Invasive aspergillosis: diagnosis, prophylaxis and treatment

HIF1-α upregulation induces proinflammatory factors to boost host killing capacity after Aspergillus fumigatus exposure

Aims: HIF1-α is an important transcription factor in the regulation of the immune response. The protective function of HIF1-α in the host epithelial immune response to Aspergillus fumigatus requires further clarification. Methods: In this study we demonstrated the effect of upregulation of HIF1-α expression in A549 cells and mouse airway cells exposed to A. fumigatus in vivo. Results: The killing capacity was enhanced by boosting proinflammatory factors both in vitro and in vivo. Moreover, airway inflammation was reduced in the HIF1-α-upregulated mice. Conclusion: We identified a protective role for HIF1-α in anti-A. fumigatus immunity. Modulation of HIF1-α might be a target for the development of aspergillosis therapy.

Aspergillus-PCR in bronchoalveolar lavage diagnostic accuracy for invasive pulmonary aspergillosis in critically ill patients

BACKGROUND

Diagnosis of invasive pulmonary aspergillosis (IPA) in intensive care unit (ICU) patients is challenging and the role of Aspergillus-PCR in bronchoalveolar lavage (BAL) is unknown.

OBJECTIVES

This study evaluated diagnostic accuracy of Aspergillus-PCR in BAL in IPA in three different cohorts: ICU-admitted patients with COVID-19, ICU-admitted patients without COVID-19 and immunocompromised patients.

METHODS

All stored available BAL samples collected from three patient groups were tested with Aspergillus-PCR (AsperGenius®). IPA was diagnosed according to appropriate criteria for each patient group.

RESULTS

We included 111 BAL samples from 101 patients: 52 (51%) patients admitted to ICU for COVID-19, 24 (24%) admitted to ICU for other reasons and 25 (25%) immunocompromised. There were 31 cases of IPA (28%). Aspergillus-PCR sensitivity was 64% (95%CI 47-79), specificity 99% (95%CI 93-100). Aspergillus-PCR sensitivity was 40% (95%CI 19-64) in ICU COVID-19, 67% (95%CI 21-93) in non-COVID-19 ICU patients and 92% (95%CI 67-98) in the immunocompromised. The concordance between positive BAL-GM and BAL-PCR in patients with and without IPA was significantly lower in ICU patients (32%; 43% in COVID-19, 18% in non-COVID-19) than in the immunocompromised (92%), p<0.001.

CONCLUSIONS

Aspergillus-PCR in BAL improves the diagnostic accuracy of BAL-GM in ICU patients.

Invasive pulmonary aspergillosis due to Aspergillus lentulus in an adult patient: A case report and literature review

Aspergillus fumigatus is the commonest cause of pulmonary aspergillosis; however, a recently developed molecular genetic technique identified A. lentulus as a sibling species. Most of the isolates were found in solid organ recipients, often associated with a fatal outcome. Moreover, there is concern that A. lentulus has low susceptibility to multiple antifungal agents. Herein, we report an adult immunocompromised patient with proven invasive pulmonary aspergillosis (IPA) caused by A. lentulus, which was identified through molecular genetic analysis. The patient was diagnosed with IPA by bronchoscopy 3 weeks after initiating systemic corticosteroid therapy for anti-neutrophil cytoplasmic antibody-associated vasculitis. The clinical course of IPA due to A. lentulus showed improvement after treatment with the antifungal agent voriconazole. In summary, we report an adult immunocompromised patient without a history of transplantation who was diagnosed with IPA due to A. lentulus successfully treated with voriconazole, and we also report the findings of a literature review on IPA caused by A. lentulus.

Serum galactomannan for diagnosing invasive aspergillosis in pediatric patients: A meta-analysis

BACKGROUND

The serum galactomannan (GM) assay is used to diagnose invasive aspergillosis (IA). We conducted a systematic review and analysis to estimate the overall accuracy of the serum GM test for diagnosing pediatric IA.

METHOD

A systematic literature review was conducted of all relevant studies published in PubMed and EMbase databases up to March 10, 2017. We selected and assessed articles that reported diagnostic data related to serum GM for diagnosis of pediatric IA. Pooled diagnostic odds ratios (DORs) and summary receiver operating characteristics (SROCs) were constructed with a cutoff value of 0.5. Additionally, pooled sensitivity (SEN), specificity (SPE), and positive and negative likelihood ratios (PLR and NLR, respectively) were estimated for summarizing overall test performance.

RESULTS

Seventeen studies were included in this systematic review. The total number of patients (age range 0-21 years old) was 1768, with 178 that had proven or probable IA. The pooled serum GM assay results, with a cutoff value of 0.5 for proven or probable IA, were DOR: 41.16 (95% confidence interval (CI) 21.48-78.86), SEN: 0.85 (95% CI 0.72-0.93), SPE: 0.88 (95% CI 0.80-0.93), PLR: 6.92 (95% CI 4.40-10.88), and NLR: 0.17 (95% CI 0.09-0.32). The SROC was 0.93.

CONCLUSION

Serum GM can be used to assist in diagnosis of proven or probable pediatric IA. However, serum GM test results should be interpreted in combination with clinical findings in pediatric IA cases, as the test results are not always sensitive or specific enough for pediatric IA.

Effect of involved Aspergillus species on galactomannan in bronchoalveolar lavage of patients with invasive aspergillosis

PURPOSE

The detection of galactomannan (GM) in bronchoalveolar lavage (BAL) fluid is an important surrogate marker for the early diagnosis and therapeutic monitoring of invasive aspergillosis (IA), regardless of the involved species of Aspergillus. Here, we utilized the Platelia Aspergillus GM enzyme immunoassay (Bio-Rad) to evaluate the GM index in BAL fluid samples from patients with proven, probable or putative IA due to Aspergillusflavus versus Aspergillusfumigatus.

METHODOLOGY

In a prospective study between 2009 and 2015, 116 BAL samples were collected from suspected IA patients referred to two university hospitals in Tehran, Iran.

KEY FINDINGS

According to European Organization for Research and Treatment of Cancer and Mycoses Study Group and Blot criteria, 35 patients were classified as IA patients, of which 33 cases tested positive for GM above 0.5 and, among these patients, 22 had a GM index ≥1. Twenty-eight were culture positive for A. flavus and seven for A. fumigatus. The GM index for A. flavus cases was between 0.5-6.5 and those of A. fumigatus ranged from 1 to 6.5. The sensitivity and specificity of a GM index ≥0.5 in cases with A. flavus were 86 and 88 % and for A. fumigatus patients were 100 and 73 %, respectively.

CONCLUSION

Overall, the mean GM index in patients with A. fumigatus (3.1) was significantly higher than those of A. flavus (1.6; P-value=0.031) and the sensitivity of GM lower for A. flavus when compared to A. fumigatus. This finding has implications for diagnosis in hospitals and countries with a high proportion of A. flavus infections.

Renal Allograft Aspergillus Infection Presenting With Obstructive Uropathy: A Case Report

BACKGROUND

Isolated renal allograft aspergillosis is rare and usually presents with fever and decreased glomerular filtration rate. Presentation with obstructive uropathy caused by aspergillus fungal balls is much less common. We report a young male patient who presented with obstructive uropathy secondary to isolated renal allograft aspergillus infection 6 weeks after transplant. He was treated with nephrectomy and antifungal medications.

CASE PRESENTATION

A 29-year-old Saudi male patient had a recent living non-related kidney transplantation in Pakistan. Early Post-transplant course was complicated by acute cellular rejection (Banff Class IB) which was managed successfully with pulse steroid and anti-thymocyte globulin. The patient presented again to our emergency room on fortieth day post-transplant with a complaint of decreased urine output and passing white particles in his urine. This presentation was three Three weeks after treatment for cellular rejection, the urine fungal culture showed growth of Aspergillus fumigatus, and ultrasound imaging of the allograft kidney revealed mild to moderate hydronephrosis with echogenic materials within the renal pelvis. Biopsy of the transplanted kidney showed severe necrotizing granulomatous inflammation and fungal elements consistent with aspergillus species. The patient was given voriconazole as an antifungal agent and was weaned from immunosuppressive medication. The patient eventually required intermittent hemodialysis and underwent surgical allograft nephrectomy.

CONCLUSION

Suboptimal environmental and infection prevention and control precautions can explain this type of infection. It is important for clinicians to have a high index of suspicion and to investigate for fungal infection as a rare cause of obstructive uropathy in high-risk patients.

Aspergillosis of the central nervous system in a previously healthy patient that simulated Creutzfeldt-Jakob disease

BACKGROUND

The presence of Aspergillus in the central nervous system (CNS) is rare in immunocompetent patients but not in immunocompromised patients who may have a more common infection. This article describes a case of an adult immunocompetent patient with a diagnosis of cerebral aspergillosis and with a clinical process of rapidly progressive dementia which simulated a Creutzfeldt-Jakob syndrome.

CASE DESCRIPTION

A 34-year-old adult was previously healthy and had no medical history of any significance. The patient had suffered only facial trauma 8 months before admission. One month prior to admission, he showed rapidly progressing changes in his behavior and higher mental functions. He was admitted to the emergency room with an occipital headache with 2 months of history. By the time he arrived, he suffered from total disability and was prostrate. He was diagnosed with meningeal and demential syndrome in the process of being studied. After starting the diagnostic approach by investigating cerebrospinal fluid, a magnetic resonance of the skull, an electroencephalogram, a brain biopsy was indicated. The histopathological study reported the presence of the hyphae characteristics of Aspergillus. The patient died 7 days after the diagnosis.

CONCLUSION

Cerebral aspergillosis is a common aggressive disease in immunosuppressed patients. However, the disease is rare in individuals with respected immunity and in individuals with neurological impairment and a rapid and progressive deterioration of mental functions. The suspected diagnosis should always be considered given its poor prognosis and the encouraging efficacy of antifungal treatment administered in a timely manner.

Exploration of Sulfur Assimilation of Aspergillus fumigatus Reveals Biosynthesis of Sulfur-Containing Amino Acids as a Virulence Determinant

Fungal infections are of major relevance due to the increased numbers of immunocompromised patients, frequently delayed diagnosis, and limited therapeutics. To date, the growth and nutritional requirements of fungi during infection, which are relevant for invasion of the host, are poorly understood. This is particularly true for invasive pulmonary aspergillosis, as so far, sources of (macro)elements that are exploited during infection have been identified to only a limited extent. Here, we have investigated sulfur (S) utilization by the human-pathogenic mold Aspergillus fumigatus during invasive growth. Our data reveal that inorganic S compounds or taurine is unlikely to serve as an S source during invasive pulmonary aspergillosis since a sulfate transporter mutant strain and a sulfite reductase mutant strain are fully virulent. In contrast, the S-containing amino acid cysteine is limiting for fungal growth, as proven by the reduced virulence of a cysteine auxotroph. Moreover, phenotypic characterization of this strain further revealed the robustness of the subordinate glutathione redox system. Interestingly, we demonstrate that methionine synthase is essential for A. fumigatus virulence, defining the biosynthetic route of this proteinogenic amino acid as a potential antifungal target. In conclusion, we provide novel insights into the nutritional requirements ofA. fumigatus during pathogenesis, a prerequisite to understanding and fighting infection.

Late aspergilloma of a renal allograft without need for operative management: a case report and review of the literature

Aspergillus infection localized to the renal allograft is a rare and potentially life-threatening infection and typically requires a combination of operative and medical management. We report the case of a renal allograft aspergilloma in a renal transplant patient presenting 2 years post transplant, successfully managed non-surgically. To our knowledge, this is the first report of a patient presenting with an allograft aspergilloma so long after transplantation and being successfully managed with antifungal therapy alone.

Republished: The clinical spectrum of pulmonary aspergillosis

The clinical presentation of Aspergillus lung disease is determined by the interaction between fungus and host. Invasive aspergillosis develops in severely immunocompromised patients, including those with neutropenia, and increasingly in the non-neutropenic host, including lung transplant recipients, the critically ill patients and patients on steroids. A high index of suspicion is required in patients without the classical risk factors as early presentation is usually silent and non-specific, pyrexia uncommon and timely treatment is crucial for survival. Invasive aspergillosis has also been diagnosed in normal hosts after massive exposure to fungal spores. Chronic pulmonary aspergillosis affects patients without obvious immune compromise, but with an underlying lung condition such as COPD or sarcoidosis, prior or concurrent TB or non-tuberculous mycobacterial disease. Aspergillus bronchitis may be responsible for persistent respiratory symptoms in patients with Aspergillus detected repeatedly in sputum without evidence of parenchymal Aspergillus disease, especially in patients with bronchiectasis and cystic fibrosis. Allergic bronchopulmonary aspergillosis affects patients with asthma and cystic fibrosis, and is important to recognise as permanent lung or airways damage may accrue if untreated. Changes in the classification of Aspergillus allergic lung disease have been proposed recently. Cases of extrinsic allergic alveolitis and chronic pulmonary aspergillosis have been observed after Aspergillus exposure. Asymptomatic colonisation of the respiratory tract needs close monitoring as it can lead to clinical disease especially with ongoing immunosuppression. The various syndromes should be viewed as a semicontinuous spectrum of disease and one form may evolve into another depending on the degree of ongoing immunosuppression.

Diagnosis and treatment of invasive fungal infections focus on liposomal amphotericin B

Invasive fungal infections (IFIs) are responsible for significant morbidity and mortality, especially in immunocompromised patients and in those requiring admission to an intensive care unit. The epidemiology of IFI is changing, and an increment in non-Aspergillus filamentous fungi and non-Candida albicans species has been observed. The present paper reviews the epidemiology and diagnosis of IFIs. Regarding the treatment of IFIs, it focuses primarily on the role of liposomal amphotericin B in this setting. The main recommendations put forth by expert societies and groups are discussed.

Regulation of sulphur assimilation is essential for virulence and affects iron homeostasis of the human-pathogenic mould Aspergillus fumigatus

Sulphur is an essential element that all pathogens have to absorb from their surroundings in order to grow inside their infected host. Despite its importance, the relevance of sulphur assimilation in fungal virulence is largely unexplored. Here we report a role of the bZIP transcription factor MetR in sulphur assimilation and virulence of the human pathogen Aspergillus fumigatus. The MetR regulator is essential for growth on a variety of sulphur sources; remarkably, it is fundamental for assimilation of inorganic S-sources but dispensable for utilization of methionine. Accordingly, it strongly supports expression of genes directly related to inorganic sulphur assimilation but not of genes connected to methionine metabolism. On a broader scale, MetR orchestrates the comprehensive transcriptional adaptation to sulphur-starving conditions as demonstrated by digital gene expression analysis. Surprisingly, A. fumigatus is able to utilize volatile sulphur compounds produced by its methionine catabolism, a process that has not been described before and that is MetR-dependent. The A. fumigatus MetR transcriptional activator is important for virulence in both leukopenic mice and an alternative mini-host model of aspergillosis, as it was essential for the development of pulmonary aspergillosis and supported the systemic dissemination of the fungus. MetR action under sulphur-starving conditions is further required for proper iron regulation, which links regulation of sulphur metabolism to iron homeostasis and demonstrates an unprecedented regulatory crosstalk. Taken together, this study provides evidence that regulation of sulphur assimilation is not only crucial for A. fumigatus virulence but also affects the balance of iron in this prime opportunistic pathogen.

Voriconazole and its clinical potential in the prophylaxis of systemic fungal infection in patients with hematologic malignancies: a perspective review

Invasive fungal infections (IFIs) have become high prevalence in patients with hematologic malignancies. Drug-based strategies for IFIs include various approaches such as prophylactic, empiric, preemptive, and directed treatment. Prophylaxis is an attractive strategy in high-risk patients, given the lack of reliable diagnostics and the high mortality rate associated with IFIs. Prophylaxis includes the use of antifungal drugs in all patients at risk. An ideal antifungal compound for prophylaxis should have a potent and broad activity, be available both orally and intravenously, and have a low toxicity profile. Voriconazole fulfills all these criteria. The clinical efficacy of voriconazole against the majority of fungal pathogens makes it potentially very useful for the prevention of IFIs in patients with hematologic malignancies. Voriconazole appears to be very effective for the primary and secondary prevention of IFIs in these patients and recipients of allogeneic hematopoietic stem-cell transplantation. Randomized controlled trials evaluating voriconazole as primary antifungal prophylaxis in patients with neutropenia treated for a variety of hematologic malignancies have been performed, confirming its value as a prophylactic agent. Voriconazole is generally safe and well tolerated; however, its use is also associated with a number of concerns. In most patients with hematologic malignancies there is the potential for pharmacokinetic drug-drug interactions given that voriconazole is metabolized through the P450 cytochrome system.

Emerging systemic fungal infections

Systemic mycoses are a heterogeneous group of infections caused by different species of fungi that mainly affect individuals with primary or secondary alterations of immunity. In recent years, there has been an increase in the incidence of infections related to migration, AIDS, and other causes of immunosuppression, such as solid organ and bone marrow transplantation; oncological, hematological, and autoimmune diseases; and the use of new drugs. In this paper, we outline the microbiological and epidemiological characteristics of 3 fungi: Aspergillus spp, Fusarium spp, and Penicillium spp. We describe the clinical manifestations of disease with emphasis on those that should alert the dermatologist to make an early diagnosis. We detail the various tools for early diagnosis, prevention, and the epidemiology of different antifungals available for treatment and their mechanism of action and therapeutic efficacy.

Deciphering metabolic traits of the fungal pathogen Aspergillus fumigatus: redundancy vs. essentiality

Incidence rates of infections caused by environmental opportunistic fungi have risen over recent decades. Aspergillus species have emerged as serious threat for the immunecompromised, and detailed knowledge about virulence-determining traits is crucial for drug target identification. As a prime saprobe, A. fumigatus has evolved to efficiently adapt to various stresses and to sustain nutritional supply by osmotrophy, which is characterized by extracellular substrate digestion followed by efficient uptake of breakdown products that are then fed into the fungal primary metabolism. These intrinsic metabolic features are believed to be related with its virulence ability. The plethora of genes that encode underlying effectors has hampered their in-depth analysis with respect to pathogenesis. Recent developments in Aspergillus molecular biology allow conditional gene expression or comprehensive targeting of gene families to cope with redundancy. Furthermore, identification of essential genes that are intrinsically connected to virulence opens accurate perspectives for novel targets in antifungal therapy.

Systematic review and meta-analysis of detecting galactomannan in bronchoalveolar lavage fluid for diagnosing invasive aspergillosis

BACKGROUND

Bronchoalveolar lavage (BAL) galactomannan (GM) assay has been used for diagnosing invasive aspergillosis (IA). We aimed to derive a definitive estimate of the overall accuracy of BAL-GM for diagnosing IA.

METHODS AND RESULTS

We undertook a systematic review of thirty diagnostic studies that evaluated the BAL-GM assay for diagnosing IA. PubMed and CBM (China Biological Medicine Database) databases were searched for relevant studies published in all languages up until Feb 2012. The pooled diagnostic odds ratio (DOR) and summary receiver operating characteristic (SROC) were constructed for each cutoff value. Additionally, pooled sensitivity (SEN), specificity (SPE), and positive and negative likelihood ratios (PLR and NLR, respectively) were calculated for summarizing overall test performance. Thirty studies were included in this meta-analysis. The summary estimates of pooled DOR, SEN, SPE, PLR, and NLR of the BAL-GM assay (cutoff value 0.5) for proven or probable IA were 52.7 (95% confidence interval (CI) 31.8-87.3), 0.87 (95% CI 0.79-0.92), 0.89 (95% CI 0.85-0.92), 8.0 (95% CI 5.7-11.1) and 0.15 (95% CI 0.10-0.23) respectively. The SROC was 0.94 (95% CI 0.92-0.96). Compared with cutoff value of 0.5, it has higher DOR, SPE and PLR, and similar SEN and NLR with cutoff value of 1.0, which indicated the optimal cutoff value might be 1.0. Compared with BAL-GM, serum GM has a lower SEN and higher SPE, while PCR displays a lower SEN and a similar SPE.

CONCLUSION

With the optimal cutoff value of 1.0, the BAL-GM assay has higher SEN compared to PCR and serum GM test. It is a useful adjunct in the diagnosis of proven and probable IA.

Interlaboratory comparison of PCR-based identification of Candida and Aspergillus DNA in spiked blood samples

Despite PCR per se being a powerful and sensitive technique, regarding the detection of fungi in patients' blood, no consensus for a standardised PCR protocol yet exists. To complement other ongoing or accomplished studies which tackle this problem, the German Reference Center for Systemic Mycoses conducted an interlaboratory comparison starting with blood samples spiked with fungal cell elements. Altogether, six laboratories using in-house PCR-protocols from Germany and Austria participated in the trial. Blood samples were spiked with vital cells of Candida albicans or Aspergillus fumigatus. Candida was used in the yeast form, whereas Aspergillus cells were either spiked as conidia or as very young germlings, also known as smoo cells. Spiked blood samples contained between 10 and 10 000 cells ml(-1). Depending on the techniques used for fungal cell disruption and DNA-amplification, detection quality was variable between laboratories, but also differed within single laboratories in different trials particularly for samples spiked with less than 100 cells ml(-1). Altogether, at least regarding the detection of A. fumigatus, two of six laboratories showed constant reliable test results also with low fungal cell number spiked samples. Protocols used by these labs do not differ substantially from others. However, as particularities, one protocol included a conventional phenol chloroform extraction during the DNA preparation process and the other included a real time PCR-protocol based on FRET probes. Other laboratory comparisons on the basis of clinical samples should follow to further evaluate the procedures. The difficulties and problems of such trials in general are discussed.

What should be the optimal cut-off of serum 1,3-β-D-glucan for the detection of invasive pulmonary aspergillosis in patients with haematological malignancies?

BACKGROUND

The detection of 1,3-β-d-glucan (BDG), a cell wall component of several medically important fungi, is a promising tool for the diagnosis of invasive pulmonary aspergillosis. The aim of this study was to evaluate the diagnostic accuracy of the BDG test in invasive pulmonary aspergillosis (IPA) by focusing on the optimal cut-off value.

METHODS

The records of the Infection Control Committee were reviewed to identify patients with haematological malignancies and stem cell transplantation who had at least 1 BDG (Fungitell kit) measurement during the period January 2008 through April 2011. The European Organization for Research and Treatment of Cancer and the Mycoses Study Group (EORTC/MSG) criteria (independent of BDG results) were used to categorize the patients with IPA. Patients with possible IPA were not included in the study.

RESULTS

A total of 128 patients (50 with proven or probable IPA) were included in the study. At the manufacturer's recommended cut-off value of 80 pg/ml, the sensitivity of BDG was 66% (95% CI 51.2-78.7), specificity 75.6% (95% CI 64.6-84.5), positive predictive value (PPV) 63.4%, and negative predictive value (NPV) 77.6%. A receiver operating characteristic (ROC) curve was constructed to define the optimum serum BDG cut-off for the diagnosis of IPA. At a cut-off value of 181 pg/ml, the sensitivity was 52% (95% CI 37.4-66.3), specificity 94.8% (95% CI 87.4-98.6), PPV 86.7%, and NPV 75.5%.

CONCLUSIONS

Although higher cut-off levels increased the specificity of the BDG test, sensitivity decreased to an unacceptable level; the commercially recommended cut-off value appears to be appropriate for screening purposes.

Antifungal treatment of small animal veterinary patients

Antifungal therapy has progressed significantly with the development of new drugs directed at various processes in fungal cell metabolism. Within veterinary medicine, treatment options for systemic mycoses remain limited to amphotericin B, ketoconazole, fluconazole, and itraconazole. However, newer triazoles, echinocandins, and lipid-based formulations of amphotericin B are now approved for use in humans. This article provides a comprehensive review of the antifungal medications available for veterinary patients, and includes a brief discussion of the newer, presently cost-prohibitive, antifungal therapies used for systemic mycoses in humans.

Rare mycoses of the oral cavity: a literature epidemiologic review

Stomatologic fungal infections display different etiologies, pathogenesis, and clinical presentations. The incidence of rare mycoses of oral cavity is very low. These infections can involve both immunocompromised and immmunocompetent patients with common predisposing factors, such as diabetes or suffering from diseases causing immune system impairment. Oral mycoses can cause acute, chronic, and mucocutaneous lesions. Candidiasis is the most common mouth mycosis. Although occasionally primary mouth pathogens, Cryptococcus spp. or filamentous fungi (Aspergillus spp. and zygomycetes) can cause oral mycoses, with the oral localization more commonly secondary to a more serious systemic infection. The diagnosis of oral mycoses is based on clinical examination; for yeasts, culture is necessary to identify the etiologic agents; for filamentous fungi, in particular for zygomycetes and dimorphic, a definitive diagnosis can be made by histologic examination and pertinent stains with or without isolation of the fungus from the same site.