Risk factors for the development of invasive fungal infections in allogeneic blood and marrow transplant recipients

Diagnosis of Infectious Diseases in the Lower Respiratory Tract: A Cytopathologist's Perspective

CONTEXT.—

Respiratory cytology continues to play an important role in the diagnosis of lower respiratory tract infections. Prompt, accurate diagnosis of causative organisms is of paramount importance, particularly in immunosuppressed patients. In addition, a rapidly expanding arsenal of ancillary testing is now available, aiding tremendously in organism identification.

OBJECTIVE.—

To provide an updated review on the cytomorphologic features of common organisms in lower respiratory tract infection. Relevant ancillary tests, differential diagnoses, and potential pitfalls of organism identification will also be discussed.

DATA SOURCES.—

Data for this review were gathered from PubMed searches of infectious diseases of the lower respiratory tract, especially related to the diagnoses.

CONCLUSIONS.—

The lower respiratory tract is subject to infection by a wide variety of infectious agents. Pathologists should be familiar with common organisms, including their general clinical characteristics, cytomorphologic features, differential diagnoses, and ancillary methods of detection. Above all, correlation with microbiologic and clinical information is necessary to make a confident diagnosis of infection.

Acidic Mammalian Chitinase Negatively Affects Immune Responses during Acute and Chronic Aspergillus fumigatus Exposure

Chitin is a polysaccharide that provides structure and rigidity to the cell walls of fungi and insects. Mammals possess multiple chitinases, which function to degrade chitin, thereby supporting a role for chitinases in immune defense. However, chitin degradation has been implicated in the pathogenesis of asthma. Here, we determined the impact of acidic mammalian chitinase (AMCase) (Chia) deficiency on host defense during acute exposure to the fungal pathogen Aspergillus fumigatus as well as its contribution to A. fumigatus-associated allergic asthma. We demonstrate that chitin in the fungal cell wall was detected at low levels in A. fumigatus conidia, which emerged at the highest level during hyphal transition. In response to acute A. fumigatus challenge, Chia^-/- mice unexpectedly demonstrated lower A. fumigatus lung burdens at 2 days postchallenge. The lower fungal burden correlated with decreased lung interleukin-33 (IL-33) levels yet increased IL-1β and prostaglandin E₂ (PGE₂) production, a phenotype that we reported previously to promote the induction of IL-17A and IL-22. During chronic A. fumigatus exposure, AMCase deficiency resulted in lower dynamic and airway lung resistance than in wild-type mice. Improved lung physiology correlated with attenuated levels of the proallergic chemokines CCL17 and CCL22. Surprisingly, examination of inflammatory responses during chronic exposure revealed attenuated IL-17A and IL-22 responses, but not type 2 responses, in the absence of AMCase. Collectively, these data suggest that AMCase functions as a negative regulator of immune responses during acute fungal exposure and is a contributor to fungal asthma severity, putatively via the induction of proinflammatory responses.

Evaluation of Mannose-Binding Lectin is a Useful Approach to Predict the Risk of Infectious Complications Following Autologous Hematopoietic Stem Cell Transplantation

Hematopoietic stem cell transplantation (HSCT) associated immunocompromised state carries high risk of infectious complications. Mannose-binding lectin (MBL) is an acute phase protein involved in innate immune response. Serum MBL level is genetically determined and quite stable. According to literature, significant association was shown between low MBL concentrations and serious infections. The association between serum MBL level and frequency and severity of infections was studied in 186 patients following autologous HSCT. Double-monoclonal antibody sandwich enzyme-linked immunosorbent assay was used to determine MBL antigen level in sera. MBL levels were measured around 100 days following transplantation, in a period without active infection. Twenty-one patients (11%) were MBL deficient. The median time of first infection and number of infections during the first year post-transplantation were not significantly different between patients with MBL deficiency and those without MBL deficiency. The occurrence and number of infections after HSCT correlated with the MBL/C-reactive protein ratio. The number of severe infections was not higher among those with MBL deficiency. The occurrence of infections after the pre-engraftment period during the first year post-transplantation was significantly different in patient groups separated by MBL cut-off level. The MBL/C-reactive protein ratio might be a useful marker of infectious complications. MBL measurement may be helpful in antibiotic treatment. In case of MBL deficiency, earlier and more intensive treatment may be indicated.

Innate Lung Defense during Invasive Aspergillosis: New Mechanisms

Invasive aspergillosis (IA) is one of the most difficult to treat and, consequently, one of the most lethal fungal infections known to man. Continued use of immunosuppressive agents during chemotherapy and organ transplantation often leads to the development of neutropenia, the primary risk factor for IA. However, IA is also becoming more appreciated in chronic diseases associated with corticosteroid therapy. The innate immune response to Aspergillus fumigatus, the primary agent in IA, plays a pivotal role in the recognition and elimination of organisms from the pulmonary system. This review highlights recent findings about innate host defense mechanisms, including novel aspects of innate cellular immunity and pathogen recognition, and the inflammatory mediators that control infection with A. fumigatus.

Stimulation with lysates of Aspergillus terreus, Candida krusei and Rhizopus oryzae maximizes cross-reactivity of anti-fungal T cells

BACKGROUND AIMS

Invasive fungal diseases caused by filamentous fungi and yeasts are significant causes of morbidity and mortality in immunosuppressed hematology patients. We previously published a method to expand Aspergillus fumigatus-specific T cells for clinical cell therapy. In the present study, we investigated expansion of T cells specific for other fungal pathogens and creation of a broadly reactive panfungal T-cell product.

METHODS

Fungal strains selected were those frequently observed in the clinical hematology setting and included Aspergillus, Candida, Fusarium, Rhizopus and Lomentospora/Scedosporium. Four T-cell cultures specific to each fungus were established. We selected lysates of Aspergillus terreus, Candida krusei and Rhizopus oryzae to expand panfungal T cells. Allelic restriction of anti-fungal activity was determined through the use of specific major histocompatibility complex class II-blocking antibodies.

RESULTS

Individual T-cell cultures specific to each fungus could be expanded in vitro, generating predominantly CD4(+) T cells of which 8% to 20% were fungus-specific. We successfully expanded panfungal T cells from the peripheral blood (n = 8) and granulocyte-colony-stimulating factor-primed stem cell products (n = 3) of normal donors by using a combination of lysates from Aspergillus terreus, Candida krusei and Rhizopus oryzae. Anti-fungal activity was mediated through human leukocyte antigen (HLA)-DR alleles and was maintained when antigen-presenting cells from partially HLA-DRB1-matched donors were used to stimulate T cells.

CONCLUSIONS

We demonstrate a method to manufacture panfungal T-cell products with specificity against a range of clinical fungal pathogens by use of the blood and stem cells of healthy donors as the starting material. The safety and efficacy of these products will need to be tested clinically.

Adoptive T-cell therapy for fungal infections in haematology patients

The prolonged immune deficiency resulting from haematopoietic stem cell transplant and chemotherapy predisposes to a high risk of invasive fungal infections. Despite the recent advances in molecular diagnostic testing, early initiation of pre-emptive antifungal therapy and the use of combination pharmacotherapy, mortality from invasive mould infections remain high among recipients of allogeneic stem cell transplant. The increasing incidences of previously rare and drug-resistant strains of fungi present a further clinical challenge. Therefore, there is a need for novel strategies to combat fungal infections in the immunocompromised. Adoptive therapy using in vitro-expanded fungus-specific CD4 cells of the Th-1 type has shown clinical efficacy in murine studies and in a small human clinical study. Several techniques for the isolation and expansion of fungus-specific T cells have been successfully applied. Here we discuss the incidence and changing patterns of invasive fungal diseases, clinical evidence supporting the role of T cells in fungal immunity, methods to expand fungus-specific T cells in the laboratory and considerations surrounding the use of T cells for fungal immunotherapy.

Could Histoplasma capsulatum Be Related to Healthcare-Associated Infections?

Healthcare-associated infections (HAI) are described in diverse settings. The main etiologic agents of HAI are bacteria (85%) and fungi (13%). Some factors increase the risk for HAI, particularly the use of medical devices; patients with severe cuts, wounds, and burns; stays in the intensive care unit, surgery, and hospital reconstruction works. Several fungal HAI are caused by Candida spp., usually from an endogenous source; however, cross-transmission via the hands of healthcare workers or contaminated devices can occur. Although other medically important fungi, such as Blastomyces dermatitidis, Paracoccidioides brasiliensis, and Histoplasma capsulatum, have never been considered nosocomial pathogens, there are some factors that point out the pros and cons for this possibility. Among these fungi, H. capsulatum infection has been linked to different medical devices and surgery implants. The filamentous form of H. capsulatum may be present in hospital settings, as this fungus adapts to different types of climates and has great dispersion ability. Although conventional pathogen identification techniques have never identified H. capsulatum in the hospital environment, molecular biology procedures could be useful in this setting. More research on H. capsulatum as a HAI etiologic agent is needed, since it causes a severe and often fatal disease in immunocompromised patients.

Cryopreserved Ex Vivo-Expanded Allogeneic Myeloid Progenitor Cell Product Protects Neutropenic Mice From a Lethal Fungal Infection

Severe neutropenia induced by chemotherapy or conditioning for hematopoietic cell transplantation often results in morbidity and mortality due to infection by opportunistic pathogens. A system has been developed to generate ex vivo-expanded mouse myeloid progenitor cells (mMPCs) that produce functional neutrophils in vivo upon transplantation in a pathogen challenge model. It has previously been demonstrated that transplantation of large numbers of freshly isolated myeloid progenitors from a single donor provides survival benefit in radiation-induced neutropenic mice. In the present work, an ex vivo-expanded and cryopreserved mMPC product generated from an allogeneic donor pool retains protective activity in vivo in a lethal fungal infection model. Infusion of the allogeneic pooled mMPC product is effective in preventing death from invasive Aspergillus fumigatus in neutropenic animals, and protection is dose dependent. Cell progeny from the mMPC product is detected in the bone marrow, spleen, blood, and liver by flow cytometry 1 week postinfusion but is no longer evident in most animals 4 weeks posttransplant. In this model, the ex vivo-generated pooled allogeneic mMPC product (i) expands and differentiates in vivo; (ii) is functional and prevents death from invasive fungal infection; and (iii) does not permanently engraft or cause allosensitization. These data suggest that an analogous ex vivo-expanded human myeloid progenitor cell product may be an effective off-the-shelf bridging therapy for the infectious complications that develop during hematopoietic recovery following hematopoietic cell transplantation or intensive chemotherapy.

Invasive fungal infections in pediatric hematopoietic stem cell transplant patients

BACKGROUND

Pediatric hematopoietic stem cell transplant (HSCT) recipients are at high risk of invasive fungal infections (IFIs).

METHODS

To characterize IFIs and changes in fungal organisms over time in pediatric HSCT patients, we performed a retrospective cohort study of all HSCTs performed in pediatric patients at UCLA between 1991 and 2006.

RESULTS

In all, 318 patients underwent 324 HSCT transplants over the 15-year period and 69 unique fungal infections were identified in 47 transplant patients. The overall incidence of fungal infections in HSCT recipients was 14.5%, with predominant organisms including Candida species (51%) and Aspergillus species (26%), with Candida albicans accounting for 18.8% of all fungal species. The distribution of organisms over time demonstrated a strong trend towards an increase in rare molds in more recent years. The respiratory tract was the main site of infection (52.6%), with urine and blood also noted as significant sites. Of all deaths in the patients with IFIs, fungal-related mortality accounted for 67.6% of deaths.

CONCLUSIONS

HSCT patients have a much higher risk of fungal infections with rarer organisms becoming more prevalent, a finding likely linked to evolving antifungal practices over time. This emphasizes the need for the development and implementation of improved diagnostic, prophylactic, and therapeutic strategies to improve patient survival.

Risk factors for invasive fusariosis in patients with acute myeloid leukemia and in hematopoietic cell transplant recipients

BACKGROUND

Risk factors for invasive fusariosis (IF) have not been characterized. We attempted to identify risk factors for IF in a prospective cohort of hematologic patients treated in 8 centers in Brazil.

METHODS

Patients with (cases) and without (controls) proven or probable IF diagnosed in a cohort of patients with acute myeloid leukemia (AML) or myelodysplasia (MDS), and in allogeneic hematopoietic cell transplant (HCT) recipients (early, until day 40; late, after day 40 posttransplant) were compared by univariate Cox regression analysis.

RESULTS

Among 237 induction remission courses of AML/MDS and 663 HCTs (345 allogeneic and 318 autologous), 25 cases of IF were diagnosed. In the AML/MDS cohort, active smoking (hazard ratio [HR], 9.11 [95% confidence interval {CI}, 2.04-40.71]) was associated with IF. Variables associated with IF in the early phase of allogeneic HCT were receipt of antithymocyte globulin (HR, 22.77 [95% CI, 4.85-101.34]), hyperglycemia (HR, 5.17 [95% CI, 1.40-19.11]), center 7 (HR, 5.15 [95% CI, 1.66-15.97]), and AML (HR, 4.38 [95% CI, 1.39-13.81]), and in the late phase were nonmyeloablative conditioning regimen (HR, 35.08 [95% CI, 3.90-315.27]), grade III/IV graft-vs-host disease (HR, 16.50 [95% CI, 2.67-102.28]), and previous invasive mold disease (HR, 10.65 [95% CI, 1.19-95.39]).

CONCLUSIONS

Attempts to reduce the risk of IF may include smoking cessation, aggressive control of hyperglycemia, and the use of a mold-active agent as prophylaxis in patients receiving nonmyeloablative HCT or ATG in the conditioning regimen. Future research should further explore smoking and other prehospital variables as risks for IF.

Infectious complications of stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) is an accepted treatment for a variety of hematologic malignancies. The profound immunosuppression these patients experience adversely affects their risk of infection. This risk is much higher than in the general population and requires aggressive diagnostic and therapeutic interventions. The chapter will outline the major infections after HSCT.

Eosinophil deficiency compromises lung defense against Aspergillus fumigatus

Exposure to the mold Aspergillus fumigatus may result in allergic bronchopulmonary aspergillosis, chronic necrotizing pulmonary aspergillosis, or invasive aspergillosis (IA), depending on the host's immune status. Neutrophil deficiency is the predominant risk factor for the development of IA, the most life-threatening condition associated with A. fumigatus exposure. Here we demonstrate that in addition to neutrophils, eosinophils are an important contributor to the clearance of A. fumigatus from the lung. Acute A. fumigatus challenge in normal mice induced the recruitment of CD11b+ Siglec F+ Ly-6G(lo) Ly-6C(neg) CCR3+ eosinophils to the lungs, which was accompanied by an increase in lung Epx (eosinophil peroxidase) mRNA levels. Mice deficient in the transcription factor dblGATA1, which exhibit a selective deficiency in eosinophils, demonstrated impaired A. fumigatus clearance and evidence of germinating organisms in the lung. Higher burden correlated with lower mRNA expression of Epx (eosinophil peroxidase) and Prg2 (major basic protein) as well as lower interleukin 1β (IL-1β), IL-6, IL-17A, granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and CXCL1 levels. However, examination of lung inflammatory cell populations failed to demonstrate defects in monocyte/macrophage, dendritic cell, or neutrophil recruitment in dblGATA1-deficient mice, suggesting that the absence of eosinophils in dlbGATA1-deficient mice was the sole cause of impaired lung clearance. We show that eosinophils generated from bone marrow have potent killing activity against A. fumigtaus in vitro, which does not require cell contact and can be recapitulated by eosinophil whole-cell lysates. Collectively, our data support a role for eosinophils in the lung response after A. fumigatus exposure.

Fungal infections: their diagnosis and treatment in transplant recipients

Systemic fungal infections typically occur in individuals who are seriously ill with recognized risk factors such as those frequently found in transplant recipients. Unfortunately, they are often diagnosed late, when the efficacy of the available treatments is low, often less than 50%, and the cost in terms of lives lost, hospital length of stay, and total hospital costs is substantially increased. The application of antifungal therapies associated with reported efficacy rates greater than 50% are those used prophylactically. When used prophylactically, these infections are reduced in greater than 95% of the expected cases. The choice of a prophylactic agent should be based upon its ease of administration, lack of adverse effects, reduced likelihood of potential drug interactions, and its efficacy in patients with established risk factors and comorbid disease processes that include renal, hepatic, and chronic pulmonary disease. The indications for the use of currently available antifungal agents, their adverse effects, drug interactions, ease of dosing, and applicability in patients with preexisting disease states, and especially in liver transplant recipients, are presented in this paper.

Weekly liposomal amphotericin B as secondary prophylaxis for invasive fungal infections in patients with hematological malignancies

There have been no published studies evaluating the efficacy and safety of weekly liposomal amphotericin B as secondary prophylaxis in leukemic patients with invasive fungal infections (IFIs). We found in a retrospective review of our experience with 14 such patients admitted from 2003-2009 that the use of this approach was associated with frequent relapse of IFIs (36%) and kidney injury (36%).

Invasive aspergillosis in hematopoietic stem cell and solid organ transplantation

Invasive aspergillosis (IA) is currently an important cause of morbidity and mortality in hematopoietic stem cell transplant and solid organ transplant recipients. A high index of suspicion and careful clinical and radiological examinations are the keys to identifying infected patients early. Chest computerized axial tomography is extremely useful in diagnosing pulmonary aspergillosis. Microbiologic or histologic identification of infection, however, remain essential. Successful management of invasive fungal infections depends on timely and appropriate treatment. There are multiple variables associated with survival in transplant patients with IA. Understanding these prognostic factors may assist in the development of treatment algorithms and clinical trials. In contrast to adult patients, large prospective comparative studies have not been performed in pediatric patients with IA. Moreover, pediatric subgroups have not been analyzed in published studies that include a broader age range. Clinicians treating pediatric IA are largely left with the results of uncontrolled trials, observatory surveys, salvage therapy data and extrapolations from adult studies to guide their treatment choices. The aim of this article is to state the main characteristics of IA in both pediatric and adult populations.

Epidemiology and treatment approaches in management of invasive fungal infections

Over the past 20 years, the number of invasive fungal infections has continued to persist, due primarily to the increased numbers of patients subjected to severe immunosuppression. Despite the development of more active, less toxic antifungal agents and the standard use of antifungal prophylaxis, invasive fungal infections (especially invasive mold infections) continue to be a significant factor in hematopoietic cell and solid organ transplantation outcomes, resulting in high mortality rates. Since the use of fluconazole as standard prophylaxis in the hematopoietic cell transplantation setting, invasive candidiasis has come under control, but no mold-active antifungal agent (except for posaconazole in the setting of acute myelogenous leukemia and myelodysplastic syndrome) has been shown to improve the survival rate over fluconazole. With the advent of new azole and echinocandin agents, we have seen the emergence of more azole-resistant and echinocandin-resistant fungi. The recent increase in zygomycosis seen in the hematopoietic cell transplantation setting may be due to the increased use of voriconazole. This has implications for the empiric approach to pulmonary invasive mold infections when zygomycosis cannot be ruled out. It is imperative that an amphotericin B product, an antifungal that has never developed resistance in over 50 years, be initiated. The clinical presentations of invasive mold infections and invasive candidiasis can be nonspecific and the diagnostic tests insensitive, so a high index of suspicion and immediate initiation of empiric therapy is required. Unfortunately, our currently available serologic tests do not predict infection ahead of disease, and, therefore cannot be used to initiate “preemptive” therapy. Also, the Aspergillus galactomannan test gives a false negative result in patients receiving antimold prophylaxis, ie, virtually all of our patients with hematologic malignancy and hematopoietic cell transplant recipients. We may eventually be able to select patients at highest risk for invasive fungal infections for prophylaxis by genetic testing. However, with our current armamentarium of antifungal agents and widespread use of prophylaxis in high-risk groups (hematologic malignancy, hematopoietic cell transplantation), we continue to see high incidence and mortality rates, and our future hope lies in reversing the immunosuppression or augmenting the immune system of these severely immunocompromised hosts by developing and utilizing immunotherapy, immunoprophylaxis, and vaccines.

Hematopoietic stem cell transplantation: an overview of infection risks and epidemiology

Hematopoietic stem cell transplantation (HSCT) is a treatment for multiple medical conditions that result in bone marrow failure and as an antineoplastic adoptive immunotherapy for hematologic malignancies. HSCT is associated with profound compromises in host barriers and all arms of innate and acquired immunity. The degree of immune compromise varies by type of transplant and over time. Immune reconstitution occurs within several months after autologous HSCT but takes up to a year or longer after allogeneic HSCT. In those patients who develop chronic graft-versus-host disease, immune reconstitution may take years or may never completely develop. Over time, with strengthening immune reconstitution and control of graft-versus-host disease, the risk for infection dissipates.

TNFR1 mRNA expression level and TNFR1 gene polymorphisms are predictive markers for susceptibility to develop invasive pulmonary aspergillosis

Tumour necrosis factor (TNF) is primarily secreted by monocytes/macrophages and activated T lymphocytes in response to fungal infections. TNF acts through TNF receptor 1 (TNFR1) triggering a pro-inflammatory response, and therefore plays a pivotal role in immune regulation and host immune responses. We hypothesized that single nucleotide polymorphisms (SNPs) in TNFR1 gene may influence the innate immune response against Aspergillus. Three SNPs were genotyped in 275 individuals (144 immunocompromised haematological patients with high-risk of developing IPA and 131 healthy controls): TNFR1(-383(A/C)) (rs2234649) and TNFR1(-609(G/T)) (rs4149570) in the 5 prime UTR region, and TNFR1(+36(A/G)) SNP (rs767455) in the first exon of the gene. Of the 144 haematological patients, 77 patients developed Invasive Pulmonary Aspergillosis (IPA) infection and the remaining 67 patients were not infected. TNFR1(+36(A/G)) and TNFR1(-609(G/T)) were associated with IPA susceptibility (p=0.033 and p=0.018, respectively). A role of TNFR1 genetic variants in the susceptibility of patients to develop IPA was also supported by the significantly lower TNFR1 mRNA expression level in IPA than in IPA-resistant patients and the strong correlation between the TNFR1(-609) genetic variant and the expression levels of TNFR1. There was also a tendency for a higher frequency of galactomannan (GM) positivity in patients with TNFR1(-609G/G) genotype than in patients with TNFR1(-609G/T) (p=0.0909) or TNFR1(-609T/T) (p=0.0913) genotype. Predictive sequence analysis of the effects of TNFR1(-609) promoter polymorphism revealed that this SNP might play a critical role in modifying the affinity of ICSBP/IRF-8, a transcription factor that is involved in the TNFR1-mediated activation of NFkappaB signalling pathway. Taken together, these data suggest that TNFR1 polymorphisms influence the risk of IPA disease and might be useful for risk stratification strategies. These findings need to be confirmed in validation studies with larger samples of haematological patients.

Hematopoietic stem cell transplantation: an overview of infection risks and epidemiology

Hematopoietic stem cell transplantation (HSCT) is a treatment for multiple medical conditions that result in bone marrow failure and as an antineoplastic adoptive immunotherapy for hematologic malignancies. HSCT is associated with profound compromises in host barriers and all arms of innate and acquired immunity. The degree of immune compromise varies by type of transplant and over time. Immune reconstitution occurs within several months after autologous HSCT but takes up to a year or longer after allogeneic HSCT. In those patients who develop chronic graft-versus-host disease, immune reconstitution may take years or may never completely develop. Over time, with strengthening immune reconstitution and control of graft-versus-host disease, the risk for infection dissipates.

Primary antifungal prophylaxis in adult hematopoietic stem cell transplant recipients: current therapeutic concepts

In recipients of hematopoietic stem cell transplants (HSCTs), the mortality associated with invasive fungal infections (IFIs) remains high, despite the introduction of broad-spectrum antifungal agents over the past 2 decades. Preventing exposure to fungal pathogens in this population is impossible; therefore, clinicians have focused on prophylactic use of antifungal agents to prevent IFIs in high-risk HSCT recipients. It is important to target antifungal prophylaxis by type of HSCT (autologous or allogeneic), local epidemiology, and risk factors for IFIs so that patients can receive the most appropriate agent while balancing costs and the risks of toxicity, and minimizing the development of resistance. To assist clinicians in weighing the pros and cons of currently available antifungal agents when choosing a suitable prophylactic regimen, we provide a review of several key prospective randomized trials that evaluated various antifungal agents for primary prophylaxis in adult HSCT recipients. In addition, we describe the epidemiology of and risk factors for IFIs in HSCT recipients, the difficulties in diagnosing IFIs, antifungal agents used for prophylaxis, and the goals of primary prophylaxis. Fluconazole remains the gold standard for primary prophylaxis in autologous HSCT recipients. For allogeneic HSCT recipients, the agent chosen for prophylaxis must be based on the patient's risk factors for IFIs. In low-risk patients, fluconazole is an appropriate agent to use for primary prophylaxis immediately after transplantation. However, in allogeneic HSCT recipients who develop complications, such as graft failure, graft-versus-host disease, or cytomegalovirus infection, prophylaxis with a mould-active agent should be used.

Stem Cell Transplantation

Hematopoietic cell transplantation (HCT) is associated with profound compromises in host defenses. The patterns of immune compromise change over time. Infections are an important cause of serious morbidity and pose substantial threats to life. Thus, the challenges of infection facing the transplant clinician are both myriad and dynamic. Early after transplant, neutropenic infections are most important. Later herpesvirus and invasive fungal infections predominate. Even late after transplant, patients with chronic graft versus host disease remain susceptible to encapsulated bacterial, varicella zoster virus, and invasive fungal infections. Over time, with robust engraftment and control of GVHD, the risk of serious infections recedes with immune reconstitution.

Dectin-1 Fc targeting of aspergillus fumigatus beta-glucans augments innate defense against invasive pulmonary aspergillosis

Invasive pulmonary aspergillosis (IPA) has significantly increased over the last decade. Here, a fusion protein consisting of the Dectin-1 extracellular domain linked to the Fc portion of murine immunoglobulin G1 augmented alveolar macrophage killing of Aspergillus fumigatus and shifted mortality associated with IPA via attenuation of A. fumigatus growth in the lung.

Imaging findings in acute invasive pulmonary aspergillosis: clinical significance of the halo sign

BACKGROUND

Computed tomography (CT) of the chest may be used to identify the halo sign, a macronodule surrounded by a perimeter of ground-glass opacity, which is an early sign of invasive pulmonary aspergillosis (IPA). This study analyzed chest CT findings at presentation from a large series of patients with IPA, to assess the prevalence of these imaging findings and to evaluate the clinical utility of the halo sign for early identification of this potentially life-threatening infection.

METHODS

Baseline chest CT imaging findings from 235 patients with IPA who participated in a previously published study were systematically analyzed. To evaluate the clinical utility of the halo sign for the early identification and treatment of IPA, we compared response to treatment and survival after 12 weeks of treatment in 143 patients who presented with a halo sign and in 79 patients with other imaging findings.

RESULTS

At presentation, most patients (94%) had > or =1 macronodules, and many (61%) also had halo signs. Other imaging findings at presentation, including consolidations (30%), infarct-shaped nodules (27%), cavitary lesions (20%), and air-crescent signs (10%), were less common. Patients presenting with a halo sign had significantly better responses to treatment (52% vs. 29%; P<.001) and greater survival to 84 days (71% vs. 53%; P<.01) than did patients who presented with other imaging findings.

CONCLUSIONS

Most patients presented with a halo sign and/or a macronodule in this large imaging study of IPA. Initiation of antifungal treatment on the basis of the identification of a halo sign by chest CT is associated with a significantly better response to treatment and improved survival.

Critical care considerations of hematopoietic stem cell transplantation

OBJECTIVE

To review the available clinical data on the critical care complications of hematopoietic stem cell transplantation (HSCT).

DATA SOURCE

The MEDLINE database and references from the identified articles related to the critical care in HSCT.

CONCLUSION

HSCT is an important treatment for a variety of malignant and nonmalignant conditions. The procedure is, however, limited by significant complications that may involve every organ of the body. Up to 40% of HSCT recipients are admitted to the intensive care unit as a result of severe complications related to the transplantation. The outcome of those critically ill patients has been traditionally poor. However, recent advances in the transplantation procedure, diagnostic studies, antimicrobial prophylaxis and therapy, and intensive care unit care have improved the outcome of these patients. The increasing number of HSCTs performed annually, the unique complications that develop in these patients, and the improvement in the intensive care unit outcome make knowledge about the critical care aspect of HSCT an essential part of the current practice of critical care medicine.

Invasive aspergillosis of the central nervous system after allogeneic stem cell transplantation

Central nervous system aspergillosis is a rare infectious complication in patients submitted to allogeneic stem cell transplantation. When it arises, this infection appears early post-transplant and most patients present with multiple central nervous system lesions. We report the clinical case of a 52 year old woman with IgGk multiple myeloma in relapse after a matched related allogeneic bone marrow transplant, who presented with a single large central nervous system Aspergillus lesion 11 months post-transplant in the setting of acute graft vs. host disease developing after the infusion of donor leucocytes. Although liposomal amphotericin B was promptly instituted, the patient died 1 week after the diagnosis.

Comparison of different protocols for DNA preparation and PCR for the detection of fungal pathogens in vitro

Although a large number of different PCR protocols for the detection of fungal DNA from clinical samples have been described, a generally recognised standardisation has not yet been developed. In a first step, we compared six different methods to isolate DNA under in vitro conditions from Aspergillus fumigatus, Candida albicans and Saccharomyces cerevisiae with respect to efficiency and expenditure of time. To this end, methods were tested that are based on both mechanical and enzymatic/thermic lysis. Thereby, enzymatic/thermic lysis were shown to be superior to mechanical lysis, although these methods of DNA isolation were more time consuming. The subsequent comparison of three different PCR protocols showed real-time PCR to be the most sensitive method.

Prophylactic use of liposomized tuftsin enhances the susceptibility ofCandida albicansto fluconazole in leukopenic mice

In the present study, we investigated the immunopotentiating activity of the immunomodulator tuftsin for the treatment of dose-dependent susceptible Candida albicans infection in a murine model. Our results demonstrated that tuftsin increases the susceptibility of C. albicans to phagocytosis by activating murine macrophages. Fluconazole used for the treatment of mice infected with C. albicans showed less in vivo efficacy and proved to be ineffective in the elimination of the infection from leukopenic mice even at higher doses. However, the antifungal activity of fluconazole against the same isolate of C. albicans significantly increased in tuftsin-pretreated mice and resulted in an improved survival rate in mice. The treated mice also showed less severity of infection as supported by a reduced fungal burden in their kidneys. This study indicates that the use of immunopotentiating substances can enhance the therapeutic efficacy of azole antifungal agents and thus can effectively combat azole-resistant fungal pathogens under conditions of immunosuppression.

Empiric antifungal therapy in neutropenic cancer patients

Hematopoietic stem cell transplant recipients and those patients with acute leukemia are at greatest risk for invasive fungal infections particularly due to Candida and Aspergillus species during periods of profound neutropenia. Empiric antifungal therapy in persistently febrile neutropenic patients has been adopted as a standard of care. Antifungal therapeutic options include: amphotericin B, lipid formulations of amphotericin B, fluconazole, itraconazole, voriconazole, and caspofungin. Amphotericin B preparations offer a beneficial effect for survival, defervescence, and a decrease in breakthrough fungal infections. Lipid formulations of amphotericin B may provide beneficial effects over amphotericin B with regard to survival, treatment of baseline fungal infection, breakthrough fungal infection, and fewer discontinuations due to lack of efficacy. Amphotericin B compounds produce a trend for better outcomes in defervescence, treatment of baseline fungal infections, prevention of breakthrough infections, and avoidance of discontinuation compared with the azoles. Caspofungin is also effective. The optimal empiric antifungal agent and the precise time of initiation remain to be determined.

Cockroaches as carriers of fungi of medical importance

The fungal pathogenic flora of the external surface of 103 cockroaches (Periplaneta americana) collected from the intensive care unit of a hospital were investigated. In this study, a high percentage of test cockroaches (93.2%) were found to carry fungi of medical importance. The main fungi isolated were species of Candida, Aspergillus and Penicillium. Information about the carriage of pathogenic fungi by cockroaches in hospital environment is scanty. The results suggest that cockroaches can play a role in dissemination of fungi, which they can carry on their external surface.

Successful treatment of disseminated aspergillosis with the combination of voriconazole, caspofungin, granulocyte transfusions, and surgery followed by allogeneic blood stem cell transplantation in a patient with primary failure of an autologous stem cell graft

The treatment of disseminated aspergillus infections in neutropenic patients remains a major challenge in spite of several new antifungal drugs. We report the case of a patient with multiple myeloma in prolonged neutropenia after primary failure of an autologous stem cell graft who developed invasive aspergillosis despite voriconazole monotherapy. He responded to a combination of voriconazole and caspofungin, supported by granulocyte transfusions and surgery. A subsequent allogeneic peripheral blood stem cell transplantation did not lead to recurring aspergillus infection. The patient is well and free of clinical disease with respect to the fungal infection and myeloma more than 18 months after the allogeneic transplantation.

Generation of cytotoxic T cell responses directed to human leucocyte antigen Class I restricted epitopes from the Aspergillus f16 allergen

Invasive aspergillosis (IA) is a major cause of infection-related mortality in patients with haematological malignancies, especially in recipients of haematopoietic stem cell transplants. We have prepared overlapping pentadecapeptides (11-aa overlap with previous peptide) spanning the entire 427-aa coding region of the Aspergillus allergen, Asp f16 shown previously in mice to induce Th1-type cell responses in vivo and in humans to induce proliferative and cytotoxic CD4(+) T cell responses. Mature dendritic cells (DC) pulsed with a complete pool of peptides were used to generate T cell lines. Two lines from HLA-B*3501(+) donors were found to be strongly cytotoxic to autologous Asp f16-peptide pool- and Aspergillus culture extract-pulsed targets after 4-5 weekly primings. Cytotoxic T lymphocyte (CTL) culture supernatant killed Aspergillus conidia, and cells directly killed Aspergillus hyphae. Cytotoxic activity and interferon (IFN)-gamma production were mediated exclusively by CD8(+) T cells in response to pool-pulsed targets. Interleukin (IL)-4 production was not detected. CTL activity was restricted by HLA-B*3501 and based on peptide prediction programmes was most probably directed to YFKYTAAAL (YFK), LPLCSAQTW (LPL) and GTRFPQTPM (GTR) in one donor, while only LPL was recognized by CTL from the second donor. Pool-pulsed B*3503(+) BLCL but not B*3502(+) or B*3508(+) BLCL presented peptide to donor no. 1. B*3503(+) BLCL presented YFK and to a lesser extent GTR, but not peptide LPL. Our data show that in addition to our previously identified Class II restricted peptide response, DC pulsed with a pentadecapeptide pool from Asp f16 are capable of inducing polyclonal, HLA-Class I-restricted, Aspergillus-specific T cells that may be capable of conferring immunity to IA.

Pharmacokinetic and maximum tolerated dose study of micafungin in combination with fluconazole versus fluconazole alone for prophylaxis of fungal infections in adult patients undergoing a bone marrow or peripheral stem cell transplant

In this dose escalation study, 74 adult cancer patients undergoing bone marrow or peripheral blood stem cell transplantation received fluconazole (400 mg/day) and either normal saline (control) (12 subjects) or micafungin (12.5 to 200 mg/day) (62 subjects) for up to 4 weeks. The maximum tolerated dose (MTD) of micafungin was not reached, based on the development of Southwest Oncology Group criteria for grade 3 toxicity; drug-related toxicities were rare. Commonly occurring adverse events considered related to micafungin were headache (6.8%), arthralgia (6.8%), hypophosphatemia (4.1%), insomnia (4.1%), maculopapular rash (4.1%), and rash (4.1%). Pharmacokinetic profiles for micafungin on days 1 and 7 were similar. The mean half-life was approximately 13 h, with little variance after repeated or increasing doses. Mean maximum concentrations of the drug in serum and areas under the concentration-time curve from 0 to 24 h were approximately proportional to dose. There was no clinical or kinetic evidence of interaction between micafungin and fluconazole. Five of 12 patients (42%) in the control group and 14 of 62 (23%) in the micafungin-plus-fluconazole groups had a suspected fungal infection during treatment which resulted in empirical treatment with amphotericin B. The combination of micafungin and fluconazole was found to be safe in this high-risk patient population. The MTD of micafungin was not reached even at doses up to 200 mg/day for 4 weeks. The pharmacokinetic profile of micafungin in adult cancer patients with blood or marrow transplants is consistent with the profile in healthy volunteers, and the area under the curve is proportional to dose.

Generation of Th1 T cell responses directed to a HLA Class II restricted epitope from the Aspergillus f16 allergen

The Aspergillus allergen Asp f16 has been shown to confer protective Th1 T cell-mediated immunity against infection with Aspergillus conidia in murine models. Here, we use overlapping (11-aa overlap with preceding peptide) pentadecapeptides spanning the entire 427-aa coding region of Asp f16 presented on autologous dendritic cells (DC) to evaluate the ability of this antigen to induce Th1 responses in humans. Proliferative responses were induced in five out of five donors, and one line with a high frequency of interferon (IFN)-gamma-producing CD4(+) T cells in response to the complete peptide pool was characterized. This line was cytotoxic to autologous pool-pulsed and Aspergillus culture extract-pulsed targets. Limitation of cytotoxicity to the CD4(+) T cell subset was demonstrated by co-expression of the degranulation marker CD107a in response to peptide pool-pulsed targets. Cytotoxic T lymphocytes (CTL) killed Aspergillus hyphae and CTL culture supernatant killed Aspergillus conidia. By screening 21 smaller pools and individual peptides shared by positive pools we identified a single candidate sequence of TWSIDGAVVRT that elicited responses equal to the complete pool. The defined epitope was presented by human leucocyte antigen (HLA)-DRB1-0301. These data identify the first known Aspergillus-specific T cell epitope and support the use of Asp f16 in clinical immunotherapy protocols to prime protective immune responses to prevent or treat Aspergillus infection in immunocompromised patients.

Aspergillus infections in transplant recipients

Aspergillus infections are occurring with an increasing frequency in transplant recipients. Notable changes in the epidemiologic characteristics of this infection have occurred; these include a change in risk factors and later onset of infection. Management of invasive aspergillosis continues to be challenging, and the mortality rate, despite the use of newer antifungal agents, remains unacceptably high. Performing molecular studies to discern new targets for antifungal activity, identifying signaling pathways that may be amenable to immunologic interventions, assessing combination regimens of antifungal agents or combining antifungal agents with modulation of the host defense mechanisms, and devising diagnostic assays that can rapidly and reliably diagnose infections represent areas for future investigations that may lead to further improvement in outcomes.

Candidaemia in allogeneic stem cell transplant recipients: low risk without fluconazole prophylaxis

Invasive fungal infections (IFI) are common in allogeneic SCT recipients. We have reviewed our experience of IFI with special reference to candidaemia in 685 adult patients transplanted in 1983-2002. The donor was a matched sibling in 505 patients and an unrelated donor in 180 patients. A BM graft was used in 561 patients and a PB graft in 124 patients. Fluconazole prophylaxis was not used during the study period. Definite or probable IFI was observed in 60 patients (8.7%) with a dominance of Aspergillus infections (46 patients, incidence 6.7%). Candidaemia was found only in nine patients (1.3%). The causative agents were Candida albicans (n=8), C. krusei (n=2), and C. glabrata (n=1); in two patients, two causative agents were found. The median time to the diagnosis of candidaemia was 53 days (range 6-249 days) post transplant. Seven patients were neutropaenic at diagnosis, and four patients had experienced acute GVHD. All patients received antifungal therapy, but only one patient was cured. According to this study, candidaemia was a rare event in allogeneic SCT recipients. Thus, systematic prophylaxis against Candida infections might not be indicated. The prognosis of established infections is still poor due to comorbid conditions, notably GVHD.

Invasive aspergillosis in patients with hematologic malignancies

Invasive aspergillosis is an increasingly common and often fatal opportunistic fungal infection in patients with hematologic malignancies. Prolonged and profound neutropenia remains a key risk factor for the development of invasive aspergillosis. However, qualitative deficiencies in host immune responses resulting from prolonged corticosteroid therapy, graft-versus-host disease, and cytomegalovirus infection are important risk factors for the recurrence and progression of Aspergillus infections after bone marrow recovery. Early diagnosis of invasive aspergillosis remains a challenge, and few tools are available for monitoring its course once the diagnosis is established. Even with the recent introduction of new antifungal therapies, mortality in patients with invasive aspergillosis remains high, and uniformly effective prophylaxis or preemptive therapeutic strategies are lacking. Strategies such as combination antifungal therapy and immunotherapy often are used as first-line treatment approaches in patients with documented invasive aspergillosis despite a paucity of clinical trial data. Recent advances in our understanding of the epidemiology, pathogenesis, and treatment of invasive aspergillosis in patients with hematologic malignancies are reviewed. The problems and controversies associated with defining optimal treatment strategies for invasive aspergillosis in this heavily immunocompromised population are highlighted.

Establishing the dose of the oral NK1 antagonist aprepitant for the prevention of chemotherapy-induced nausea and vomiting

BACKGROUND

The neurokinin-1 antagonist aprepitant (EMEND; Merck Research Laboratories, West Point, PA) has been shown to reduce chemotherapy-induced nausea and vomiting when it is given with a 5-hydroxytryptamine-3 receptor antagonist and dexamethasone. The current study sought to define the most appropriate dose regimen of oral aprepitant.

METHODS

This multicenter, randomized, double-blind, placebo-controlled study was conducted in patients with cancer who were receiving initial cisplatin (> or = 70 mg/m(2)) and standard antiemetic therapy (intravenous ondansetron plus oral dexamethasone). Patients were randomized to receive standard therapy plus either aprepitant 375 mg on Day 1 and 250 mg on Days 2-5, aprepitant 125 mg on Day 1 and 80 mg on Days 2-5, or placebo. Due to an apparent interaction with dexamethasone suggested by pharmacokinetic data obtained while the study was ongoing, the aprepitant 375/250 mg dose was discontinued and replaced with aprepitant 40 mg on Day 1 and 25 mg on Days 2-5, and a new randomization schedule was generated. Patients recorded nausea and emesis in a diary. The primary endpoint was complete response (no emesis and no rescue therapy), which was analyzed using an intent-to-treat approach with data obtained after the dose adjustment. Treatment comparisons were made using logistic regression models. Tolerability was assessed by reported adverse events and physical and laboratory assessments, and included all available data.

RESULTS

The percentages of patients who achieved a complete response in the overall study period were 71.0% for the aprepitant 125/80-mg group (n = 131 patients), 58.8% for the aprepitant 40/25-mg group (n = 119 patients), and 43.7% for the standard therapy group (n = 126 patients; P < 0.05 for either aprepitant regimen vs. standard therapy). Rates for Day 1 were 83.2% for the aprepitant 125/80-mg group, 75.6% for aprepitant 40/25-mg group, and 71.4% for the standard therapy group (P < 0.05 for aprepitant 125/80 mg vs. standard therapy), and rates on Days 2-5 were 72.7% for the aprepitant 125/80-mg group, 63.9% for the aprepitant 40/25-mg group, and 45.2% for the standard therapy group (P < 0.01 for either aprepitant group vs. standard therapy). The efficacy of the aprepitant 375/250-mg regimen was similar to that of the aprepitant 125/80-mg regimen. The overall incidence of adverse events was generally similar across treatment groups: 85% in the aprepitant 375/250-mg group (n = 34 patients), 76% in the aprepitant 125/80-mg group (n = 214 patients), 71% in the aprepitant 40/25-mg group (n = 120 patients), and 72% in the standard therapy group (n = 212 patients), with the exception of a higher incidence of infection in the aprepitant 125/80-mg group (13%) compared with the standard therapy group (4%).

CONCLUSIONS

When it was added to a standard regimen of intravenous ondansetron and oral dexamethasone in the current study, aprepitant reduced chemotherapy-induced nausea and vomiting and was generally well tolerated, although increases in infection were noted that were assumed to be due to elevated dexamethasone levels as a result of the pharmacokinetic interaction. The aprepitant 125/80-mg regimen had the most favorable benefit:risk profile.