Prospective surveillance for invasive fungal infections in hematopoietic stem cell transplant recipients, 2001-2006: overview of the Transplant-Associated Infection Surveillance Network (TRANSNET) Database

Drosophila melanogaster as a model organism for invasive aspergillosis

Mammalian hosts have traditionally been considered the "gold standard" models for studying pathogenesis and antifungal drug activity in invasive aspergillosis (IA). Nevertheless, logistical, economical, and ethical constraints make these host systems difficult to use for high-throughput screening of putative Aspergillus virulence factors and novel antifungal compounds. Here, we present Drosophila melanogaster, a heterologous non-vertebrate host with conserved innate immunity and genetic tractability, as an alternative, easy-to-use, and inexpensive pathosystem for studying Aspergillus pathogenesis and antifungal activity. We describe three different infection protocols (i.e., injection, rolling, ingestion) that introduce Aspergillus conidia at different anatomical sites of Toll-deficient Drosophila flies. These reproducible assays can be used to (1) determine the virulence of various Aspergillus strains and to (2) assess the anti-Aspergillus activity of orally absorbed antifungal agents in vivo. These methods can also be adapted to study pathogenesis and antifungal drug activity against other medically important human fungal pathogens.

Dectin-1-dependent interleukin-22 contributes to early innate lung defense against Aspergillus fumigatus

We have previously reported that mice deficient in the beta-glucan receptor Dectin-1 displayed increased susceptibility to Aspergillus fumigatus lung infection in the presence of lower interleukin 23 (IL-23) and IL-17A production in the lungs and have reported a role for IL-17A in lung defense. As IL-23 is also thought to control the production of IL-22, we examined the role of Dectin-1 in IL-22 production, as well as the role of IL-22 in innate host defense against A. fumigatus. Here, we show that Dectin-1-deficient mice demonstrated significantly reduced levels of IL-22 in the lungs early after A. fumigatus challenge. Culturing cells from enzymatic lung digests ex vivo further demonstrated Dectin-1-dependent IL-22 production. IL-22 production was additionally found to be independent of IL-1β, IL-6, or IL-18 but required IL-23. The addition of recombinant IL-23 augmented IL-22 production in wild-type (WT) lung cells and rescued IL-22 production by lung cells from Dectin-1-deficient mice. In vivo neutralization of IL-22 in the lungs of WT mice resulted in impaired A. fumigatus lung clearance. Moreover, mice deficient in IL-22 also demonstrated a higher lung fungal burden after A. fumigatus challenge in the presence of impaired IL-1α, tumor necrosis factor alpha (TNF-α), CCL3/MIP-1α, and CCL4/MIP-1β production and lower neutrophil recruitment, yet intact IL-17A production. We further show that lung lavage fluid collected from both A. fumigatus-challenged Dectin-1-deficient and IL-22-deficient mice had compromised anti-fungal activity against A. fumigatus in vitro. Although lipocalin 2 production was observed to be Dectin-1 and IL-22 dependent, lipocalin 2-deficient mice did not demonstrate impaired A. fumigatus clearance. Moreover, lung S100a8, S100a9, and Reg3g mRNA expression was not lower in either Dectin-1-deficient or IL-22-deficient mice. Collectively, our results indicate that early innate lung defense against A. fumigatus is mediated by Dectin-1-dependent IL-22 production.

Infections in Leukemia and Hematopoietic Stem Cell Transplantation

Infections are one of the most common complications in patients diagnosed with leukemia and serve as a major obstacle to treatment. Through the early 1970s, infections were the most common cause of death in patients diagnosed with acute leukemia, but improvement in treatment and supportive care over the past few decades, coupled with expanded prophylaxis and prevention regimens, have led to reduction in both the frequency and severity of infections. Regardless, due in part to an aging cancer population and the diversity of cancer treatments and procedures, infectious diseases remain a major cause of morbidity and mortality in patients with leukemia.

Transcript profiling of the murine immune response to invasive aspergillosis

Invasive aspergillosis is an opportunistic infection for which complex host-pathogen interactions determine infection outcome. In particular, immunosuppressive therapies and other host factors, such as neutropenia, need to be taken into account when modelling the immune response to aspergillosis. Mammalian models have been developed in order to gain a deeper understanding of these biological interactions, which cannot be easily replicated in vitro. In vivo transcript profiling is emerging as a valuable technique to gain an overview of host responses to invasive infections. This approach can be applied to specific tissue sections, whole organs, or peripheral blood leukocyte populations. Here we describe a microarray technique for analyzing transcript profiles from whole lung homogenates in the context of invasive aspergillosis. This approach has the advantage of enabling a broad overview of the immune responses that govern disease outcome. The generic techniques described, however, have wider application to other infectious processes and tissue types.

Genetically-determined hyperfunction of the S100B/RAGE axis is a risk factor for aspergillosis in stem cell transplant recipients

Invasive aspergillosis (IA) is a major threat to the successful outcome of hematopoietic stem cell transplantation (HSCT), although individual risk varies considerably. Recent evidence has established a pivotal role for a danger sensing mechanism implicating the S100B/receptor for advanced glycation end products (RAGE) axis in antifungal immunity. The association of selected genetic variants in the S100B/RAGE axis with susceptibility to IA was investigated in 223 consecutive patients undergoing HSCT. Furthermore, studies addressing the functional consequences of these variants were performed. Susceptibility to IA was significantly associated with two distinct polymorphisms in RAGE (-374T/A) and S100B (+427C/T) genes, the relative contribution of each depended on their presence in both transplantation counterparts [patient SNP_RAGE, adjusted hazard ratio (HR), 1.97; P = 0.042 and donor SNP_RAGE, HR, 2.03; P = 0.047] or in donors (SNP_S100B, HR, 3.15; P = 7.8e-⁴) only, respectively. Functional assays demonstrated a gain-of-function phenotype of both variants, as shown by the enhanced expression of inflammatory cytokines in RAGE polymorphic cells and increased S100B secretion in vitro and in vivo in the presence of the S100B polymorphism. These findings point to a relevant role of the danger sensing signaling in human antifungal immunity and highlight a possible contribution of a genetically-determined hyperfunction of the S100B/RAGE axis to susceptibility to IA in the HSCT setting.

The incidence and risk factors of invasive fungal infection after haploidentical haematopoietic stem cell transplantation without in vitro T-cell depletion

In recent years, we have successfully established a novel method of haploidentical haematopoietic stem cell transplantation (HSCT) without in vitro T-cell depletion. This study was aimed at analysing the incidence and risk factors of invasive fungal infection (IFI) with this transplantation method. The study comprised 291 patients who had undergone haploidentical HSCT from 1 January 2007 to 31 December 2008. IFI was diagnosed according to the European Organization for Research and Treatment of Cancer/Mycoses Study Group 2002 criteria, and only proven or probable cases of IFI were regarded as true cases. A total of 39 patients were documented as having IFI, including four proven cases and 35 probable cases. The median time of diagnosis was 26 days (range: 6-405 days) after transplantation. The cumulative incidence rates of IFI at 40 days, 1 year, 2 years and 3 years after transplantation were 8.25%, 13.1%, 13.4% and 13.4%, respectively. Multivariate analysis identified platelet engraftment time (>17 days) (p 0.027; hazard ratio (HR) 2.432; 95% CI 1.105-5.355), a high risk of underlying disease (p 0.001; HR 2.916; 95% CI 1.515-5.611) and grade III-IV acute graft-versus-host disease (p 0.019; HR 2.407; 95% CI 1.154-5.022) as risk factors for IFI. The incidence rates of IFI in patients with no, one, two or three risk factors at 3 years after transplantation were 4.48%, 7.86%, 29.6% and 23.1%, respectively. In conclusion, IFI is an important complication following haploidentical HSCT without in vitro T-cell depletion.

Imaging studies for diagnosing invasive fungal pneumonia in immunocompromised patients

PURPOSE OF REVIEW

The aim is to review imaging advances in invasive fungal pneumonia in cancer and transplant recipients and how their use can help guide treatment.

RECENT FINDINGS

Early chest computed tomographic (CT) imaging of immunocompromised patients with neutropenic fever leads to improved survival. Some of the typical CT findings of invasive fungal pneumonia are transitory and are most common during the first week of symptoms. The reversed halo sign, an early sign of disease, is more common in mucormycosis. During the first 10 days of infection, invasive fungal pneumonia nodules may grow on follow-up CT scans, but this does not necessarily equate to worsening disease. Because of the excessive radiation of chest CT and because pulmonary nodule size typically expands during the first few weeks of treatment, follow-up CT scans should be ordered only when therapy changes are dependent on imaging findings.

SUMMARY

Early chest CT imaging in immunocompromised patients suspected of having invasive fungal pneumonia can help identify disease early, leading to improved outcome.

Fungal pneumonia in patients with hematologic malignancies: current approach and management

PURPOSE OF REVIEW

Fungal pneumonia is the most frequent presentation of invasive mold infections (IMIs) in patients with hematologic malignancies. In this review, we summarize recent advances in the epidemiology, diagnosis, and treatment of fungal pneumonia and improvement in the outcome of such patients.

RECENT FINDINGS

The epidemiology of IMIs in hematopoietic stem cell transplant recipients has evolved in response to changes in conditioning regimens, increasing use of alternative sources of stem cells and antifungal prophylaxis, among other factors. PCR analysis and serologic tests, used in combination with imaging findings, have improved the timing and accuracy of diagnosis of these infections.Recent guidelines incorporated evidence-based treatment recommendations; however, application in real world situations is often difficult. A new treatment approach known as preemptive therapy, based on screening with biomarkers combined with early clinical and imaging findings, is being compared with the traditional empirical therapy in neutropenic patients with persistent or recurrent fever. The use of new triazoles and prompt diagnosis has contributed to improved outcomes in these patients. In addition, therapeutic drug monitoring may be useful when administering voriconazole.

SUMMARY

Evidence-based diagnosis and treatment of fungal pneumonia in patients with hematologic malignancies are becoming increasingly institution-specific and patient-specific, integrating host factors, new diagnostic methods, and epidemiologic and pharmacologic considerations.

Galactomannan detection in bronchoalveolar lavage fluid for the diagnosis of invasive aspergillosis in patients with hematological diseases-the role of factors affecting assay performance

BACKGROUND

We evaluated the performance of a galactomannan (GM) assay in bronchoalveolar lavage (BAL) fluid compared to serum samples for the diagnosis of invasive pulmonary aspergillosis (IPA) in patients with hematological diseases.

METHODS

Two hundred and fifty-five bronchoscopies were performed on 230 patients. Bronchial and alveolar samples from BAL fluid as well as serum samples were analyzed in the GM assay.

RESULTS

Twenty-eight cases of IPA (11%) were diagnosed. The sensitivity, specificity, positive predictive value, and negative predictive value of the GM assay using a cut-off of 0.5 were 57.1%, 99.3%, 94.1%, and 92.5%, respectively, for the alveolar sample; 44.0%, 99.3%, 91.7%, and 91.4%, respectively, for the bronchial sample; and 60.7%, 100%, 100%, and 92.9%, respectively, for serum. The highest sensitivity (78.6%) with good specificity (98.6%) was obtained with a 'triple detection' of GM in bronchial, alveolar, and serum samples. Neutropenia and antifungal therapy for only 24h increased the sensitivity, while antifungal treatment for ≥ 2 days decreased assay performance. Moreover, a trend towards a higher volume of aspirated fluid in GM-negative BAL (p=0.092) was observed.

CONCLUSIONS

In contrast to recently published data, we found only moderate sensitivity, but high specificity and high positive predictive value of the detection of GM in BAL fluid. In addition, neutropenia, antifungal therapy, and BAL standardization affected GM assay performance.

Susceptibility of 100 filamentous fungi: comparison of two diffusion methods, Neo-Sensitabs and E-test, for amphotericin B, caspofungin, itraconazole, voriconazole and posaconazole

We compared the E-test method to that of the Neo-Sensitabs tablet diffusion assay for evaluating the in vitro susceptibility of 100 clinical isolates of filamentous fungi (Aspergillus spp., Fusarium spp., Scedosporium spp., zygomycetes and other molds) to amphotericin B, itraconazole, voriconazole, caspofungin, and posaconazole. We determined the categorical agreement level between E-test minimum inhibitory concentrations (MIC) and tablet end-points, as opposed to the following disagreement parameters: very major error - resistant parameter (R) in E-test and susceptible (S) in tablet; major error - S by E-test and R by tablet; minor error - shifts between S and susceptible dose-dependent (S-DD) or S-DD and R. We also performed linear regression analyses and computed Pearson's correlation coefficients (R values) between the log transforms of MICs and the inhibition zone diameters of the five studied antifungal agents. For itraconazole we obtained 97% categorical agreement and R = -0.727. Categorical agreement for caspofungin and voriconazole was 96% and R =-0.821 and R = -0.789, respectively. For posaconazole the categorical agreement was 94% and R =-0.743. Amphotericin B exhibited a lower degree of agreement (76%, R = -0.672), especially in studies of Aspergillus spp. Our results suggest a potential value of the Neo-Sensitabs assay for in vitro susceptibility testing of molds to itraconazole, voriconazole, caspofungin and posaconazole, while amphotericin B exhibited an overall lower degree of agreement.

Molecular detection and species-specific identification of medically important Aspergillus species by real-time PCR in experimental invasive pulmonary aspergillosis

Diagnosis of invasive pulmonary aspergillosis (IPA) remains a major challenge to clinical microbiology laboratories. We developed rapid and sensitive quantitative PCR (qPCR) assays for genus- and species-specific identification of Aspergillus infections by use of TaqMan technology. In order to validate these assays and understand their potential diagnostic utility, we then performed a blinded study of bronchoalveolar lavage (BAL) fluid specimens from well-characterized models of IPA with the four medically important species. A set of real-time qPCR primers and probes was developed by utilizing unique ITS1 regions for genus- and species-specific detection of the four most common medically important Aspergillus species (Aspergillus fumigatus, A. flavus, A. niger, and A. terreus). Pan-Aspergillus and species-specific qPCRs with BAL fluid were more sensitive than culture for detection of IPA caused by A. fumigatus in untreated (P < 0.0007) and treated (P ≤ 0.008) animals, respectively. For infections caused by A. terreus and A. niger, culture and PCR amplification from BAL fluid yielded similar sensitivities for untreated and treated animals. Pan-Aspergillus PCR was more sensitive than culture for detection of A. flavus in treated animals (P = 0.002). BAL fluid pan-Aspergillus and species-specific PCRs were comparable in sensitivity to BAL fluid galactomannan (GM) assay. The copy numbers from the qPCR assays correlated with quantitative cultures to determine the pulmonary residual fungal burdens in lung tissue. Pan-Aspergillus and species-specific qPCR assays may improve the rapid and accurate identification of IPA in immunocompromised patients.

Differences in efficacy and cytokine profiles following echinocandin or liposomal amphotericin B monotherapy or combination therapy for murine pulmonary or systemic Aspergillus flavus infections

Given the recent increase in aspergillosis caused by species other than Aspergillus fumigatus, micafungin, caspofungin, and liposomal amphotericin B (L-AmBi) were investigated as monotherapy or combination therapy for murine systemic or pulmonary Aspergillus flavus infection. Treatment for 3 or 6 days was begun at 24 h (intravenous [i.v.], 2.8 × 10(4) conidia) or 2 h (intranasal, 4.1 × 10(6) to 6.75 × 10(6) conidia) postchallenge as follows: 5 or 10 mg/kg L-AmBi, 10 mg/kg caspofungin, 15 mg/kg micafungin, L-AmBi plus echinocandin, L-AmBi on days 1 to 3 and echinocandin on days 4 to 6, or echinocandin on days 1 to 3 and L-AmBi on days 4 to 6. Mice were monitored for survival, fungal burden, serum or tissue cytokines, and lung histopathology. In the systemic infection, micafungin or caspofungin was more effective than L-AmBi in prolonging survival (P < 0.05), and L-AmBi was associated with significantly elevated serum levels of interleukin-6 (IL-6), macrophage inflammatory protein 1α (MIP-1α), and IL-12 (P < 0.05). In contrast, L-AmBi was significantly more effective than the echinocandins in reducing fungal growth in most tissues (P < 0.05). Concomitant therapies produced significantly enhanced survival, reduction in fungal burden, and low levels of proinflammatory cytokines, while antagonism was seen with some sequential regimens. In comparison, in the pulmonary infection, L-AmBi was significantly better (P < 0.05) than caspofungin or the combination of L-AmBi and caspofungin in prolonging survival and reducing lung fungal burden. Caspofungin stimulated high lung levels of IL-1α, tumor necrosis factor alpha (TNF-α), and IL-6, with extensive tissue damage. In summary, systemic A flavus infection was treated effectively with L-AmBi plus micafungin or caspofungin provided that the drugs were administered concomitantly and not sequentially, while pulmonary A. flavus infection responded well to L-AmBi but not to caspofungin.

Efficacy of oral E1210, a new broad-spectrum antifungal with a novel mechanism of action, in murine models of candidiasis, aspergillosis, and fusariosis

E1210 is a first-in-class, broad-spectrum antifungal with a novel mechanism of action-inhibition of fungal glycosylphosphatidylinositol biosynthesis. In this study, the efficacies of E1210 and reference antifungals were evaluated in murine models of oropharyngeal and disseminated candidiasis, pulmonary aspergillosis, and disseminated fusariosis. Oral E1210 demonstrated dose-dependent efficacy in infections caused by Candida species, Aspergillus spp., and Fusarium solani. In the treatment of oropharyngeal candidiasis, E1210 and fluconazole each caused a significantly greater reduction in the number of oral CFU than the control treatment (P < 0.05). In the disseminated candidiasis model, mice treated with E1210, fluconazole, caspofungin, or liposomal amphotericin B showed significantly higher survival rates than the control mice (P < 0.05). E1210 was also highly effective in treating disseminated candidiasis caused by azole-resistant Candida albicans or Candida tropicalis. A 24-h delay in treatment onset minimally affected the efficacy outcome of E1210 in the treatment of disseminated candidiasis. In the Aspergillus flavus pulmonary aspergillosis model, mice treated with E1210, voriconazole, or caspofungin showed significantly higher survival rates than the control mice (P < 0.05). E1210 was also effective in the treatment of Aspergillus fumigatus pulmonary aspergillosis. In contrast to many antifungals, E1210 was also effective against disseminated fusariosis caused by F. solani. In conclusion, E1210 demonstrated consistent efficacy in murine models of oropharyngeal and disseminated candidiasis, pulmonary aspergillosis, and disseminated fusariosis. These data suggest that further studies to determine E1210's potential for the treatment of disseminated fungal infections are indicated.

Role of Aspergillus lentulus 14-α sterol demethylase (Cyp51A) in azole drug susceptibility

Recent studies have demonstrated that some morphologically atypical Aspergillus fumigatus strains are different species belonging to the section Fumigati. Aspergillus lentulus, one of these sibling species, is increasingly reported in patients under corticosteroid treatment. MICs of most antifungals in clinical use are elevated against A. lentulus, and it shows primary resistance to azole drugs. Two A. lentulus cytochrome P450 14-α sterol demethylases, encoded by A. lentulus cyp51A (Alcyp51A) and Alcyp51B genes, were identified. Targeted cyp51A gene knockout in A. lentulus showed that the intrinsic azole resistance of this species is cyp51A dependent. The Δcyp51A strain was morphologically indistinguishable from the A. lentulus wild-type strain, retaining the ability to cause pulmonary disease in neutropenic mice. The heterologous expression of A. lentulus cyp51A was performed in an A. fumigatus cyp51A-deficient strain, confirming that Cyp51A is responsible for the differences in A. lentulus-azole drug interaction.

Mucorales-specific T cells emerge in the course of invasive mucormycosis and may be used as a surrogate diagnostic marker in high-risk patients

Mucorales-specific T cells were investigated in 28 hematologic patients during the course of their treatment. Three developed proven invasive mucormycosis (IM), 17 had infections of known origin but other than IM, and 8 never had fever during the period of observation. Mucorales-specific T cells could be detected only in patients with IM, both at diagnosis and throughout the entire course of the IM, but neither before nor for long after resolution of the infection. Such T cells predominantly produced IL-4, IFN-γ, IL-10, and to a lesser extent IL-17 and belonged to either CD4(+) or CD8(+) subsets. The specific T cells that produced IFN-γ were able to directly induce damage to Mucorales hyphae. None of the 25 patients without IM had Mucorales-specific T cells. Specific T cells contribute to human immune responses against fungi of the order Mucorales and could be evaluated as a surrogate diagnostic marker of IM.

Evaluation of Luminex xTAG fungal analyte-specific reagents for rapid identification of clinically relevant fungi

Invasive fungal infections (IFI) remain a serious threat to immunocompromised hosts. Current diagnostic methods, including fungal culture and antigen detection, are slow and often lack specificity. Rapid diagnostic tools with increased sensitivity and specificity could improve the care of patients with IFI. Recently, Luminex Molecular Diagnostics (Toronto, Canada) developed 23 analyte-specific reagents (ASRs) for the detection of the most common clinically relevant fungi. This study's objective was to evaluate the sensitivity and specificity of a subset of these ASRs for fungal isolates and clinical specimens. Previously characterized fungal and bacterial isolates (n = 110), blood culture specimens (n = 34), and respiratory specimens (n = 44) were tested using either a Candida 7-plex panel (Candida albicans, Candida glabrata, Candida tropicalis, Candida parapsilosis, Candida lusitaniae, Candida guilliermondii, and Candida krusei) or a mold 11-plex panel (Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger, Aspergillus terreus, Scedosporium prolificans, Scedosporium apiospermum, Fusarium oxysporum/Fusarium solani, Rhizopus arrhizus, Rhizopus microsporus, Mucor indicus, and Cunninghamella bertholletiae). The Candida 7-plex panel correctly identified all Candida isolates as confirmed by fungal culture and biochemical tests, for a sensitivity and specificity of 100%. The mold 11-plex panel correctly identified all mold isolates tested except for A. niger. Fungal isolates of Rhizopus and Mucor species were not detected, either, although they could represent species other than those targeted by the ASRs. Further evaluation will be necessary to confirm the sensitivities of some of the mold ASRs. Implementation of these ASRs will allow same-day detection of fungal DNA in clinical specimens.

T cell immunity and vaccines against invasive fungal diseases

Over the past two decades much has been learned about the immunology of invasive fungal infection, especially invasive candidiasis and invasive aspergillosis. Although quite different in their pathogenesis, the major common protective host response is Th1 mediated. It is through Th1 cytokine production that the effector cells, phagocytes, are activated to kill the fungus. A more thorough understanding of the pathogenesis of disease, the elicited protective Th1 immune response, the T cell antigen(s) which elicit this response, and the mechanism(s) whereby one can enhance, reconstitute, or circumvent the immunosuppressed state will, hopefully, lead to the development of a vaccine(s) capable of protecting even the most immunocompromised of hosts.

Generation of a multipathogen-specific T-cell product for adoptive immunotherapy based on activation-dependent expression of CD154

Viral and fungal infections remain a leading cause of mortality in patients after hematopoietic stem cell transplantation (HSCT). Adoptive transfer of multipathogen-specific T cells is promising in restoring immunity and thereby preventing and treating infections, but approaches are currently limited because of time-consuming and laborious procedures. Therefore, we investigated a new strategy to simultaneously select T cells specific for viral and fungal pathogens based on activation-dependent expression of CD154. Single- and multipathogen-specific T-cell lines with high specificity for adenovirus (AdV), Epstein-Barr virus (EBV), cytomegalovirus (CMV), Candida albicans, and/or Aspergillus fumigatus could be readily generated within 14 days irrespective of the precursor frequency. The T-cell lines responded reproducibly to endogenously processed antigen and specifically proliferated upon antigenic stimulation. Although isolation based on CD154 favors enrichment of CD4+ T cells, AdV-, EBV- and CMV-specific CD8+ T cells could be expanded and demonstrated lysis of target cells. Conversely, T cell–mediated alloreactivity was almost abrogated compared with the starting fraction. This selection and/or expansion strategy may form the basis for future adoptive immunotherapy trials in patients at risk for multiple infections and may be translated to other antigens.

Comparison of quantitative real time PCR with Sequencing and ribosomal RNA-FISH for the identification of fungi in formalin fixed, paraffin-embedded tissue specimens

Background

Identification of the causative agents of invasive fungal infections (IFI) is critical for guiding antifungal therapy. Cultures remain negative in a substantial number of IFI cases. Accordingly, species identification from formalin fixed, paraffin embedded (FFPE) tissue specimens by molecular methods such as fluorescence in situ hybridisation (FISH) and PCR provides an appealing approach to improve management of patients.

Methods

We designed FISH probes targeting the 28S rRNA of Aspergillus and Candida and evaluated them with type strains. Fluorescence microscopy (FM), using FISH probes and quantitative broad-range fungal PCR targeting the rRNA gene were applied to FFPE tissue specimens from patients with proven IFI in order to explore benefits and limitations of each approach.

Results

PCR followed by sequencing identified a broad spectrum of pathogenic fungi in 28 of 40 evaluable samples (70%). Hybridisation of FISH probes to fungal rRNA was documented in 19 of 40 tissue samples (47.5%), including 3 PCR negative samples with low fungal burden. The use of FISH was highly sensitive in invasive yeast infections, but less sensitive for moulds. In samples with hyphal elements, the evaluation of hybridisation was impaired due to autofluorescence of hyphae and necrotic tissue background.

Conclusions

While PCR appears to be more sensitive in identifying the causative agents of IFI, some PCR negative and FISH positive samples suggest that FISH has some potential in the rapid identification of fungi from FFPE tissue samples.

Comparison of the occurrence of mold infection among patients receiving chemotherapy for acute leukemia versus patients undergoing stem cell transplantation

OBJECTIVES

Invasive mold infections (IMI) are an important cause of morbidity and mortality in patients with hematological malignancies. Cumulative incidence numbers vary greatly, probably because local circumstances influence the incidence of IMI. Therefore, comparison of different patient groups at risk should be performed at one hospital.

METHODS

We performed a single-center retrospective analysis examining both adult patients treated with chemotherapy for acute leukemia or MDS and patients undergoing allogeneic or autologous stem cell transplantation (SCT) between June 2007 and August 2009. IMI were classified according to the EORTC criteria.

RESULTS

A total of 211 patients with 237 predefined risk episodes were analyzed. A total of 22 IMI were observed: three of them were classified as proven, 15 as probable, and four as possible. No IMI were observed in the autologous SCT group. The incidence of proven and probable IMI in the allogeneic SCT group was 7.2%, and in the chemotherapy group, 14.3%. Patients with IMI had a higher mortality risk.

CONCLUSIONS

We demonstrate for the first time that patients receiving intensive chemotherapy for acute leukemia have the highest risk of developing IMI during their treatment compared to patients with allogeneic SCT.

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.

Recent advances in invasive pulmonary aspergillosis

PURPOSE OF REVIEW

This review highlights the most important and salient recent developments with regards to invasive pulmonary aspergillosis (IPA), currently the most common opportunistic fungal pneumonia in patients with hematological malignancies.

RECENT FINDINGS

Besides patients in hematology units, other immunosuppressed and critically ill patients are also at risk of IPA. Identification of patients who possess specific polymorphisms of Toll-like receptor 4 and dectin-1, both of which are involved in the immune sensing of Aspergillus spp., may facilitate risk-stratification. The use of the galactomannan assay in bronchoalveolar fluid to improve diagnosis of IPA is undergoing validation. Trending galactomannan and other biomarker results may prognosticate clinical outcomes. During intensive chemotherapy for leukemia, posaconazole and aerosolized liposomal amphotericin B (L-AMB) have demonstrated efficacy as prophylaxis against invasive fungal infection. However, fluconazole remains an effective prophylactic agent in the setting of hematopoietic stem cell transplantation despite availability of newer antifungal agents. Although voriconazole is still the drug of choice for IPA, both caspofungin and L-AMB are viable alternatives.

SUMMARY

Despite increasing knowledge of IPA and availability of newer antifungal agents, clinical management remains a challenge in the setting of a compromised host defense system that is unable to mount an appropriate immune response against the pathogen.

Immunity and tolerance to infections in experimental hematopoietic transplantation

Resistance and tolerance are two types of host defense mechanisms that increase fitness in response to fungi. Several genetic polymorphisms in pattern recognition receptors, most remarkably Toll-like receptors (TLRs), have been described to influence resistance and tolerance to aspergillosis in distinct clinical settings. TLRs on dendritic cells pivotally contribute in determining the balance between immunopathology and protective immunity to the fungus. Epithelial cells also contribute to this balance via selected TLRs converging on indoleamine-2,3-dioxygenase (IDO). Studies in experimental hematopoietic transplantation confirmed the dichotomy of pathways leading to resistance and tolerance to the fungus providing new insights on the relative contribution of the hematopoietic/nonhematopoietic compartments.

Fatal invasive infection with fungemia due to Microascus cirrosus after heart and lung transplantation in a patient with cystic fibrosis

Scopulariopsis species are rarely but increasingly recognized as opportunistic pathogens in immunocompromised patients. We report on a patient suffering from cystic fibrosis who developed disseminated fungal infection due to a rare Scopulariopsis species, Microascus cirrosus, after heart and lung transplantation. Despite antifungal combination therapy with voriconazole and caspofungin, the patient died 4 weeks after transplantation. Diagnostic difficulties and optimal management of disseminated Scopulariopsis/Microascus infections are discussed.

Emerging fungal infections in immunocompromised patients

Invasive fungal infections are infections of importance and are increasing in incidence in immunocompromised hosts such as patients who have had hematopoietic stem cell and solid organ transplants. Despite our expanded antifungal armamentarium, these infections cause considerable morbidity and mortality. Indeed, certain trends have emerged in these invasive fungal infections: a rise in the incidence of invasive mold infections, an increase in the non-albicans strains of Candida spp. causing invasive disease and, finally, the emergence of less susceptible fungal strains that are resistant to the broader-spectrum antifungal agents due to overutilization of these agents. Clinicians must recognize the patient groups that are potentially at risk for these invasive fungal infections, as well as the risk factors for such infections. By using more sensitive nonculture-based diagnostic techniques, appropriate therapy may be initiated earlier to enhance survival in these immunocompromised patient populations.

Invasive fungal infections in pediatric oncology

BACKGROUND

Data on the epidemiology and outcome of invasive fungal infections in children with cancer are limited. The aim of the study was to delineate the epidemiologic, clinical features, risk factors, and outcome of invasive fungal infections in this population.

PROCEDURE

The medical records of all children with malignancies diagnosed with an invasive fungal infection in 1998-2006 at a tertiary pediatric medical center were reviewed for demographic, clinical, and laboratory data. Invasive fungal infection was diagnosed according to the latest EORTC/MSG criteria.

RESULTS

Of the 1,047 children hospitalized in the hematology/oncology department during the study period, 75 (7.2%) were diagnosed with a proven (n = 16, 21.3%), probable (n = 18, 24%), or possible (n= 41, 54.7%) invasive fungal infection. Fifteen (20%) had candidemia (non-albicans in 60%), and 60 (80%) had a mold infection (non-Aspergillus in 55%). Crude mortality was 21.7%. The most common underlying diseases were myeloid leukemia (n = 26, 34.7%) and acute lymphoblastic leukemia (n = 24, 32%). Compared to other malignancies, acute myeloid leukemia was significantly associated with the development of invasive fungal infections. Profound neutropenia and high treatment intensity were present in 89% and 73% of patients with IFI respectively.

CONCLUSIONS

The current mortality rates of invasive fungal infection in children with cancer are lower than previously reported in children and adults. However, the proportion of non-albicans candidemia is increasing, and non-Aspergillus molds are emerging as important pathogens, which may have important implications for prophylaxis and empiric therapy. Improved prevention, early detection, and advanced treatment strategies are needed to improve the outcome.

In vitro echinocandin susceptibility of Aspergillus isolates from patients enrolled in the Transplant-Associated Infection Surveillance Network

We determined the echinocandin minimum effective concentration (MEC) values for caspofungin, micafungin, and anidulafungin against 288 Aspergillus isolates prospectively collected from transplant patients with proven or probable invasive aspergillosis between 2001 and 2006 as part of the Transplant-Associated Infection Surveillance Network (TRANSNET). We demonstrated that the vast majority of Aspergillus isolates had MEC values at or below the epidemiological cutoff values for caspofungin, micafungin, and anidulafungin, including those from patients who had received caspofungin.

Five-years surveillance of invasive aspergillosis in a university hospital

Background

As the most common invasive fungal infection, invasive aspergillosis (IA) remains a serious complication in immunocompromised patients, leading to increased mortality. Antifungal therapy is expensive and may result in severe adverse effects.

The aim of this study was to determine the incidence of invasive aspergillosis (IA) cases in a tertiary care university hospital using a standardized surveillance method.

Methods

All inpatients at our facility were screened for presence of the following parameters: positive microbiological culture, pathologist's diagnosis and antifungal treatment as reported by the hospital pharmacy. Patients fulfilling one or more of these indicators were further reviewed and, if appropriate, classified according to international consensus criteria (EORTC).

Results

704 patients were positive for at least one of the indicators mentioned above. Applying the EORTC criteria, 214 IA cases were detected, of which 56 were proven, 25 probable and 133 possible. 44 of the 81 (54%) proven and probable cases were considered health-care associated. 37 of the proven/probable IA cases had received solid organ transplantation, an additional 8 had undergone stem cell transplantation, and 10 patients were suffering from some type of malignancy. All the other patients in this group were also suffering from severe organic diseases, required long treatment and experienced several clinical complications. 7 of the 56 proven cases would have been missed without autopsy. After the antimycotic prophylaxis regimen was altered, we noticed a significant decrease (p = 0.0004) of IA during the investigation period (2003-2007).

Conclusion

Solid organ and stem cell transplantation remain important risk factors for IA, but several other types of immunosuppression should also be kept in mind. Clinical diagnosis of IA may be difficult (in this study 13% of all proven cases were diagnosed by autopsy only). Thus, we confirm the importance of IA surveillance in all high-risk patients.

Mucormycosis: its contemporary face and management strategies

Several countries have seen rising frequencies of mucormycosis among patients with haematological disorders, malignancies, or diabetes mellitus, and among transplant recipients. Growing numbers of immunocompromised hosts, widespread use of antifungal agents inactive against mucormycosis, or other unidentified factors, could be contributing to this situation. The predominant clinical manifestations of mucormycosis vary from host to host. Additionally, risk factors specific to different subgroups have been identified, such as leukaemia, allogeneic haemopoietic stem-cell transplant, voriconazole prophylaxis, diabetes, and malnutrition. We summarise the current state of knowledge of characteristics and risk factors and discuss topical developments in therapeutic methods and strategies in the management of mucormycosis.

Immunotherapy against invasive fungal diseases in stem cell transplant recipients

Despite the availability of new antifungal compounds, morbidity and mortality of invasive fungal disease in allogeneic hematopoietic stem cell recipients are still unacceptably high. Over the past decade, one could witness an exciting improvement of the understanding of the molecular pathogenesis and of the complexity of host antifungal immune responses. This, in turn, provides critical information to augment host immunity against fungal pathogens. Strategies for enhancing the immune system include the administration of effector and regulatory cells (e.g., granulocytes, antigen-specific T cells, dendritic cells) as well as the administration of recombinant cytokines, interferons and growth factors (e.g., interferon-γ, keratinocyte growth factor, granulocyte- and granulocyte-macrophage colony stimulating factor). One has to recognize at the same time, however, that data of in vitro assays and animal models cannot necessarily be transferred into the clinical setting. In addition, meaningful clinical trials in allogeneic stem cell recipients suffering from invasive fungal disease require sufficiently large and homogenous cohorts of patients and can only be performed in international collaboration, but may ultimately improve the outcome of allogeneic transplant recipients with invasive fungal disease.

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.

Comparison of in vitro susceptibility characteristics of Candida species from cases of invasive candidiasis in solid organ and stem cell transplant recipients: Transplant-Associated Infections Surveillance Network (TRANSNET), 2001 to 2006

Invasive fungal infections (IFI) are a major cause of morbidity and mortality among both solid organ transplant (SOT) and hematopoietic stem cell transplant (HSCT) recipients. Candida is the most common cause of IFI in SOT recipients and the second most common cause of IFI in HSCT recipients. We determined susceptibilities to fluconazole, voriconazole, itraconazole, posaconazole, amphotericin B, and caspofungin for 383 invasive Candida sp. isolates from SOT and HSCT recipients enrolled in the Transplant-Associated Infection Surveillance Network and correlated these results to clinical data. Fluconazole resistance in C. albicans, C. tropicalis, and C. parapsilosis isolates was low (1%), but the high percentage of C. glabrata and C. krusei isolates within this group of patients increased the overall percentage of fluconazole resistance to 16%. Voriconazole resistance was 3% overall but was 8% among C. glabrata isolates. On multivariable analysis, among HSCT recipients fluconazole nonsusceptibility was independently associated with C. glabrata, non-Hodgkin's lymphoma, cytomegalovirus (CMV) antigenemia, diabetes active at the time of the IFI, and any prior amphotericin B use; among SOT recipients, fluconazole nonsusceptibility was independently associated with any fluconazole use in the 3 months prior to the IFI, C. glabrata, ganciclovir use in the 3 months prior to the IFI, diabetes acquired since the transplant, and gender.