Molecular identification of Fusarium species in onychomycoses

Onychomycosis due to Fusarium species in different continents, literature review on diagnosis and treatment

Fusarium species are an emerging cause of onychomycosis, and the number of cases has dramatically increased in recent decades worldwide. This review presents an overview of the onychomycosis cases caused by Fusarium species and diagnosis and treatment that have been reported in the literature. The most common causative agent of onychomycosis is F. solani species complex, which accounts for 11.68% of the cases of Fusarium onychomycosis, followed by the F. oxysporum species complex (164 out of 1669), which is accounted for 9.83% of the total. F. fujikuroi species complex (42 out of 1669) and F. dimerum species complex (7 out of 1669) are responsible for 2.52% and 0.42 cases, respectively. Fusarium nail infections were reported in patients aged range 1-98, accounting for 5.55% (1669 out of 30082) of all cases. Asia has the highest species diversity of Fusarium onychomycosis (31.51%). South America accounts for 21.09%, and the most common causative agent is F. solani (19.32%), followed by F. oxysporum species complex (15.63%). Europe accounts for 4.90% of cases caused by F. oxysporum, followed by F. solani. Africa accounts for 23.87% of the cases due to the F. solani species complex, followed by F. oxysporum and F. fujikuroi. Distal and lateral subungual onychomycosis was the most common clinical symptom accounting for 58.7% (135 out of 230) of the cases. Data analysis relieved that terbinafine and itraconazole are active treatments for Fusarium onychomycosis. For a definitive diagnosis, combining of direct examination, culture and sequencing of the elongation factor of translation 1α are recommended. Accurate identification of the causative agents of onychomycosis due to Fusarium species and antifungal susceptibility testing is essential in patient management.

A Case of Laying Hens Mycosis Caused by Fusarium proliferatum

In this article, we present the first case report of a chicken mycosis caused by F. proliferatum occurred on a private farm in the Russian Federation. Lesions on the skin of the legs and scallops were reported. The object of this study was samples of feed and pathological material from sick hens-layers. Mycological analysis included determination of the total number of fungi (TNF) and identification and determination of the toxicity and pathogenicity of the isolates. The identification of the isolate was carried out taking into account direct microscopy, morphological features, and the method of molecular genetic analysis. Microscopic fungi of the genus Penicillium and Rhizopus were isolated by mycological analysis of the feed. The test feed was nontoxic. Mycological examination of pathological material (scrapings from the combs and affected legs) identified an isolate of Fusarium proliferatum, which showed toxicity on biological objects (protozoa, rabbits) and pathogenicity (white mice). Dermal application of F. proliferatum suspension was accompanied by reddening of the rabbit skin. Intraperitoneal injection of fungal spores caused mycosis in white mice. Polymerase chain reaction (PCR) made it possible to identify this type of microscopic fungus (F. proliferatum) with high accuracy in the samples under study. The research results allow us to consider F. proliferatum as a cause of poultry disease against the background of predisposing factors in the form of desquamation of the stratum corneum of the skin against the background of immunosuppression and metabolic disorders caused by an imbalance in the diet.

Prevalence, genetic diversity and antifungal susceptibility profiles of F. fujikuroi, F. solani, and Fusarium incarnatum-equiseti species complexes from onychomycosis in North of Iran

Onychomycosis, a nail fungal infection, is normally caused by dermatophytes. However, yeasts and non-dermatophyte molds (NDM) are among pathogens that cause nail disease. Regarding, this study aimed to describe the molecular epidemiology of Fusarium onychomycosis in the North of Iran. 257 nail samples collected from the patients clinically suspected of onychomycosis were subjected to direct microscopy, calcofluor white staining, and culture. Fusarium isolates were identified at a species level through determination of multi-locus sequences for internal transcribed spacer and translation elongation factor 1 alpha. Based on the findings, Fusarium species were isolated from onychomycosis patients (n=27). According to a previous partial genes analysis, the species in the resent study belonged to the members of F. fujikuroi species complex (n=14), Fusarium incarnatum-equiseti species complex (n=1) and F. solani species complex (n=12). In rhis study, F. proliferatum was the dominant Fusarium species collected from the samples. The correct identification of Fusarium species is essential regarding the increased prevalence of Fusarium onychomycosis and the inherent resistance of these agents to a wide spectrum of antifungals. The obtained results indicated variation in the epidemiology of Fusarium species isolated from onychomycosis. Moreover, the minimum inhibitory concentration (MIC) of luliconazole and lanoconazole was in the range of 0.001-1 μg/mL, with the geometric mean of MICs obtained at 0.0103 and 0.0343 μg/mL against Fusarium species, respectively. These findings can increase researchers' knowledge regarding diversity of species, distribution of onychomycosis, and the choice of a proper treatment.

Antifungal Properties of Essential Oils and Their Compounds for Application in Skin Fungal Infections: Conventional and Nonconventional Approaches

Essential oils (EOs) are known to have varying degrees of antimicrobial properties that are mainly due to the presence of bioactive compounds. These include antiviral, nematicidal, antifungal, insecticidal and antioxidant properties. This review highlights the potential of EOs and their compounds for application as antifungal agents for the treatment of skin diseases via conventional and nonconventional approaches. A search was conducted using three databases (Scopus, Web of Science, Google Scholar), and all relevant articles from the period of 2010-2020 that are freely available in English were extracted. In our findings, EOs with a high percentage of monoterpenes showed strong ability as potential antifungal agents. Lavandula sp., Salvia sp., Thymus sp., Citrus sp., and Cymbopogon sp. were among the various species found to show excellent antifungal properties against various skin diseases. Some researchers developed advanced formulations such as gel, semi-solid, and ointment bases to further evaluate the effectiveness of EOs as antifungal agents. To date, most studies on the application of EOs as antifungal agents were performed using in vitro techniques, and only a limited number pursued in vivo and intervention-based research.

Non-dermatophyte Mould Onychomycosis in Japan

The incidence of non-dermatophyte mould onychomycosis has been increasing worldwide for the past several decades, but it is not well recognized in Japan. Recent molecular techniques and phylogenetic analyses contributed to the identification of uncommon and emerging species. We came across 13 (0.5%) cases of non-dermatophyte onychomycosis among a total of 2,591 onychomycosis cases in 106,703 outpatients during the past 5 years (January 2015-December 2019). The cases included 5 patients with Aspergillus species, 4 patients with Fusarium species, and one patient each with Scopulariopsis brevicaulis and Botryosphaeria dothidea, respectively. Botryosphaeria dothidea is closely related phylogenetically to Neoscytalidium dimidiatum. In Japan, at the time of writing this report, there are 26 reported cases of ungual aspergillosis and 18 cases of hyalohyphomycosis caused by Fusarium species. We summarize these cases and report the symptoms and mycological features.

Colonization of human opportunistic Fusarium oxysporum (HOFo) isolates in tomato and cucumber tissues assessed by a specific molecular marker

Fusarium oxysporum is a large complex cosmopolitan species composed of plant pathogens, human opportunistic pathogens, and nonpathogenic isolates. Many plant pathogenic strains are known based on host plant specificity and the large number of plant species attacked. F. oxysporum is an opportunistic pathogen in humans with a compromised immune system. The objectives of this study were: (1) to develop a specific marker to detect human opportunistic F. oxysporum (HOFo) isolates; (2) to determine whether or not HOFo isolates can colonize and cause disease symptoms in plants; and (3) to assess Taiwan isolates sensitivity to two agro-fungicides. The primer pair, Primer 5/ST33-R, specifically amplifying Taiwan and international reference HOFo isolates was developed and used to detect and assess the distribution of a Taiwan isolate in inoculated tomato plants and tomato and cucumber fruit. Taiwan HOFo isolate MCC2074 was shown to colonize tomato roots, hypocotyls, and cotyledons, but did not show any visible symptoms. Four days after surface inoculation of tomato and cucumber fruit with the same isolate, MCC2074 was detected in the pericarp and locular cavities of both tomato and cucumber fruit and in columella of tomato fruit. Three Taiwan HOFo isolates were found to be moderately sensitive to azoxystrobin and highly sensitive to difenconazole.

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.

Molecular identification of clinical isolates of Fusarium in Colombia

OBJECTIVE

Identifying Fusarium isolates from mycosis symptomatic patients through molecular techniques as PCR and sequencing.

METHODS

In this study, samples were taken from 101 mycosis symptomatic patients in-between 2004-2006. To determine isolates belonging to the Fusarium genus, the DNAr 28S region was amplified through PCR and specific PCR primers further confirmed their identity to the species level. Additionally, in order to confirm the identity of the species of the isolates, 75 isolates of these were analyzed by partial sequencing of the 28S rDNA and the TEF1-α gene.

RESULTS

The 28S rDNA portion detected all 101 isolates as belonging to Fusarium and the PCR specific primers detected 52 and 29 isolates as F. oxysporum and F. solani, respectively; 34 and 41 of these, afterwards studied by partial sequencing of the 28S rDNA and TEF1- α genes respectively, were effectively identified by the technique.

CONCLUSION

From all the molecular markers used to identify Fusarium isolates, the sequence of the TEF1-α gene provided the best resolution in the identification of species level; however it is possible to discriminate between F. oxysporum and F. solani isolates by PCR, in most of the cases, what is important considering the simplicity of the technique and a faster diagnosis.

Epitypification of Fusarium oxysporum - clearing the taxonomic chaos

Fusarium oxysporum is the most economically important and commonly encountered species of Fusarium. This soil-borne fungus is known to harbour both pathogenic (plant, animal and human) and non-pathogenic strains. However, in its current concept F. oxysporum is a species complex consisting of numerous cryptic species. Identification and naming these cryptic species is complicated by multiple subspecific classification systems and the lack of living ex-type material to serve as basic reference point for phylogenetic inference. Therefore, to advance and stabilise the taxonomic position of F. oxysporum as a species and allow naming of the multiple cryptic species recognised in this species complex, an epitype is designated for F. oxysporum. Using multi-locus phylogenetic inference and subtle morphological differences with the newly established epitype of F. oxysporum as reference point, 15 cryptic taxa are resolved in this study and described as species.

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.

Molecular identification of entomopathogenic Fusarium species associated with Tribolium species in stored grains

Fusarium species are common pathogens of plants, animals and insects worldwide, including Iran. The occurrence of entomopathogenic Fusarium species isolated from Tribolium species as one of the most important insect pests of stored grains were sampled from various provinces in western Iran. In total, 15 Tribolium species belonging to T. castaneum (Herbst) and T. confusum (Du Val) (Col: Tenebrionidae) were detected and 8 isolates from Fusarium spp. were collected from them. Based on morphological features, the Fusarium isolates were classified into F. keratoplasticum and F. proliferatum. The phylogenetic trees based on tef1 dataset clearly separated all morphological taxa. DNA sequences of ITS regions and β-tubulin gene were also confirmed morphological taxa. All of the Fusarium isolates were evaluated for their pathogenicity on T. confusum. Maximum mortality rate was observed for F. keratoplasticum (isolate FSSCker2) and this isolate may be considered as a good candidate for biological control in the ecosystem of stored grains. This is the first report on molecular identification of Fusarium species isolated from insects in Iran and F. keratoplasticum and F. proliferatum were isolated for the first time from Tribolium species as two entomopathogenic fungi.

Global molecular epidemiology and genetic diversity of Fusarium, a significant emerging group of human opportunists from 1958 to 2015

Fusarium is a rapidly emerging, multidrug-resistant genus of fungal opportunists that was first identified in 1958 and is presently recognized in numerous cases of fusariosis each year. The authors examined trends in global Fusarium distribution, clinical presentation and prevalence since 1958 with the assumption that their distributions in each region had remained unaltered. The phylogeny and epidemiology of 127 geographically diverse isolates, representing 26 Fusarium species, were evaluated using partial sequences of the RPB2 and TEF1 genes, and compared with AFLP fingerprinting data. The molecular data of the Fusarium species were compared with archived data, which enabled the interpretation of hundreds of cases published in the literature. Our findings indicate that fusariosis is globally distributed with a focus in (sub)tropical areas. Considerable species diversity has been observed; genotypic features did not reveal any clustering with either the clinical data or environmental origins. This study suggests that infections with Fusarium species might be truly opportunistic. The three most common species are F. falciforme and F. keratoplasticum (members of F. solani species complex), followed by F. oxysporum (F. oxysporum species complex).

Ungual hyalohyphomycosis caused by Fusarium proliferatum in an immunocompetent patient

The patient was a 73-year-old healthy female farmer who had been treated with terbinafine for 25.5 months by a primary physician. She exhibited a discoloration and thickening of the right big toenail. She had no concomitant paronychia. Direct microscopy revealed chlamydoconidia and hyphae, and periodic acid-Schiff stained nail specimen showed septate hyphae. On the basis of these morphological features and gene analysis, the final diagnosis was ungual hyalohyphomycosis caused by Fusarium proliferatum. Topical application of 10% efinaconazole solution cured the disease in 10 months.

Challenges in Fusarium, a Trans-Kingdom Pathogen

Fusarium species are emerging human pathogens, next to being plant pathogens. Problems with Fusarium are in their diagnostics and in their difficult treatment, but also in what are actual Fusarium species or rather Fusarium-like species. In this issue Guevara-Suarez et al. (Mycopathologia. doi: 10.1007/s11046-016-9983-9 , 2016) characterized 89 isolates of Fusarium from Colombia showing especially lineages within the Fusarium solani and oxysporum species complexes to be responsible for onychomycosis.

Genotyping of Fusarium Isolates from Onychomycoses in Colombia: Detection of Two New Species Within the Fusarium solani Species Complex and In Vitro Antifungal Susceptibility Testing

Fusariosis have been increasing in Colombia in recent years, but its epidemiology is poorly known. We have morphologically and molecularly characterized 89 isolates of Fusarium obtained between 2010 and 2012 in the cities of Bogotá and Medellín. Using a multi-locus sequence analysis of rDNA internal transcribed spacer, a fragment of the translation elongation factor 1-alpha (Tef-1α) and of the RNA-dependent polymerase subunit II (Rpb2) genes, we identified the phylogenetic species and circulating haplotypes. Since most of the isolates studied were from onychomycoses (nearly 90 %), we carried out an epidemiological study to determine the risk factors associated with such infections. Five phylogenetic species of the Fusarium solani species complex (FSSC), i.e., F. falciforme, F. keratoplasticum, F. lichenicola, F. petroliphilum, and FSSC 6 as well as two of the Fusarium oxysporum species complex (FOSC), i.e., FOSC 3 and FOSC 4, were identified. The most prevalent species were FOSC 3 (38.2%) followed by F. keratoplasticum (33.7%). In addition, our isolates were distributed into 23 haplotypes (14 into FOSC and nine into FSSC). Two of the FSSC phylogenetic species and two haplotypes of FSSC were not described before. Our results demonstrate that recipients of pedicure treatments have a lower probability of acquiring onychomycosis than those not receiving such treatments. The antifungal susceptibility of all the isolates to five clinically available agents showed that amphotericin B was the most active drug, while the azoles exhibited lower in vitro activity.

Dermatitis in the Fringe-Toed Lizard, Acanthodactylus nilsoni Rastegar-Pouyani, 1998 (Sauria: Lacertidae) Associated with Fusarium proliferatum

From July to October 2013, nine out of 40 Acanthodactylus nilsoni collected from Western Iran, showed clinical signs of dermatitis in the dorsal and ventral surface of neck and fingers. Therefore, the aim of this survey was to identify the fungal flora colonizing the skin of A. nilsoni using morphological and molecular studies. Nine isolates of Fusarium were obtained from infected lizard samples and identified as Fusarium proliferatum through study of morphological characters. In the present study, selected F. proliferatum isolates (USMGFSC 230-112, USMGFSC 186-113, and USMGFSC 33-114) were examined and phylogenetically analysed on the basis of partial sequences of the tef1 and tub2 genes. Sequence analysis supported the morphological data, and all isolates were placed within F. proliferatum species. This is the first report on morphological and molecular identification of F. proliferatum isolated from lizards' dermatitis in Iran.

Spectrum of Fusarium infections in tropical dermatology evidenced by multilocus sequencing typing diagnostics

Fusarium species are emerging causative agents of superficial, cutaneous and systemic human infections. In a study of the prevalence and genetic diversity of 464 fungal isolates from a dermatological ward in Thailand, 44 strains (9.5%) proved to belong to the genus Fusarium. Species identification was based on sequencing a portion of translation elongation factor 1-alpha (tef1-α), rDNA internal transcribed spacer and RNA-dependent polymerase subunit II (rpb2). Our results revealed that 37 isolates (84%) belonged to the Fusarium solani species complex (FSSC), one strain matched with Fusarium oxysporum (FOSC) complex 33, while six others belonged to the Fusarium incarnatum-equiseti species complex. Within the FSSC two predominant clusters represented Fusarium falciforme and recently described F. keratoplasticum. No gender differences in susceptibility to Fusarium were noted, but infections on the right side of the body prevailed. Eighty-nine per cent of the Fusarium isolates were involved in onychomycosis, while the remaining ones caused paronychia or severe tinea pedis. Comparing literature data, superficial infections by FSSC appear to be prevalent in Asia and Latin America, whereas FOSC is more common in Europe. The available data suggest that Fusarium is a common opportunistic human pathogens in tropical areas and has significant genetic variation worldwide.

Fusarium onychomycosis: prevalence, clinical presentations, response to itraconazole and terbinafine pulse therapy, and 1-year follow-up in nine cases

BACKGROUND

Invasive fusariosis is an infection with Fusarium spp. that primarily affects patients with hematologic malignancies and hematopoietic cell transplant recipients. Wounds, digital ulcers, onychomycosis, and paronychia are the typical cutaneous portals of entry. Early management of mycotic nails in immunocompromised and diabetic hosts is crucial to prevent life-threatening disease.

OBJECTIVES

We report nine cases of Fusarium onychomycosis (F. dimerum, n = 5; F. oxysporum, n = 3; Fusarium spp., n = 1) in immunocompetent hosts and their response to itraconazole and terbinafine pulse therapy.

METHODS

The patients received either itraconazole 400 mg daily or terbinafine 500 mg daily for 7 d/month; two pulses for fingernails and three pulses for toenails.

RESULTS

Of the 68 confirmed cases of onychomycosis, eight (11.7%) were Fusarium spp.; the ninth patient was culture positive but microscopy negative and responded well to itraconazole. Distal subungual onychomycosis was the commonest clinical manifestation (seven of nine), one had proximal subungual onychomycosis, and total onychodystrophy was noted on four patients. Associated paronychia was marked on 66.7% (six of eight) patients. Itraconazole was given to six patients/25 nails and terbinafine to three patients/20 nails. All nine patients completed treatments, but one defaulted at 12 months follow-up. The efficacy parameters were clinical cure (CC) and mycological cure (MC). At month 12 after the start of treatment, the response was itraconazole CC 13 of 25 (52%)/MC four of six (66.6%) and terbinafine CC four of eight (50%)/MC one of two (50%). Recurrence was noted in four of 13 (30.7%) and eight of 13 (61.5%) cured nails in the itraconazole group within 3 and 12 months, respectively.

CONCLUSIONS

Fusarium onychomycosis was clinically indistinguishable from other onychomycosis. Both itraconazole and terbinafine pulse therapy were only partially effective on Fusarium onychomycosis. Antifungals that are more effective should be sought.

[Onychomycoses due to molds]

Onychomycoses represent about 30% of superficial mycosis that are encountered in Dermatology consults. Fungi such as dermatophytes, which are mainly found on the feet nails, cause nearly 50% of these onychopathies. Yeasts are predominantly present on hands, whereas non-dermatophytic moulds are very seldom involved in both foot and hand nails infections. According to literature, these moulds are responsible for 2 to 17% of onychomycoses. Nevertheless, we have to differentiate between onychomycoses due to pseudodermatophytes such as Neoscytalidium (ex-Scytalidium) and Onychocola canadensis, which present a high affinity for keratin, and onychomycoses due to filamentous fungi such as Aspergillus, Fusarium, Scopulariopsis, Acremonium... These saprophytic moulds are indeed most of the time considered as colonizers rather than real pathogens agents. Mycology and histopathology laboratories play an important role. They allow to identify the species that is involved in nail infection, but also to confirm parasitism by the fungus in the infected nails. Indeed, before attributing any pathogenic role to non-dermatophytic moulds, it is essential to precisely evaluate their pathogenicity through samples and accurate mycological and/or histological analysis. The treatment of onychomycoses due to non-dermatophytic moulds is difficult, as there is today no consensus. The choice of an antifungal agent will first depend on the species that is involved in the infection, but also on the severity of nail lesions and on the patient himself. In most cases, the onychomycosis will be cured with chemical or mechanical removing of the infected tissues, followed by a local antifungal treatment. In some cases, a systemic therapy will be discussed.

Molecular determination of mixed infections of dermatophytes and nondermatophyte molds in individuals with onychomycosis

BACKGROUND

Reports of mixed infections with nondermatophyte molds (NDMs) and dermatophytes in onychomycosis are rare, possibly owing to the inhibition of NDM growth during traditional culture. We sought to determine the prevalence of mixed infections in onychomycosis using molecular identification.

METHODS

Molecular analyses were used to identify infecting organisms directly from at least two serial great toenail samples from each of the 44 patients.

RESULTS

Mixed infections were present in 41% of the patients (18 of 44). A single coinfecting NDM was the most common mixed infection and was detected in 34% of patients with onychomycosis (15 of 44), with Fusarium oxysporum present in 14% (6 of 44), Scopulariopsis brevicaulis in 9% (4 of 44), Acremonium spp in 2% (1 of 44), Aspergillus spp in 4.5% (2 of 44), and Scytalidium spp in 4.5% (2 of 44). Mixed infections with two NDMs were found in 7% of patients (3 of 44).

CONCLUSIONS

Mixed onychomycosis infections may be more prevalent than previously reported.

Identification of fungal microorganisms by MALDI-TOF mass spectrometry

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has emerged as a reliable tool for fast identification and classification of microorganisms. In this regard, it represents a strong challenge to microscopic and molecular biology methods. Nowadays, commercial MALDI systems are accessible for biological research work as well as for diagnostic applications in clinical medicine, biotechnology and industry. They are employed namely in bacterial biotyping but numerous experimental strategies have also been developed for the analysis of fungi, which is the topic of the present review. Members of many fungal genera such as Aspergillus, Fusarium, Penicillium or Trichoderma and also various yeasts from clinical samples (e.g. Candida albicans) have been successfully identified by MALDI-TOF MS. However, there is no versatile method for fungi currently available even though the use of only a limited number of matrix compounds has been reported. Either intact cell/spore MALDI-TOF MS is chosen or an extraction of surface proteins is performed and then the resulting extract is measured. Biotrophic fungal phytopathogens can be identified via a direct acquisition of MALDI-TOF mass spectra e.g. from infected plant organs contaminated by fungal spores. Mass spectrometric peptide/protein profiles of fungi display peaks in the m/z region of 1000-20000, where a unique set of biomarker ions may appear facilitating a differentiation of samples at the level of genus, species or strain. This is done with the help of a processing software and spectral database of reference strains, which should preferably be constructed under the same standardized experimental conditions.

[Fusariosis diagnosed in the laboratory of an UH in Tunisia: epidemiological, clinical and mycological study]

The genus Fusarium, initially known for its important agro-economic impact, is more and more often implicated in human pathology. In fact, multiples allergic, toxic and infectious manifestations are more reported in immunocompetent and immunocompromised hosts. The objective of our study was to analyse the epidemiological, mycological and clinical features of fusariosis reported in our CHU. Eighty-seven cases of Fusarium infections were collected: 34 cases of onychomycosis (39%), 26 cases of intertrigos (30%), 25 cases of keratomycosis (29%), one case of atypical invasive fusariosis due to Fusarium oxysporum species complex (FOSC) and one case of localized gingivolabial fusariosis due to Fusarium solani species complex (FSSC) in a patient with leukemia in phase of deep bone marrow aplasia, whose outcome was favorable after exiting of aplasia period and a treatment by amphotericine B. The case of pseudotumoral cutaneous fusariosis to F. oxysporum complicated with osteolysis and septic arthritis occurred in a pregnant woman without any immune deficit. The evolution was fatal in spite of prescription of multiple systemic antifungals. Concerning keratomycosis, Fusarium was the first agent responsible for these infections (43%). The corneal traumatism was found in 37.5% of cases and FSSC was the most isolated (72%). For superficial dermatomycosis, Fusarium was the third agent of onychomycosis in molds (25%). The most isolated species were FSSC (68%) and FOSC (20%). The intertrigo frequency was 0.07% and they were mostly caused by FSSC (84%) and FOSC (16%). Fusarium is an important cause of mold infections in our region. So, the species identification is useful because some species are resistant to the most common systemic antifungal agents.

Isolation of Fusarium sp. from a claw of a dog with onychomycosis

An 8-year-old male Golden Retriever had lameness and claw abnormality in the second digit of the left forelimb. Radiography revealed osteomyelitis in the distal phalanx bone of the affected limb. Microscopic examination of the claw revealed numerous hyphae in the claw matrix. Fungal DNA fragments coding the ribosomal internal transcribed spacer region (ITS) were detected from the claw matrix as well as fungal colonies of the clinical isolates by PCR. Nucleotide sequencing revealed that the amplicons shared > 99% homology with Fusarium sp. Therapy including oral itraconazole resulted in regrowth of a new claw, in which no hyphae were detected. To the authors' knowledge, this is the first case report of canine onychomycosis in which Fusarium sp. was isolated from the affected claw.

[Fusarium in dermatology]

The relevance of infections with moulds in humans is increasing. Relevant genera are Alternaria, Cladosporium, Scopulariopsis, and Fusarium. Fusarium thereby is characterized by typical makroconidia and special makroscopical features. Known as pathogen in plants the fungi can also cause intoxications and - more seldom - infections, mainly in immunosuppressed patients. Problematic are infections of the eye, which were described in users of contact lenses, they are difficult to treat. Manifestations of skin fusariosis are necroses, ulcerations, papulo-pustular skin lesions as well as abscesses and paronychia. In immuno-compromised patients, these circumscribed lesions can merge into generalized infections. Thus, systemical fusariosis is one differential diagnosis in neutropenic fever. Thereby, systemic fusariosis is often associated with generalized papular and nodular skin lesions, which tend to ulcerate. In some cases, these lesions may be surrounded by a targetoid erythema. Altogether, the prognosis of systemic fusariosis is not favourable. Thus, early diagnosis of the disease is crucial and requires especially the dermatologist as medical consultant.

Use of mass spectrometry to identify clinical Fusarium isolates

Fusarium spp. have recently emerged as significant human pathogens. Identification of these species is important, both for epidemiological purposes and for patient management, but conventional identification based on morphological traits is hindered by major phenotypic polymorphism. In this study, 62 strains, or isolates, belonging to nine Fusarium species were subjected to both molecular identification TEF1 gene sequencing and matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) analysis. Following stringent standardization, the proteomic-based method appeared to be both reproducible and robust. Mass spectral analysis by comparison with a database, built in this study, of the most frequently isolated species, including Fusarium solani, Fusarium oxysporum, Fusarium verticilloides, Fusarium proliferatum and Fusarium dimerum, correctly identified 57 strains. As expected, the four species (i.e. Fusarium chlamydosporum, Fusarium equiseti, Fusarium polyphialidicum, Fusarium sacchari) not represented in the database were not identified. Results from mass spectrometry and molecular identification agreed in five of the six cases in which results from morphological and molecular identification were not in agreement. MALDI-TOF yielded results within 1 h, making it a valuable tool for identifying clinical Fusarium isolates at the species level. Uncommon species must now be added to the database. MALDI-TOF may also prove useful for identifying other clinically important moulds.

NB-002, a novel nanoemulsion with broad antifungal activity against dermatophytes, other filamentous fungi, and Candida albicans

NB-002 is an oil-in-water emulsion designed for use for the treatment of skin, hair, and nail infections. The activity of NB-002 was compared to the activities of the available antifungal drugs against the major dermatophytes responsible for cutaneous infections, Trichophyton rubrum, Trichophyton mentagrophytes, Epidermophyton floccosum, and Microsporum spp., as well as 12 other genera of filamentous fungi. NB-002 consistently displayed fungicidal activity against all dermatophytes. The comparator compounds were either fungistatic or fungicidal, and for some strain-drug combinations, tolerance was observed. Assessment of the development of spontaneous resistance to NB-002 in different dermatophyte species yielded few stably resistant mutants. For filamentous nondermatophyte fungi, the MIC range varied from 0.06 to 0.5 microg/ml for Alternaria spp. to 2 to 8 microg/ml for Paecilomyes spp. NB-002 had activity against both azole-susceptible and -resistant Candida albicans yeast isolates, with MIC(90)s of 2 microg/ml, respectively, and minimum fungicidal concentrations at which 90% of isolates are inhibited of 4 and 8 microg/ml, respectively. The kinetics of the fungicidal activity of NB-002 against T. rubrum isolates were compared to those of the other antifungal drugs. NB-002 killed both mycelia and microconidia even when the fungal forms were dormant or not actively growing. Electron micrographs of mycelia and spores treated with NB-002 showed the significant disruption of the fungal structure. The in vitro broad coverage of NB-002 against filamentous fungi, dermatophytes, and C. albicans, as well as its rapid fungicidal activity, warrants further investigations to ascertain if NB-002 would be useful for the treatment of cutaneous mycoses.

Molecular detection of dermatophytes and nondermatophytes in onychomycosis by nested polymerase chain reaction based on 28S ribosomal RNA gene sequences

BACKGROUND

Onychomycosis is often caused by dermatophytes, but the role of nondermatophytes is underestimated due to the difficulty of identifying them by conventional direct microscopy and culture.

OBJECTIVES

This study aims to detect nondermatophytes, as well as dermatophytes, in the nail samples of patients with onychomycosis using a polymerase chain reaction (PCR)-based culture-independent method.

MATERIALS AND METHODS

The nested PCR assay targeting the sequence of the 28S ribosomal RNA gene was used to amplify fungal DNAs from 50 microscopy-positive nail specimens. Newly designed primer sets for dermatophyte universal, Trichophyton rubrum, T. mentagrophytes, Aspergillus spp., Scopulariopsis brevicaulis, Fusarium solani, F. oxysporum, F. verticillioides, Candida albicans and C. tropicalis were used after confirmation of their specificity.

RESULTS

Forty-seven cases (94%) were positive for fungal DNA, among which dermatophytes were detected in 39 cases (83.0%): T. rubrum in 35 cases (74.5%) and T. mentagrophytes in eight cases (17.0%). Surprisingly, nondermatophytes were detected in 18 cases (38.3%), both dermatophytes and nondermatophytes in 10 cases (21.3%) and nondermatophytes alone in eight cases (17.0%). Aspergillus spp. alone was observed in five cases (10.6%).

CONCLUSIONS

This study indicates that most of the affected nail plates of patients with onychomycosis were positive for specific fungal DNAs, and suggests that nondermatophytes detected at high rates may be involved in the pathogenesis of onychomycosis.

Fusarium infections in immunocompromised patients

Fusarium species cause a broad spectrum of infections in humans, including superficial, locally invasive, and disseminated infections. The clinical form of fusariosis depends largely on the immune status of the host and the portal of entry, with superficial and localized disease occurring mostly in immunocompetent patients and invasive and disseminated disease affecting immunocompromised patients. Risk factors for severe fusariosis include prolonged neutropenia and T-cell immunodeficiency, especially in hematopoietic stem cell transplant recipients with severe graft-versus-host disease. The most frequent presentation of disseminated fusariosis is a combination of characteristic cutaneous lesions and positive blood cultures, with or without lung or sinus involvement. The prognosis is poor and is determined largely by degree of immunosuppression and extent of infection, with virtually a 100% death rate among persistently neutropenic patients with disseminated disease. These infections may be clinically suspected on the basis of a constellation of clinical and laboratory findings, which should lead to prompt therapy. Treatment options include the lipid formulations of amphotericin B, voriconazole, and posaconazole. Prevention of fusarial infection among high-risk patients should be considered.

Fusarium spp. as agents of onychomycosis in immunocompetent hosts

BACKGROUND

Fusarium spp. are nondermatophyte filamentous fungi, frequently reported as an etiologic agent of opportunistic infections in humans; however, their involvement in the etiology of cutaneous lesions is still debatable, especially in immunocompetent patients, where they are often considered as contaminant fungi.

OBJECTIVE

The aims of this study were to report the high prevalence of onychomycosis by Fusarium spp. in immunocompetent patients in the region of Maringá, Paraná, Brazil, to establish clinical and laboratory criteria for this genus as a causal agent of onychomycosis, and to determine the susceptibility profile to the systemic antifungal drugs most frequently used in Brazil (itraconazole, ketoconazole, terbinafine, and amphotericin B).

METHODS

The fungi were isolated and identified through the classical method, and sensitivity tests were carried out according to the National Committee for Clinical Laboratory Standards (NCCLS) M38-A protocol.

RESULTS

Of the 360 confirmed cases of onychomycosis, 27 (7.5%) were attributed to the genus Fusarium, and F. oxysporum was the most commonly isolated species. Nail lesions with paronychia and pain, combined with direct suggestive microscopy and a high concentration of microorganisms, were predictive of onychomycosis by Fusarium spp. The minimum inhibitory concentration was high for itraconazole, ketoconazole, and terbinafine, but low for amphotericin B.

CONCLUSIONS

It is recommended that more attention should be given to the interpretation and identification of species of the Fusarium genus in superficial clinical samples. This fungus may be considered as an agent of onychomycosis, even in immunocompetent individuals, by identifying criteria that separate situations of clinical significance from those of simple contamination.

Sewage and community shower drains are environmental reservoirs of Fusarium solani species complex group 1, a human and plant pathogen

In two recent studies, clinical isolates in the Fusarium solani species complex (FSSC) were sequenced; one of the most common lineages was FSSC Group 1 (FSSC 1), a phylogenetic species that is synonymous with F. solani f. sp. cucurbitae race 2, a pathogen of cucurbit fruits. FSSC 1 was also identified in sink and shower drains in two hospitals. The environmental sources of FSSC 1 are important for understanding the epidemiology of both human and plant diseases caused by this organism. FSSC 1 was detected in sewage influent at all six tested urban wastewater treatment plants (WWTPs) in California with a concentration ranging from 75 to 413 colony-forming units (cfu) l(-1), a mean of 246 +/- 52 cfu l(-1) and a median of 254 cfu l(-1). During the treatment process, the concentration of FSSC 1 in the solid and liquid fractions diminished. FSSC 1 was detected in five and six of 14 community shower drains by culturing and polymerase chain reaction, respectively, whereas FSSC DNA was detected in all drains. FSSC accounted for 17 +/- 6% (n = 14) of the total fungal DNA in the drains. FSSC 1 was rarely isolated from post-harvest cucurbit fruits and was not found in cucurbit fields in California.

Phylogenetic diversity and microsphere array-based genotyping of human pathogenic Fusaria, including isolates from the multistate contact lens-associated U.S. keratitis outbreaks of 2005 and 2006

In 2005 and 2006, outbreaks of Fusarium keratitis associated with soft contact lens use occurred in multiple U.S. states and Puerto Rico. A case-control study conducted by the Centers for Disease Control and Prevention (CDC) showed a significant association between infections and the use of one particular brand of lens solution. To characterize the full spectrum of the causal agents involved and their potential sources, partial DNA sequences from three loci (RPB2, EF-1alpha, and nuclear ribosomal rRNA) totaling 3.48 kb were obtained from 91 corneal and 100 isolates from the patient's environment (e.g., contact lens and lens cases). We also sequenced a 1.8-kb region encoding the RNA polymerase II second largest subunit (RPB2) from 126 additional pathogenic isolates to better understand how the keratitis outbreak isolates fit within the full phylogenetic spectrum of clinically important fusaria. These analyses resulted in the most robust phylogenetic framework for Fusarium to date. In addition, RPB2 nucleotide variation within a 72-isolate panel was used to design 34 allele-specific probes to identify representatives of all medically important species complexes and 10 of the most important human pathogenic Fusarium in a single-well diagnostic assay, using flow cytometry and fluorescent microsphere technology. The multilocus data revealed that one haplotype from each of the three most common species comprised 55% of CDC's corneal and environmental isolates and that the corneal isolates comprised 29 haplotypes distributed among 16 species. The high degree of phylogenetic diversity represented among the corneal isolates is consistent with multiple sources of contamination.

Onychomycosis in Lebanon: a mycological survey of 772 patients

Accurate diagnosis of onychomycosis is based on clinical findings, direct microscopic investigation and mycological culture. If the diagnosis is not confirmed by culture and improvement does not occur, it is impossible to tell whether this represents treatment failure or an initial incorrect diagnosis. The aim of this study was to identify the major organisms involved in onychomycosis with emphasis on the importance of culture in treating onychomycosis. The study was performed at the Lebanese University, Beirut, Lebanon over a 5-year period (2000-2004). Clinically suspected patients were referred to our mycology laboratory for KOH test and culture. The study included 772 patients (520 women, 252 men). Cultures were positive in 54.3% of cases (predominantly male). The ratio of onychomycosis in toenails/fingernails was 1.9. In toenails, dermatophytes were found in 77.1% of cases, Candida in 18.9% and moulds in 4%. In fingernails, Candida was found in 81% of cases, dermatophytes in 18.1% and moulds in 0.9%. The most commonly isolated dermatophytes were Trichophyton mentagrophytes (36%), T. rubrum (27.5%) and T. tonsurans (26%). Pathogens involved in onychomycosis change according to each geographical area. Therefore, treatments should be based on studies carried out in the same region.