Fusariosis associated with pathogenic fusarium species colonization of a hospital water system: a new paradigm for the epidemiology of opportunistic mold infections

Fusarium species,Scedosporium species, and Lomentospora prolificans: A systematic review to inform the World Health Organization priority list of fungal pathogens

Recognizing the growing global burden of fungal infections, the World Health Organization established a process to develop a priority list of fungal pathogens (FPPL). In this systematic review, we aimed to evaluate the epidemiology and impact of infections caused by Fusarium spp., Scedosporium spp., and Lomentospora prolificans to inform the first FPPL. PubMed and Web of Sciences databases were searched to identify studies published between January 1, 2011 and February 23, 2021, reporting on mortality, complications and sequelae, antifungal susceptibility, preventability, annual incidence, and trends. Overall, 20, 11, and 9 articles were included for Fusarium spp., Scedosporium spp., and L. prolificans, respectively. Mortality rates were high in those with invasive fusariosis, scedosporiosis, and lomentosporiosis (42.9%-66.7%, 42.4%-46.9%, and 50.0%-71.4%, respectively). Antifungal susceptibility data, based on small isolate numbers, showed high minimum inhibitory concentrations (MIC)/minimum effective concentrations for most currently available antifungal agents. The median/mode MIC for itraconazole and isavuconazole were ≥16 mg/l for all three pathogens. Based on limited data, these fungi are emerging. Invasive fusariosis increased from 0.08 cases/100 000 admissions to 0.22 cases/100 000 admissions over the time periods of 2000-2009 and 2010-2015, respectively, and in lung transplant recipients, Scedosporium spp. and L. prolificans were only detected from 2014 onwards. Global surveillance to better delineate antifungal susceptibility, risk factors, sequelae, and outcomes is required.

Successful Treatment of Disseminated Fusariosis in a 15-Month-Old Boy With Refractory Acute Lymphoblastic Leukemia Using High-Dose Voriconazole

BACKGROUND

Infections due to rare molds, such as Fusarium spp., cause severe and difficult-to-control diseases with increasing frequency. Data on fusariosis in children and on the use of voriconazole (VCZ), considered a drug of choice, are scarce in infants and children <2 years of age.

CASE PRESENTATION

We present the first, to our knowledge, pediatric case of disseminated mycosis due to Fusarium musae in a 15-month-old boy with relapsed/refractory acute lymphoblastic leukemia, diagnostics and outcome. Herein, at this severely immunocompromised patient, after prompt diagnosis, disseminated fusariosis was successfully treated with high-dose VCZ at a final dose of 15 mg/kg of body weight twice a day. This occurred by achieving adequate drug exposures as determined by drug susceptibility testing and followed by therapeutic drug monitoring without observed toxicity.

CONCLUSIONS

Appropriate diagnostic approach and timely administration of optimal antifungal therapy with VCZ were important for the successful treatment of disseminated fusariosis. Therapeutic drug monitoring, especially in <2-year-old children, is necessary to achieve sufficient drug exposure for optimal therapeutic response without toxicity.

It's getting hot in here: Effects of heat on temperature, disinfection, and opportunistic pathogens in drinking water distribution systems

As global temperatures rise with climate change, the negative effects of heat on drinking water distribution systems (DWDS) are of increasing concern. High DWDS temperatures are associated with degradation of water quality through physical, chemical and microbial mechanisms. Perhaps the most pressing concern is proliferation of thermotolerant opportunistic pathogens (OPs) like Legionella pneumophila and Naegleria Fowleri. Many OPs can be controlled in DWDS by residual disinfectants such as chlorine or chloramine, but maintaining protective residuals can be challenging at high temperatures. This critical review evaluates the literature on DWDS temperature, residual disinfectant decay, and OP survival and growth with respect to high temperatures. The findings are synthesized to determine the state of knowledge and future research priorities regarding OP proliferation and control at high DWDS temperatures. Temperatures above 40 °C were reported from multiple DWDS, with a maximum of 52 °C. Substantial diurnal temperature swings from ∼30-50 °C occurred in one DWDS. Many OPs can survive or even replicate at these temperatures. However, most studies focused on just a few OP species, and substantial knowledge gaps remain regarding persistence, infectivity, and shifts in microbial community structure at high temperatures relative to lower water temperatures. Chlorine decay rates substantially increase with temperature in some waters but not in others, for reasons that are not well understood. Decay rates within real DWDS are difficult to accurately characterize, presenting practical limitations for application of temperature-dependent decay models at full scale. Chloramine decay is slower than chlorine except in the presence of nitrifiers, which are especially known to grow in DWDS in warmer seasons and climates, though the high temperature range for nitrification is unknown. Lack of knowledge about DWDS nitrifier communities may hinder development of solutions. Fundamental knowledge gaps remain which prevent understanding even the occurrence of high temperatures in DWDS, much less the overall effect on exposure risk. Potential solutions to minimize DWDS temperatures or mitigate the impacts of heat were identified, many which could be aided by proven models for predicting DWDS temperature. Industry leadership and collaboration is needed to generate practical knowledge for protecting DWDS water quality as temperatures rise.

Compilation of regulations and procedures for monitoring filamentous fungi in hospital environments

Air and surfaces in the hospital environment are a potential source of exposure to filamentous fungi (FF) that could cause invasive fungal diseases (IFD) in severely immunocompromised patients. The prevalent FF in IFD are species from the genera Aspergillus, Fusarium, Scedosporium, and those within the order Mucorales. We have compiled regulations and described the procedures used in the clinical mycology laboratory to assess the presence of FF in areas at risk for the development of IFD. The infection control committees of each establishment implement hospital policies to regulate and control processes aimed at preventing infections. Fungal load monitoring is an important step in this process to validate air quality in order to ensure a clean and protected environment for severely immunocompromised patients.

Invasive fungal rhinosinusitis by Fusarium proliferatum/annulatum in a patient with acute myeloid leukemia: A case report and review of the literature

Antifungal prophylaxis with a mold-effective agent has led to a substantial decrease in invasive infections caused by Aspergillus spp. in the management of patients with acute myeloid leukemia undergoing induction chemotherapy. However, difficult-to-treat infections caused by other molds, such as Fusarium, Lomentospora, and Scedosporium species may still complicate the neutropenic period. Here, we present a case of a 23-year-old woman with acute myeloid leukemia who developed a breakthrough invasive fungal rhinosinusitis caused by Fusarium proliferatum/annulatum on posaconazole prophylaxis. The infection was diagnosed using clinical, microbiological, and radiological criteria and the isolate was identified using Matrix Assisted Lazer Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) and sequencing. We searched Pubmed with "Fusarium proliferatum", "Fusarium annulatum", "immunosuppression AND fusariosis", "rhinosinusitis AND Fusarium proliferatum" and summarized the English literature for similar rhinosinusitis cases infected with the same pathogen.

Epidural anesthesia causes outbreak of mycotic aneurysms: complications of Fusarium solani meningitis

BACKGROUND

A health advisory was issued in response to a fungal meningitis outbreak linked to epidural anesthesia exposure in two plastic surgery clinics in Mexico, from January 1 to May 13, 2023. This descriptive analysis describes the neuroendovascular and neurosurgical observations and management of patients treated at a single stroke center located along the US-Mexico Border.

METHODS

We conducted a retrospective chart review of fungal meningitis patients presenting between April and July 2023.

RESULTS

Among the patients diagnosed with fungal meningitis (n=12), the majority (n=11) were afflicted with angio-invasive Fusarium solani. 83% received dual antifungal therapy, with 40% initiated on alternate-day intrathecal amphotericin B. Diagnostic cerebral angiography was performed on all patients, revealing aneurysms in 58% of cases, predominantly within the posterior circulation, notably the basilar artery, with a median size of 4.2 mm (IQR 3.3-4.8). Treatment strategies included flow diversion (70%) and primary coiling (14%) for aneurysms. Ventriculostomy placement was undertaken in 67% of patients, with 37.5% of these requiring conversion to ventriculoperitoneal shunts. Subarachnoid hemorrhage development was uniformly associated with 100% mortality.

CONCLUSIONS

In patients presenting with Fusarium solani meningitis, weekly angiographic surveillance proved instrumental for monitoring aneurysm and vasospasm development. Conventional angiography outperformed CT angiography due to its enhanced ability to detect small aneurysms. A proactive approach to aneurysm treatment is advocated, given their elevated rupture risk. While our findings suggest the potential reversibility of angiographic vasospasm with effective antifungal treatment, we acknowledge the challenge of drawing definitive conclusions based on a limited sample size.

Invasive fusariosis

Invasive fusariosis is a serious invasive fungal disease, affecting immunocompetent and, more frequently, immunocompromised patients. Localized disease is the typical clinical form in immunocompetent patients. Immunocompromised hosts at elevated risk of developing invasive fusariosis are patients with acute leukemia receiving chemotherapeutic regimens for remission induction, and those undergoing allogeneic hematopoietic cell transplant. In this setting, the infection is usually disseminated with positive blood cultures, multiple painful metastatic skin lesions, and lung involvement. Currently available antifungal agents have poor in vitro activity against Fusarium species, but a clear-cut correlation between in vitro activity and clinical effectiveness does not exist. The outcome of invasive fusariosis is largely dependent on the resolution of immunosuppression, especially neutrophil recovery in neutropenic patients.

Environmental monitoring for filamentous fungal pathogens in hematopoietic cell transplant units

The incidence of invasive fungal disease (IFD) is on the rise due to increasing numbers of highly immunocompromized patients. Nosocomial IFD remains common despite our better understanding of its risk factors and pathophysiology. High-efficiency particulate air filtration with or without laminar air flow, frequent air exchanges, a positive pressure care environment, and environmental hygiene, amongst other measures, have been shown to reduce the mould burden in the patient environment. Environmental monitoring for moulds in areas where high-risk patients are cared for, such as hematopoietic cell transplant units, has been considered an adjunct to other routine environmental precautions. As a collaborative effort between authors affiliated to the Infection Prevention and Control Working Group and the Fungal Infection Working Group of the International Society of Antimicrobial Chemotherapy (ISAC), we reviewed the English language literature and international guidance to describe the evidence behind the need for environmental monitoring for filamentous fungi as a quality assurance approach with an emphasis on required additional precautions during periods of construction. Many different clinical sampling approaches have been described for air, water, and surface sampling with significant variation in laboratory methodologies between reports. Importantly, there are no agreed-upon thresholds that correlate with an increase in the clinical risk of mould infections. We highlight important areas for future research to assure a safe environment for highly immunocompromized patients.

Waterborne infections in haemato-oncology units - a narrative review

Bone marrow transplant and haemato-oncology patients are at risk of healthcare associated infections due to waterborne pathogens. We undertook a narrative review of waterborne outbreaks in haemato-oncology patients from 2000-2022. Databases searched included Pubmed, DARE and CDSR and were undertaken by two authors. We analysed the organisms implicated, sources identified and infection prevention and control strategies implemented. The most commonly implicated pathogens were Pseudomonas aeruginosa, non-tuberculous mycobacteria and Legionella pneumophila. Bloodstream infection was the most common clinical presentation. The majority of incidents employed multimodal strategies to achieve control, addressing both the water source and routes of transmission. This review highlights the risk to haemato-oncology patients from waterborne pathogens and discusses future preventative strategies and the requirement for new UK guidance for haemato-oncology units.

Invasive fusariosis in acute leukaemia patients-An outbreak in the haematology ward

Fusarium, a common fungus, emerges as a pathogen in severely immunocompromised patients. We present a series of patients who developed invasive fusariosis (IF) during admission to an acute leukaemia ward: an outbreak of 12 cases in June and July 2018, followed by four sporadic cases until 2021. No case was reported earlier. All patients were clustered in the same location with indoor air and water installations found to be contaminated with Fusarium spp. thus a nosocomial outbreak was assumed. Following the water installation replacement, the number of Fusarium cases dramatically dropped to one or two isolated instances per year in the same location. All 16 patients had acute leukaemia and developed IF during severe neutropenia following induction therapy. IF diagnosis was based on positive blood cultures (14 patients) and/or on tissue biopsies (3 patients). The median time from admission to the IF onset was 20 days, and from the first day of severe neutropenia (≤500/mm3) was 11.5 days. All patients were febrile, eight had moderate-to-severe myalgias, eight had respiratory involvements: lung lesions and/or sinusitis and seven had characteristic skin lesions. Follow-up: 12 out of 16 (75%) were alive on Day 90; nine out of 15 (60%) were alive on Month 6. All with intractable neutropenia died. In severely neutropenic febrile patients, the triad of respiratory involvement/skin lesions/severe myalgia may suggest Fusarium aetiology. The ability to recover from neutropenia is critical to surmount IF. The indoor environment in immunocompromised dedicated settings must be constantly controlled.

Clinical characteristics and outcomes of invasive and non-invasive fusariosis in South Korea

BACKGROUND

Invasive fusariosis mainly affects immunocompromised patients including haematopoietic stem cell transplant recipients and those with haematologic malignancy. There are limited studies on invasive fusariosis in the Asia-Pacific region.

OBJECTIVE

To describe the clinical characteristics and outcomes of invasive and non-invasive fusariosis in South Korea.

PATIENTS/METHODS

From 2005 to 2020, patients with fusariosis who met the revised European Organisation for Research and Treatment of Cancer and the Mycoses Study Group criteria for the definition of proven or probable invasive fusariosis, and those with non-invasive fusariosis were retrospectively reviewed in a tertiary medical centre in Seoul, South Korea.

RESULTS

Overall, 26 and 75 patients had invasive and non-invasive fusariosis, respectively. Patients with invasive fusariosis commonly had haematologic malignancy (62%), were solid organ transplant recipients (23%), and had a history of immunosuppressant usage (81%). In non-invasive fusariosis, diabetes mellitus (27%) and solid cancer (20%) were common underlying conditions. Disseminated fusariosis (54%) and invasive pulmonary disease (23%) were the most common clinical manifestations of invasive fusariosis; skin infection (48%) and keratitis (27%) were the most common manifestations of non-invasive fusariosis. Twenty-eight-day and in-hospital mortalities were high in invasive fusariosis (40% and 52%, respectively). In multivariate analysis, invasive fusariosis (adjusted odds ratio, 9.6; 95% confidence interval 1.3-70.8; p = .03) was an independent risk factor for 28-day mortality.

CONCLUSIONS

Patients with invasive fusariosis were frequently immunocompromised, and more than half had disseminated fusariosis. Invasive fusariosis was associated with poor prognosis.

Occurrence and control of fungi in water: New challenges in biological risk and safety assurance

Recently, the contamination of fungi in water has aroused widespread concern, which will pose a threat to water quality and safety, and raise diseases risk in the immunocompromised individuals. In this review, the characteristics and different physiological state of fungi in water are summarized. A comprehensive evaluation of the control efficiency and mechanism of waterborne fungi by the commonly used disinfection methods is provided as well. During the disinfection processes of chlorine, chlorine dioxide, chloramine and advanced disinfection processes (ADPs) such as O₃-based ADPs and UV-based ADPs, the fungal spores firstly lost their culturability, followed by membrane integrity, and the intracellular reactive oxygen species level increased at the same time, eventually the fungal spores were completely inactivated. The security strategies of drinking water against the contamination of fungi are also discussed in terms of water sources, water treatment plants and pipe network. Finally, future researches need to be explored are proposed: the rapid detection methods, the production laws and control of mycotoxin, and the outbreak conditions of fungi in water. Specifically, exploring efficient, safe and economical technologies, especially ADPs, is still the main direction in the disinfection of fungi in future studies. This review can offer a comprehensive understanding on the occurrence and control of fungi in water to fill the knowledge gap and provide guidance for the future research.

Non-Aspergillus Hyaline Molds: A Host-Based Perspective of Emerging Pathogenic Fungi Causing Sinopulmonary Diseases

The incidence of invasive sino-pulmonary diseases due to non-Aspergillus hyaline molds is increasing due to an enlarging and evolving population of immunosuppressed hosts as well as improvements in the capabilities of molecular-based diagnostics. Herein, we review the following opportunistic pathogens known to cause sinopulmonary disease, the most common manifestation of hyalohyphomycosis: Fusarium spp., Scedosporium spp., Lomentospora prolificans, Scopulariopsis spp., Trichoderma spp., Acremonium spp., Paecilomyces variotii, Purpureocillium lilacinum, Rasamsonia argillacea species complex, Arthrographis kalrae, and Penicillium species. To facilitate an understanding of the epidemiology and clinical features of sino-pulmonary hyalohyphomycoses in the context of host immune impairment, we utilized a host-based approach encompassing the following underlying conditions: neutropenia, hematologic malignancy, hematopoietic and solid organ transplantation, chronic granulomatous disease, acquired immunodeficiency syndrome, cystic fibrosis, and healthy individuals who sustain burns, trauma, or iatrogenic exposures. We further summarize the pre-clinical and clinical data informing antifungal management for each pathogen and consider the role of adjunctive surgery and/or immunomodulatory treatments to optimize patient outcome.

Occurrence of fungal spores in drinking water: A review of pathogenicity, odor, chlorine resistance and control strategies

Fungi in drinking water have been long neglected due to the lack of convenient analysis methods, widely accepted regulations and efficient control strategies. However, in the last few decades, fungi in drinking water have been widely recognized as opportunity pathogens that cause serious damage to the health of immune-compromised individuals. In drinking water treatment plants, fungal spores are more resistant to chlorine disinfection than bacteria and viruses, which can regrow in drinking water distribution systems and subsequently pose health threats to water consumers. In addition, fungi in drinking water may represent an ignored source of taste and odor (T&O). This review identified 74 genera of fungi isolated from drinking water and presented their detailed taxonomy, sources and biomass levels in drinking water systems. The typical pathways of exposure of water-borne fungi and the main effects on human health are clarified. The fungi producing T&O compounds and their products are summarized. Data on free chlorine or monochloramine inactivation of fungal spores and other pathogens are compared. At the first time, we suggested four chlorine-resistant mechanisms including aggregation to tolerate chlorine, strong cell walls, cellular responses to oxidative stress and antioxidation of melanin, which are instructive for the future fungi control attempts. Finally, the inactivation performance of fungal spores by various technologies are comprehensively analyzed. The purpose of this study is to provide an overview of fungi distribution and risks in drinking water, provide insight into the chlorine resistance mechanisms of fungal spores and propose approaches for the control of fungi in drinking water.

Disseminated Bisifusarium infection following toxic epidermal necrolysis in a child with B-cell acute lymphoblastic leukemia

Fusarium is a polyphyletic genus of plant pathogens, members of which can cause opportunistic human infections with varying superficial and systemic presentations, including disseminated infections which typically occur in immunocompromised patients and have a poor prognosis. Treatment is challenging due to intrinsic resistance to many antifungal agents, and antifungal susceptibility testing is therefore essential. Early suspicion, isolation of the organism, and prompt initiation of management are crucial to improving survival. We present a case of disseminated Bisifusarium infection following toxic epidermal necrolysis in a child with B-cell acute lymphoblastic leukemia, successfully treated with liposomal amphotericin B, voriconazole, flucytosine, and terbinafine.

Light-emitting diodes effect on Aspergillus species in filtered surface water: DNA damage, proteome response and potential reactivation

DNA damage and changes in proteome response can occur as a consequence of UV light exposure. The emerging light-emitting diodes (LEDs) can be acquired with different wavelengths. In this study, LEDs that emit at 255 nm and 265 nm were selected to test the DNA damage and proteome response after inactivation of A. fumigatus, A. niger and A. terreus spiked into filtered surface water. Additionally, photoreactivation and dark repair studies were performed to evaluate the potential ability of the spores to recover after UV exposure. Results showed that both LEDs were able to induce the formation of cyclobutane pyrimidine dimers in A. fumigatus and A. terreus whereas, for A. niger, the formation of cyclobutane pyrimidine dimers was only detected when the LEDs that induced inactivation (that emit at 265 nm) were used. Proteome response showed that UV radiation treatment triggered different types of stress response, mainly concerning the protection from oxidative stress by A. fumigatus and A. terreus. Photoreactivation was detected for all the species except A. niger and, no dark repair was observed.

Invasive Fusariosis in Patients with Hematologic Diseases

Fusarium species are filamentous fungi widely encountered in nature, and may cause invasive disease in patients with hematologic conditions. Patients at higher risk are those with acute leukemia receiving induction remission chemotherapy or allogeneic hematopoietic cell transplant recipients. In these hosts, invasive fusariosis presents typically with disseminated disease, fever, metastatic skin lesions, pneumonia, and positive blood cultures. The prognosis is poor and the outcome is largely dependent on the immune status of the host, with virtually a 100% death rate in persistently neutropenic patients, despite monotherapy or combination antifungal therapy. In this paper, we will review the epidemiology, clinical manifestations, diagnosis, and management of invasive fusariosis affecting patients with hematologic diseases.

Epidemiological Characterization of Clinical Fungal Isolates from Pauls Stradinš Clinical University Hospital, Latvia: A 4-Year Surveillance Report

Nosocomial fungal infections are an emerging global public health threat that requires urgent attention and proper management. With the limited availability of treatment options, it has become necessary to understand the emerging epidemiological trends, mechanisms, and risk factors. However, very limited surveillance reports are available in the Latvian and broader European context. We therefore conducted a retrospective analysis of laboratory data (2017-2020) from Pauls Stradinš Clinical University Hospital (PSCUH), Riga, Latvia, which is one of the largest public multispecialty hospitals in Latvia. A total of 2278 fungal isolates were analyzed during the study period, with Candida spp. comprising 95% of the isolates, followed by Aspergillus spp. and Geotrichum spp. Amongst the Candida spp., C. albicans and C. glabrata made up about 75% of the isolates. The Department of Lung Diseases and Thoracic Surgery had the highest caseload followed by Intensive Care Department. Majority of the fungal isolates were collected from the bronchoalveolar lavage (37%), followed by urine (19%) and sputum (18%) samples. A total of 34 cases of candidemia were noted during the study period with C. albicans being the most common candidemia pathogen. Proper surveillance of emerging epidemiological trends serve as the most reliable and powerful cornerstone towards tackling this emerging threat.

Fungal Genomics in Respiratory Medicine: What, How and When?

Respiratory infections caused by fungal pathogens present a growing global health concern and are a major cause of death in immunocompromised patients. Worryingly, coronavirus disease-19 (COVID-19) resulting in acute respiratory distress syndrome has been shown to predispose some patients to airborne fungal co-infections. These include secondary pulmonary aspergillosis and mucormycosis. Aspergillosis is most commonly caused by the fungal pathogen Aspergillus fumigatus and primarily treated using the triazole drug group, however in recent years, this fungus has been rapidly gaining resistance against these antifungals. This is of serious clinical concern as multi-azole resistant forms of aspergillosis have a higher risk of mortality when compared against azole-susceptible infections. With the increasing numbers of COVID-19 and other classes of immunocompromised patients, early diagnosis of fungal infections is critical to ensuring patient survival. However, time-limited diagnosis is difficult to achieve with current culture-based methods. Advances within fungal genomics have enabled molecular diagnostic methods to become a fast, reproducible, and cost-effective alternative for diagnosis of respiratory fungal pathogens and detection of antifungal resistance. Here, we describe what techniques are currently available within molecular diagnostics, how they work and when they have been used.

Implications of Climate Change: How Does Increased Water Temperature Influence Biofilm and Water Quality of Chlorinated Drinking Water Distribution Systems?

Temperature variation can promote physico-chemical and microbial changes in the water transported through distribution systems and influence the dynamics of biofilms attached to pipes, thus contributing to the release of pathogens into the bulk drinking water. An experimental real-scale chlorinated DWDS was used to study the effect of increasing temperature from 16 to 24°C on specific pathogens, bacterial-fungal communities (biofilm and water samples) and determine the risk of material accumulation and mobilisation from the pipes into the bulk water. Biofilm was developed for 30 days at both temperatures in the pipe walls, and after this growth phase, a flushing was performed applying 4 gradual steps by increasing the shear stress. The fungal-bacterial community characterised by Illumina MiSeq sequencing, and specific pathogens were studied using qPCR: Mycobacterium spp., Mycobacterium avium complex, Acanthamoeba spp., Pseudomonas aeruginosa, Legionella pneumophilia, and Stenotrophomonas maltophilia. Sequencing data showed that temperature variation significantly modified the structure of biofilm microbial communities from the early stages of biofilm development. Regarding bacteria, Pseudomonas increased its relative abundance in biofilms developed at 24°C, while fungal communities showed loss of diversity and richness, and the increase in dominance of Fusarium genus. After the mobilisation phase, Pseudomonas continued being the most abundant genus at 24°C, followed by Sphingobium and Sphingomonas. For biofilm fungal communities after the mobilisation phase, Helotiales incertae sedis and Fusarium were the most abundant taxa. Results from qPCR showed a higher relative abundance of Mycobacterium spp. on day 30 and M. avium complex throughout the growth phase within the biofilms at higher temperatures. The temperature impacts were not only microbial, with physical mobilisation showing higher discolouration response and metals release due to the increased temperature. While material accumulation was accelerated by temperature, it was not preferentially to either stronger or weaker biofilm layers, as turbidity results during the flushing steps showed. This research yields new understanding on microbial challenges that chlorinated DWDS will undergo as global temperature rises, this information is needed in order to protect drinking water quality and safety while travelling through distribution systems.

Emerging Fungal Infections

Various uncommon fungal pathogens have been increasingly identified as causes of disseminated and invasive fungal disease (IFD) worldwide. Growing recognition and clinical knowledge of these emerging fungal pathogens has occurred through improved molecular diagnostics, nucleic sequence databases, and taxonomic reclassification of medically significant fungi. However, emerging fungal diseases carry significant morbidity and mortality and, due to a paucity of published literature, the collective clinical experience with these fungi is often limited. In this review, we focus on unusual emerging fungal pathogens not extensively covered elsewhere in this issue of Infectious Diseases Clinics of North America.

Water distribution systems in Sardinian hospitals host invasive clonal lineages of the Fusarium oxysporum and Fusarium solani species complexes

Several Fusarium species cause disease on human hosts, including commonly fatal infections in immunocompromised individuals. Recently, cases of hospitalized patients affected by fusaria were reported in the Tyrrhenian Island of Sardinia, Italy. To precisely characterize the Fusarium species and haplotypes present in hospitals of the region, a multilocus DNA sequence typing (MLST) approach was applied. Water distribution systems in four departments belonging to four Sardinian hospitals were sampled. Fusarium species and sequence types (STs) were identified using MLST based on sequences of the elongation factor 1-alpha (EF-1α) gene, the nuclear ribosomal DNA intergenic spacer region (IGS rDNA), and/or a portion of the second-largest subunit of RNA polymerase (RPB2) gene. The majority of isolates obtained from Sardinian hospitals (90.7%) were identified as representatives of the Fusarium oxysporum species complex (FOSC), followed by those of the F. solani species complex (FSSC) (8.2%), and F. dimerum (1.1% of all isolates). Ten STs were found among the FOSC and FSSC, with more than 60% of the isolates identified as either FOSC ST 33 or FSSC 1 (F. petroliphilum). More than half of the FOSC isolates obtained from the water systems in all four hospitals belonged to the worldwide distributed clonal lineage ST 33. This haplotype is the most prevalent among the FOSC in different countries, being responsible for the vast majority of cases of human fusariosis.

Disinfectants in a Hemodialysis Setting: Antifungal Activity Against Aspergillus and Fusarium Planktonic and Biofilm Cells and the Effect of Commercial Peracetic Acid Residual in Mice

Aspergillus and Fusarium cause a broad spectrum of infections in humans, mainly in immunocompromised patients. Among these, patients undergoing hemodialysis are highly susceptible to infections, requiring a constant and adequate environmental disinfection program. Nevertheless, monitoring the residual disinfectants can contribute to the morbidity and mortality reduction in these patients. Here, we evaluated the susceptibility of Aspergillus spp. (n=19) and Fusarium spp. (n=13) environmental isolates against disinfectants (acetic acid, citric acid, peracetic acid, sodium hypochlorite, and sodium metabisulphite) at different concentrations and time exposures. Also, we investigated the in vivo toxicity of the peracetic acid residual concentration in mice. Fusarium isolates were identified by F. equiseti, F. oxysporum and F. solani while Aspergillus presented clinically relevant species (A. fumigatus, A. niger and A. terreus) and environmental ones. Against planktonic cells, only two disinfectants (acetic acid and sodium hypochlorite) showed a fungicidal effect on Fusarium spp., while only one (sodium hypochlorite) was effective against Aspergillus spp. Both fungi formed robust in vitro biofilms with large amounts of the extracellular matrix, as evidenced by electron micrographs. Exposure of fungal biofilms to disinfectants showed sensitivity to three (acetic, citric, and peracetic acids), although the concentrations and times of exposure varied according to the fungal genus. Mice exposure to the residual dose of peracetic acid during 60 weeks showed anatomopathological, hematological, and biochemical changes. The implementation of news control measures and those that already exist can help reduce infections, the second cause of death and morbidity in these patients, besides providing safety and well-being to them, a priority of any quality health program.

Case Report: Molecular Diagnosis of Fungal Keratitis Associated With Contact Lenses Caused by Fusarium solani

Fusarium is a filamentous fungus commonly found in the environment and is the major cause of fungal keratitis. We report a case of keratomycosis caused by Fusarium solani in a patient using disposable soft contact lenses. A delay in diagnosis led to the initiation of an empirical antifungal treatment with the subsequent deterioration of the patient's clinical condition. The use of the real-time quantitative PCR assay confirmed keratitis from F. solani providing a result in <48 h and therefore giving the possibility of quickly starting targeted antifungal therapy. The patient had an improvement in eye condition after the diagnosis of keratitis by F. solani and the rapid change to targeted antifungal treatment. For the rapid identification of corneal fungal pathogens, we believe that PCR may be added for the diagnosis of mycotic keratitis pending the isolation in culture that is necessary for in vitro susceptibility testing.

Occurrence of filamentous fungi in drinking water: their role on fungal-bacterial biofilm formation

Water is indispensable to life and safe and accessible supply must be available to all. The presence of microorganisms is a threat to this commitment. Biofilms are the main reservoir of microorganisms inside water distribution systems and they are extremely ecologically diverse. Filamentous fungi and bacteria can coexist inside these systems forming inter-kingdom biofilms. This review has the goal of summarizing the most relevant and recent reports on the occurrence of filamentous fungi in water distribution systems along with the current knowledge and gaps about filamentous fungal biofilm formation. Special focus is given on fungal-bacterial interactions in water biofilms.

A One Health Perspective to Recognize Fusarium as Important in Clinical Practice

Any strategy that proposes solutions to health-related problems recognizes that people, animals, and the environment are interconnected. Fusarium is an example of this interaction because it is capable of infecting plants, animals, and humans. This review provides information on various aspects of these relations and proposes how to approach fusariosis with a One Health methodology (a multidisciplinary, and multisectoral approach that can address urgent, ongoing, or potential health threats to humans, animals, and the environment). Here, we give a framework to understand infection pathogenesis, through the epidemiological triad, and explain how the broad utilization of fungicides in agriculture may play a role in the treatment of human fusariosis. We assess how plumbing systems and hospital environments might play a role as a reservoir for animal and human infections. We explain the role of antifungal resistance mechanisms in both humans and agriculture. Our review emphasizes the importance of developing interdisciplinary research studies where aquatic animals, plants, and human disease interactions can be explored through coordination and collaborative actions.

Broad Diversity of Fungi in Hospital Water

INTRODUCTION

Some studies have reported the occurrence of microorganisms isolated from water. Considering these microorganisms, fungi are known to occur ubiquitously in the environment, including water, and some are pathogenic and may cause health problems, especially in immunocompromised individuals. The aim of this study was to identify fungi in hospital water samples and to correlate their presence with the concentration of free residual chlorine.

METHODS

Water samples (100 mL) were collected from taps (n = 74) and water purifiers (n = 14) in different locations in a university hospital. Samples were filtered through a nitrocellulose membrane and placed on Sabouraud dextrose agar and incubated for 24 hours at 30°C. Fungi were identified according to established methods based on macroscopic and microscopic characteristics (filamentous) and physiological tests (yeasts). Free chlorine residual content was measured at the time of sample collection.

RESULTS

Seventy species of fungi were identified in the water samples and about 56% of the water samples contained culturable fungi. Cladosporium oxysporum, Penicillium spinulosum, and Aspergillus fumigatus were the most common filamentous fungi. Aureobasidium pullulans and Candida parapsilosis were the most common yeasts. Chemical analyses revealed that free residual chlorine was present in 81.8% of the samples within recommended concentrations. Among samples from water purifiers, 92.9% showed low levels of free residual chlorine (<0.2 mg/L). There was no significant association between chlorine concentrations (either within or outside the recommended range) and the presence of filamentous fungi and yeasts.

CONCLUSIONS

This study showed that hospital water can be a reservoir for fungi, some of which are potentially harmful to immunocompromised patients. Free residual chlorine was ineffective in some samples.

Phylogenetic Analysis of Clinically Relevant Fusarium Species in Iran

Fungi of the genus Fusarium are well known as major plant pathogens but also cause a broad spectrum of human infections. Sixty-three clinical isolates, collected during 2014-2017, were identified using a part of the TEF1 gene as barcoding marker. Fusarium fujikuroi species complex (FFSC, n = 41, 65%) showed to be the dominant etiological agent, followed by F. solani species complex (FSSC, n = 14, 22%) and F. oxysporum species complex (FOSC, n = 7, 11%). There was one strain belonging to F. lateritium species complex (FLSC, n = 1, 1.5%). For final identification, a phylogenetic tree was constructed including the type strains of each species complex. Most cases of fusariosis were due to nail infection (n = 38, 60.3%), followed by keratitis (n = 22, 34%). Fusarium infections are difficult to be treated due to their intrinsic resistance to different azoles; however, accurate and fast identification of etiological agents may enhance management of the infection. We present the first phylogenetic study on clinical Fusarium spp. from Iran.

Human fusariosis: An emerging infection that is difficult to treat

Fusarium spp. has been associated with a broad spectrum of emerging infections collectively termed fusariosis. This review includes articles published between 2005 and 2018 that describe the characteristics, clinical management, incidence, and emergence of these fungal infections. Fusarium solani and F. oxysporum are globally distributed and represent the most common complexes. Few therapeutic options exist due to intrinsic resistance, especially for the treatment of invasive fusariosis. Therefore, the use of drug combinations could be an important alternative for systemic antifungal resistance. Increase in the number of case reports on invasive fusariosis between 2005 and 2018 is evidence of the emergence of this fungal infection.

Drain outlets in patient rooms as sources for invasive fusariosis: an analysis of patients with haematological disorders

BACKGROUND

Invasive fusariosis (IF) is a frequently fatal disease as there are few antifungals to treat it, making the prevention of IF crucial. However, fusarium infections have not been as thoroughly studied as other common pathogenic fungi such as Aspergillus or Candida.

AIM

To investigate the epidemiology of IF in patients with haematological diseases in Japan and to elucidate the infectious route of fusarium infection.

METHODS

We retrospectively analysed 29 IF cases in patients with haematological diseases from 2009 to 2019 in Japan. To discover the infectious source of IF, we performed an indoor environment survey targeted at indoor air and drain outlets in medical institutions and residences using culture-based and metagenomic methods. Finally, we performed aerosol- and droplet-mediated dispersion studies.

FINDINGS

The epidemiological study showed that the primary pathogen of IF was Fusarium solani species complex (FSSC), and the most common species was Fusarium petroliphilum. Most patients were likely to develop IF during hospitalization. A fusarium culture was positive in 26 of 72 drain samples. Few fusarium were detected from air samples; by contrast, 29 of 108 isolates from the drain outlets were identified as fusarium. Furthermore, similar results were obtained in the metagenomic analysis. Interestingly, species belonging to FSSC were isolated from indoor drain outlets, which was similar to those of the IF patients. In the droplet-mediated dispersion study, eight to 17 colonies of fusarium were isolated.

CONCLUSION

Our study indicates that causative Fusarium spp. could inhabit drain outlets in hospitals or residences, and droplet-mediated fusarium dispersion is a potential cause of IF.

Detection of the 'Big Five' mold killers of humans: Aspergillus, Fusarium, Lomentospora, Scedosporium and Mucormycetes

Fungi are an important but frequently overlooked cause of morbidity and mortality in humans. Life-threatening fungal infections mainly occur in immunocompromised patients, and are typically caused by environmental opportunists that take advantage of a weakened immune system. The filamentous fungus Aspergillus fumigatus is the most important and well-documented mold pathogen of humans, causing a number of complex respiratory diseases, including invasive pulmonary aspergillosis, an often fatal disease in patients with acute leukemia or in immunosuppressed bone marrow or solid organ transplant recipients. However, non-Aspergillus molds are increasingly reported as agents of disseminated diseases, with Fusarium, Scedosporium, Lomentospora and mucormycete species now firmly established as pathogens of immunosuppressed and immunocompetent individuals. Despite well-documented risk factors for invasive fungal diseases, and increased awareness of the risk factors for life-threatening infections, the number of deaths attributable to molds is likely to be severely underestimated driven, to a large extent, by the lack of readily accessible, cheap, and accurate tests that allow detection and differentiation of infecting species. Early diagnosis is critical to patient survival but, unlike Aspergillus diseases, where a number of CE-marked or FDA-approved biomarker tests are now available for clinical diagnosis, similar tests for fusariosis, scedosporiosis and mucormycosis remain experimental, with detection reliant on insensitive and slow culture of pathogens from invasive bronchoalveolar lavage fluid, tissue biopsy, or from blood. This review examines the ecology, epidemiology, and contemporary methods of detection of these mold pathogens, and the obstacles to diagnostic test development and translation of novel biomarkers to the clinical setting.

Water Exposure and the Risk of Contact Lens-Related Disease

PURPOSE

To describe the association of water exposure with contact lens (CL)-related disease and explore the guidelines regarding water exposure to CL wearers, provided by CL manufacturing industry, global public health, and CL-related professional associations.

METHODS

A review of the literature was conducted by searching PubMed, MEDLINE, and Web of Science databases up to September 2017 for articles published or translated in English using keywords: contact lens* AND tap water OR swimming OR showering OR water exposure AND microbial keratitis OR Acanthamoeba keratitis OR corneal infiltrate* OR ocular adverse event*. References in all relevant publications were also reviewed.

RESULTS

Water exposure during CL wear is associated with complications ranging from sterile corneal infiltrative events to sight-threatening infections. Despite the documented risks due to water exposure, water-related habits are common among CL wearers. This suggests a lack of awareness and understanding regarding the risks among CL wearers and potentially CL practitioners. Discrepancies exist in guidelines for CL hygiene and compliance provided by the CL manufacturing industry, global public health, and CL-related professional associations. There is also widespread use of water imagery within CL marketing and packaging materials. These factors may give rise to confusion among wearers and may contribute toward risk-taking behaviors.

CONCLUSIONS

Consensus among stakeholders about water and CL care is needed. Guidelines should unequivocally advocate for the avoidance of any water exposure including handling CLs with wet hands, rinsing CLs or storage cases in tap water, showering while wearing CLs and swimming with CLs without wearing goggles.

Emerging and reemerging fungal infections

Fungal infections throughout the world appear to be increasing. This may in part be due to the increase in the population of patients that are susceptible to otherwise rare fungal infections resulting from the use of immune modulating procedures such as hematopoietic stem cell transplants and drugs like tissue necrosis factor antagonists. Histoplasma capsulatum, an endemic fungus throughout North and South America, is reemerging among HIV+ patients in Central and South America and among patients taking tissue necrosis factor antagonists and other biologics in North America. Fusarium species, a relatively rare fungal infection, is reemerging worldwide in the immunocompromised populations, especially those who are neutropenic like hematopoietic stem cell transplant recipients. A new yeast species is currently emerging worldwide: Candida auris, unknown just a decade ago. It is causing large healthcare-associated outbreaks on four continents and is spreading throughout the world through patient travel. In this review the epidemiology, pathology, detection and treatment of these three emerging and reemerging fungi will be discussed.

Emerging fungal infections in solid organ transplant recipients: Guidelines of the American Society of Transplantation Infectious Diseases Community of Practice

These updated AST-IDCOP guidelines review the epidemiology, diagnosis, and management of emerging fungi after organ transplantation. Infections due to numerous generally innocuous fungi are increasingly recognized in solid organ transplant (SOT) recipients, comprising about 7%-10% of fungal infections in this setting. Such infections are collectively referred to as emerging fungal infections and include Mucormycetes, Fusarium, Scedosporium, and dematiaceous fungi among others. The causative organisms are diverse in their pathophysiology, uncommon in the clinical setting, have evolving nomenclature, and are often resistant to multiple commonly used antifungal agents. In recent years significant advances have been made in understanding of the epidemiology of these emerging fungal infections, with improved diagnosis and expanded treatment options. Still, treatment guidelines are generally informed by and limited to experience from cohorts of patients with hematological malignancies and/or solid and stem cell transplants. While multicenter randomized controlled trials are not feasible for these uncommon infections in SOT recipients, collaborative prospective studies can be valuable in providing information on the epidemiology, clinical manifestations, treatment strategies, and outcomes associated with the more commonly encountered infections.

Infections in Allogeneic Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has become a widely used modality of therapy for a variety of malignant and nonmalignant diseases. Despite advances in pharmacotherapy and transplantation techniques, infection remains one of the most severe and frequently encountered complications of allo-HSCT.

This chapter will address the risk factors for development of infection following allo-HSCT, including those related to the host, the conditioning regimen, and the graft, as well as the timing of opportunistic infections after allo-HSCT. The most common bacterial, viral, fungal, and parasitic infections, as well as issues surrounding their diagnostics and treatment, will be discussed. Finally, this chapter will address vaccination and other preventative strategies to be utilized when caring for patients undergoing allo-HSCT.

Multi-locus sequence typing provides epidemiological insights for diseased sharks infected with fungi belonging to the Fusarium solani species complex

Fusarium spp. are saprobic moulds that are responsible for severe opportunistic infections in humans and animals. However, we need epidemiological tools to reliably trace the circulation of such fungal strains within medical or veterinary facilities, to recognize environmental contaminations that might lead to infection and to improve our understanding of factors responsible for the onset of outbreaks. In this study, we used molecular genotyping to investigate clustered cases of Fusarium solani species complex (FSSC) infection that occurred in eight Sphyrnidae sharks under managed care at a public aquarium. Genetic relationships between fungal strains were determined by multi-locus sequence typing (MLST) analysis based on DNA sequencing at five loci, followed by comparison with sequences of 50 epidemiologically unrelated FSSC strains. Our genotyping approach revealed that F. keratoplasticum and F. solani haplotype 9x were most commonly isolated. In one case, the infection proved to be with another Hypocrealian rare opportunistic pathogen Metarhizium robertsii. Twice, sharks proved to be infected with FSSC strains with the same MLST sequence type, supporting the hypothesis the hypothesis that common environmental populations of fungi existed for these sharks and would suggest the longtime persistence of the two clonal strains within the environment, perhaps in holding pools and life support systems of the aquarium. This study highlights how molecular tools like MLST can be used to investigate outbreaks of microbiological disease. This work reinforces the need for regular controls of water quality to reduce microbiological contamination due to waterborne microorganisms.

Production of mycotoxins by filamentous fungi in untreated surface water

Several research studies reported that mycotoxins and other metabolites can be produced by fungi in certain matrices such as food. In recent years, attention has been drawn to the wide occurrence and identification of fungi in drinking water sources. Due to the large demand of water for drinking, watering, or food production purposes, it is imperative that further research is conducted to investigate if mycotoxins may be produced in water matrices. This paper describes the results obtained when a validated analytical method was applied to detect and quantify the presence of mycotoxins as a result of fungi inoculation and growth in untreated surface water. Aflatoxins B1 and B2, fumonisin B3, and ochratoxin A were detected at concentrations up to 35 ng/L. These results show that fungi can produce mycotoxins in water matrices in a non-negligible quantity and, as such, attention must be given to the presence of fungi in water.

Airborne transmission of invasive fusariosis in patients with hematologic malignancies

From 2006 to 2013, an increasing incidence of fusariosis was observed in the hematologic patients of our University Hospital. We suspected of an environmental source, and the indoor hospital air was investigated as a potential source of the fungemia. Air samplings were performed in the hematology and bone marrow transplant (BMT) wards using an air sampler with pre-defined air volumes. To study the molecular relationship among environmental and clinical isolates, 18 Fusarium spp. recovered from blood cultures were included in the study. DNA sequencing of a partial portion of TEF1α gene was performed for molecular identification. Molecular typing was carried out by multi-locus sequence typing (MLST) using a four-gene scheme: TEF1α, rDNA, RPB1 and RPB2. One hundred four isolates were recovered from the air of the hematology (n = 76) and the BMT (n = 28) wards. Fusarium isolates from the air were from five species complexes: Fusarium fujikuroi (FFSC, n = 56), Fusarium incarnatum-equiseti (FIESC, n = 24), Fusarium solani (FSSC, n = 13), Fusarium chlamydosporum (FCSC, n = 10), and Fusarium oxysporum (FOSC, n = 1). Fifteen Fusarium isolates recovered from blood belonged to FSSC, and three to FFSC. MLST identified the same sequence type (ST) in clinical and environmental isolates. ST1 was found in 5 isolates from blood and in 7 from the air, both identified as FSSC (Fusarium petroliphilum). STn1 was found in one isolate from blood and in one from the air, both identified as FFSC (Fusarium napiforme). F. napiforme was isolated from the air of the hospital room of the patient with fungemia due to F. napiforme. These findings suggested a possible clonal origin of the Fusarium spp. recovered from air and bloodcultures. In conclusion, our study found a diversity of Fusarium species in the air of our hospital, and a possible role of the air as source of systemic fusariosis in our immunocompromised patients.

Fungal contaminants in man-made water systems connected to municipal water

Water-related fungi are known to cause taste and odor problems, as well as negative health effects, and can lead to water-pipeline clogging. There is no legal regulation on the occurrence of fungi in water environments. However, much research has been performed, but further studies are needed. The main objectives of this study were to evaluate the fungal load and the presence of mycotoxigenic fungi in man-made water systems (for homes, hospitals, and shopping centers) connected to municipal water in Istanbul, Turkey. The mean fungal concentrations found in the different water samples were 98 colony-forming units (CFU)/100 mL in shopping centers, 51 CFU/100 mL in hospitals, and 23 CFU/100 mL in homes. The dominant fungal species were identified as Aureobasidium pullulans and Fusarium oxysporum. Aflatoxigenic Aspergillus flavus and ochratoxigenic Aspergillus westerdijkiae were only detected in the hospital water samples. Alternaria alternata, Aspergillus clavatus, Aspergillus fumigatus, and Cladosporium cladosporioides were also detected in the samples. The study reveals that the municipal water supplies, available for different purposes, could thus contain mycotoxigenic fungi. It was concluded that current disinfection procedures may be insufficient, and the presence of the above-mentioned fungi is important for people with suppressed immune systems.

Prevention of Infections in Patients with Hematological Malignancies

Infection is a major complication of patients with hematological malignancies. Prophylaxis is a key element in the management of these patients, and is composed by two main components: infection control measures and antimicrobial chemoprophylaxis. Infection control measures are safe, but not always effective. Antimicrobial prophylaxis is usually effective but may increase resistance rates, toxicity, and cost. Therefore, a careful evaluation of the actual risk for infection, the pathogens that predominate in a particular setting, and the periods at risk are important in order to define the most appropriate strategy. In this chapter we review the most important parameters to assess the risk on an individual basis, and the evidences and recommendations supporting infection control measures and antimicrobial prophylaxis against bacteria, fungi, viruses, and parasites.

Rare fungal infectious agents: a lurking enemy

In the expanding population of immunocompromised patients and those treated in intensive care units, rare fungal infectious agents have emerged as important pathogens, causing invasive infections associated with high morbidity and mortality. These infections may present either as de novo or as breakthrough invasive infections in high-risk patients with hematologic malignancies receiving prophylactic or empirical antifungal therapy or in patients with central venous catheters. Diagnosis and treatment are challenging. Physicians should have a high index of suspicion because early diagnosis is of paramount importance. Conventional diagnostic methods such as cultures and histopathology are still essential, but rapid and more specific molecular techniques for both detection and identification of the infecting pathogens are being developed and hopefully will lead to early targeted treatment. The management of invasive fungal infections is multimodal. Reversal of risk factors, if feasible, should be attempted. Surgical debridement is recommended in localized mold infections. The efficacy of various antifungal drugs is not uniform. Amphotericin B is active against most yeasts, except Trichosporon, as well as against Mucorales, Fusarium, and some species of Paecilomyces and dimorphic fungi. The use of voriconazole is suggested for the treatment of trichosporonosis and scedosporiosis. Combination treatment, though recommended as salvage therapy in some infections, is controversial in most cases. Despite the use of available antifungals, mortality remains high. The optimization of molecular-based techniques, with expansion of reference libraries and the possibility for direct detection of resistance mechanisms, is awaited with great interest in the near future. Further research is necessary, however, in order to find the best ways to confront and destroy these lurking enemies.

Deciphering Pathogenicity of Fusarium oxysporum From a Phylogenomics Perspective

Fusarium oxysporum is a large species complex of both plant and human pathogens that attack a diverse array of species in a host-specific manner. Comparative genomic studies have revealed that the host-specific pathogenicity of the F. oxysporum species complex (FOSC) was determined by distinct sets of supernumerary (SP) chromosomes. In contrast to common vertical transfer, where genetic materials are transmitted via cell division, SP chromosomes can be transmitted horizontally between phylogenetic lineages, explaining the polyphyletic nature of the host-specific pathogenicity of the FOSC. The existence of a diverse array of SP chromosomes determines the broad host range of this species complex, while the conserved core genome maintains essential house-keeping functions. Recognition of these SP chromosomes enables the functional and structural compartmentalization of F. oxysporum genomes. In this review, we examine the impact of this group of cross-kingdom pathogens on agricultural productivity and human health. Focusing on the pathogenicity of F. oxysporum in the phylogenomic framework of the genus Fusarium, we elucidate the evolution of pathogenicity within the FOSC. We conclude that a population genomics approach within a clearly defined phylogenomic framework is essential not only for understanding the evolution of the pathogenicity mechanism but also for identifying informative candidates associated with pathogenicity that can be developed as targets in disease management programs.

Epidemiological Study of Fusarium Species Causing Invasive and Superficial Fusariosis in Japan

In Japan, Fusarium species are known etiological agents of human fungal infection; however, there has been no report of a large-scale epidemiological study on the etiological agents of fusariosis. A total of 73 Fusarium isolates from patients with invasive fusariosis (IF, n= 36) or superficial fusariosis (SF, n= 37), which were obtained at hospitals located in 28 prefectures in Japan between 1998 and 2015, were used for this study. Fusarium isolates were identified using Fusarium- and Fusarium solani species complex (FSSC) -specific real-time PCR and partial DNA sequences of the elongation factor-1 alpha (EF-1α) gene and the nuclear ribosomal internal transcribed spacer (ITS) region. FSSC was predominately isolated from both patients with IF and SF (IF, 77.8% and SF, 67.6%). Distribution of the phylogenetic species of FSSC isolates from patients with IF and SF exhibited different spectra; specifically, F. keratoplasticum (FSSC 2) (25.0%) was the most frequent isolate from patients with IF, whereas F. falciforme (FSSC 3+4) (32.4%) was the most frequent isolate from patients with SF. Fusarium sp. (FSSC 5) was the second most frequent isolate from both patients with IF and SF (IF, 22.2% and SF, 24.3%). Notably, F. petroliphilum (FSSC 1) was isolated only from patients with IF. Each species was isolated from a broad geographic area, and an epidemic was not observed. This is the first epidemiological study of Fusarium species causing IF and SF in Japan.