Rapid identification of Fonsecaea by duplex polymerase chain reaction in isolates from patients with chromoblastomycosis

Domain Fusion of Two Oxygenases Affords Organophosphonate Degradation in Pathogenic Fungi

Proteins of the HD-domain superfamily employ a conserved histidine-aspartate (HD) dyad to coordinate diverse metallocofactors. While most known HD-domain proteins are phosphohydrolases, new additions to this superfamily have emerged such as oxygenases and lyases, expanding their functional repertoire. To date, three HD-domain oxygenases have been identified, all of which employ a mixed-valent FeIIFeIII cofactor to activate their substrates and utilize molecular oxygen to afford cleavage of C-C or C-P bonds via a diferric superoxo intermediate. Phylogenetic analysis reveals an uncharacterized multidomain protein in the pathogenic soil fungus Fonsecaea multimorphosa, herein designated PhoF. PhoF consists of an N-terminal FeII/α-ketoglutarate-dependent domain resembling that of PhnY and a C-terminal HD-domain like that of PhnZ. PhnY and PhnZ are part of an organophosphonate degradation pathway in which PhnY hydroxylates 2-aminoethylphosphonic acid, and PhnZ cleaves the C-P bond of the hydroxylated product yielding phosphate and glycine. Employing electron paramagnetic resonance and Mössbauer spectroscopies in tandem with activity assays, we determined that PhoF carries out the O2-dependent degradation of two aminophosphonates, demonstrating an expanded catalytic efficiency with respect to the individual, but mechanistically coupled PhnY and PhnZ. Our results recognize PhoF as a new example of an HD-domain oxygenase and show that domain fusion of an organophosphonate degradation pathway may be a strategy for disease-causing fungi to acquire increased functional versatility, potentially important for their survival.

Molecular Diagnosis of Two Major Implantation Mycoses: Chromoblastomycosis and Sporotrichosis

Chromoblastomycosis and sporotrichosis are the two main implantation mycoses that are now recognized as fungal neglected tropical diseases (NTDs). Their laboratory diagnosis mainly relies on direct microscopy, histopathology, and identification of the fungus by culture. However, to be appropriately used, these techniques require mycological expertise that is not widely available and may be absent in peripheral health care facilities in endemic areas. In addition, they lack sensitivity and specificity, and the culture for isolation and identification can have a long time-to-results period. Molecular methods, including matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), have been developed in well-equipped reference laboratories. They greatly improve the rapidity and accuracy of diagnosis; in particular, for species identification. Recently, PCR and sequencing have paved the way for more user-friendly point-of-care tests, such as those based on LAMP or RCA technologies, which can be used in basic healthcare settings and even in field consultations.

Chromoblastomycosis in the Amazon region, Brazil, caused by Fonsecaea pedrosoi, Fonsecaea nubica, and Rhinocladiella similis: Clinicopathology, susceptibility, and molecular identification

Chromoblastomycosis is a chronic subcutaneous disease caused by human contact with melanized fungi occurring mainly in tropical and subtropical zones worldwide. This study assessed 12 patients with chromoblastomycosis from Rondônia, Brazil, Amazon region. In sum, 83.3% were men, 41.6% were from Monte Negro city, median age was 52.9 years, and median time to disease progression was 12.2 years. Lesions were located on the lower limbs (75%), and verruciform was prevalent form (66.6%). After 3 years of treatment with itraconazole, two patients were considered cured. The etiological agents were identified by the molecular sequence of the ribosomal internal transcribed spacer ITS1, 5.8S, and ITS2 region and β-tubulin genes. Eight strains were identified as Fonsecaea pedrosoi, two were F. nubica, and two were Rhinocladiella similis. The antifungal activity of five drugs was evaluated, and the most active drug was terbinafine (range minimal inhibitory concentration [MIC] 0.015-0.12 μg/ml), itraconazole (range MIC 0.03-0.5 μg/ml) and voriconazole (range MIC 0.06-0.5 μg/ml). The highest MIC was 5-fluorocytosine (range MIC 2-32 μg/ml), and amphotericin B (range MIC 0.25-2 μg/ml). In conclusion, the present study expanded the epidemiological disease database and described for the first time F. nubica and R. similis as chromoblastomycosis agents in the Brazilian Amazon region. Our results confirmed the importance of using molecular methods to identify the melanized fungi and stimulate the recognition of the disease in other places where no cases have been reported.

New Molecular Markers Distinguishing Fonsecaea Agents of Chromoblastomycosis

The species belonging to the genus Fonsecaea are the main causative agents of chromoblastomycosis. The invasive potential of Fonsecaea differs significantly among its various sibling species. Moreover, the lack of clarity on the virulence and availability of precise markers to distinguish and detect Fonsecaea species is attributed to the different ways of dissemination and pathogenicity. Therefore, the present study aimed to propose new molecular tools to differentiate between sibling species causing chromoblastomycosis. We used an infection model of chromoblastomycosis in BALB/c to study species-specific molecular markers for the in vivo detection of Fonsecaea species in biological samples. Specific primers based on the CBF5 gene were developed for Fonsecaea pedrosoi, Fonsecaea monophora, Fonsecaea nubica, and Fonsecaea pugnacius. In addition, a padlock probe was designed for F. pugnacius based on ITS sequences. We also assessed the specificity of Fonsecaea species using in silico, in vitro, and in vivo assays. The results showed that markers and probes could effectively discriminate the species in both clinical and environmental samples, enabling bioprospecting of agents of chromoblastomycosis, thereby elucidating the infection route of the disease.

Chromoblastomycosis: an etiological, epidemiological, clinical, diagnostic, and treatment update

Chromoblastomycosis is a chronic, granulomatous, suppurative mycosis of the skin and subcutaneous tissue caused by traumatic inoculation of dematiaceous fungi of the family Herpotrichiellaceae. The species Fonsecaea pedrosoi and Cladophialophora carrionii are prevalent in regions where the disease is endemic. Chromoblastomycosis lesions are polymorphous: verrucous, nodular, tumoral, plaque-like, and atrophic. It is an occupational disease that predominates in tropical and subtropical regions, but there have been several reports of cases in temperate regions. The disease mainly affects current or former farm workers, mostly males, and often leaving disabling sequelae. This mycosis is still a therapeutic challenge due to frequent recurrence of lesions. Patients with extensive lesions require a combination of pharmacological and physical therapies. The article provides an update of epidemiological, clinical, diagnostic, and therapeutic features.

Chromoblastomycosis

Chromoblastomycosis is a chronic fungal infection of the skin and subcutaneous tissue. The infection usually results from a traumatic injury and inoculation of microorganism from a specific group of dematiaceous fungi (usually Fonsecaea pedrosoi, Phialophora verrucosa, Cladophialophora carrionii). In the tissues fungi produce characteristic sclerotic cells or muriform cells. Dermal lesions can range from small nodules to large papillary-like eruptions. The disease has been described worldwide but the prevalence is higher in rural populations in countries with a tropical or subtropical climate, such as Madagascar in Africa and Brazil in South America. Diagnostic techniques are based on direct examination, culture and histopathology. Despite a variety of treatment modalities, which include long courses of antifungals, surgical excision and destructive physical therapies, the disease remains one of the most difficult deep mycotic infections to eradicate.

Subcutaneous fungal infections

Subcutaneous mycoses are common in tropical and subtropical regions of the world. These infections have multiple features in common, including similar epidemiology, mode of transmission, indolent chronic presentation with low potential for dissemination in immunocompetent hosts, and pyogranulomatous lesions on histopathology. Herein, we provide up-to-date epidemiologic, clinical, diagnostic, and therapeutic data for three important subcutaneous mycoses: chromoblastomycosis, mycetoma, and sporotrichosis.

Molecular diversity of Cladophialophora carrionii in patients with chromoblastomycosis in Venezuela

We identified 29 Cladophialophora carrionii isolates recovered from Venezuelan patients with chromoblastomycosis using phenotypic and molecular characteristics. The genetic diversity of isolates was assessed by enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) fingerprinting. We detected four electrophoretic patterns divided into two main clusters (I and II) comprising 10 and 17 isolates, respectively, and two minor clusters (III and IV) with one isolate each. An interesting cluster-age-lesion type association was detected. The median age of patients in cluster I was 37.5 years and in cluster II, 55 years of age (P = 0.04). The C. carrionii isolates found in cluster I were generally obtained from crusty lesions (60%) and isolates in cluster II were usually recovered from plaque type lesions (53%) even though the P values were only slightly less than significant (P = 0.08). No associations were found among the genetic features strains in the two clusters and gender, occupation, geographic origin, lesion size, severity, and duration of the disease. There was also no correlation between antifungal susceptibilities and strain clustering. In conclusion, molecular typing using ERIC-PCR revealed a genomic heterogeneity in the C. carrionii clinical isolates studied.

Chromoblastomycosis: a clinical and molecular study of 18 cases in Rio de Janeiro, Brazil

BACKGROUND

Chromoblastomycosis (CBM) is a chronic subcutaneous mycosis caused by dematiaceous fungi.

METHODS

We described epidemiological data, clinical presentation, and treatment of 18 cases of CBM diagnosed in Rio de Janeiro, Brazil. Diagnosis was obtained by mycological, histopathological findings demonstrating typical muriform cells with confirmation of isolated by DNA sequencing of the ribosomal internal transcribed spacer.

RESULTS

The majority of patients were male (72.2%) ranging from 39 to 83 years old, farm laborers and construction workers. The duration of disease varied from four months to 32 years. The most common presentations were verrucous form in ten (55.6%) patients, followed by tumoral in three (16.7%) patients, primarily of moderate (55.6%) and severe (38.9%) intensity. Lower (44.4%) and upper limbs (33.3%) were the most affected sites. Fonsecaea pedrosoi isolated from 14 (77.8%), and Cladophialophora carrionii isolated from one case (5.6%). Fifteen patients (83.3%) were treated. Six patients (40%) received oral itraconazole 200-400 mg/day, five patients (33.3%) received oral itraconazole 200-400 mg/day combined with fluconazole 200 mg/day, and four (26.7%) patients were submitted to surgery. The duration of therapy varied from 12 to 48 months. Cure rate was 80% (12/15). No relapse was observed after two years of follow-up.

CONCLUSIONS

Success was due to attending a center with specialized clinical care, laboratory support, and pharmaceutical care.

Chromoblastomycosis after a leech bite complicated by myiasis: a case report

Background

Chromoblastomycosis is a chronic mycotic infection, most common in the tropics and subtropics, following traumatic fungal implantation.

Case presentation

A 72 year-old farmer was admitted to Luang Namtha Provincial Hospital, northern Laos, with a growth on the left lower leg which began 1 week after a forefoot leech bite 10 years previously. He presented with a cauliflower-like mass and plaque-like lesions on his lower leg/foot and cellulitis with a purulent tender swelling of his left heel. Twenty-two Chrysomya bezziana larvae were extracted from his heel. PCR of a biopsy of a left lower leg nodule demonstrated Fonsecaea pedrosoi, monophora, or F. nubica. He was successfully treated with long term terbinafin plus itraconazole pulse-therapy and local debridement.

Conclusions

Chromoblastomycosis is reported for the first time from Laos. It carries the danger of bacterial and myiasis superinfection. Leech bites may facilitate infection.

Experimental medical mycological research in Latin America - a 2000-2009 overview

An overview of current trends in Latin American Experimental Medical Mycological research since the beginning of the 21(st) century is done (search from January 2000 to December 2009). Using the PubMed and LILACS databases, the authors have chosen publications on medically important fungi which, according to our opinion, are the most relevant because of their novelty, interest, and international impact, based on research made entirely in the Latin American region or as part of collaborative efforts with laboratories elsewhere. In this way, the following areas are discussed: 1) molecular identification of fungal pathogens; 2) molecular and clinical epidemiology on fungal pathogens of prevalence in the region; 3) cell biology; 4) transcriptome, genome, molecular taxonomy and phylogeny; 5) immunology; 6) vaccines; 7) new and experimental antifungals.

Managing chromoblastomycosis

Chromoblastomycosis is a subcutaneous fungal infection caused by the traumatic inoculation of the skin with pigmented saprophytic moulds. Although infection is rarely fatal, it is characteristically chronic and can be complicated by lymphatic damage and malignant transformation. Despite a variety of treatment modalities, which are often combined and include long courses of antifungals, surgical excision and destructive physical therapies, it remains one of the most difficult deep mycotic infections to eradicate.

Difficult mycoses of the skin: advances in the epidemiology and management of eumycetoma, phaeohyphomycosis and chromoblastomycosis

PURPOSE OF REVIEW

Eumycetoma, phaeohyphomycosis and chromoblastomycosis are subcutaneous mycoses having in common the fact that they are acquired as a result of penetrating trauma to the skin and may be caused by a large variety of fungi. This article will review recent data regarding the epidemiology and treatment of these infections.

RECENT FINDINGS

Recent epidemiologic observations in these mycoses include an increased incidence of phaeohyphomycosis in immunosuppressed patients, the association of polymorphisms in genes involved in innate immunity, the occurrence of eumycetoma caused by Madurella mycetomatis and the nosocomial acquisition of phaeohyphomycosis. The management of these infections continues to be challenging. An approach that involves early diagnosis, the use of systemic antifungal agents and local therapies, including surgical removal of lesions, is the basis of the treatment of these diseases.

SUMMARY

It is crucial that the epidemiology and clinical presentation of these infections are understood if we are to improve their outcomes.

Rapid detection of pathogenic fungi using loop-mediated isothermal amplification, exemplified by Fonsecaea agents of chromoblastomycosis

Loop-mediated isothermal amplification (LAMP) was developed for rapid detection of pathogenic or allergenic fungal in the environment. Primers applied were derived from the rDNA Internal Transcribed Spacer and the 5.8S rRNA gene. The assay enabled amplification of target fungi at the level of genus or closely related species using pure cultures after 1h reaction at 65 degrees C in a water bath. No cross-reactivity to related species was observed. The DNA detection limit was 0.2fg. The method also proved to work well with fungi on non-sterile adhesive tape. Amplification products were detected by visual inspection using SYBR Green I as well as by electrophoresis on agarose gels. As a model organism we selected Fonsecaea, a fungal genus containing etiologic agents of chromoblastomycosis, a widely distributed tropical and subtropical skin disease in otherwise healthy patients and supposed to be acquired by environmental inoculation. It is suggested that LAMP can also be used for rapid clinical diagnosis, for environmental detection, and for retrospective studies in archived clinical samples.

Cladophialophora carrionii: a rare agent of chromoblastomycosis in Rio de Janeiro State, Brazil

A 73 year-old male farm laborer from a rural area presented a 15 year history of extensive tumoral lesions over his left leg. Histological studies of skin biopsy showed pseudoepitheliomatous hyperplasia and granulomatous chronic inflammatory process with muriform cells, confirming chromoblastomycosis (CBM). Cladophialophora carrionii was isolated in culture. Treatment with itraconazole 400 mg/day for 12 months resulted in complete remission of lesions. As far we aware, this is the first case report of CBM caused by Cladophialophora carrionii in Rio de Janeiro State, Brazil.