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

Invasive mold infections in solid organ transplant recipients

Invasive mold infections represent an increasing source of morbidity and mortality in solid organ transplant recipients. Whereas there is a large literature regarding invasive molds infections in hematopoietic stem cell transplants, data in solid organ transplants are scarcer. In this comprehensive review, we focused on invasive mold infection in the specific population of solid organ transplant. We highlighted epidemiology and specific risk factors for these infections and we assessed the main clinical and imaging findings by fungi and by type of solid organ transplant. Finally, we attempted to summarize the diagnostic strategy for detection of these fungi and tried to give an overview of the current prophylaxis treatments and outcomes of these infections in solid organ transplant recipients.

Fungal Pathogens: Survival and Replication within Macrophages

The innate immune system is a critical line of defense against pathogenic fungi. Macrophages act at an early stage of infection, detecting and phagocytizing infectious propagules. To avoid killing at this stage, fungal pathogens use diverse strategies ranging from evasion of uptake to intracellular parasitism. This article will discuss five of the most important human fungal pathogens (Candida albicans, Aspergillus fumigatus, Cryptococcus neoformans, Coccidiodes immitis, and Histoplasma capsulatum) and consider the strategies and virulence factors adopted by each to survive and replicate within macrophages.

Aspergillus fumigatus and related species

The genus Aspergillus contains etiologic agents of aspergillosis. The clinical manifestations of the disease range from allergic reaction to invasive pulmonary infection. Among the pathogenic aspergilli, Aspergillus fumigatus is most ubiquitous in the environment and is the major cause of the disease, followed by Aspergillus flavus, Aspergillus niger, Aspergillus terreus, Aspergillus nidulans, and several species in the section Fumigati that morphologically resemble A. fumigatus. Patients that are at risk for acquiring aspergillosis are those with an altered immune system. Early diagnosis, species identification, and adequate antifungal therapy are key elements for treatment of the disease, especially in cases of pulmonary invasive aspergillosis that often advance very rapidly. Incorporating knowledge of the basic biology of Aspergillus species to that of the diseases that they cause is fundamental for further progress in the field.

Stability in the cumulative incidence, severity and mortality of 101 cases of invasive mucormycosis in high-risk patients from 1995 to 2011: a comparison of eras immediately before and after the availability of voriconazole and echinocandin-amphotericin combination therapies

As invasive mucormycosis (IM) numbers rise, clinicians suspect prior voriconazole worsens IM incidence and severity, and believe combination anti-fungal therapy improves IM survival. To compare the cumulative incidence (CI), severity and mortality of IM in eras immediately before and after the commercial availability of voriconazole all IM cases from 1995 to 2011 were analysed across four risk-groups (hematologic/oncologic malignancy (H/O), stem cell transplantation (SCT), solid organ transplantation (SOT) and other), and two eras, E1 (1995-2003) and E2, (2004-2011). Of 101 IM cases, (79 proven, 22 probable): 30 were in E1 (3.3/year) and 71 in E2 (8.9/year). Between eras, the proportion with H/O or SCT rose from 47% to 73%, while 'other' dropped from 33% to 11% (P = 0.036). Between eras, the CI of IM did not significantly increase in SCT (P = 0.27) or SOT (P = 0.30), and patterns of anatomic location (P = 0.122) and surgical debridement (P = 0.200) were similar. Significantly more patients received amphotericin-echinocandin combination therapy in E2 (31% vs. 5%, P = 0.01); however, 90-day survival did not improve (54% vs. 59%, P = 0.67). Since 2003, the rise of IM reflects increasing numbers at risk, not prior use of voriconazole. Frequent combination of anti-fungal therapy has not improved survival.

A breath fungal secondary metabolite signature to diagnose invasive aspergillosis

BACKGROUND

Invasive aspergillosis (IA) remains a leading cause of mortality in immunocompromised patients, in part due to the difficulty of diagnosing this infection.

METHODS

Using thermal desorption-gas chromatography/mass spectrometry, we characterized the in vitro volatile metabolite profile of Aspergillus fumigatus, the most common cause of IA, and other pathogenic aspergilli. We prospectively collected breath samples from patients with suspected invasive fungal pneumonia from 2011 to 2013, and assessed whether we could discriminate patients with proven or probable IA from patients without aspergillosis, as determined by European Organization for Research and Treatment of Cancer/Mycoses Study Group consensus definitions, by direct detection of fungal volatile metabolites in these breath samples.

RESULTS

The monoterpenes camphene, α- and β-pinene, and limonene, and the sesquiterpene compounds α- and β-trans-bergamotene were distinctive volatile metabolites of A. fumigatus in vitro, distinguishing it from other pathogenic aspergilli. Of 64 patients with suspected invasive fungal pneumonia based on host risk factors, clinical symptoms, and radiologic findings, 34 were diagnosed with IA, whereas 30 were ultimately diagnosed with other causes of pneumonia, including other invasive mycoses. Detection of α-trans-bergamotene, β-trans-bergamotene, a β-vatirenene-like sesquiterpene, or trans-geranylacetone identified IA patients with 94% sensitivity (95% confidence interval [CI], 81%-98%) and 93% specificity (95% CI, 79%-98%).

CONCLUSIONS

In patients with suspected fungal pneumonia, an Aspergillus secondary metabolite signature in breath can identify individuals with IA. These results provide proof-of-concept that direct detection of exogenous fungal metabolites in breath can be used as a novel, noninvasive, pathogen-specific approach to identifying the precise microbial cause of pneumonia.

The pH-responsive PacC transcription factor of Aspergillus fumigatus governs epithelial entry and tissue invasion during pulmonary aspergillosis

Destruction of the pulmonary epithelium is a major feature of lung diseases caused by the mould pathogen Aspergillus fumigatus. Although it is widely postulated that tissue invasion is governed by fungal proteases, A. fumigatus mutants lacking individual or multiple enzymes remain fully invasive, suggesting a concomitant requirement for other pathogenic activities during host invasion. In this study we discovered, and exploited, a novel, tissue non-invasive, phenotype in A. fumigatus mutants lacking the pH-responsive transcription factor PacC. Our study revealed a novel mode of epithelial entry, occurring in a cell wall-dependent manner prior to protease production, and via the Dectin-1 β-glucan receptor. ΔpacC mutants are defective in both contact-mediated epithelial entry and protease expression, and significantly attenuated for pathogenicity in leukopenic mice. We combined murine infection modelling, in vivo transcriptomics, and in vitro infections of human alveolar epithelia, to delineate two major, and sequentially acting, PacC-dependent processes impacting epithelial integrity in vitro and tissue invasion in the whole animal. We demonstrate that A. fumigatus spores and germlings are internalised by epithelial cells in a contact-, actin-, cell wall- and Dectin-1 dependent manner and ΔpacC mutants, which aberrantly remodel the cell wall during germinative growth, are unable to gain entry into epithelial cells, both in vitro and in vivo. We further show that PacC acts as a global transcriptional regulator of secreted molecules during growth in the leukopenic mammalian lung, and profile the full cohort of secreted gene products expressed during invasive infection. Our study reveals a combinatorial mode of tissue entry dependent upon sequential, and mechanistically distinct, perturbations of the pulmonary epithelium and demonstrates, for the first time a protective role for Dectin-1 blockade in epithelial defences. Infecting ΔpacC mutants are hypersensitive to cell wall-active antifungal agents highlighting the value of PacC signalling as a target for antifungal therapy.

Inhaled spores of the pathogenic mould Aspergillus fumigatus cause fungal lung infections in humans having immune defects. A. fumigatus spores germinate within the immunocompromised lung, producing invasively growing, elongated cells called hyphae. Hyphae degrade the surrounding pulmonary tissue, a process thought to be caused by secreted fungal enzymes; however, A. fumigatus mutants lacking one or more protease activities retain fully invasive phenotypes in mouse models of disease. Here we report the first discovery of a non-invasive A. fumigatus mutant, which lacks a pH-responsive transcription factor PacC. Using global transcriptional profiling of wild type and mutant isolates, and in vitro pulmonary invasion assays, we established that loss of PacC leads to a compound non-invasive phenotype characterised by deficits in both contact-mediated epithelial entry and protease expression. Consistent with an important role for epithelial entry in promoting invasive disease in mammalian tissues, PacC mutants remain surface-localised on mammalian epithelia, both in vitro and in vivo. Our study sets a new precedent for involvement of both host and pathogen activities in promoting epithelial invasion by A. fumigatus and supports a model wherein fungal protease activity acting subsequently to, or in parallel with, host-mediated epithelial entry provides the mechanistic basis for tissue invasion.

Risk factors for invasive fungal disease in heart transplant recipients

BACKGROUND

Heart transplant (HT) recipients are at risk for invasive fungal disease (IFD), a morbid and potentially fatal complication.

METHODS

We performed a retrospective cohort study to evaluate the incidence and risk factors for IFD in HT recipients from 1995 to 2012 at a single center. IFD cases were classified as proven or probable IFD according to current consensus definitions of the European Organization for Research and Treatment of Cancer/Mycoses Study Group. We calculated IFD incidence rates and used Cox proportional hazards models to determine IFD risk factors.

RESULTS

Three hundred sixty patients underwent HT during the study period. The most common indications were dilated (39%) and ischemic (37%) cardiomyopathy. There were 23 (6.4%) cases of proven (21) or probable (2) IFD, for a cumulative incidence rate of 1.23 per 100 person-years (95% CI 0.78 to 1.84). Candida (11) and Aspergillus (5) were the most common etiologic fungi. Thirteen cases (56%) occurred within 3 months of HT, with a 3-month incidence of 3.8% (95% CI 2.2 to 6.4). Delayed chest closure (HR 3.3, 95% CI 1.4 to 7.6, p = 0.01) and the addition of OKT3, anti-thymocyte globulin or daclizumab to standard corticosteroid induction therapy (HR 2.7, 95% CI 1.1 to 6.2, p = 0.02) were independently associated with an increased risk of IFD.

CONCLUSIONS

IFD incidence was greatest within the first 3 months post-HT, largely reflecting early surgical-site and nosocomial Candida and Aspergillus infections. Patients receiving additional induction immunosuppression or delayed chest closure were at increased risk for IFD. Peri-transplant anti-fungal prophylaxis should be considered in this subset of HT recipients.

Disseminated Mucormycosis With Cerebral Involvement Owing to Rhizopus Microsporus in a Kidney Recipient Treated With Combined Liposomal Amphotericin B and Posaconazole Therapy

Three months after a kidney transplant, a man experienced an internuclear ophthalmoplegia. Magnetic resonance imaging found a punctuate hyperintensity of the brainstem. Afterwards, the patient presented with peripheral facial paralysis. A complete morphologic assessment showed an increase of the brainstem lesion, together with an excavated pulmonary nodule. Combination therapy with high-dose liposomal amphotericin B and voriconazole was begun for the putative aspergillosis. Owing to its atypical clinical presentation and negative detection of Aspergillus galactomannan antigen on sera, a biopsy specimen of the lung lesion was obtained. Histopathological and mycological investigations allowed the diagnosis of mucormycosis owing to Rhizopus microsporus. Accordingly, voriconazole was replaced with posaconazole. After 5 months, regression of the cerebral lesion was noted. Disseminated mucormycosis in solid-organ recipients is uncommon and mycological diagnosis is challenging. Mortality is high and is increased by diagnostic delay. Treating mucormycosis requires surgical debridement and appropriate antifungal therapy (usually intravenous liposomal amphotericin B). This report suggests that a combination of liposomal amphotericin B and posaconazole can be a therapeutic option in patients with a poor prognosis.

Heat shock protein 90 (Hsp90): A novel antifungal target against Aspergillus fumigatus

Invasive aspergillosis is a life-threatening and difficult to treat infection in immunosuppressed patients. The efficacy of current anti-Aspergillus therapies, targeting the cell wall or membrane, is limited by toxicity (polyenes), fungistatic activity and some level of basal resistance (echinocandins), or the emergence of acquired resistance (triazoles). The heat shock protein 90 (Hsp90) is a conserved molecular chaperone involved in the rapid development of antifungal resistance in the yeast Candida albicans. Few studies have addressed its role in filamentous fungi such as Aspergillus fumigatus, in which mechanisms of resistance may differ substantially. Hsp90 is at the center of a complex network involving calcineurin, lysine deacetylases (KDAC) and other client proteins, which orchestrate compensatory repair mechanisms of the cell wall in response to the stress induced by antifungals. In A. fumigatus, Hsp90 is a trigger for resistance to high concentrations of caspofungin, known as the paradoxical effect. Disrupting Hsp90 circuitry by different means (Hsp90 inhibitors, KDAC inhibitors and anti-calcineurin drugs) potentiates the antifungal activity of caspofungin, thus representing a promising novel antifungal approach. This review will discuss the specific features of A. fumigatus Hsp90 and the potential for antifungal strategies of invasive aspergillosis targeting this essential chaperone.

Salvage combination antifungal therapy for acute invasive aspergillosis may improve outcomes: a systematic review and meta-analysis

OBJECTIVE

A meta-analysis was performed to compare mold-active triazoles or lipid amphotericin B plus an echinocandin to non-echinocandin monotherapy for acute invasive aspergillosis (IA).

METHODS

We searched PubMed, EMBASE, and other databases through May 2013 unrestricted by language. We included observational and experimental studies wherein patients with proven or probable IA by EORTC/MSG criteria underwent our comparative intervention. PRISMA and MOOSE guidelines were followed and quality was assessed using the Jadad and Newcastle-Ottawa criteria. Meta-regression with fixed and random effects and sensitivity analyses were performed. The primary study outcome measure was 12-week overall mortality. The secondary outcome assessed was complete and partial response.

RESULTS

Only observational studies of primary 12-week survival showed heterogeneity (I(2)=48.96%, p=0.05). For salvage IA therapy, fixed effects models demonstrated improved 12-week survival (Peto odds ratio (OR) 1.80, 95% confidence interval (CI) 1.08-3.01) and success (Peto OR 2.17, 95% CI 1.21-3.91) of combination therapy. Significance remained after applying random effects as a sensitivity analysis (12-week survival: Peto OR 1.90, 95% CI 1.04-3.46, and unchanged value for success). Restriction to high quality studies and including echinocandins as the comparator for refractory IA revealed an adjusted OR of 1.72 (95% CI 0.96-3.09; p=0.07) for global success, while the survival endpoint remained unaltered.

CONCLUSIONS

Combination antifungals for IA demonstrate improved outcomes over monotherapy in the salvage setting. Clinicians should consider this approach in certain situations.

STAT1 signaling is essential for protection against Cryptococcus neoformans infection in mice

Nonprotective immune responses to highly virulent Cryptococcus neoformans strains, such as H99, are associated with Th2-type cytokine production, alternatively activated macrophages, and inability of the host to clear the fungus. In contrast, experimental studies show that protective immune responses against cryptococcosis are associated with Th1-type cytokine production and classical macrophage activation. The protective response induced during C. neoformans strain H99γ (C. neoformans strain H99 engineered to produce murine IFN-γ) infection correlates with enhanced phosphorylation of the transcription factor STAT1 in macrophages; however, the role of STAT1 in protective immunity to C. neoformans is unknown. The current studies examined the effect of STAT1 deletion in murine models of protective immunity to C. neoformans. Survival and fungal burden were evaluated in wild-type and STAT1 knockout (KO) mice infected with either strain H99γ or C. neoformans strain 52D (unmodified clinical isolate). Both strains H99γ and 52D were rapidly cleared from the lungs, did not disseminate to the CNS, or cause mortality in the wild-type mice. Conversely, STAT1 KO mice infected with H99γ or 52D had significantly increased pulmonary fungal burden, CNS dissemination, and 90-100% mortality. STAT1 deletion resulted in a shift from Th1 to Th2 cytokine bias, pronounced lung inflammation, and defective classical macrophage activation. Pulmonary macrophages from STAT1 KO mice exhibited defects in NO production correlating with inefficient inhibition of fungal proliferation. These studies demonstrate that STAT1 signaling is essential not only for regulation of immune polarization but also for the classical activation of macrophages that occurs during protective anticryptococcal immune responses.

Invasive Candida infections in low risk liver transplant patients given no antifungal prophylaxis in the post-operative period

BACKGROUND

In recent years the incidence of invasive fungal infections (IFIs) in post liver transplant (LT) has reduced to about 5%, however the majority of IFIs develops early in the post-transplant course. Candida species are the most frequent causative pathogens followed by Aspergillus species. Mortality for invasive candidiasis is still 40-50%. For this reason universal prophylaxis is still considered useful and is adopted by different LT centers, although it is not justified by available data. The aim of study is to evaluate Candida infection incidence and mortality in low risk patients and therefore not subjected to antifungal prophylaxis in the immediate post-LT.

METHODS

The patient is defined low risk if without any risk factor for IFIs as reported in literature and according to our center protocol described below. We analyzed retrospectively the records (with 90 days follow-up) of all adult patients underwent to LT at our center in 2011-2012.

RESULTS

At our center between 2011 and 2012, 247 LT in 232 adult patients were performed: 137 patients (59%) received prophylaxis with Amphotericin B lipid complex or liposomal Amphotericin B, 95 patients (41%) didn't receive any prophylaxis. In these latter patients was observed only one case of Candida oesophagitis at the second month post-LT. The incidence of invasive candidiasis was 0%, and there wasn't mortality ascribed to Candida infection.

CONCLUSIONS

It is possible to identify low risk patients for IFIs post-LT and the no prophylaxis policy in the early LT course appears safe and feasible.

Renal Infections

This review discusses the various gross and histologic findings seen in renal infections due to bacteria, viruses, fungi, and mycobacteria. It is crucially important to separate infectious processes in the kidney from other inflammatory or neoplastic processes, as this will have a major impact on therapy. We describe the diagnostic features of renal infections with a specific focus on the differential diagnosis and other processes that may mimic infection. The topics discussed include acute bacterial pyelonephritis, chronic bacterial pyelonephritis, xanthogranulomatous pyelonephritis, malacoplakia, viral infections in the kidney, fungal pyelonephritis and mycobacterial infection of the kidney.

Genetic variants of innate immune receptors and infections after liver transplantation

Infection is the leading cause of complication after liver transplantation, causing morbidity and mortality in the first months after surgery. Allograft rejection is mediated through adaptive immunological responses, and thus immunosuppressive therapy is necessary after transplantation. In this setting, the presence of genetic variants of innate immunity receptors may increase the risk of post-transplant infection, in comparison with patients carrying wild-type alleles. Numerous studies have investigated the role of genetic variants of innate immune receptors and the risk of complication after liver transplantation, but their results are discordant. Toll-like receptors and mannose-binding lectin are arguably the most important studied molecules; however, many other receptors could increase the risk of infection after transplantation. In this article, we review the published studies analyzing the impact of genetic variants in the innate immune system on the development of infectious complications after liver transplantation.

Interaction of amphotericin B with lipid monolayers

Langmuir isotherm, neutron reflectivity, and Brewster angle microscopy experiments have been performed to study the interaction of amphotericin B (AmB) with monolayers prepared from 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) and mixtures of this lipid with cholesterol or ergosterol to mimic mammalian and fungal cell membranes, respectively. Isotherm data show that AmB causes a more pronounced change in surface pressure in the POPC/ergosterol system than in the POPC and POPC/cholesterol systems, and its interaction with the POPC/ergosterol monolayer is also more rapid than with the POPC and POPC/cholesterol monolayers. Brewster angle microscopy shows that, in interaction with POPC monolayers, AmB causes the formation of small domains which shrink and disappear within a few minutes. The drug also causes domain formation in the POPC/cholesterol and POPC/ergosterol monolayers; in the former case, these are formed more slowly than is seen with the POPC monolayers and are ultimately much smaller; in the latter case, they are formed rather more quickly and are more heterogeneous in size. Neutron reflectivity data show that the changes in monolayer structure following interaction with AmB are the same for all three systems studied: the data are consistent with the drug inserting into the monolayers with its macrocyclic ring intercalated among the lipid acyl chains and sterol ring systems, with its mycosamine moiety colocalizing with the sterol hydroxyl and POPC head groups. On the basis of these studies, it is concluded that AmB inserts in a similar manner into POPC, POPC/cholesterol, and POPC/ergosterol monolayers but does so with differing kinetics and with the formation of quite different in-plane structures. The more rapid time scale for interaction of the drug with the POPC/ergosterol monolayer, its more pronounced effect on monolayer surface pressure, and its more marked changes as regards domain formation are all consistent with the drug's selectivity for fungal vs mammalian cell membranes.

Successful lung transplant in a child with cystic fibrosis and persistent Blastobotrys rhaffinosifermentans infection

Fungal respiratory infections in patients with CF are a significant concern both pre- and post-lung transplantation (LTx). Fungal infection is associated with increased mortality post-LTx, and in the past decade, the prevalence of fungal colonization in Canadian pediatric patients with CF has increased. The emergence of novel fungal pathogens is particularly challenging to the transplant community, as little is known regarding their virulence and optimal management. We present a case of a successful double-lung transplant in a pediatric patient with CF who was infected pretransplantation with a novel yeast, Blastobotrys rhaffinosifermentans. This patient was treated successfully with aggressive antifungal therapy post-transplantation, followed by extended fungal prophylaxis. The significance of fungal colonization and infection in children with CF pre- and post-LTx is reviewed.

Mucor irregularis-associated cutaneous mucormycosis: Case report and review

Solid organ transplant recipients are at risk for invasive fungal diseases, and are also exposed to healthcare-associated mucormycosis. Mainly causing localized cutaneous mucormycosis, Mucor irregularis infection is reported for the first time in a kidney-transplant recipient. A healthcare-associated origin was highly suspected in this case. We performed a literature review and highlight the characteristics of this very rare fungus.

Cryptococcosis in kidney transplant recipients in a Chinese university hospital and a review of published cases

BACKGROUND

Cryptococcosis is a severe fungal infection with a high mortality rate among solid-organ transplant recipients. Today, China is among the countries performing the most kidney transplants worldwide, however data on the association of cryptococcosis with kidney transplantation in mainland China remain scarce and fragmented.

METHODS

We retrospectively analyzed cases of culture-confirmed cryptococcosis following kidney transplantation that have occurred at our hospital and reviewed the published cases in China over the last 30 years.

RESULTS

Cryptococcosis in kidney transplant recipients was mainly caused by Cryptococcus neoformans var. grubii VNI strains and occurred most frequently in patients aged 41-50 years (37.9%, 11/29). The average time to infection after kidney transplantation was 5.16 ± 3.97 years. The clinical manifestations were found to be diverse, with slight to moderate headache and fever, meningeal irritation, and high cerebrospinal fluid pressure being relatively common. Physicians should be alert to these symptoms among kidney transplant recipients.

CONCLUSIONS

Cryptococcosis is a serious infection among kidney transplant recipients in mainland China. It has unique characteristics, such as a relatively long time to onset after kidney transplantation, and diverse clinical manifestations. Treatment with intrathecal injection of amphotericin B is considered effective for central nervous system involvement. The findings of this study also highlight the urgent need for multicenter, prospective, and multidisciplinary clinical studies and education on cryptococcosis in kidney transplant recipients in China.

[Epidemiological transition of mycosis diseases in sub-Saharan Africa: from surface to depth]

Fungi are schematically responsible for three distinct kinds of infections: superficial mycoses, subcutaneous and deep ones. The current socio-epidemiological transition observed in sub-Saharan Africa does not actually lead to similar consequences regarding these three categories of fungal entities. For instance, it has long been known that superficial mycoses are very prevalent in tropical areas, since they are partly due to the warm climate and the promiscuity. They are mostly caused by dermatophytic fungi or Malassezia sp. (Pityriasis versicolor). Subcutaneous mycoses are rarer, and usually due to dimorphic fungi which are accidentally inoculated into the body after a skin injury or a trauma. Sometimes very spectacular, the clinical outcome is then described as chronic. Thus, chromoblastomycosis, rhinoentomophtoromycosis or mycetoma are some examples of subcutaneous mycoses which remain well-known by practitioners of endemic countries. Deep mycoses (or invasive / systemic mycoses) are defined by fungal infections of deep anatomical sites that should be normally sterile. By contrast with the other entities mentioned above, the outcome may be rapidly fatal for the patient. One of the most outstanding examples was the great increasing of cryptococcal meningitis during the HIV outbreak in the 80'. A few other similar mycoses may be feared in a near future, since they usually occur in contexts of important immunosuppression which are about to be definitely experienced in Africa: overall increase of chronic diseases like diabetes, lengthening life expectancy and its associated diseases, widespread medical practices which were only seen in advanced intensive care units, onco-haematology departments or graft centers so far. Thus, the deep mycoses will inevitably increase in Africa, as they did in all developed countries over the last two decades. The consequences will not only be limited to the clinical management as described above: the diagnostic approach is also quite particular, since the identification of the involved fungal species should be established in emergency, if not the outcome will be fatal. Besides, the antifungal drugs are expensive, and their therapeutic monitoring is quite challenging all along the follow up. Overall, we have to thoroughly take into account the emergence of invasive mycoses right now in Intertropical Africa, in order to successfully achieve the socio-economic development of this continent.

[Nosocomial infection in patients receiving a solid organ transplant or haematopoietic stem cell transplant]

Bacterial infections are the most common infections in solid organ transplant recipients. These infections occur mainly in the first month after transplantation and are hospital-acquired. Nosocomial infections cause significant morbidity and are the most common cause of mortality in this early period of transplantation. These infections are caused by multi-drug resistant (MDR) microorganisms, mainly Gram-negative enterobacteria, non-fermentative Gram-negative bacilli, enterococci, and staphylococci. The patients at risk of developing nosocomial bacterial infections are those previously colonized with MDR bacteria while on the transplant waiting list. Intravascular catheters, the urinary tract, the lungs, and surgical wounds are the most frequent sources of infection. Preventive measures are the same as those applied in non-immunocompromised, hospitalized patients except in patients at high risk for developing fungal infection. These patients need antifungal therapy during their hospitalization, and for preventing some bacterial infections in the early transplant period, patients need vaccinations on the waiting list according to the current recommendations. Although morbidity and mortality related to infectious diseases have decreased during the last few years in haematopoietic stem cell transplant recipients, they are still one of the most important complications in this population. Furthermore, as occurs in the general population, the incidence of nosocomial infections has increased during the different phases of transplantation. It is difficult to establish general preventive measures in these patients, as there are many risk factors conditioning these infections. Firstly, they undergo multiple antibiotic treatments and interventions; secondly, there is a wide variability in the degree of neutropenia and immunosuppression among patients, and finally they combine hospital and home stay during the transplant process. However, some simple measures could be implemented to improve the current situation.

Central nervous system syndromes in solid organ transplant recipients

Solid organ transplant recipients have a high incidence of central nervous system (CNS) complications, including both focal and diffuse neurologic deficits. In the immunocompromised host, the initial clinical evaluation must focus on both life-threatening CNS infections and vascular or anatomic lesions. The clinical signs and symptoms of CNS processes are modified by the immunosuppression required to prevent graft rejection. In this population, these etiologies often coexist with drug toxicities and metabolic abnormalities that complicate the development of a specific approach to clinical management. This review assesses the multiple risk factors for CNS processes in solid organ transplant recipients and establishes a timeline to assist in the evaluation and management of these complex patients.

Hospital days, hospitalization costs, and inpatient mortality among patients with mucormycosis: a retrospective analysis of US hospital discharge data

Background

Mucormycosis is a rare and potentially fatal fungal infection occurring primarily in severely immunosuppressed patients. Because it is so rare, reports in the literature are mainly limited to case reports or small case series. The aim of this study was to evaluate inpatient mortality, length of stay (LOS), and costs among a matched sample of high-risk patients with and without mucormycosis in a large nationally representative database.

Methods

We conducted a retrospective analysis using the 2003–2010 Healthcare Cost and Utilization Project – Nationwide Inpatient Sample (HCUP-NIS). The NIS is a nationally representative 20% sample of hospitalizations from acute care United States (US) hospitals, with survey weights available to compute national estimates. We classified hospitalizations into four mutually exclusive risk categories for mucormycosis: A- severely immunocompromised, B- critically ill, C- mildly/moderately immunocompromised, D- major surgery or pneumonia. Mucormycosis hospitalizations (“cases”) were identified by ICD-9-CM code 117.7. Non-mucormycosis hospitalizations (“non-cases”) were propensity-score matched to cases 3:1. We examined demographics, clinical characteristics, and hospital outcomes (mortality, LOS, costs). Weighted results were reported.

Results

From 319,366,817 total hospitalizations, 5,346 cases were matched to 15,999 non-cases. Cases and non-cases did not differ significantly in age (49.6 vs. 49.7 years), female sex (40.5% vs. 41.0%), White race (53.3% vs. 55.9%) or high-risk group (A-49.1% vs. 49.0%, B-20.0% vs. 21.8%, C-25.5% vs. 23.8%, D-5.5% vs. 5.4%). Cases experienced significantly higher mortality (22.1% vs. 4.4%, P < 0.001), with mean LOS and total costs more than 3-fold higher (24.5 vs. 8.0 days and $90,272 vs. $25,746; both P < 0.001).

Conclusions

In a national hospital database, hospitalizations with mucormycosis had significantly higher inpatient mortality, LOS, and hospital costs than matched hospitalizations without mucormycosis. Findings suggest that interventions to prevent or more effectively treat mucormycosis are needed.

Cryptococcus antigens and immune responses: implications for a vaccine

Cryptococcosis is a fungal disease primarily occurring in immunocompromised individuals, such as AIDS patients, and is associated with high morbidity and mortality. However, cryptococcosis can occur within immunocompetent populations as observed during an outbreak in Vancouver Island, British Columbia, Canada, the Pacific Northwest and other regions of the USA and in Mediterranean Europe. Mortality rates due to cryptococcosis have significantly declined in economically developed countries since the widespread implementation of highly active antiretroviral therapy. However, the incidence and mortality of this disease remains high in economically undeveloped areas in Africa and Asia where HIV infections are high and availability of HAART is limited. The continuing AIDS epidemic coupled with the increased usage of immunosuppressive drugs to prevent organ transplant rejection or to treat autoimmune diseases has resulted in an increase in individuals at risk for developing cryptococcosis. The purpose of this review is to discuss the need, challenges and potential for developing vaccines against cryptococcosis.

Epidemiology of invasive mold infections in lung transplant recipients

Invasive mold infections (IMIs) are a major source of morbidity and mortality among lung transplant recipients (LTRs), yet information regarding the epidemiology of IMI in this population is limited. From 2001 to 2006, multicenter prospective surveillance for IMIs among LTR was conducted by the Transplant-Associated Infection Surveillance Network. The epidemiology of IMI among all LTRs in the cohort is reported. Twelve percent (143/1173) of LTRs under surveillance at 15 US centers developed IMI infections. The 12-month cumulative incidence of IMIs was 5.5%; 3-month all-cause mortality was 21.7%. Aspergillus caused the majority (72.7%)of IMIs; non-Aspergillus infections (39, 27.3%) included Scedosporium (5, 3.5%), mucormycosis (3, 2.1%) and "unspecified" or "other" mold infections (31, 21.7%). Late-onset IMI was common: 52% occurred within 1 year posttransplant (median 11 months, range 0-162 months). IMIs are common late-onset complications with substantial mortality in LTRs. LTRs should be monitored for late-onset IMIs and prophylactic agents should be optimized based on likely pathogen.

Use of the Bruker MALDI Biotyper for identification of molds in the clinical mycology laboratory

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is increasingly used for the identification of bacteria and fungi in the diagnostic laboratory. We evaluated the mold database of Bruker Daltonik (Bremen, Germany), the Filamentous Fungi Library 1.0. First, we studied 83 phenotypically and molecularly well-characterized, nondermatophyte, nondematiaceous molds from a clinical strain collection. Using the manufacturer-recommended interpretation criteria, genus and species identification rates were 78.3% and 54.2%, respectively. Reducing the species cutoff from 2.0 to 1.7 significantly increased species identification to 71.1% without increasing misidentifications. In a subsequent prospective study, 200 consecutive clinical mold isolates were identified by the MALDI Biotyper and our conventional identification algorithm. Discrepancies were resolved by ribosomal DNA (rDNA) internal transcribed spacer region sequence analysis. For the MALDI Biotyper, genus and species identification rates were 83.5% and 79.0%, respectively, when using a species cutoff of 1.7. Not identified were 16.5% of the isolates. Concordant genus and species assignments of MALDI-TOF MS and the conventional identification algorithm were observed for 98.2% and 64.2% of the isolates, respectively. Four erroneous species assignments were observed using the MALDI Biotyper. The MALDI Biotyper seems highly reliable for the identification of molds when using the Filamentous Fungi Library 1.0 and a species cutoff of 1.7. However, expansion of the database is required to reduce the number of nonidentified isolates.

Cryptococcal meningitis: epidemiology and therapeutic options

Cryptococcal meningitis causes morbidity and mortality worldwide. The burden of disease is greatest in middle- and low-income countries with a high incidence of human immunodeficiency virus (HIV) infection. Patients taking immunosuppressive drugs and some immunocompetent hosts are also at risk. Treatment of cryptococcal meningitis consists of three phases: induction, consolidation, and maintenance. Effective induction therapy requires potent fungicidal drugs (amphotericin B and flucytosine), which are often unavailable in low-resource, high-endemicity settings. As a consequence, mortality is unacceptably high. Wider access to effective treatment is urgently required to improve outcomes. For human immunodeficiency virus-infected patients, judicious management of asymptomatic cryptococcal antigenemia and appropriately timed introduction of antiretroviral therapy are important.

Endoplasmic reticulum localized PerA is required for cell wall integrity, azole drug resistance, and virulence in Aspergillus fumigatus

GPI-anchoring is a universal and critical post-translational protein modification in eukaryotes. In fungi, many cell wall proteins are GPI-anchored, and disruption of GPI-anchored proteins impairs cell wall integrity. After being synthesized and attached to target proteins, GPI anchors undergo modification on lipid moieties. In spite of its importance for GPI-anchored protein functions, our current knowledge of GPI lipid remodelling in pathogenic fungi is limited. In this study, we characterized the role of a putative GPI lipid remodelling protein, designated PerA, in the human pathogenic fungus Aspergillus fumigatus. PerA localizes to the endoplasmic reticulum and loss of PerA leads to striking defects in cell wall integrity. A perA null mutant has decreased conidia production, increased susceptibility to triazole antifungal drugs, and is avirulent in a murine model of invasive pulmonary aspergillosis. Interestingly, loss of PerA increases exposure of β-glucan and chitin content on the hyphal cell surface, but diminished TNF production by bone marrow-derived macrophages relative to wild type. Given the structural specificity of fungal GPI-anchors, which is different from humans, understanding GPI lipid remodelling and PerA function in A. fumigatus is a promising research direction to uncover a new fungal specific antifungal drug target.

Candida norvegensis fungemia in a liver transplant recipient

BACKGROUND

The incidence of candidemia due to non-Candida albicans Candida species has been progressively increasing in recent years. The use of fluconazole as antifungal prophylaxis has been described as a risk factor for the development of infections by fluconazole resistant Candida strains. We report a case of Candida norvegensis bloodstream infection in a liver transplant recipient.

CASE REPORT

A 61-year-old man, who received a third liver allograft and became worse with the onset of ischemic cholangiopathy and recurrent episodes of cholangitis, was admitted to our hospital due to the development of intra-abdominal abscesses. He received multiple antibiotic schemes, and after 3 months he was discharged, maintaining parenteral antibiotic at home. While he was on fluconazole prophylaxis, a breakthrough candidemia due to C. norvegensis occurred. In vitro susceptibilities of the isolate to several antifungal agents were as follows: amphotericin B MIC 0.5 mg/l, flucytosine 64 mg/l, fluconazole 64 mg/l, itraconazole 4 mg/l, voriconazole 0.75 mg/l, and caspofungin 0.047 mg/l. He was treated with anidulafungin with resolution of candidemia.

CONCLUSIONS

The use of fluconazole for antifungal prophylaxis may lead to the emergence of fluconazole-resistant Candida infections, with C. norvegensis being a possible emerging pathogen in organ transplant recipients.

Management of infections pre- and post-liver transplantation: report of an AISF consensus conference

The burden of infectious diseases both before and after liver transplantation is clearly attributable to the dysfunction of defensive mechanisms of the host, both as a result of cirrhosis, as well as the use of immunosuppressive agents. The present document represents the recommendations of an expert panel commended by the Italian Association for the Study of the Liver (AISF), on the prevention and management of infectious complications excluding hepatitis B, D, C, and HIV in the setting of liver transplantation. Due to a decreased response to vaccinations in cirrhosis as well as within the first six months after transplantation, the best timing for immunization is likely before transplant and early in the course of disease. Before transplantation, a vaccination panel including inactivated as well as live attenuated vaccines is recommended, while oral polio vaccine, Calmette-Guerin's bacillus, and Smallpox are contraindicated, whereas after transplantation, live attenuated vaccines are contraindicated. Before transplant, screening protocols should be divided into different levels according to the likelihood of infection, in order to reduce costs for the National Health Service. Recommended preoperative and postoperative prophylaxis varies according to the pathologic agent to which it is directed (bacterial vs. viral vs. fungal). Timing after transplantation greatly determines the most likely agent involved in post-transplant infections, and specific high-risk categories of patients have been identified that warrant closer surveillance. Clearly, specifically targeted treatment protocols are needed upon diagnosis of infections in both the pre- as well as the post-transplant scenarios, not without considering local microbiology and resistance patterns.

Current status of antifungal resistance and its impact on clinical practice

Mortality linked to invasive fungal diseases remains very high despite the availability of novel antifungals and new therapeutic strategies. Candida albicans and Aspergillus fumigatus account for most invasive mycosis produced by yeast or moulds, respectively. Other Candida non-albicans are increasingly being reported and newly emerging, as well as cryptic, filamentous fungi often cause disseminated infections in immunocompromised hosts. Management of invasive fungal infections is becoming a challenge as emerging fungal pathogens generally show poor response to many antifungals. The ability of reference antifungal susceptibility testing methods to detect emerging resistance patterns, together with the molecular characterization of antifungal resistance mechanisms, are providing useful information to optimize the effectiveness of antifungal therapy. The current status of antifungal resistance epidemiology with special emphasis on the molecular resistant mechanisms that have been described in the main pathogenic fungal species are reviewed.

Nonmolecular methods for the diagnosis of respiratory fungal infections

Diagnosis of invasive fungal pneumonias by conventional culture methods is difficult to assess and often delayed. Nonmolecular fungal markers have emerged as an important adjunctive tool to support their diagnosis in combination with other clinical, radiologic, and microbiological criteria of invasive fungal diseases. Concerns about the sensitivity and specificity of some tests in different patient populations should lead to warnings about their widespread use. None can identify the emerging and particularly deadly fungal pathogens responsible for mucormycosis. The role of nonmolecular fungal markers should be better defined in combination with other microbiological and radiologic tools in preemptive antifungal strategies.

Performance of galactomannan, beta-d-glucan, Aspergillus lateral-flow device, conventional culture, and PCR tests with bronchoalveolar lavage fluid for diagnosis of invasive pulmonary aspergillosis

Galactomannan detection in bronchoalveolar lavage (BAL) fluid samples (GM test) is currently considered the gold standard test for diagnosing invasive pulmonary aspergillosis (IPA). The limitations, however, are the various turnaround times and availability of testing. We compared the performance of GM testing with that of conventional culture, an Aspergillus lateral-flow-device (LFD) test, a beta-d-glucan (BDG) test, and an Aspergillus PCR assay by using BAL fluid samples from immunocompromised patients. A total of 78 BAL fluid samples from 78 patients at risk for IPA (74 samples from Graz and 4 from Mannheim) collected between December 2012 and May 2013 at two university hospitals in Austria and Germany were included. Three patients had proven IPA, 14 probable IPA, and 17 possible IPA, and 44 patients had no IPA. The diagnostic accuracies of the different methods for probable/proven IPA were evaluated. The diagnostic odds ratios were the highest for the GM, PCR, and LFD tests. The sensitivities for the four methods (except culture) were between 70 and 88%. The combination of the GM (cutoff optical density index [ODI], >1.0) and LFD tests increased the sensitivity to 94%, while the combination of the GM test (>1.0) and PCR resulted in 100% sensitivity (specificity for probable/proven IPA, 95 to 98%). The performance of conventional culture was limited by low sensitivity, while that of the BDG test was limited by low specificity. We evaluated established and novel diagnostic methods for IPA and found that the Aspergillus PCR, LFD, and GM tests were the most useful methods for diagnosing the disease by using BAL fluid samples. In particular, the combination of the GM test and PCR or, if PCR is not available, the LFD test, allows for sensitive and specific diagnosis of IPA.

The Prospective Antifungal Therapy Alliance(®) registry: A two-centre Canadian experience

BACKGROUND

The Prospective Antifungal Therapy Alliance(®) registry is a prospective surveillance study that collected data on the diagnosis, management and outcomes of invasive fungal infections (IFIs) from 25 centres in North America from 2004 to 2008.

OBJECTIVE

To evaluate surveillance data on IFIs obtained from study centres located in Canada.

METHODS

Patients with proven or probable IFIs at two Canadian medical centres were enrolled in the registry. Information regarding patient demographics, fungal species, infection sites, diagnosis techniques, therapy and survival were analyzed.

RESULTS

A total of 347 patients from Canada with documented IFIs were enrolled in the Prospective Antifungal Therapy Alliance registry. Infections occurred most commonly in general medicine (71.8%), nontransplant surgery (32.6%) and patients with hematological malignancies (21.0%). There were 287 proven IFIs, including 248 Candida infections. Forty-six patients had invasive aspergillosis (IA); all of these were probable infections. Most cases of invasive candidiasis were confirmed using blood culture (90.5%), while IA was most frequently diagnosed using computed tomography scan (82.6%) and serological methods (82.6%). Fluconazole was the most common therapy used for Candida infections, followed by the echinocandins. Voriconazole therapy was most commonly prescribed for IA.

CONCLUSIONS

The present study demonstrated that general medicine, surgery and hematological malignancy patients in Canada are susceptible to developing IFIs. In contrast to the United States, Candida albicans remains responsible for most IFIs in these Canadian centres. Surrogate serum markers are commonly being used for the diagnosis of IA, while therapy for both IFIs has shifted to broader-spectrum azoles and echinocandins.

Clinical characteristics and outcomes in 303 HIV-infected patients with invasive fungal infections: data from the Prospective Antifungal Therapy Alliance registry, a multicenter, observational study

This analysis aimed to characterize the epidemiology, diagnosis, treatment, and outcomes of invasive fungal infections (IFIs) in patients with human immunodeficiency virus (HIV). Data were examined for HIV patients enrolled in the Prospective Antifungal Therapy (PATH) Alliance registry, a multicenter, observational study of patients with IFIs in North America from 2004 to 2008. Patient demographics, clinical characteristics, comorbidities, antifungal therapies, and survival were assessed. In total, 320 fungal isolates were identified from 303 HIV patients with IFIs in the PATH Alliance® registry. These included Cryptococcus (50.0%), Candida (33.1%), Histoplasma (9.1%), and Aspergillus (4.4%). Candida infection occurred mainly as candidemia (86.0%); Cryptococcus as central nervous system infection (76.7%); Histoplasma as disseminated infection (74.1%); and Aspergillus as pulmonary infection (81.8%). The CD4 cell count was ≤200 cells/μL in 91.2% of patients with available data. The majority of patients with Cryptococcus (77.9%), Histoplasma (100.0%), and Aspergillus (71.4%) infections had CD4 cell counts <50 cells/μL compared with 48.9% of patients with Candida infections. Patients with candidiasis were more likely to have other conditions requiring medical services compared with patients with other IFIs. Survival probability was lower in patients with Aspergillus (0.58) and Candida (0.59) infection than in patients with Histoplasma (0.84) and Cryptococcus (0.81) infection. In the highly active antiretroviral therapy era, traditional opportunistic IFIs such as cryptococcosis and histoplasmosis still mainly occur in HIV patients with CD4 counts <50 cells/μL. Fungal infections remain a clinical challenge in HIV patients with severe immunosuppression. Our data also suggest that HIV patients with CD4 cell counts >200 cells/μL and other underlying conditions may be susceptible to invasive candidiasis.