Invasive fungal infections among organ transplant recipients: results of the Transplant-Associated Infection Surveillance Network (TRANSNET)

Lung transplant infection

Lung transplantation has become an accepted therapeutic procedure for the treatment of end‐stage pulmonary parenchymal and vascular disease. Despite improved survival rates over the decades, lung transplant recipients have lower survival rates than other solid organ transplant recipients. The morbidity and mortality following lung transplantation is largely due to infection‐ and rejection‐related complications. This article will review the common infections that develop in the lung transplant recipient, including the general risk factors for infection in this population, and the most frequent bacterial, viral, fungal and other less frequent opportunistic infections. The epidemiology, diagnosis, prophylaxis, treatment and outcomes for the different microbial pathogens will be reviewed. The effects of infection on lung transplant rejection will also be discussed.

Identification and antifungal susceptibility of a large collection of yeast strains isolated in Tunisian hospitals

In this study, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used as a rapid method to identify yeasts isolated from patients in Tunisian hospitals. When identification could not be exstablished with this procedure, sequencing of the internal transcribed spacer with 5.8S ribosomal DNA (rDNA) (ITS1-5.8S-ITS2) and D1/D2 domain of large-subunit (LSU rDNA) were employed as a molecular approach for species differentiation. Candida albicans was the dominant species (43.37% of all cases), followed by C. glabrata (16.55%), C. parapsilosis (13.23%), C. tropicalis (11.34%), C. dubliniensis (4.96%), and other species more rarely encountered in human diseases such as C. krusei, C. metapsilosis, C. lusitaniae, C. kefyr, C. palmioleophila, C. guilliermondii, C. intermedia, C. orthopsilosis, and C. utilis. In addition, other yeast species were obtained including Saccharomyces cerevisiae, Debaryomyces hansenii (anamorph known as C. famata), Hanseniaspora opuntiae, Kodamaea ohmeri, Pichia caribbica (anamorph known as C. fermentati), Trichosporon spp. and finally a novel yeast species, C. tunisiensis. The in vitro antifungal activities of fluconazole and voriconazole were determined by the agar disk diffusion test and Etest, while the susceptibility to additional antifungal agents was determined with the Sensititre YeastOne system. Our results showed low incidence of azole resistance in C. albicans (0.54%), C. tropicalis (2.08%) and C. glabrata (4.28%). In addition, caspofungin was active against most isolates of the collection with the exception of two K. ohmeri isolates. This is the first report to describe caspofungin resistant isolates of this yeast.

Invasive fungal infections in transplant recipients

Invasive fungal infections are an important cause of morbidity and mortality in hematopoietic stem cell transplant and solid organ transplant recipients. Evolving transplant modalities and techniques, complex and extensive immunosuppressant strategies, and the increased use of broad spectrum antifungal prophylaxis has greatly impacted the epidemiology and temporal pattern of invasive fungal infections in the transplant population. The goal of this article is to provide an up-to-date review of the most commonly encountered invasive fungal infections seen in transplant recipients, including epidemiology, risk factors, clinical features, diagnostic dilemmas, management and their overall influence on outcomes.

Population-based survey of filamentous fungi and antifungal resistance in Spain (FILPOP Study)

A population-based survey was conducted to investigate the epidemiology of and antifungal resistance in Spanish clinical strains of filamentous fungi isolated from deep tissue samples, blood cultures, and respiratory samples. The study was conducted in two different periods (October 2010 and May 2011) to analyze seasonal variations. A total of 325 strains were isolated in 29 different hospitals. The average prevalence was 0.016/1,000 inhabitants [corrected]. Strains were identified by sequencing of DNA targets and susceptibility testing by the European Committee for Antimicrobial Susceptibility Testing reference procedure. The most frequently isolated genus was Aspergillus, accounting for 86.3% of the isolates, followed by Scedosporium at 4.7%; the order Mucorales at 2.5%; Penicillium at 2.2%, and Fusarium at 1.2%. The most frequent species was Aspergillus fumigatus (48.5%), followed by A. flavus (8.4%), A. terreus (8.1%), A. tubingensis (6.8%), and A. niger (6.5%). Cryptic/sibling Aspergillus species accounted for 12% of the cases. Resistance to amphotericin B was found in 10.8% of the isolates tested, while extended-spectrum triazole resistance ranged from 10 to 12.7%, depending on the azole tested. Antifungal resistance was more common among emerging species such as those of Scedosporium and Mucorales and also among cryptic species of Aspergillus, with 40% of these isolates showing resistance to all of the antifungal compounds tested. Cryptic Aspergillus species seem to be underestimated, and their correct classification could be clinically relevant. The performance of antifungal susceptibility testing of the strains implicated in deep infections and multicentric studies is recommended to evaluate the incidence of these cryptic species in other geographic areas.

Fungal infections after liver transplantation: outcomes and risk factors revisited in the MELD era

Antifungal prophylaxis is recommended in high-risk patients, but risk criteria remain unclear and the predictive value of Model of End-Stage Liver Disease (MELD) score is unknown. In a retrospective, single-center analysis of 667 liver transplants, potential risk factors for fungal infection were assessed, including MELD score. Antifungal prophylaxis was administered in 198 patients (29.4%). During follow-up (mean 43.6 ± 29.6 months), 263 patients (39.4%) developed ≥ 1 episode of fungal infection, and 187 (28.0%) patients developed a probable or proven invasive fungal infection requiring systemic antifungal treatment. Patients receiving antifungal prophylaxis had a lower incidence of fungal infection (29.8% vs. 43.5% without prophylaxis, p < 0.001) and invasive fungal infection (17.7% vs. 32.4%, p < 0.001). One-yr patient survival was 91%, 85% and 69%, respectively, in patients with no fungal infection, fungal colonization and treated invasive fungal infection (p < 0.001); graft survival was 88%, 85% and 66% (p < 0.001). Multivariate analysis indicated that MELD score of 20-30 or ≥ 30 was associated with a 2.0-fold or 4.3-fold increase in relative risk of fungal infection, respectively, and a 2.1-fold or 3.1-fold increase in relative risk of invasive fungal infection. In conclusion, liver transplant patients with a MELD score ≥ 20, and particularly patients with a score ≥ 30, are candidates for antifungal prophylaxis.

A new and clinically relevant murine model of solid-organ transplant aspergillosis

Invasive fungal infections (IFIs) are a major cause of death in organ transplant patients. The murine hydrocortisone-mediated immunosuppression model of pulmonary aspergillosis is commonly used to characterise IFIs in these patients. However, this model does not take into account the effects of calcineurin inhibitors on transplant immunity to IFIs or the fungal calcineurin pathway, which is required for both virulence and antifungal drug resistance. To address these two issues, a new and clinically relevant transplant immunosuppression model of tacrolimus (FK506) and hydrocortisone-associated pulmonary aspergillosis was developed. We first characterised IFIs in 406 patients with a lung transplant. This showed that all of the patients with pulmonary aspergillosis were immunosuppressed with calcineurin inhibitors and steroids. Murine pharmacokinetic studies demonstrated that an ideal dose of 1 mg/kg/day of FK506 intraperitoneally produced blood trough levels in the human therapeutic range (5-12 ng/ml). There was increased mortality from pulmonary aspergillosis in a transplant-relevant immunosuppression model using both FK506 and hydrocortisone as compared with immunosuppression using hydrocortisone only. Lung histopathology showed neutrophil invasion and tracheobronchitis that was associated with reduced lung tumour necrosis factor-α (TNFα), JE (homologue of human MCP-1) and KC (homologue of human IL-8) at 24 hours, but increased lung TNFα, JE and KC at 48 hours when fungal burden was high. Furthermore, FK506 directly impaired fungal killing in alveolar macrophages in vitro, with FK506-mediated inhibition of the radial growth of Aspergillus fumigatus in vitro occurring at the low concentration of 5 ng/ml. Taken together, these findings show that the immunosuppressive activity of FK506 outweighs its antifungal activity in vivo. These observations demonstrate that FK506 impairs innate immune responses and leads to an incremental increase in susceptibility to IFIs when it is combined with steroids. This new and clinically relevant mouse model of invasive aspergillosis is a valuable addition to the further study of both fungal immunity and antifungal therapy in organ transplantation.

Pretransplant model for end stage liver disease score predicts posttransplant incidence of fungal infections after liver transplantation

Liver transplant recipients are at a significant risk for invasive fungal infections (IFI). This retrospective study evaluated the impact of the pretransplant model for end stage liver disease (MELD) on the incidence of posttransplant IFI in a single centre. From 2004 to 2008, 385 liver transplantations were included, from which 210 transplantations were conducted allocated by Child Turcotte Pugh and 175 were allocated by MELD score. Both groups differed regarding the age of transplant recipients (50.1 ± 10.7 vs. 52.5 ± 9.9, P = 0.036), pretransplant MELD score (16.43 ± 8.33 vs. 18.29 ± 9.05), rate of re-transplantations, duration of surgery, demand in blood transfusions and rates of renal impairments. In the MELD era, higher incidences of IFI (pre-MELD 11.9%, MELD 24.0%, P < 0.05) and Candida infections (9% vs. 18.9%, P < 0.05) were observed. There was no difference in the incidence of probable or possible aspergillosis. Mortality, length of stay in intensive care or hospital, and duration of mechanical ventilation did not differ between the pre-MELD and MELD era. Regardless the date of transplantation, patients with fungi-positive samples showed higher mortality rates than patients without. MELD score was analysed as independent predictors for posttransplant IFI. Higher MELD scores predispose to a more problematic postoperative course and are associated with an increase in fungal infections.

Potential factors for inadequate voriconazole plasma concentrations in intensive care unit patients and patients with hematological malignancies

Voriconazole plasma concentrations (VPCs) vary widely, and concentrations outside the therapeutic range are associated with either worse outcome in invasive aspergillosis (IA) or increased toxicity. The primary goal of this cohort study conducted in a real-life setting was to identify potential factors associated with inadequate VPCs in ICU patients and patients with hematological malignancies. Within a period of 12 months, trough VPCs were obtained and analyzed with high-performance liquid chromatography, and the adequate range was defined as 1.5 to 5.5 mg/liter. VPCs of <1.5 mg/liter were defined as low, whereas VPCs of >5.5 mg/liter were defined as potentially toxic. A total of 221 trough VPCs were obtained in 61 patients receiving voriconazole, and 124/221 VPCs (56%) were found to be low. Multivariate analysis revealed that low VPCs were significantly associated with clinical failure of voriconazole, prophylactic use, younger age, underlying hematological malignancy, concomitant proton pump inhibitor (PPI) (pantoprazole was used in 88% of the patients), and absence of side effects. Low VPCs remained an independent predictor of clinical failure of voriconazole. The defined adequate range was reached in 79/221 (36%) VPCs. In 18 samples (8%), potentially toxic levels were measured. Multivariate analysis revealed higher body mass index (BMI), absence of hematological malignancy, therapeutic application, and diarrhea as factors associated with potentially toxic VPCs. Neurotoxic adverse events occurred in six patients and were mostly associated with VPCs in the upper quartile of our defined adequate range. In conclusion, potential factors like younger age, prophylaxis, underlying hematological malignancy, BMI, and concomitant PPI should be considered within the algorithm of voriconazole treatment.

Is azole resistance in Aspergillus fumigatus a problem in Spain?

Aspergillus fumigatus complex comprises A. fumigatus and other morphologically indistinguishable cryptic species. We retrospectively studied 362 A. fumigatus complex isolates (353 samples) from 150 patients with proven or probable invasive aspergillosis or aspergilloma (2, 121, and 6 samples, respectively) admitted to the hospital from 1999 to 2011. Isolates were identified using the β-tubulin gene, and only 1 isolate per species found in each sample was selected. Antifungal susceptibility to azoles was determined using the CLSI M38-A2 procedure. Isolates were considered resistant if they showed an MIC above the breakpoints for itraconazole, voriconazole, or posaconazole (>2, >2, or >0.5 μg/ml). Most of the samples yielded only 1 species (A. fumigatus [n = 335], A. novofumigatus [n = 4], A. lentulus [n = 3], A. viridinutans [n = 1], and Neosartorya udagawae [n = 1]). The remaining samples yielded a combination of 2 species. Most of the patients were infected by a single species (A. fumigatus [n = 143] or A. lentulus [n = 2]). The remaining 5 patients were coinfected with multiple A. fumigatus complex species, although A. fumigatus was always involved; 4 of the 5 patients were diagnosed in 2009 or later. Cryptic species were less susceptible than A. fumigatus. The frequency of resistance among A. fumigatus complex and A. fumigatus to itraconazole, voriconazole, and posaconazole was 2.5 and 0.3%, 3.1 and 0.3%, and 4.2 and 1.8%, respectively, in the per-isolate analysis and 1.3 and 0.7%, 2.6 and 0.7%, and 6 and 4% in the per-patient analysis. Only 1 of the 6 A. fumigatus isolates in which the cyp51A gene was sequenced had a mutation at position G448. The proportion of patients infected by azole-resistant A. fumigatus isolates was low.

Dectin-1 activation controls maturation of β-1,3-glucan-containing phagosomes

Elimination of fungal pathogens by phagocytes requires phagosome maturation, a process that involves the recruitment and fusion of intracellular proteins. The role of Dectin-1, a β-1,3-glucan receptor, critical for fungal recognition and triggering of Th17 responses, to phagosomal maturation has not been defined. We show that GFP-Dectin-1 translocates to the fungal phagosome, but its signal decays after 2 h. Inhibition of acidification results in retention of GFP-Dectin-1 to phagosome membranes highlighting the requirement for an acidic pH. Following β-1,3-glucan recognition, GFP-Dectin-1 undergoes tyrosine phosphorylation by Src kinases with subsequent Syk activation. Our results demonstrate that Syk is activated independently of intraphagosomal pH. Inhibition of Src or Syk results in prolonged retention of GFP-Dectin-1 to the phagosome signifying a link between Syk and intraphagosomal pH. β-1,3-glucan phagosomes expressing a signaling incompetent Dectin-1 failed to mature as demonstrated by prolonged Dectin-1 retention, presence of Rab5B, failure to acquire LAMP-1 and inability to acidify. Phagosomes containing Candida albicans also require Dectin-1-dependent Syk activation for phagosomal maturation. Taken together, these results support a model where Dectin-1 not only controls internalization of β-1,3-glucan containing cargo and triggers proinflammatory cytokines, but also acts as a master regulator for subsequent phagolysosomal maturation through Syk activation.

Emerging fungal infections in solid organ transplant recipients

The most important emerging and rare fungal pathogens in solid organ transplant recipients are the Zygomycetes, Scedosporium, Fusarium, and the dark molds. Factors affecting the emergence of these fungi include the combination of intensive immunosuppressive regimens with increasingly widespread use of long-term azole antifungal therapy; employment of aggressive diagnostic approaches (eg, sampling of bronchoalveolar lavage fluid); and changes in patients' interactions with the environment. This article reviews the epidemiology, microbiology, and clinical impact of emerging fungal infections in solid organ transplant recipients, and provides up-to-date recommendations on their treatment.

Relevance of cohort studies for the study of transplant infectious diseases

PURPOSE OF REVIEW

The debate on the merits of observational studies as compared with randomized trials is ongoing. We will briefly touch on this subject, and demonstrate the role of cohort studies for the description of infectious disease patterns after transplantation. The potential benefits of cohort studies for the clinical management of patients outside of the expected gain in epidemiological knowledge are reviewed. The newly established Swiss Transplantation Cohort Study and in particular the part focusing on infectious diseases will serve as an illustration.

RECENT FINDINGS

A neglected area of research is the indirect value of large, multicenter cohort studies. These benefits can range from a deepened collaboration to the development of common definitions and guidelines. Unfortunately, very few data exist on the role of such indirect effects on improving quality of patient management.

SUMMARY

This review postulates an important role for cohort studies, which should not be viewed as inferior but complementary to established research tools, in particular randomized trials. Randomized trials remain the least bias-prone method to establish knowledge regarding the significance of diagnostic or therapeutic measures. Cohort studies have the power to reflect a real-world situation and to pinpoint areas of knowledge as well as of uncertainty. Prerequisite is a prospective design requiring a set of inclusive data coupled with the meticulous insistence on data retrieval and quality.

Does the current treatment of invasive fungal infection need to be reviewed?

Invasive fungal infections (IFIs) are becoming more frequent due to the increasing number of patients at risk. Over the last decade, their prognosis has improved with the diagnostic and therapeutic advances, including new antifungals. In the two years, from 2007 to 2009, antifungal consumption increased by 27%, 67 times more than antibacterial consumption, albeit with great differences between hospitals. The scientific evidence of the indications for antifungal prophylaxis and targeted antifungal therapy is strong; however, it is weak for empirical antifungal therapy, which is the most common indication. Antifungals are not harmless, since they are associated with a wide range of adverse effects and drug interactions, favor the development of resistance, contribute to other fungal superinfections and cause significant healthcare spending. Therefore, the question arises whether this extraordinary increase in consumption is justified, whether the use of antifungals is optimal, or whether it is necessary to reconsider the current treatment of IFIs instead.

Cutaneous presentation of progressive disseminated histoplasmosis nine years after renal transplantation

Initial presentation of invasive fungal infections such as histoplasmosis can include non-specific clinical manifestations, especially in immunocompromised patients. A high index of suspicion is required to identify atypical manifestations of these diseases, which carry a high risk of mortality, if the diagnosis is delayed or missed. We describe a case of a kidney transplant recipient with cutaneous lesions as initial manifestation of progressive disseminated histoplasmosis where a skin biopsy was crucial to an early diagnosis.

The utility of diagnostic testing for active coccidioidomycosis in solid organ transplant recipients

Solid organ transplant recipients who acquire coccidioidomycosis have high rates of disseminated infection and mortality, and diagnosis of infection in these immunosuppressed patients is challenging because of suboptimal sensitivity of diagnostic tests. To characterize the utility of diagnostic tests for coccidioidomycosis in this population, we conducted a retrospective chart review of all solid organ transplant recipients with newly acquired coccidioidomycosis who were seen at our institution from 1999 to 2011. We identified 27 solid organ transplant recipients with newly acquired, active coccidioidomycosis. The positivity of any single serologic test ranged from 21% (5/24; immunoglobulin M by immunodiffusion) to 56% (14/25; immunoglobulin G by enzyme immunoassay), compared with 77% (20/26) seropositivity for a battery of serologic tests (enzyme immunoassay, immunodiffusion and complement fixation). Serology performed approximately 1 month later increased positive test findings to 92%. Culture of respiratory or tissue specimens yielded Coccidioides sp in 54% (14/26) of the cultures submitted, and 10/16 (63%) of patients tested. Chest-computed tomography was abnormal in 86% (19/22). Multiple test modalities may be needed to diagnose coccidioidomycosis in solid organ transplant recipients, and repeat studies over time may increase sensitivity of the diagnostic assays.

Pulmonary infections in transplant recipients

PURPOSE OF REVIEW

Hematopoietic stem cell as well as solid-organ transplantation is being carried out with increasing frequency throughout the world. Lower respiratory tract infections (LRTIs) remain a common life-threatening complication faced by the transplant recipients. The purpose of this review is to provide up-to-date information on pulmonary infections among the transplant recipients, especially emphasizing the endemicity of microorganisms, epidemiology, work-up of infections, and principles of their management.

RECENT FINDINGS

A lower respiratory tract infection such as pneumonia is the most frequent of all the infections and is associated with high morbidity and mortality. Factors increasing the risk of pulmonary infections include surgical techniques, immune status, chemoradiotherapy, alloimmune mechanisms between the host and the graft, and the environment. A high degree of suspicion, computed tomography (CT) scan of the chest, and flexible bronchoscopy are required in most to establish the diagnosis.

SUMMARY

Proper management of LRTI in transplant recipients requires a high degree of suspicion, thorough knowledge of the epidemiology and endemicity of the suspected organisms, CT scan of the chest, and expertise at bronchoscopy. Utmost teamwork among transplant physicians, infectious disease specialist, and bronchoscopist is essential.

Utility of galactomannan antigen detection in bronchoalveolar lavage fluid in immunocompromised patients

Diagnosis of invasive pulmonary aspergillosis (IPA) is a challenging process in immunocompromised patients. Galactomannan (GM) antigen detection in bronchoalveolar lavage (BAL) fluid is a method to detect IPA with improved sensitivity over conventional studies. We sought to determine the diagnostic yield of BAL GM assay in a diverse population of immunocompromised patients. A retrospective review of 150 fiberoptic bronchoscopy (FOB) with BAL for newly diagnosed pulmonary infiltrate in immunocompromised patients was performed. Patient information, procedural details and laboratory studies were collected. BAL and serum samples were evaluated for GM using enzyme-linked immunoassay. Of 150 separate FOB with BAL, BAL GM was obtained in 143 samples. There were 31 positive BAL GM assays. In those 31 positive tests, 13 were confirmed as IPA, giving a positive predictive value of 41.9%. There was one false negative BAL GM. Of the 18 false positive BAL GM, 4 were receiving piperacillin-tazobactam and 11 were receiving an alternative beta-lactam antibiotic. BAL GM assay shows excellent sensitivity for diagnosing IPA. There was a significant number of false positive BAL GM assays and several of those patients were receiving beta-lactam antibiotics at the time of bronchoscopy.

Irreversible liver failure: treatment by transplantation: part 3 of a series on liver cirrhosis

BACKGROUND

Liver transplantation is the only established, causally directed treatment for irreversible chronic or acute liver failure.

METHODS

This review is based on papers retrieved by a selective search in the PubMed database, the index of randomized controlled trials of the European Society of Organ Transplantation, and the Cochrane database, along with an analysis of data from the authors' own center.

RESULTS

1199 liver transplantations were performed in Germany in 2011. The most common indications were alcoholic cirrhosis (28%), cirrhosis of other causes (24%), and intrahepatic tumors (20%). Among recipients, the sex ratio was nearly 1:1 and the median age was just under 50. Across Europe, the 1-, 5-, and 10-year survival rates after liver transplantation were 82%, 71% and 61%. In our own center, the Charité in Berlin, the corresponding rates were 90.4%, 79.6% and 70.3%, based on an experience of 100 to 120 cases per year. The current rate of functioning transplants five years after liver transplantation is 52.6% in Germany and 66.2% internationally. Standard immunosuppression consists of a calcineurin inhibitor, tacrolimus or cyclosporine A, and steroids. Early complications include primary functional failure of the transplant, hemorrhage, thrombosis, acute rejection, and biliary complications. Over the long term, complications that can impair the outcome include chronic rejection, biliary strictures, cardiovascular and metabolic adverse effects, nephrotoxicity, neurotoxicity, and opportunistic infections and malignancies.

CONCLUSION

Liver transplantation is a successful and well-established form of treatment that is nonetheless endangered by a shortage of donor organs and other structural and organizational difficulties.

Epidemiology, outcomes, and mortality predictors of invasive mold infections among transplant recipients: a 10-year, single-center experience

BACKGROUND

The epidemiology of invasive mold infections (IMI) in transplant recipients differs based on geography, hosts, preventative strategies, and methods of diagnosis.

METHODS

We conducted a retrospective observational study to evaluate the epidemiology of proven and probable IMI, using prior definitions, among all adult hematopoietic stem cell transplant (HSCT) and solid organ transplant (SOT) recipients in the era of "classic" culture-based diagnostics (2000-2009). Epidemiology was evaluated before and after an initiative was begun to increase bronchoscopy in HSCT recipients after 2005.

RESULTS

In total, 106 patients with one IMI were identified. Invasive aspergillosis (IA) was the most common IMI (69; 65.1%), followed by mucormycosis (9; 8.5%). The overall rate of IMI (and IA) was 3.5% (2.5%) in allogeneic HSCT recipients. The overall incidence for IMI among lung, kidney, liver, and heart transplant recipients was 49, 2, 11, and 10 per 1000 person-years, respectively. The observed rate of IMI among human leukocyte antigen-matched unrelated and haploidentical HSCT recipients increased from 0.6% annually to 3.0% after bronchoscopy initiation (P < 0.05). The 12-week mortality among allogeneic HSCT, liver, kidney, heart, and lung recipients with IMI was 52.4%, 47.1%, 27.8%, 16.7%, and 9.5%, respectively. Among allogeneic HSCT (odds ratio [OR]: 0.07, P = 0.007) and SOT (OR: 0.22, P = 0.05) recipients with IA, normal platelet count was associated with improved survival. Male gender (OR: 14.4, P = 0.007) and elevated bilirubin (OR: 5.7, P = 0.04) were significant predictors of mortality for allogeneic HSCT and SOT recipients with IA, respectively.

CONCLUSIONS

During the era of culture-based diagnostics, observed rates of IMI were low among all transplants except lung transplant recipients, with relatively higher mortality rates. Diagnostic aggressiveness and host variables impact the reported incidence and outcome of IMI and likely account for institutional variability in multicenter studies. Definitions to standardize diagnoses among SOT recipients are needed.

The cell biology of the innate immune response to Aspergillus fumigatus

The development of invasive aspergillosis is a feared complication for immunocompromised patients. Despite the use of antifungal agents with excellent bioactivity, the morbidity and mortality rates for invasive aspergillosis remain unacceptably high. Defects within the innate immune response portend the highest risk for patients, but detailed knowledge of molecular pathways in neutrophils and macrophages in response to this fungal pathogen is lacking. Phagocytosis of fungal spores is a key step that places the pathogen into a phagosome, a membrane-delimited compartment that undergoes maturation and ultimately delivers antigenic material to the class II MHC pathway. We review the role of Toll-like receptor 9 (TLR9) in phagosome maturation of Aspergillus fumigates-containing phagosomes. Advanced imaging modalities and the development of fungal-like particles are promising tools that will aid in the dissection of the molecular mechanism to fungal immunity.

Adoptive T-cell immunotherapy from third-party donors: characterization of donors and set up of a T-cell donor registry

Infection with and reactivation of human cytomegalovirus (CMV), Epstein-Barr virus (EBV), and adenovirus (ADV) are frequent and severe complications in immunocompromised recipients after hematopoietic stem cell transplantation (HSCT) or solid organ transplantation (SOT). These serious adverse events are associated with significant morbidity and mortality. Donor lymphocyte infusions (DLIs) are often used to treat both viral infections and leukemia relapses after transplantation but are associated with potentially life-threatening graft-versus-host disease (GvHD). Adoptive immunotherapy with virus-specific cytotoxic effector T cells (CTLs) derived from seropositive donors can rapidly reconstitute antiviral immunity after HSCT and organ transplantation. Therefore, it can effectively prevent the clinical manifestation of these viruses with no significant acute toxicity or increased risk of GvHD. In conditions, where patients receiving an allogeneic cord blood (CB) transplant or a transplant from a virus-seronegative donor and since donor blood is generally not available for solid organ recipients, allogeneic third party T-cell donors would offer an alternative option. Recent studies showed that during granulocyte colony-stimulating factor (G-CSF) mobilization, the functional activity of antiviral memory T cells is impaired for a long period. This finding suggests that even stem cell donors may not be the best source of T cells. Under these circumstances, partially human leukocyte antigen (HLA)-matched virus-specific CTLs from healthy seropositive individuals may be a promising option. Therefore, frequency assessments of virus-specific memory T cells in HLA-typed healthy donors as well as in HSCT/SOT donors using a high throughput T-cell assay were performed over a period of 4 years at Hannover Medical School. This chapter will address the relevance and potential of a third-party T-cell donor registry and will discuss its clinical implication for adoptive T-cell immunotherapy.

The diagnostic yield of CT-guided percutaneous lung biopsy in solid organ transplant recipients

BACKGROUND

Despite the widespread use of computed tomography(CT)-guided percutaneous lung biopsy (PLB) in immunocompetent patients, the diagnostic yield and safety in solid organ transplant (SOT)recipients is unknown. The purpose of this investigation was to determine the test performance of CT-PLB in SOT recipients.

METHODS

We performed a 10-yr single-center, retrospective analysis among heart, lung, kidney, and liver transplant recipients. We included all adult patients who underwent a PLB of a parenchymal lung nodule following their transplantation.

RESULTS

Within the study period, 1754 SOTs were performed, of which 45 biopsies met study criteria. Overall, the incidence of PLB in SOT was 3%.PLB established a diagnosis in 24 of 45 cases. The yield of PLB was better for combined biopsy technique (fine-needle aspiration biopsy [FNAB]) and core biopsy than for FNAB alone (odds ratio [OR]: 4.2, 95% confidence interval [CI]: 1.2, 15.6), and for lesions that were malignant (OR: 10.0, 95%CI: 1.8, 75.4) or caused by an invasive fungal infection (OR: 5.0, 95% CI:1.1, 27.9). Complications occurred in 13% (6/45) of patients.

CONCLUSION

CT-guided PLB is a safe modality that provides a moderate yield for diagnosing pulmonary nodules of malignant or fungal etiology in SOT recipients.

Invasive fungal infections in patients with chronic granulomatous disease

Invasive fungal infections are a major threat for chronic granulomatous disease (CGD) patients. The present study provides a comprehensive overview of published invasive fungal infections in the CGD host through an extensive review of epidemiological, clinical, diagnostic and therapeutic data. In addition to the often mild clinical presentation, the currently used diagnostics for invasive aspergillosis have low sensitivity in CGD patients and cannot be easily translated to this non-neutropenic host. Aspergillus fumigatus and A. nidulans are the most commonly isolated species. A. nidulans infections are seldom reported in other immunocompromised patients, indicating a unique interaction between this fungus and the CGD host. The occurrence of mucormycosis is mainly noted in the setting of treatment of inflammatory complications with immunosuppressive drugs. Candida infections are infrequently seen and do not cause mucocutaneous disease but do show an age-dependent clinical presentation. The CGD patient is susceptible to a wide range of fungal pathogens, indicating the need to determine the causative fungus, often by invasive diagnostics, to guide optimal and rational treatment. This review summarizes current understanding of invasive fungal infections in patients with CGD and will serve as a starting point to guide optimal treatment strategies and to direct further research aimed at improving outcomes.

Quantification of voriconazole in human bronchoalveolar lavage fluid using high-performance liquid chromatography with fluorescence detection

The quantification of voriconazole concentration in lung epithelial lining fluid to facilitate the management of pulmonary fungal colonisation or aspergillosis is of increasing interest. An accurate and reproducible high-performance liquid chromatography method to quantify voriconazole in human bronchoalveolar lavage (BAL) fluid was developed and validated. BAL samples were concentrated by freeze-drying and reconstituted with water prior to deproteinisation. Separation was achieved with a C18 column employing fluorescence detection (excitation: 260nm, emission: 370nm). The calibration curves were linear from 2.5 to 500ng/mL. The intra- and inter-day precisions were within 7%. Accuracies ranged from 102% to 107%. The clinical applicability was established by successful measurement of voriconazole concentrations in lung transplant recipients. The assay provides an alternative approach for those with negligible access to liquid chromatography-tandem mass spectrometry instrumentation.

An invisible threat: mutation-mediated resistance to triazole drugs in Aspergillus

Aspergillosis has emerged as an important contributor to infection-related morbidity and mortality in susceptible populations. This comes at a time when we are also seeing an increase in the vulnerable populations themselves. At the same time, some parts of the world are reporting an increased incidence of aspergillosis refractory to triazole therapy. Resistance to triazole drugs may have major implications for aspergillosis management since our antifungal armamentarium is limited. This review gives an overview of populations at risk of developing aspergillosis and highlights resistance mechanisms that may contribute to morbidity and mortality in these vulnerable populations.

Renal allograft recipients fail to increase interferon-γ during invasive fungal diseases

Invasive fungal diseases are a major cause of death in renal allograft recipients. We previously reported that adjunctive recombinant human interferon-γ therapy has clinical utility for invasive fungal diseases after renal transplantation. We have now developed a rapid peripheral blood-based quantitative real-time PCR assay that enables accurate profiling of cytokine imbalances. Our preliminary studies in renal transplant patients with invasive fungal diseases suggest that they fail to mount an adequate interferon-γ response to the fungal infection. In addition, they have reduced IL-10 and increased TNF-α when compared to stable renal transplant patients. These preliminary cytokine profiling-based observations provide a possible explanation for the therapeutic benefit of adjunctive human interferon-γ therapy in renal allograft recipients with invasive fungal diseases.

Invasive aspergillosis among heart transplant recipients is rare but causes rapid death due to septic shock and multiple organ dysfunction syndrome

Between 2000 and 2011, proven or probable invasive aspergillosis (IA) was diagnosed in 1.7% (8/455) of heart transplant (HTx) recipients at our center, in the absence of antifungal prophylaxis. All patients had invasive pulmonary infections and 75% (6/8) were diagnosed during 2 separate 3-month periods. Cases were notable for their association with septic shock and multiple organ dysfunction syndrome (MODS) (75%, 6/8 each), non-specific clinical and radiographic findings, and rapid mortality despite mould-active antifungal therapy (88%, 7/8; occuring at a median 11 days after diagnosis). All patients had predisposing conditions known to be risk factors for IA. For patients with early IA (within 90 days of HTx), conditions included hemodialysis, thoracic re-operation, and the presence of another case in the institution within the preceding 3 months. For late-onset IA, conditions included hemodialysis and receipt of augmented immunosuppression. Clinicians should suspect IA in HTx recipients with risk factors who present with non-specific and unexplained respiratory syndromes, including those in septic shock and MODS, and institute prompt antifungal therapy without waiting for the results of cultures or other diagnostic tests.

Posaconazole pharmacodynamic target determination against wild-type and Cyp51 mutant isolates of Aspergillus fumigatus in an in vivo model of invasive pulmonary aspergillosis

Invasive pulmonary aspergillosis (IPA) is a devastating disease of immunocompromised patients. Pharmacodynamic (PD) examination of antifungal drug therapy in IPA is one strategy that may improve outcomes. The current study explored the PD target of posaconazole in an immunocompromised murine model of IPA against 10 A. fumigatus isolates, including 4 Cyp51 wild-type isolates and 6 isolates carrying Cyp51 mutations conferring azole resistance. The posaconazole MIC range was 0.25 to 8 mg/liter. Following infection, mice were given 0.156 to 160 mg/kg of body weight of oral posaconazole daily for 7 days. Efficacy was assessed by quantitative PCR (qPCR) of lung homogenate and survival. At the start of therapy, mice had 5.59 ± 0.19 log(10) Aspergillus conidial equivalents (CE)/ml of lung homogenate, which increased to 7.11 ± 0.29 log(10) CE/ml of lung homogenate in untreated animals. The infection was uniformly lethal prior to the study endpoint in control mice. A Hill-type dose response function was used to model the relationship between posaconazole free drug area under the concentration-time curve (AUC)/MIC and qPCR lung burden. The static dose range was 1.09 to 51.9 mg/kg/24 h. The free drug AUC/MIC PD target was 1.09 ± 0.63 for the group of strains. The 1-log kill free drug AUC/MIC was 2.07 ± 1.02. The PD target was not significantly different for the wild-type and mutant organism groups. Mortality mirrored qPCR results, with the greatest improvement in survival noted at the same dosing regimens that produced static or cidal activity. Consideration of human pharmacokinetic data and the current static dose PD target would predict a clinical MIC threshold of 0.25 to 0.5 mg/liter.

Emerging invasive fungal diseases in transplantation

Invasive fungal infections continue to be a major cause of morbidity and mortality in severely immunocompromised transplant patients. Although Candida spp. and Aspergillus spp. represent the majority of identified pathogens, other fungi have become increasingly prevalent among this patient population. Diagnosis and treatment of invasive fungal infections remain a challenge in transplant medicine despite recent major advances. In this review, we will emphasize emerging topics in invasive fungal infections in transplantations that occurred in 2011-2012. The current literature was reviewed to synthesize new trends in epidemiology, recent outbreaks, clinical findings, and advances in diagnostic and therapeutic resources.

Cytomegalovirus and Aspergillus spp. coinfection in organ transplantation: a case report and review of the literature

With the advent of potent immunosuppressive options, acute rejection episodes have decreased at the expense of increased incidence of opportunistic infections in solid organ recipients. In the absence of any preventive therapy, 30–75 % of transplant recipients develop cytomegalovirus (CMV) infection. Candida spp. and Aspergillus spp. account for more than 80 % of invasive fungal infections in solid organ recipients. This co-occurrence of two commonly seen opportunistic infections may end up in fatality. Here, we present a case of concomitant Aspergillus spp. and CMV infection and discuss the relevant literature. A 54-year-old male patient presented with fever, shortness of breath, and chest pain on the 9th posttransplant week after renal transplantation. CMV-DNA by polymerase chain reaction (PCR) was 1,680,000 copies/ml, thus, valganciclovir dose was increased. There were inspiratory crackles at both lung bases, and chest computed tomography (CT) revealed multiple fungal balls throughout the right lung. Galactomannan antigen was positive, and voriconazole and other antimicrobials were subsequently added to the treatment. At the end of the therapy, on control CT, pneumonic consolidation had disappeared, sputum cultures didn’t show Aspergillus spp., and CMV-DNA reduced to 700 copies/ml. The patient showed a favorable clinical response to combined treatment; fever, dyspnea, and pleuritic chest pain disappeared. Both CMV disease and aspergillosis may present as pulmonary disease; thus, the characterization of one may not preclude the search for the other and the timely initiation of treatment is of paramount importance for good outcomes.

Candidal psoas abscess following persistent pyuria in a renal transplant recipient

Candidal infections occur commonly in renal transplant recipients especially in genitourinary system. Although the epidemiology of candiduria has not been well characterized in renal transplant population, it is the most common cause of fungal infections. However, candidal psoas abscess is very rare in the literature. We report a 42-year-old male renal transplant recipient with prolonged pyuria and candiduria followed by candidal psoas abscess formation. The treatment consisted of prolonged antifungal therapy along with percutaneous drainage. However, eventually, a surgical drainage had to be performed for the successful eradication.

The PATH (Prospective Antifungal Therapy) Alliance® registry and invasive fungal infections: update 2012

The Prospective Antifungal Therapy Alliance (PATH Alliance®) performed prospective surveillance of invasive fungal infections (IFIs) among patients hospitalized at 25 medical centers in North America between 2004 and 2008, collecting information on the epidemiology, diagnosis, treatment, and mortality rates of IFIs. In total, 7526 IFIs were identified in 6845 patients. Candida spp. (73.4%) were the most common pathogens, followed by Aspergillus spp. (13.3%), and other yeasts (6.2%). Culture was the most frequently used diagnostic test in the majority of IFI categories. Most patients with invasive candidiasis were treated with fluconazole (48.3%) and the echinocandins (34.0%), while voriconazole (45.5%) was the main antifungal agent for invasive aspergillosis. The 12-week survival rate ranged from 37.5% for hematopoietic stem cell transplant recipients to ~75.0% for those with HIV/AIDS. In summary, the findings of the PATH Alliance® registry provide a better understanding of the epidemiology of a vast variety and large numbers of IFIs.

Coordination of hypoxia adaptation and iron homeostasis in human pathogenic fungi

In mammals, hypoxia causes facilitated erythropoiesis that requires increased iron availability with established links between oxygen and iron in regulation of the transcription factor hypoxia-inducible factor. Therefore, cellular responses to hypoxia and iron starvation are linked in mammals and are host conditions that pathogens encounter during infection. In human pathogenic fungi, molecular mechanisms underlying hypoxia adaptation and iron homeostasis have been investigated. However, the interconnected regulation of hypoxia adaptation and iron homeostasis remains to be fully elucidated. This review discusses the potential transcriptional regulatory links between hypoxia adaptation and iron homeostasis in human pathogenic fungi. Transcriptome analyses demonstrate that core regulators of hypoxia adaptation and iron homeostasis are involved in regulation of several common genes responsible for iron acquisition and ergosterol biosynthesis. Importantly, iron starvation increases susceptibility of fungal cells to antifungal drugs and decreased levels of ergosterol, while key hypoxia regulators are also involved in responses to antifungal drugs and mediating ergosterol levels. We suggest that pathogenic fungi have developed a coordinated regulatory system in response to hypoxia and iron starvation through (i) regulation of expression of hypoxia-responsive and iron-responsive genes via cross-linked key regulators, and/or (ii) regulation of factors involved in ergosterol biosynthesis. Thus, both oxygen and iron availability are intimately tied with fungal virulence and responses to existing therapeutics and further elucidation of their interrelationship should have significant clinical implications.