recipients. Among FI, zygomycosis and aspergillosis were independently associated with both increased patient mortality and length of hospital stay. Most fungal infections in renal transplant recipients were opportunistic, occurred later than previously reported, and were associated with greatly decreased patient survival. Recipients with diabetes, prolonged pre-transplant dialysis, rejection, and tacrolimus immunosuppression should be considered high risk for FI.     

Simultaneous mold infections in an orthotopic heart transplant recipient

Abstract: Simultaneous mold infections in heart transplant recipients have not been previously reported. Here we describe early onset post‐transplant pulmonary aspergillosis and cutaneous zygomycosis in a 46‐year‐old heart transplant recipient who was also treated with basiliximab. Along with surgical debridement, medical treatment of his cutaneous abdominal wall zygomycosis at the former left ventricular assist device driveline site with liposomal amphotericin B and voriconazole also led to cure of his pulmonary aspergillosis.     

Viral infections in immunocompromised patients: what's new with respiratory viruses?

PURPOSE OF REVIEW: The leading cause of death in solid organ and hematopoietic stem cell transplant recipients is infection. The respiratory viruses, particularly respiratory syncytial virus, influenza, parainfluenza, adenovirus, and picornaviruses, are increasingly recognized as significant pathogens in these populations. RECENT FINDINGS: Respiratory syncytial virus has again been found to be the most common of the respiratory viruses causing severe infections in transplant recipients. Advances in prevention, particularly with regard to infection control practices, and to lesser extent treatment have had a substantial impact on the frequency and outcomes of this infection. New studies have clarified the impact of influenza in the hematopoietic stem cell transplant recipients and have provided evidence to support the use of M2 and neuraminidase inhibitors for early treatment. The epidemiology of parainfluenza and adenovirus in transplant recipients has been clarified, although therapeutic modalities are still limited and understudied. New antiviral medications may bring improved outcomes of picornavirus infections in this population. Finally, a new virus, the human metapneumovirus, has recently been described and may be a significant respiratory pathogen in immunocompromised transplant recipients. SUMMARY: Studies published over the past year have documented a new respiratory pathogen. They have also resulted in improved understanding of the epidemiology of all of the respiratory virus pathogens, and have contributed to improve management of respiratory syncytial virus and influenza infection in hematopoietic stem cell transplant and solid organ transplant recipients.     

A serological investigation of BK virus and JC virus infections in recipients of renal allografts

BK virus (BKV) and JC virus (JCV) infections were evaluated in a serological study of 496 renal transplant recipients and their donors. A seropositive donor increased the rate of primary and reactivation infections with BKV and of primary infections with JCV. BKV infection rates were not influenced by the source of the renal allograft (cadaver versus living related donor); however, primary JCV infections occurred more often in recipients of seropositive cadaveric kidneys. Reactivated JCV infections occurred less frequently in patients treated with antilymphocyte preparation. BKV and JCV infections in renal transplant recipients may be caused either by reactivation of the recipient's latent virus or by virus from the donor kidney. These infections are, however, not associated with adverse outcome (death, high serum creatinine level, or loss of renal function) in the recipient in the early post-transplant period.     

Respiratory viral infections in hematopoietic stem cell and solid organ transplant recipients

Respiratory viral infections (RVIs) are common causes of mild illness in immunocompetent children and adults with rare occurrences of significant morbidity or mortality. Complications are more common in the very young, very old, and those with underlying lung diseases. However, RVIs are increasingly recognized as a cause of morbidity and mortality in recipients of hematopoietic stem cell transplants (HSCT) and solid organ transplants (SOTs). Diagnostic techniques for respiratory syncytial virus (RSV), parainfluenza, influenza, and adenovirus have been clinically available for decades, and these infections are known to cause serious disease in transplant recipients. Modern molecular technology has now made it possible to detect other RVIs including human metapneumovirus, coronavirus, and bocavirus, and the role of these viruses in causing serious disease in transplant recipients is still being worked out. This article reviews the current information regarding epidemiology, pathogenesis, clinical presentation, diagnosis, and treatment of these infections, as well as the aspects of clinical significance of RVIs unique to HSCT or SOT.     

Early infections in adults undergoing matched related and matched unrelated/mismatched donor stem cell transplantation: a comparison of incidence

We compared the incidence of early infectious complications between matched related (MR) and matched unrelated/mismatched (MU/MM) allogeneic stem cell transplant (allo-SCT) recipients in a single centre over a 6-year period in 214 consecutive adult patients. Early infections were defined as occurring from hospital admission for SCT until discharge. One hundred and fifty-nine patients received an allograft from MR donors and 55 patients received MU/MM allo-SCT. One hundred and eight of 214 patients had 147 episodes of fever. Ninety-three episodes (63%) were due to clinically or microbiologically documented infections and 54 episodes (37%) to fever not related to infection. Patients undergoing MU/MM transplantation tended to have more documented infections compared to recipients of MR allo-SCT (P = 0.06). Significantly more MU/MM transplant recipients had breakthrough infections with Herpes simplex virus type 1 (HSV-1, P = 0.003), and more CMV reactivation (P = 0.015). The mortality rate in all patients during hospitalisation post-SCT was 6.3% in MR and 18.2% in MU/MM allo-SCT recipients (P = 0.009). Early mortality was associated with infection in 70% of the patients, with a similar distribution between MR and MU/MM transplant recipients. However, MU/MM transplant recipients had significantly more early deaths due to toxic causes (P < 0.001). We conclude that early post-transplant MU/MM transplant recipients tend to have more documented infections, and have significantly more breakthrough infections with HSV-1 and more CMV reactivation. MU/MM transplant recipients are at higher risk of early mortality, especially due to toxic causes.     

Longitudinal study of bacterial, viral, and fungal infections in adult recipients of bone marrow transplants.

The epidemiology of infections was studied in a retrospective cohort of 446 recipients of bone marrow transplants (BMTs; 92 of which were allogeneic and 354 of which were autologous) during 1993--1996. Infections that were microbiologically documented in 274 recipients included bacteremia, urinary tract infections, cytomegalovirus viremia, fungemia, invasive aspergillosis, and catheter-related infections. During the period of neutropenia, no differences were found between recipients of allogeneic BMTs and recipients of autologous BMTs with regard to the incidence and the nature of infection. After patients underwent engraftment, bacteremia, cytomegalovirus viremia, and invasive aspergillosis were significantly more common in recipients of allogeneic BMTs than in recipients of autologous BMTs. Deaths caused by infection were uncommon and were mainly the result of invasive aspergillosis. Therefore, empirical antimicrobial therapy should be the same for recipients of both allogeneic and autologous BMTs during the period of neutropenia; after engraftment, more attention should be paid to the risk of infection in allogeneic BMT recipients, particularly with regard to detection and prevention of invasive aspergillosis.     

Aspergillus infection in lung transplant recipients with cystic fibrosis: risk factors and outcomes comparison to other types of transplant recipients

STUDY OBJECTIVES: To characterize Aspergillus infections in lung transplant recipients with cystic fibrosis (CF). DESIGN: A retrospective analysis of 32 consecutive lung transplant recipients with CF who underwent bilateral lung transplant at the University of Wisconsin from 1994 to 2000 to determine the incidence, risk factors, and consequences of Aspergillus infection. The findings were compared to 101 non-CF recipients of lung transplants (93) and heart-lung transplants (8) for other transplant indications. SETTING: A university hospital. Patients or participants: Lung transplant recipients with CF or other indications for transplantation. INTERVENTIONS: None. Measurements and results: Seventeen of 32 CF recipients (53%) had Aspergillus fumigatus isolated from their respiratory secretions prior to undergoing transplantation. Ten of these 17 (59%) recipients had A fumigatus persistently found in their respiratory secretions posttransplant vs 6 of 15 CF patients (40%) who had not been colonized pretransplant and 28 of 101 of the non-CF recipients (28%). Four of the preoperatively colonized CF recipients developed tracheobronchial aspergillosis (TBA) just distal to the bronchial anastomoses, and one recipient had dehiscence of the involved anastomosis. None of the CF recipients developed disseminated aspergillosis or pneumonia. Prophylactic antifungal therapy did not prevent TBA, and IV amphotericin B therapy was required to clear the infection in all four patients, with endobronchial debridement of necrotic tissue required in two of them. In contrast, 10 of the non-CF (10%) recipients developed Aspergillus infections posttransplant (TBA, 4 recipients; pneumonitis, 6 recipients), and only 3 patients had successful treatment and long-term survival (TBA, 2 patients; pneumonia, 1 patient). Donor lung ischemia time, cytomegalovirus infection or pneumonia, or pretransplant mechanical ventilation did not increase the risk of developing TBA in CF recipients. CONCLUSIONS: The risk of TBA for patients receiving lung transplants for CF warrants early surveillance bronchoscopy to detect TBA, particularly in recipients with pretransplant colonization.     

Community respiratory virus infections following lung transplantation

Abstract: Respiratory infections remain a significant cause of morbidity and mortality after lung transplantation. In addition to cytomegalovirus, the community respiratory viruses such as respiratory syncytial virus (RSV), parainfluenza virus (PIV), influenza virus, and adenovirus, are important causes of infection in transplant recipients, often involve the lower respiratory tract, and may be associated with significant morbidity and mortality. In this review, we summarize the current state of knowledge regarding the epidemiology, clinical manifestations, diagnosis, treatment and outcomes associated with RSV, PIV, influenza virus, and adenovirus infections in lung transplant recipients.     

Infectious complications in organ transplant recipients with the use of calcineurin-inhibitor agent-based immunosuppressive regimens

PURPOSE OF REVIEW: The rates and types of infections associated with conventional immunosuppression regimens comprising calcineurin-inhibitor agents, tacrolimus, and cyclosporine could be used to compare similar data with the use of novel immunosuppressive regimens in organ transplant recipients. RECENT FINDINGS: Tacrolimus appears to be superior to cyclosporine in preventing rejection. The frequency and spectrum of infections in organ transplant recipients does not appear to be notably modified by the choice of calcineurin-inhibitor agents per se. A higher risk of cytomegalovirus and poorer outcomes associated with hepatitis C virus with cyclosporine in some studies may be related to a greater requirement of adjunctive immunosuppression with cyclosporine-based regimens. Potent immunosuppression with tacrolimus, however, particularly when combined with mycophenolate mofetil, is believed to be a significant contributor to a higher incidence of BK virus nephropathy in renal transplant recipients in recent years. Calcineurin-inhibitor agents possess in-vitro activity against a number of fungal pathogens. In the clinical setting, however, the immunosuppressive effect outweighs their antifungal activity. SUMMARY: Calcineurin inhibitor-based regimens have been the mainstay of immunosuppression after organ transplantation for almost two decades. However, suboptimal long-term outcomes in transplant recipients have led to a growing interest in the use of calcineurin inhibitor agent-sparing regimens. Whether novel immunosuppressive agents with a more selective mechanism of action would lead to a further reduction in the risk of posttransplant infections remains to be discerned.     

Risks, diagnosis and outcomes of invasive fungal infections in haematopoietic stem cell transplant recipients

Invasive fungal infections (IFIs) continue to cause considerable morbidity and mortality in haematopoietic stem cell transplant (HSCT) recipients. This review focuses on the risks for, and diagnosis of, IFIs (candidiasis, aspergillosis and other mould infections), and factors that affect current outcomes. Diagnosis of IFI is difficult, with the sensitivity of the gold standard tests (culture and histopathology) often <50%. Therefore, physicians rely on a constellation of clinical signs, radiography, culture, histopathology and adjunctive tests to establish diagnosis. HSCT recipients often have multiple co-morbidities, and understanding the current outcomes and prognostic variables is therefore important for overall management. This paper reviews historical trends and current data.     

Association of renal allograft rejection with virus infections

Sixty-one immunosuppressed renal transplant recipients were systematically screened for virus infections and the findings correlated with their clinical course. Only herpesvirus (cytomegalovirus, herpes simplex and herpes zoster) were consistently isolated. The onset of virus infections could usually be associated with clinical syndromes. Patients without virus infections were usually asymptomatic. The clinical syndrome associated with virus infection consisted of fever, leukopenia and renal allograft rejection. Renal biopsy, performed at the time serum creatinine levels were elevated, revealed classic rejection; most rejections were reversed by increasing the dose of steroids. Patients continued to excrete virus even after antibody response and clinical recovery. Virus infections do not appear to be incidental findings in transplant patients except after recovery when the virus persists in the immune patient. The clear-cut association between virus infection and rejection episodes suggests a pathogenic relationship. The two mechanisms which seem to best explain the relationship are (1) the virus infection acting as an adjuvant and triggering the rejection of the allograft or (2) the allograft rejection activating a latent virus infection.