First occurrence of feline sporotrichosis in a metropolitan area of Central-West Brazil

Sporotrichosis is a neglected mycosis that affects human and animal hosts, including domestic cats. In Brazil, its most frequently diagnosed etiological agent is Sporothrix brasiliensis. Zoonotic transmission of S. brasiliensis occurs via direct contact between an infected cat and a susceptible human host. Notification of confirmed cases of feline sporotrichosis is not mandatory in Brazil. The metropolitan area of Goiania city can be considered a silent area for the occurrence of feline sporotrichosis. In this context, voluntary reporting of feline sporotrichosis cases is recommended for all healthcare professionals. This study aimed to report the first occurrence of S. brasiliensis in a cat from the metropolitan area of Goiania city. Cytopathology, mycology, thermal dimorphism and calmodulin gene amplification tests were performed. The mycological and molecular biological diagnoses corresponded to S. brasiliensis. The etiological agent of zoonotic sporotrichosis was detected in the metropolitan area of Goiania city, and therefore there is a risk of the emergence of new cases of cats infected with S. brasiliensis and the occurrence of zoonotic transmission of this fungus.

Low toxicity contributes to Sporothrix globosa invade the skin of patients in low-epidemic areas of China

OBJECTIVE

This study aims to assess the clinical characteristics of sporotrichosis in low-endemic areas of China, including the prevalence geography, genotypic traits of patients, clinical manifestations, and strain virulence and drug sensitivities. The objective is to improve the currently used clinical management strategies for sporotrichosis.

METHODS

Retrospective data were collected from patients diagnosed with sporotrichosis through fungal culture identification. The isolates from purified cultures underwent identification using CAL (Calmodulin) gene sequencing. Virulence of each strain was assessed using a Galleria mellonella (G. mellonella) larvae infection model. In vitro susceptibility testing against commonly used clinical antifungal agents for sporotrichosis was conducted following CLSI criteria.

RESULTS

In our low-endemic region for sporotrichosis, the majority of cases (23) were observed in middle-aged and elderly women with a history of trauma, with a higher incidence during winter and spring. All clinical isolates were identified as Sporothrix globosa (S. globosa). The G. mellonella larvae infection model indicated independent and dose-dependent virulence among strains, with varying toxicity levels demonstrated by the degree of melanization of the G. mellonella. Surprisingly, lymphocutaneous types caused by S. globosa exhibited lower in vitro virulence but were more common in affected skin. In addition, all S.globosa strains displayed high resistances to fluconazole, while remaining highly susceptible to terbinafine, itraconazole and amphotericin B.

CONCLUSION

Given the predominance of elderly women engaged in agricultural labour in our region, which is a low-epidemic areas, they should be considered as crucial targets for sporotrichosis monitoring. S. globosa appears to be the sole causative agent locally. However, varying degrees of melanization in larvae were observed among these isolates, indicating a divergence in their virulence. Itraconazole, terbinafine and amphotericin B remain viable first-line antifungal options for treating S.globosa infection.

Human interleukin-36γ plays a crucial role in cytokine induction during Sporothrix brasiliensis and S. schenckii infection in keratinocytes and PBMCs

Cytokines of the interleukin (IL)-1 superfamily including the different IL-36 isoforms, have been reported as mediators of acute and chronic inflammation in human skin diseases, such as psoriasis. Here, we demonstrated for the first time that Sporothrix schenckii and S. brasiliensis, the fungi that cause subcutaneous infection sporotrichosis, can induce the expression of IL-36α, IL-36γ and IL-36Ra in human keratinocytes and primary peripheral blood mononuclear cells (PBMCs). Specifically, IL-36γ was differentially expressed by keratinocytes stimulated with Sporothrix yeasts when compared to the commensal microorganism Staphylococcus epidermidis. The exposure of keratinocytes to 24 h or 7-days culture supernatant of PBMCs stimulated with Sporothrix induced higher IL-36γ production compared to direct stimulation of keratinocytes with the live fungus. We identified that IL-36γ mRNA expression in keratinocytes is increased in the presence of IL-17, TNF, IL-1β and IL-1α and these cytokines may act synergistically to maintain IL-36γ production. Lastly, using a cohort of 164 healthy individuals, we showed that individuals carrying variants of the IL36G gene (rs11690399 and rs11683399) exhibit increased IL-36γ production as well as increased innate cytokine production after Sporothrix exposure. Importantly, stimulation of PBMCs with recombinant IL-36γ increased the production of IL-1β and IL-6, while IL-36Ra were able to decrease the concentration of these cytokines. Our findings contribute to the understanding of the pathogenesis of sporotrichosis and suggest that IL-36γ may be involved in maintaining the cytokine loop that leads to tissue destruction by exacerbating the immune response in sporotrichosis. Of high interest, we present the IL-36 signalling pathway as a potential new therapeutic target.

Emergence of zoonotic sporotrichosis in Brazil: a genomic epidemiology study

BACKGROUND

Zoonotic sporotrichosis is a neglected fungal disease, whereby outbreaks are primarily driven by Sporothrix brasiliensis and linked to cat-to-human transmission. To understand the emergence and spread of sporotrichosis in Brazil, the epicentre of the current epidemic in South America, we aimed to conduct whole-genome sequencing (WGS) to describe the genomic epidemiology.

METHODS

In this genomic epidemiology study, we included Sporothrix spp isolates from sporotrichosis cases from Brazil, Colombia, and the USA. We conducted WGS using Illumina NovaSeq on isolates collected by three laboratories in Brazil from humans and cats with sporotrichosis between 2013 and 2022. All isolates that were confirmed to be Sporothrix genus by internal transcribed spacer or beta-tubulin PCR sequencing were included in this study. We downloaded eight Sporothrix genome sequences from the National Center for Biotechnology Information (six from Brazil, two from Colombia). Three Sporothrix spp genome sequences from the USA were generated by the US Centers for Disease Control and Prevention as part of this study. We did phylogenetic analyses and correlated geographical and temporal case distribution with genotypic features of Sporothrix spp isolates.

FINDINGS

72 Sporothrix spp isolates from 55 human and 17 animal sporotrichosis cases were included: 67 (93%) were from Brazil, two (3%) from Colombia, and three (4%) from the USA. Cases spanned from 1999 to 2022. Most (61 [85%]) isolates were S brasiliensis, and all were reported from Brazil. Ten (14%) were Sporothrix schenckii and were reported from Brazil, USA, and Colombia. For S schenckii isolates, two distinct clades were observed wherein isolates clustered by geography. For S brasiliensis isolates, five clades separated by more than 100 000 single-nucleotide polymorphisms were observed. Among the five S brasiliensis clades, clades A and C contained isolates from both human and cat cases, and clade A contained isolates from six different states in Brazil. Compared with S brasiliensis isolates, larger genetic diversity was observed among S schenckii isolates from animal and human cases within a clade.

INTERPRETATION

Our results suggest that the ongoing epidemic driven by S brasiliensis in Brazil represents several, independent emergence events followed by animal-to-animal and animal-to human transmission within and between Brazilian states. These results describe how S brasiliensis can emerge and spread within a country.

FUNDING

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Brazil; the São Paulo Research Foundation; Productivity in Research fellowships by the National Council for Scientific and Technological Development, and Ministry of Science and Technology of Brazil.

Phenotypic and genotypic characterization of Colombian clinical isolates of Sporothrix spp

INTRODUCTION

For over a century, Sporothrix schenckii was considered the sole species responsible for sporotrichosis. In 2007, scientific community confirmed the disease could be caused by various Sporothrix species. These species differed in their virulence factors and their antifungal sensitivity.

OBJECTIVE

This study aims to characterize 42 Colombian clinical isolates of Sporothrix spp. phenotypically and genotypically.

MATERIAL AND METHODS

Forty-two clinical isolates were characterized using phenotypic methods. It involved various culture media to determine their growth range at different temperatures and to assess the type and distribution of pigment and colony texture. Microscopic morphology was evaluated through microcultures, as well as the conidia diameter, type of sporulation, and morphology. Additionally, the assimilation of carbohydrates was selected as a physiological trait for species identification. Genotyping of 40 isolates was performed through partial amplification of the calmodulin gene, followed by sequence analysis.

RESULTS

Molecular studies enabled the identification of 32 isolates of S. schenckii and 8 isolates of S. globosa. The combination of phenotypic and genotypic methods eased these species characterizations and the recognition keys development based on parameters such as growth diameter at 25 and 30 ºC, colony texture (membranous or velvety) on potato dextrose agar, and microscopic morphology with predominance of pigmented triangular, elongated oval globose, or subglobose conidia.

CONCLUSIONS

Confirmation of the phenotypic characteristics and molecular analysis is crucial for identifying Sporothrix species and determining adequate treatment. This study represents the first phenotypical and genotypical characterization of clinical isolates of Sporothrix spp. reported in Colombia.

Sporotrichosis Caused by Non-Wild Type Sporothrix brasiliensis Strains

The zoonotic transmission of sporotrichosis due to Sporothrix brasiliensis occurs largely in Rio de Janeiro state, Brazil since the 1990´s. Most patients infected with S. brasiliensis respond well to itraconazole or terbinafine. However, a few patients have a slow response or do not respond to the treatment and develop a chronic infection. The aim of this study was to analyze strains of S. brasiliensis against five different drugs to determine minimal inhibitory concentration distributions, to identify non-wild type strains to any drug evaluated and the clinical aspects of infections caused by them. This study evaluated 100 Sporothrix spp. strains obtained from 1999 to 2018 from the Evandro Chagas National Institute of Infectious Diseases, Fiocruz, which were identified through a polymerase chain reaction using specific primers for species identification. Two-fold serial dilutions of stock solutions of amphotericin B, itraconazole, posaconazole, ketoconazole and terbinafine prepared in dimethyl sulfoxide were performed to obtain working concentrations of antifungal drugs ranging from 0.015 to 8.0 mg/L. The broth microdilution reference method was performed according the M38-A2 CLSI guideline. All strains were identified as S. brasiliensis and thirteen were classified as non-wild type, two of them against different drugs. Non-wild type strains were identified throughout the entire study period. Patients infected by non-wild type strains presented prolonged treatment times, needed increased antifungal doses than those described in the literature and one of them presented a permanent sequel. In addition, three of them, with immunosuppression, died from sporotrichosis. Despite the broad use of antifungal drugs in hyperendemic areas of sporotrichosis, an emergence of non-wild type strains did not occur. The results of in vitro antifungal susceptibility tests should guide sporotrichosis therapy, especially in immunosuppressed patients.

Environmental Isolation of Sporothrix brasiliensis in an Area With Recurrent Feline Sporotrichosis Cases

Sporotrichosis has been expanding throughout the Brazilian territory in recent years. New outbreaks have emerged, and consequently, the sporotrichosis agents, mainly Sporothrix brasiliensis, should remain in the environment somehow. Therefore, the aim of this study was to investigate the presence of Sporothrix spp. in the environment from an area of ​​the Rio de Janeiro state, Brazil, with recurrent cases of human and animal sporotrichosis. Abandoned demolition timber wood samples were collected in the garden of a house where the cases of human and feline sporotrichosis have occurred in the last 10 years. The environmental survey revealed a Sporothrix spp. colony from the serial dilution cultures of one abandoned demolition wood sample. In addition, a fungal strain isolated from a cat with skin lesions that lived in the house was also included in the study. The species-specific PCR, and calmodulin partial sequencing identified the environmental and cat isolates as S. brasiliensis. Furthermore, the phylogenetic analysis performed with the partial sequences of internal transcribed spacer region and constitutive genes (calmodulin, β-tubulin, and chitin synthase) showed high similarity between environmental and cat isolates from the same geographic region. Moreover, the antifungal susceptibility test revealed that the minimal inhibitory concentration of itraconazole from the environment isolate was lower than the cat isolate, while amphotericin B and terbinafine were similar. Our results show that S. brasiliensis is able to maintain itself in the environmental material for years. With this, we corroborate that the eco-epidemiology of sporotrichosis is not well understood, and despite the major occurrence of S. brasiliensis in Brazil, it is rarely isolated from the environment.

Feline sporotrichosis in Asia

Sporothrix schenckii sensu lato is currently recognized as a species complex with only Sporothrix brasiliensis, Sporothrix schenckii sensu stricto, Sporothrix globosa and Sporothrix pallida identified to cause disease in the cat. Feline sporotrichosis in Asia is mainly reported from Malaysia where a single clonal strain of clinical clade D, Sporothrix schenckii sensu stricto manifesting low susceptibility to major antifungal classes, has been identified as the agent of the disease. Sporothrix globosa has been identified to cause disease from a single cat in Japan while the specific species of agent has not been identified yet for the disease in Thailand. Despite efforts to elucidate and describe the pathogenicity of the agent and the disease it causes, the paucity of data highlights the need for further molecular epidemiological studies to characterize this fungus and the disease it causes in Asia. Its prognosis remains guarded to poor due to issues pertaining to cost, protracted treatment course, zoonotic potential and low susceptibility of some strains to antifungals.

Guideline for the management of feline sporotrichosis caused by Sporothrix brasiliensis and literature revision

We herein present a Brazilian guideline for the management of feline sporotrichosis, a mycosis caused by Sporothrix brasiliensis. This guideline is an effort of a national technical group organized by the Working Group on Sporothrix and Sporotrichosis of the International Society for Human and Animal Mycology (ISHAM). This publication intends to provide information on clinical-epidemiological aspects of this zoonosis, as well as a literature revision. Moreover, it gives some practical information on diagnosis and treatment of feline sporotrichosis. It also contains information that can be helpful for the prevention and control of S. brasiliensis transmission.

Sporotrichosis in Mexico

Sporotrichosis is an endemic mycosis caused by the species of the Sporothrix genus, and it is considered one of the most frequent subcutaneous mycoses in Mexico. This mycosis has become a relevant fungal infection in the last two decades. Today, much is known of its epidemiology and distribution, and its taxonomy has undergone revisions. New clinical species have been identified and classified through molecular tools, and they now include Sporothrix schenckii sensu stricto, Sporothrix brasiliensis, Sporothrix globosa, and Sporothrix luriei. In this article, we present a systematic review of sporotrichosis in Mexico that analyzes its epidemiology, geographic distribution, and diagnosis. The results show that the most common clinical presentation of sporotrichosis in Mexico is the lymphocutaneous form, with a higher incidence in the 0-15 age range, mainly in males, and for which trauma with plants is the most frequent source of infection. In Mexico, the laboratory diagnosis of sporotrichosis is mainly carried out using conventional methods, but in recent years, several researchers have used molecular methods to identify the Sporothrix species. The treatment of choice depends mainly on the clinical form of the disease, the host's immunological status, and the species of Sporothrix involved. Despite the significance of this mycosis in Mexico, public information about sporotrichosis is scarce, and it is not considered reportable according to Mexico's epidemiological national system, the "Sistema Nacional de Vigilancia Epidemiológica." Due to the lack of data in Mexico regarding the epidemiology of this disease, we present a systematic review of sporotrichosis in Mexico, between 1914 and 2019, that analyzes its epidemiology, geographic distribution, and diagnosis.

A novel Sporothrix brasiliensis genomic variant in Midwestern Brazil: evidence for an older and wider sporotrichosis epidemic

Sporotrichosis is a subcutaneous infection caused by fungi from the genus Sporothrix. It is transmitted by inoculation of infective particles found in plant-contaminated material or diseased animals, characterizing the classic sapronotic and emerging zoonotic transmission, respectively. Since 1998, southeastern Brazil has experienced a zoonotic sporotrichosis epidemic caused by S. brasiliensis, centred in the state of Rio de Janeiro. Our observation of feline sporotrichosis cases in Brasília (Midwestern Brazil), around 900 km away from Rio de Janeiro, led us to question whether the epidemic caused by S. brasiliensis has spread from the epicentre in Rio de Janeiro, emerged independently in the two locations, or if the disease has been present and unrecognized in Midwestern Brazil. A retrospective analysis of 91 human and 4 animal cases from Brasília, ranging from 1993 to 2018, suggests the occurrence of both sapronotic and zoonotic transmission. Molecular typing of the calmodulin locus identified S. schenckii as the agent in two animals and all seven human patients from which we were able to recover clinical isolates. In two other animals, the disease was caused by S. brasiliensis. Whole-genome sequence typing of seven Sporothrix spp. strains from Brasília and Rio de Janeiro suggests that S. brasiliensis isolates from Brasília are genetically distinct from those obtained at the epicentre of the outbreak in Rio de Janeiro, both in phylogenomic and population genomic analyses. The two S. brasiliensis populations seem to have separated between 2.2 and 3.1 million years ago, indicating independent outbreaks or that the zoonotic S. brasiliensis outbreak might have started earlier and be more widespread in South America than previously recognized.

Transcriptome-wide expression profiling of Sporothrix schenckii yeast and mycelial forms and the establishment of the Sporothrix Genome DataBase

Sporothrix schenckii is a dimorphic fungus existing as mould in the environment and as yeast in the host. The morphological shift between mycelial/yeast phases is crucial for its virulence, but the transcriptional networks implicated in dimorphic transition are still not fully understood. Here, we report the global transcriptomic differences occurring between mould and yeast phases of S. schenckii, including changes in gene expression profiles associated with these distinct cellular phenotypes. Moreover, we also propose a new genome annotation, which reveals a more complex transcriptional architecture than previously assumed. Using RNA-seq, we identified a total of 17 307 genes, of which 11 217 were classified as protein-encoding genes, whereas 6090 were designated as non-coding RNAs (ncRNAs). Approximately ~71 % of all annotated genes were found to overlap and the different-strand overlapping type was the most common. Gene expression analysis revealed that 8795 genes were differentially regulated among yeast and mould forms. Differential gene expression was also observed for antisense ncRNAs overlapping neighbouring protein-encoding genes. The release of transcriptome-wide data and the establishment of the Sporothrix Genome DataBase (http://sporothrixgenomedatabase.unime.it) represent an important milestone for Sporothrix research, because they provide a strong basis for future studies on the molecular pathways involved in numerous biological processes.

Canine sporotrichosis: polyphasic taxonomy and antifungal susceptibility profiles of Sporothrix species in an endemic area in Brazil

Sporotrichosis, a mycosis caused by pathogenic species of the genus Sporothrix, affects diverse species of mammals. Until 2007, Sporothrix schenckii was considered the unique etiologic agent of sporotrichosis. Canine sporotrichosis is a poorly reported disease, and the majority of cases are from Rio de Janeiro, Brazil. There are scarce studies on the characterization of canine isolates of Sporothrix schenckii complex, as well as few antifungal susceptibility data available. The aim of this study was to characterize the clinical isolates of Sporothrix from dogs from Brazil at species level and evaluate their antifungal susceptibility profile. Polyphasic taxonomy was used to characterization at species level (morphological, phenotypical characteristics, and molecular identification). Antifungal susceptibility profiles (amphotericin B, itraconazole, ketoconazole, posaconazole, and terbinafine) were determined using the Clinical and Laboratory Standards Institute broth microdilution method (M38-A2). According to phenotypic identification and molecular analysis, 46 isolates included in this study were identified as S. brasiliensis and one as S. schenckii. Amphotericin B presented the highest minimum inhibitory concentration values, and the other drugs showed effective in vitro antifungal activity. This is the first report of S. schenckii in dogs from Brazil, since S. brasiliensis is the only species that has been described in canine isolates from Rio de Janeiro to date. Nevertheless, no differences were observed in the antifungal susceptibility profiles between the S. brasiliensis and S. schenckii isolates, and it is important to continuously study new canine clinical isolates from Rio de Janeiro, Brazil.

Development and evaluation of a real-time polymerase chain reaction for fast diagnosis of sporotrichosis caused by Sporothrix globosa

Sporothrix globosa is an important clinical pathogen in the Sporothrix complex, which is causing sporotrichosis. S. globosa is distributed worldwide, especially in Asia. The transmission medium of S. globosa is mainly contaminated soil or decaying vegetation, and the infection usually caused by transcutaneous trauma, through which the fungal conidia or yeast cells enter the host. Although the clinical manifestations of sporotrichosis caused by S. globosa is always benign, there have been several outbreaks worldwide. In this study, we established a novel real-time polymerase chain reaction (PCR) method based on the internal transcribed spacer (ITS) sequence for the identification of S. globosa. The assay was further evaluated by clinical specimens obtained from patients of sporotrichosis. The sensitivity and specificity of the real-time PCR method was both 100%. The detection limit was 10 fg. The positive detection rate for 30 clinical specimens, which were confirmed infected by S. globosa, was 100%. The real-time PCR method established in this paper is a rapid, sensitive and specific method for the identification of S. globosa. It can detect S. globosa in clinical specimen from patients with sporotrichosis, which is helpful for fast clinical diagnosis.

Geographical distribution and ecological niche modeling of the etiological agents of human sporotrichosis in Venezuela

The geographical distribution and ecological niche of the two circulating species of the Sporothrix genus in Venezuela was established. For this, 68 isolates of Sporothrix spp. from patients of different regions of the country were analyzed. A molecular taxonomy analysis was conducted using a fragment of the calmodulin gene (CAL), and ITS regions, confirming the presence of S. schenckii (62%) and S. globosa (38%). Computational models of ecological niche for each species were obtained by the maximum entropy method using the MaxEnt software, which predicted the best environmental conditions for the presence of the two species. These models predict that the main variables influencing the presence of S. schenckii were altitude and annual mean temperature, while for S. globosa, the more influent variable was the land use, with 82% of S. globosa located at urban areas vs 56% for S. schenckii. The results here presented could contribute to understand the specific environmental factors that might modulate the occurrence of Sporothrix spp. as well as its transmission. To our knowledge, our analyses show for the first time Sporothrix spp.-specific ecological niche data, a valuable tool to promote evidence-based public health policymaking within endemic areas of sporotrichosis.

Human serum proteins bind to Sporothrix schenckii conidia with differential effects on phagocytosis

Serum is an important source of proteins that interact with pathogens. Once bound to the cell surface, serum proteins can stimulate the innate immune system. The phagocytosis of Sporothrix schenckii conidia by human macrophages is activated through human serum opsonisation. In this study, we have attempted to characterise human blood serum proteins that bind to the cell wall of S. schenckii conidia. We systematically observed the same four proteins independent of the plasma donor: albumin, serum amyloid protein (SAP), α-1 antitrypsin (AAT), and transferrin were identified with the help of tandem mass spectrometry. Phagocytosis depended on the concentration of the SAP or α-1 antitrypsin that was used to opsonise the conidia; however, transferrin or albumin did not have any effect on conidia internalisation. The presence of mannose did not affect macrophage phagocytosis of the conidia opsonised with SAP or α-1 antitrypsin, which suggests that these proteins are not recognised by the mannose receptor.

Is Sporothrix chilensis circulating outside Chile?

Sporothrix chilensis is a mild-pathogenical specie of Sporothrix pallida complex, until now, known as restrict to Chile. Herein, we describe the first clinical isolates identified as S. chilensis in Brazil, preserved in the URM Culture Collection, by polyphasic taxonomy, and their respective antifungal profile of this emergent fungus.

Interaction with Pantoea agglomerans Modulates Growth and Melanization of Sporothrix brasiliensis and Sporothrix schenckii

Sporothrix brasiliensis and Sporothrix schenckii stand as the most virulent agents of sporotrichosis, a worldwide-distributed subcutaneous mycosis. The origin of Sporothrix virulence seems to be associated with fungal interactions with organisms living in the same environment. To assess this hypothesis, the growth of these two species in association with Pantoea agglomerans, a bacterium with a habitat similar to Sporothrix spp., was evaluated. Growth, melanization, and gene expression of the fungus were compared in the presence or absence of the bacterium in the same culture medium. Both S. brasiliensis and S. schenckii grew in contact with P. agglomerans yielding heavily melanized conidia after 5 days of incubation at 30 °C in Sabouraud agar. This increased melanin production occurred around bacterial colonies, suggesting that fungal melanization is triggered by a diffusible bacterial product, which is also supported by a similar pattern of melanin production during Sporothrix spp. growth in contact with heat-killed P. agglomerans. Growth of P. agglomerans was similar in the presence or absence of the fungus. However, the growth of S. brasiliensis and S. schenckii was initially inhibited, but further enhanced when these species were co-cultured with P. agglomerans. Moreover, fungi were able to use killed bacteria as both carbon and nitrogen sources for growth. Representational difference analysis identified overexpressed genes related to membrane transport when S. brasiliensis was co-cultured with the bacteria. The down-regulation of metabolism-related genes appears to be related to nutrient availability during bacterial exploitation. These findings can lead to a better knowledge on Sporothrix ecology and virulence.

Complete mitogenome of the entomopathogenic fungus Sporothrix insectorum RCEF 264 and comparative mitogenomics in Ophiostomatales

The fungal order Ophiostomatales contains numerous species important in medical fields, agriculture, and forestry, and several species have had available mitogenome information. The nuclear genome of the entomopathogenic fungus Sporothrix insectorum has been reported, while its mitogenome remains unknown. Herein, we firstly described the mitogenome of S. insectorum RCEF 264 and then compared Ophiostomatales mitogenomes from both interspecific and intraspecific perspectives. The mitogenome of S. insectorum RCEF 264 was 31,454 bp in length, containing typical fungal mitochondrial genes plus rnpB. Four group I introns interrupted rnl and cox1. Phylogenetic analyses confirmed the placement of S. insectorum RCEF 264 in Ophiostomatales. Comparison of mitogenomes among seven Ophiostomatales species revealed conserved gene contents and a high synteny, although there were also some differences among them. Their mitogenomes showed more than two-fold variations (26.6-65.1 kb) in size, with a total of 37 intron insertional loci from 11 genes (1-25 introns per species). The sole intron shared by all species was an rps3-encoding intron in rnl (mL2450), and this intron-based phylogeny was highly consistent with those constructed using mitochondrial/nuclear genes, suggesting convergent evolution of this intron with Ophiostomatales species. The dendrogram based on presence/absence patterns at all intron loci was quite different from those based on mitochondrial/nuclear genes. Comparison of mitogenomes among two to three intraspecific individuals in Ophiostoma novo-ulmi subsp. novo-ulmi and Sporothrix schenckii revealed mitogenome size variations due to single-nucleotide polymorphisms (SNPs) and indels but without fluctuation of intron numbers for each species. This study greatly enhanced our understanding of mitogenome evolution in Ophiostomatales.

Effects of metaperiodate and urea solutions on the serological diagnosis of human sporotrichosis using an indirect ELISA test

Sporotrichosis is an infection of the skin caused by traumatic inoculation of the fungus Sporothrix schenckii. Definitive diagnosis relies on direct visualization of the fungus or its isolation on culture medium, although both have low sensitivity. Alternatively, the detection of the antibody response offers a more rapid alternative for diagnosis. Although the available immunoassays possess good sensitivity and specificity, cross-reactivity is still a problem. This study aimed to evaluate the effect of sodium metaperiodate and 6 M urea solutions on the serological diagnosis of sporotrichosis using an enzyme-linked immunosorbent assay (ELISA) test. Ninety-six-well plates were sensitized with exoantigens from the yeast phase of S. schenckii. Sera of patients with confirmed sporotrichosis, sera of patients with paracoccidioidomycosis, and sera of individuals with a sporotrichin-negative skin test were tested. Two strategies were used; the first consisted of treating the antigen with sodium metaperiodate solution for different incubation times, and the second consisted of treating the serum with 6 M urea solution for different incubation times. ROC curve analysis revealed that the best discrimination parameters were obtained using 6 M urea solution incubated for 5 min and serum dilution at 1/600. The use of 6 M urea solution improves the performance of the ELISA test in the diagnosis of sporotrichosis.

Genetic variation of Sporothrix globosa isolates from diverse geographic and clinical origins in China

Sporothrix globosa is the main causative agent of sporotrichosis, a common mycosis that usually affects the skin, in China. Despite increasing efforts in the molecular identification of this fungal pathogen, its modes of transmission and epidemiology remain poorly understood. The goals of this study were to assess the genetic diversity of S. globosa using amplified fragment length polymorphism (AFLP) analysis and to assess the correlation of AFLP profiles with the geographic origins, growth rates, clinical forms, and antifungal susceptibilities of S. globosa isolates. AFLP analysis of 225 clinical S. globosa isolates from eight provinces or municipalities in China identified eight distinct clustering groups (I-VIII), with groups I, II and IV being the most common. The AFLP genotypes showed distinct distribution patterns among different regions within Jilin Province and between northern and southern China, but there was no obvious association between the AFLP genotypes and the growth rates, clinical forms or antifungal susceptibilities of the S. globosa isolates. These results expand our understanding of the genetic variation of S. globosa and suggest that AFLP analysis is a potentially useful tool for studying the epidemiology of this fungal pathogen.

Molecular Diagnosis of Pathogenic Sporothrix Species

Background

Sporotrichosis is a chronic (sub)cutaneous infection caused by thermodimorphic fungi in the order, Ophiostomatales. These fungi are characterized by major differences in routes of transmission, host predilections, species virulence, and susceptibilities to antifungals. Sporothrix species emerge in the form of outbreaks. Large zoonoses and sapronoses are ongoing in Brazil and China, respectively. Current diagnostic methods based on morphology and physiology are inaccurate due to closely related phenotypes with overlapping components between pathogenic and non-pathogenic Sporothrix. There is a critical need for new diagnostic tools that are specific, sensitive, and cost-effective.

Methodology

We developed a panel of novel markers, based on calmodulin (CAL) gene sequences, for the large-scale diagnosis and epidemiology of clinically relevant members of the Sporothrix genus, and its relative, Ophiostoma. We identified specific PCR-based markers for S. brasiliensis, S. schenckii, S. globosa, S. mexicana, S. pallida, and O. stenoceras. We employed a murine model of disseminated sporotrichosis to optimize a PCR assay for detecting Sporothrix in clinical specimens.

Results

Primer-BLAST searches revealed candidate sequences that were conserved within a single species. Species-specific primers showed no significant homology with human, mouse, or microorganisms outside the Sporothrix genus. The detection limit was 10–100 fg of DNA in a single round of PCR for identifying S. brasiliensis, S. schenckii, S. globosa, S. mexicana, and S. pallida. A simple, direct PCR assay, with conidia as a source of DNA, was effective for rapid, low-cost genotyping. Samples from a murine model of disseminated sporotrichosis confirmed the feasibility of detecting S. brasiliensis and S. schenckii DNA in spleen, liver, lungs, heart, brain, kidney, tail, and feces of infected animals.

Conclusions

This PCR-based method could successfully detect and identify a single species in samples from cultures and from clinical specimens. The method proved to be simple, high throughput, sensitive, and accurate for diagnosing sporotrichosis.

Sporotrichosis, a disease caused by infections from Sporothrix species, primarily affects warm-blooded animals, particularly humans and cats. Sporotrichosis is emerging as a global threat, with high incidences in Brazil and China. The gold standard for diagnosing sporotrichosis is microscopic characterization of the pathogen isolated in culture. This methodology is tedious and time-consuming. Moreover, closely related Sporothrix species are often misidentified, due to similar phenotypic characteristics. The introduction of dissimilar species with specific geographic distributions, host predilections, virulence, and antifungal susceptibilities, has made species-level identification of Sporothrix mandatory. To facilitate meeting this requirement, we developed a PCR-based method for detecting and identifying Sporothrix species. We designed species-specific primers for identifying S. brasiliensis, S. schenckii, S. globosa, S. mexicana, S. pallida, and Ophiostoma stenoceras. With this method, we could detect as little as 1 pg and 10 fg (depending on the species) of Sporothrix DNA derived from isolated cultures. Furthermore, we successfully detected S. brasiliensis and S. schenckii DNA in tissue samples derived from a murine model of disseminated sporotrichosis. These species-specific primers can be applied in epidemiology, clinical diagnosis, and experimental studies of sporotrichosis. Improvements in early diagnosis and surveillance systems may facilitate rapid identification and control of future outbreaks.

Comparative genomics of the major fungal agents of human and animal Sporotrichosis: Sporothrix schenckii and Sporothrix brasiliensis

BACKGROUND

The fungal genus Sporothrix includes at least four human pathogenic species. One of these species, S. brasiliensis, is the causal agent of a major ongoing zoonotic outbreak of sporotrichosis in Brazil. Elsewhere, sapronoses are caused by S. schenckii and S. globosa. The major aims on this comparative genomic study are: 1) to explore the presence of virulence factors in S. schenckii and S. brasiliensis; 2) to compare S. brasiliensis, which is cat-transmitted and infects both humans and cats with S. schenckii, mainly a human pathogen; 3) to compare these two species to other human pathogens (Onygenales) with similar thermo-dimorphic behavior and to other plant-associated Sordariomycetes.

RESULTS

The genomes of S. schenckii and S. brasiliensis were pyrosequenced to 17x and 20x coverage comprising a total of 32.3 Mb and 33.2 Mb, respectively. Pair-wise genome alignments revealed that the two species are highly syntenic showing 97.5% average sequence identity. Phylogenomic analysis reveals that both species diverged about 3.8-4.9 MYA suggesting a recent event of speciation. Transposable elements comprise respectively 0.34% and 0.62% of the S. schenckii and S. brasiliensis genomes and expansions of Gypsy-like elements was observed reflecting the accumulation of repetitive elements in the S. brasiliensis genome. Mitochondrial genomic comparisons showed the presence of group-I intron encoding homing endonucleases (HE's) exclusively in S. brasiliensis. Analysis of protein family expansions and contractions in the Sporothrix lineage revealed expansion of LysM domain-containing proteins, small GTPases, PKS type1 and leucin-rich proteins. In contrast, a lack of polysaccharide lyase genes that are associated with decay of plants was observed when compared to other Sordariomycetes and dimorphic fungal pathogens, suggesting evolutionary adaptations from a plant pathogenic or saprobic to an animal pathogenic life style.

CONCLUSIONS

Comparative genomic data suggest a unique ecological shift in the Sporothrix lineage from plant-association to mammalian parasitism, which contributes to the understanding of how environmental interactions may shape fungal virulence. . Moreover, the striking differences found in comparison with other dimorphic fungi revealed that dimorphism in these close relatives of plant-associated Sordariomycetes is a case of convergent evolution, stressing the importance of this morphogenetic change in fungal pathogenesis.

Chromosomal polymorphism in the Sporothrix schenckii complex

Sporotrichosis is a polymorphic disease caused by a complex of thermodimorphic fungi including S. brasiliensis, S. schenckii sensu stricto (s. str.), S. globosa and S. luriei. Humans and animals can acquire the disease through traumatic inoculation of propagules into the subcutaneous tissue. Despite the importance of sporotrichosis as a disease that can take epidemic proportions there are just a few studies dealing with genetic polymorphisms and genomic architecture of these pathogens. The main objective of this study was to investigate chromosomal polymorphisms and genomic organization among different isolates in the S. schenckii complex. We used pulsed field gel electrophoresis (PFGE) to separate chromosomal fragments of isolated DNA, followed by probe hybridization. Nine loci (β-tubulin, calmodulin, catalase, chitin synthase 1, Internal Transcribed Spacer, Pho85 cyclin-dependent kinase, protein kinase C Ss-2, G protein α subunit and topoisomerase II) were mapped onto chromosomal bands of Brazilian isolates of S. schenckii s. str. and S. brasiliensis. Our results revealed the presence of intra and interspecies polymorphisms in chromosome number and size. The gene hybridization analysis showed that closely related species in phylogenetic analysis had similar genetic organizations, mostly due to identification of synteny groups in chromosomal bands of similar sizes. Our results bring new insights into the genetic diversity and genome organization among pathogenic species in the Sporothrix schenckii complex.

Phylogenetic analysis reveals a high prevalence of Sporothrix brasiliensis in feline sporotrichosis outbreaks

Sporothrix schenckii, previously assumed to be the sole agent of human and animal sporotrichosis, is in fact a species complex. Recently recognized taxa include S. brasiliensis, S. globosa, S. mexicana, and S. luriei, in addition to S. schenckii sensu stricto. Over the last decades, large epidemics of sporotrichosis occurred in Brazil due to zoonotic transmission, and cats were pointed out as key susceptible hosts. In order to understand the eco-epidemiology of feline sporotrichosis and its role in human sporotrichosis a survey was conducted among symptomatic cats. Prevalence and phylogenetic relationships among feline Sporothrix species were investigated by reconstructing their phylogenetic origin using the calmodulin (CAL) and the translation elongation factor-1 alpha (EF1α) loci in strains originated from Rio de Janeiro (RJ, n = 15), Rio Grande do Sul (RS, n = 10), Paraná (PR, n = 4), São Paulo (SP, n =3) and Minas Gerais (MG, n = 1). Our results showed that S. brasiliensis is highly prevalent among cats (96.9%) with sporotrichosis, while S. schenckii was identified only once. The genotype of Sporothrix from cats was found identical to S. brasiliensis from human sources confirming that the disease is transmitted by cats. Sporothrix brasiliensis presented low genetic diversity compared to its sister taxon S. schenckii. No evidence of recombination in S. brasiliensis was found by split decomposition or PHI-test analysis, suggesting that S. brasiliensis is a clonal species. Strains recovered in states SP, MG and PR share the genotype of the RJ outbreak, different from the RS clone. The occurrence of separate genotypes among strains indicated that the Brazilian S. brasiliensis epidemic has at least two distinct sources. We suggest that cats represent a major host and the main source of cat and human S. brasiliensis infections in Brazil.

Evaluation of cats as the source of endemic sporotrichosis in Peru

Although contact with domestic cats has been shown to be a risk factor for sporotrichosis in endemic areas, systematic evaluation of apparently unaffected cats as possible reservoirs for infection has not been explored. The goals of this study were to identify the following aspects of sporotrichosis in the endemic area of Abancay, Peru: (i) the overall prevalence of sporotrichosis in the cat population, (ii) the most common site where the fungus can be isolated from these cats, and (iii) whether cats without identifiable skin lesions may be carriers of the fungus in the oral mucosa, nasal mucosa, or nails. One household cat in each of 85 neighborhoods within the endemic area of Abancay, Peru was randomly selected. Oral and nasal swabs, as well as nail clippings were taken from 84 of the cats. In addition, samples from skin lesions that were suspected to be due to sporotrichosis were collected from cats or members of families that owned the pets. Cultures inoculated with two nasal swabs and one set of nail clippings from two different cats yielded Sporothrix schenckii, the identity of which were confirmed by rDNA sequencing. The overall prevalence of Sporothrix schenckii colonization was 2.38% (95% CI 0.41-9.14) in this cat population. None of the skin lesion samples from the cats and only one such sample from a family member were positive for Sporothrix schenckii in culture. These results suggest a role for domestic cats as a possible reservoir for sporotrichosis infection in Abancay.

Epidemiological data and molecular characterization (mtDNA) of Sporothrix schenckii in 13 cases from Mexico

BACKGROUND

Sporotrichosis is an endemic mycosis in Mexico and Central America.

OBJECTIVES

To present epidemiological data and characterize molecular subtypes of 13 strains of Sporothrix schenckii, and to correlate clinical and epidemiologic presentation with subtypes.

METHODOLOGY

Thirteen Mexican cases of sporotrichosis were identified, and mitochondrial DNA (mtDNA) from clinical isolates of S. schenckii were analyzed using RFLP Hae III. Molecular types 2, 3, 14, 28, and 29 were observed.

RESULTS

Clinical presentations and molecular types were consistent with established epidemiologic patterns for S. schenckii in this region.

CONCLUSIONS

This investigation provides further evidence of the strong regional specificity of molecular types of this organism.

Relationships among genotypes, virulence and clinical forms of Sporothrix schenckii infection

This study explored the relationships among genotypes, virulence and clinical forms of Sporothrix schenckii. Genomic DNA from isolates of S. schenckii, collected from different clinical forms of sporotrichosis, was amplified by randomly amplified polymorphic DNA (RAPD). Suspensions of different isolates of S. schenckii were inoculated into healthy BALB/c mice to compare their virulence, and the numbers and distribution of spores were determined by histological analysis. RAPD analysis indicated that the isolates from different clinical forms of sporotrichosis belonged to different genotypes. The mice inoculated with isolates from disseminated sporotrichosis showed an earlier onset of illness and more severe lesions than those inoculated with isolates from lymphocutaneous sporotrichosis, which, in turn, showed an earlier onset of illness and more severe lesions than those inoculated with isolates from fixed cutaneous sporotrichosis. Healthy BALB/c mice injected with isolates from disseminated sporotrichosis died within 10 days, whereas isolates from lymphocutaneous sporotrichosis and fixed cutaneous sporotrichosis failed to cause death. Histologically, mice inoculated with isolates from disseminated sporotrichosis had more spores than those inoculated with isolates from lymphocutaneous sporotrichosis and fixed cutaneous sporotrichosis. Thus, different genotypes may be associated closely with the virulence of different clinical forms of S. schenckii infection.

Molecular phylogeny of Sporothrix schenckii

The pathogenic dimorphic fungus Sporothrix schenckii is the agent responsible for sporotrichosis, an important fungal infection with a worldwide distribution. Little is known about the population structure of S. schenckii, although recent molecular and phenotypic data seem to demonstrate that different genetic lineages exist within this species. The aim of this study was to determine, by sequence analysis of three protein coding loci (chitin synthase, beta-tubulin, and calmodulin), whether this variability is due to species divergence or intraspecific diversity in S. schenckii. We included in the analysis 60 isolates (59 of clinical and 1 of environmental origin) of this species from a wide geographical range. DNA sequence data from the three nuclear regions were used in a phylogenetic analysis. The combined analysis of the three loci revealed the presence of three major clades, one grouping all of the European isolates, another with only Brazilian isolates, and the third with isolates from other South American countries and Africa. A total of 14 100% bootstrap-supported nodes were shown, 6 of them representing putative phylogenetic species. Our data also demonstrated that most of these species prevail in different geographical regions.

Macrorestriction analysis of clinical and environmental isolates of Sporothrix schenckii

Sporothrix schenckii causes sporotrichosis, a disease that most commonly presents as a subacute or chronic skin infection. An unusually high incidence of clinical cases of sporotrichosis occurred in the southwest of Western Australia over the last 5 years. Anecdotal accounts from patients implicated contact with hay prior to infection. Isolates of S. schenckii from hay and clinical cases were investigated by traditional phenotypic methods and pulsed-field gel electrophoresis (PFGE). The phenotypic evaluation separated S. schenckii from Ophiostoma spp. A DNA macrorestriction method using SfiI and NotI macrorestriction digestion by PFGE was developed to investigate the epidemiological connections. BioNumerics software was used to analyze the results. DNA macrorestriction digestion patterns for the recent Western Australian clinical isolates and four hay isolates were indistinguishable. Eastern state clinical isolates, national Quality Assurance Program isolates, and other environmental isolates gave different macrorestriction patterns. Clinical isolates from the southwest of Western Australia collected in the 1980s and 1990s were also characterized using PFGE. The patterns generated were indistinguishable from those of the recent clinical isolates. PFGE showed that the dominant strain of S. schenckii causing sporotrichosis in Western Australia is present in hay, has caused sporotrichosis for at least 15 years, and is a different strain from the strains found in other parts of Australia.

Genotyping of Sporothrix schenckii by analysis of ribosomal DNA regions

An attempt was made to identify the genotypes of 31 Sporothrix schenckii strains and the relationship between the genotypes, the geographic distributions and clinical manifestations using restriction fragment length polymorphic analysis. The total DNA was extracted by cetyltrimethyl ammonium bromide. The polymorphisms were detected by hybridisation of ApaI-digested Sporothrix genomic DNA with a probe amplified from the small subunit ribosomal DNA and adjacent internal transcribed spacer regions. The band patterns manifested by Southern blotting were explored to investigate the genotypes of the 31 strains of S. schenckii collected from five different areas in China. Of the data from the 31 strains of S. schenckii studied, 15 individual patterns (DNA type A-O) were recognised. Type A-C accounted for 51.61% of all the strains. The DNA typing of S. schenckii by Southern blotting was highly sensitive and highly distinguishable. We also found a significant correlation between DNA patterns and different geographic areas and clinical manifestations.

Ophiostoma dentifundum sp. nov. from oak in Europe, characterized using molecular phylogenetic data and morphology

Previous phylogenetic studies based on ITS sequence data have shown that Ophiostoma species with Sporothrix anamorphs include several species complexes. Isolates from oak in Poland and Hungary, which have previously been referred to as O. stenoceras, as well as isolates morphologically similar to S. inflata formed the basis of this study. Identification was based on sequences for the ITS region of rDNA operon and partial beta-tubulin gene. Analyses showed that isolates from Poland and Hungary reside in a well resolved clade, separate from those in the O. stenoceras-complex. The morphology of these isolates was compared with those of strains in the O. stenoceras complex and S. inflata. Morphological differences in teleomorph and anamorph structures were found between the isolates from Poland and Hungary and those in the O. stenoceras-complex. Growth characteristics and the presence of the teleomorph in culture could be used to separate this fungus from isolates in the S. inflata-complex. The fungus from Poland and Hungary is described here as O. dentifundum sp. nov. It is phylogenetically most closely related to isolates of S. inflata, which represent four well defined groups based on morphology and DNA sequence phylogeny.

Epidemiology of human sporotrichosis investigated by amplified fragment length polymorphism

Amplified fragment length polymorphism (AFLP) was used to analyze the genetic diversity of Peruvian strains of Sporothrix schenckii and to compare them to a panel of non-Peruvian strains. AFLP analysis suggests that the Peruvian strains can be divided into two homogeneous clusters with no reference to geographical origin or the clinical form of sporotrichosis. The strains from abroad present heterogeneous profiles, with the Bolivian strain and the Colombian strains related to one of the Peruvian population. Sequencing of internal transcribed spacer 2, used to examine the relationships over a longer distance, confirmed the division of Peruvian strains into two populations that can be identified on the basis of a single but specific sequence divergence. This paper introduces automated AFLP analysis as a valuable tool for further investigation of the epidemiology and ecology of S. schenckii.

Rapid and specific identification of Sporothrix schenckii by PCR targeting the DNA topoisomerase II gene

BACKGROUND

In order to study the genotype variation of Sporothrix schenckii, we previously analyzed the genomic sequences of the DNA topoisomerase II genes of this fungus and S. schenckii-related species, such as S. schenckii var. luriei and Ceratocystis stenoceras.

OBJECTIVE

To develop a PCR-based identification system that can distinguish S. schenckii from its related species for clinical diagnosis of sporotrichosis.

METHODS

Based on the nucleotide sequences of the DNA topoisomerase II genes of S. schenckii, S. schenckii var. luriei and C. stenoceras, three gene-specific primers (SSHF31 and SSHR97 for S. schenckii, and SSLF64 for S. schenckii var. luriei) were designed and evaluated for their specificities in PCR amplifications.

RESULTS

The primer set SSHF31/SSHR97 amplified PCR products of 663-817 bp from S. schenckii and approximately 660 bp from S. schenckii var. luriei, while SSLF64/SSHR97 exclusively amplified a major product of 305 bp from S. schenckii var. luriei.

CONCLUSION

PCR targeting the DNA topoisomerase II gene specifically and rapidly distinguished S. schenckii from its related species.

RFLP Analysis of the Internal Transcribed Spacer Regions of Sporothrix schenckii

Restriction fragment length polymorphism (RFLP) analysis was performed on the internal transcribed spacer regions of 204 Sporothrix schenckii isolates and on one strain each of the related fungi, S. schenckii var. luriei, S. curviconia, S. inflata and Ceratocystis stenoceras. S. schenckii isolates, which have been collected from around the world, have already been typed according to their mitochondrial DNA (mtDNA), and are kept in the Department of Dermatology, Kanazawa Medical University, Japan. Approximately 600 bp of the internal transcribed spacer region 1 (ITS1) of their nuclear ribosomal RNA gene (rDNA), 5.8S rDNA and ITS2 was amplified by PCR. From ITS-RFLP analysis of the PCR products, S. schenckii isolates comprised 4 types, rDNA types I - IV. The rDNA type I - III strains corresponded to the Group A strains (mtDNA types 1 - 3, 11, 14 - 19, 22 and 23), while the rDNA type IV strains corresponded to the Group B strains (mtDNA types 4 - 10, 12, 13, 20 and 21), as previously categorized according to their mtDNA-RFLP. The ITS-RFLP patterns of the above 4 related fungi all differed from those of the 4 rDNA types of S. schenckii. Furthermore, only 22 (3.5%) out of a sequence of about 620 bases of the ITS regions of the rDNA differed among representatives of the mtDNA types 1 - 5, 7, 11, 14 - 19, 22 and 23. This difference in the ITS region is smaller than the 10% difference among isolates when estimated by mtDNA-RFLP. From the phylogenetic tree based on the base sequences, rDNA type I - III strains belong to Group I, while rDNA type IV strains belong to Group II which correspond with Groups A and B based on their mtDNA. The Group I strains are predominant in South America and Africa, while Group II are predominant in Australia and Asia. ITS-RFLP analysis is better than mtDNA-RFLP in allowing faster discrimination and identification, and for its ability to divide the 4 types into groups, which is useful in clinical diagnosis and epidemiological investigations of S. schenckii.

Mitochondrial DNA Analysis of Sporothrix schenckii from China, Korea and Spain

Sporothrix schenckii isolates from China, Korea and Spain were investigated for mtDNA types based on restriction fragment length polymorphism patterns with HaeIII. Sixty-one isolates from China, 8 from Korea and 11 from Spain were comprised of 7, 2 and 2 mtDNA types, respectively. All the isolates belonged to Group B.

Detection of Sporothrix schenckii in clinical samples by a nested PCR assay

Cutaneous sporotrichosis is a chronic granulomatous fungal infection caused by Sporothrix schenckii with worldwide distribution. Its traditional diagnosis is time-consuming and difficult to differentiate from that of a clinical sporotrichoid lesion caused by various pathogens. In this study, a nested PCR assay for the detection of S. schenckii was evaluated by using a sequence of 18S rRNA gene as a target. For the examination of specificity and sensitivity, five clinical isolates with 1 ATCC 10213 strain of S. schenckii, 10 strains of clinical common fungi, 3 strains of Mycobacterium spp., Staphylococcus aureus, and normal human skin tissue were used. The expected fragment was amplified from six S. schenckii isolates in the first round and nested PCR but not from other microorganisms and human DNA. Their sequences were 100% identical to the S. schenckii 18S rRNA gene sequence deposited in GenBank. A detection limit of 40 fg of S. schenckii DNA extract was determined with ethidium bromide staining. Serial dilution studies demonstrated that the nested PCR could detect a DNA amount of 1 CFU of S. schenckii in tissue samples. We further investigated the nested PCR assay for the detection of S. schenckii from the tail tissues of 5 experimentally infected mice and from the clinical biopsy specimens of 12 patients with sporotrichosis confirmed by culture or histochemical staining. The nested PCR assay was positive in all 5 infected mice and in 11 of the 12 clinical specimens. The high sensitivity and specificity of this nested PCR indicate that the assay can provide rapid diagnosis with sufficient accuracy to be clinically useful for patients with sporotrichosis.

[Environmental Isolates of Sporothrix schenckii in China]

Restriction fragment length polymorphism (RFLP) in mitochondrial DNA (mtDNA) from 25 environmental isolates of Sporothrix schenckii from northeastern China was investigated. Based on the mtDNA-RELP patterns with Hae III, 6 isolates were confirmed to be S. schenckii, while the other 19 isolates were confirmed to be species distinct from S. schenckii. The mtDNA RFLP patterns of the 19 non-S. schenckii were identical to each other. The non-S. schenckii isolates could not be discriminated from S. schenckii by their macro- or micro-morphological features, and were not pathogenic in guinea pigs. Serological and delayed hypersensitivity cross-reactions were found between S. schenckii and the non-S. schenckii species, suggesting antigenic similarity. These results indicate that RFLP analysis of mtDNA is essential for the identification of environmental isolates of S. schenckii.

Characterization of Sporothrix schenckii by random amplification of polymorphic DNA assay

OBJECTIVES

To investigate the DNA polymorphism of Sporothrix schenckii (S. schenckii) and to find the relationship between DNA patterns and geographic areas and clinical manifestations.

METHOD

The total DNA was extracted with hexadecyltrimethyl-ammonium bromide. Random Amplification of Polymorphic DNA (RAPD) assay was used to study DNA typing of 24 strains of S. schenckii collected from different areas and isolated from different clinical types.

RESULTS

Of seven random primers used, three primers (OPAA11, OPD18 and OPB07) gave good reactions, the sequences of which were 5'-ACCCGACCTG-3', 5'-GAGAGCCAAC-3', 5'-GGTGAC~GCAG-3' respectively. The RAPD patterns of the 24 isolates were not completely identical, showing certain degrees of hereditary variability. Different isolates showed a common conserved DNA band with the same primer. Different clinical types showed different genotypes.

CONCLUSION

RAPD analysis is useful in DNA typing of S. schenckii, the DNA band type of which is related to geographic origin and Clinical manifestation.

Expression of a Pho85 cyclin-dependent kinase is repressed during the dimorphic transition in Sporothrix schenckii

Sporothrix schenckii is a pathogenic fungus that undergoes a dimorphic transition from yeast to mycelium in response to environmental conditions such as cell density, temperature, and calcium. We identified a homolog of the Pho85 cyclin-dependent kinase (Cdk) that mediates cellular responses to environmental conditions in other organisms. By Western blot, three proteins containing the PSTAIRE motif, which characterize the cyclin-dependent protein kinases, were identified in S. schenckii. The gene encoding a Pho85 homolog, PhoSs, was identified and sequenced. The phoSs gene consists of 990bp, contains one intron, and encodes a protein of 306 amino acids. The S. schenckii Pho85 homolog shares features with Cdks, including the PSTAIRE motif, an ATP binding domain, and a serine-threonine kinase domain. By quantitative competitive RT-PCR, expression of the phoSs gene was found to decrease 30-fold during the yeast to mycelium transition. The addition of extracellular calcium accelerated the dimorphic transition and restored phoSs expression. These findings suggest PhoSs may participate in the control of the yeast to mycelium transition in S. schenckii.

Phenotyping and genotyping of Sporothrix schenckii isolates according to geographic origin and clinical form of Sporotrichosis

Sporothrix schenckii isolates of fixed and lymphocutaneous clinical forms from Mexico (MX), Guatemala (GT), and Colombia (CO) as well as environmental isolates from MX were studied by analyzing their phenotypic characteristics (conidial length, thermotolerance by percent growth inhibition [GI] at 35 and 37 degrees C, median lethal dose [LD(50)]) and genotypic characteristics (by random amplified polymorphic DNA [RAPD] analysis-PCR). A significant difference (P < 0.01) in the mean conidial length of S. schenckii clinical isolates from CO ( = 4.03 +/- 1.04 microm) compared with those of clinical isolates from MX ( = 2.06 +/- 0.53 microm) and GT ( = 2.68 +/- 0.83 microm) was observed. The lowest thermotolerance, as determined by measurement of percent GI, was exhibited by isolates from CO at 35 degrees C ( = 50.1% +/- 15.9%) and 37 degrees C ( = 72.7% +/- 10.9%). In general, the highest virulence, as determined by measurement of the LD(50) for mice, was observed for the MX environmental isolates. RAPD analysis-PCR with 10-mer primers OPBG-01, OPBG-14, and OPBG-19 generated 52 reproducible bands. The 44 Sporothrix isolates fell into four major groups by hierarchical cluster analysis. The first group (group I), formed by 25 (of 27) isolates from MX, had two subgroups: subgroup Ia with 10 environmental isolates and subgroup Ib with 14 clinical isolates. The second group (group II) had two subgroups: subgroup IIa, formed by isolates from CO, and subgroup IIb, formed by isolates from GT. Groups III and IV each had only one clinical isolate from MX. A principal-component analysis of the same data yielded three distinct groups, depending on the geographical origins of the isolates, including the isolates in groups III and IV from MX, which were grouped with the isolates from MX by principal-component analysis. This study revealed that isolates from CO had low thermotolerances at 35 and 37 degrees C and could be associated with superficial skin lesions in patients with fixed clinical forms of sporotrichosis, the most frequent form of the disease in CO. Distinct patterns dependent on geographical origins were also revealed by RAPD analysis-PCR, but these had no relation to the clinical form of the disease.

Characterization of a protein kinase C gene in Sporothrix schenckii and its expression during the yeast-to-mycelium transition

The yeast-to-mycelium transition in Sporothrix schenckii has been shown to respond to protein kinase C (PKC) effectors, indicating the involvement of PKC in this regulation. In this study, we identified the presence of two pkcl-like genes in S. schenckii. Using fungal genomic DNA as template and primers targeted to conserved sequences in the Saccharomyces cerevisiae pkc1 gene, two partially overlapping extra long polymerase chain reaction (XL-PCR) products were obtained. These XL-PCR products were sequenced and found to encode part of the C3/C4 domains of two different PKC-like proteins. The presence of two different genes was confirmed by Southern blot analysis. These two genes were named pkcSs-1 and pkcSs-2. The sequence of the pkcSs-2 gene was completed and revealed an open reading frame of 3942 nucleotides interrupted by five introns. A transcript of 8.7 kb was detected in northern blot analysis of poly A+ RNA. The pkcSs-2 gene encodes a protein of 1194 amino acids and 132.84 kDa that contains the characteristic structure and domains of other fungal PKCs reported to date. Using reverse transcription-PCR (RT-PCR), the pkcSs-2 gene was found to be expressed at all intervals tested during the yeast-to-mycelium transition.

Identification of Sporothrix schenckii based on sequences of the chitin synthase 1 gene

Sporothrix schenckii is pathogenic to human and animals. To detect S. schenckii in the tissue, we designed specific oligonucleotide primers based on the chitin synthase gene. Amplification products were selectively obtained from S. schenckii DNA. Polymerase chain reaction analysis with the primer pair S2-R2 was able to detect 10 pg genomic DNA of S. schenckii with ethidium bromide staining. This detection system will be useful as a microbiological tool for the diagnosis of human and animal sporotrichosis.

Analysis of restriction profiles of mitochondrial DNA from Sporothrix schenckii

Mitochondrial DNA (mtDNA) diversity was analyzed in 42 clinical isolates of Sporothrix schenckii from Mexico (n = 29), Guatemala (n = 4) and Colombia (n = 9). Based on HaeIII restriction digestion profiles, the isolates were classified into eight types. In addition to 24 mtDNA types previously reported in another study, 6 new types were found in this study. Most of the strains belong to type 14 and type 30, the former restricted to Mexico, whereas the latter was distributed in Mexico, Guatemala and Colombia. The new types (25-30) were identified in Mexico, Guatemala and Colombia. Restriction-fragment length polymorphism in mtDNA of S. schenckii revealed high levels of genetic variation attributable to differences in restriction sites as well as in mtDNA size. Based on genetic distances S. schenckii types were clustered into two main groups.

Sporothrix schenckii thermo-intolerant mutants losing fatal visceral infectivity but retaining high cutaneous infectivity

Four mutants of the Sporothrix schenckii lung isolate IFM 41598 were isolated by their inability to form colonies on a Sabouraud glucose agar plate incubated at 37 degrees C for 4 days. In contrast to the parent IFM 41598, these thermo-intolerant mutants were all defective in producing fatal visceral infections in mice, even though they retained infectivity in footpad tissues with a small fungal inoculum (approximately equals 10 cfu).

[Molecular epidemiology of Sporothrix schenckii]

Restriction fragment length polymorphism (RFLP) in mitochondrial DNA (mtDNA) of clinical and environmental isolates of Sporothrix schenckii was investigated. Among mtDNA RFLP patterns with Hae III, of 14 environmental isolates morphologically identified as S. schenckii, only 2 isolates were confirmed as S. schenckii, while of more than 500 clinical isolates, all were confirmed to have this condition. Therefore, RFLP analysis of mtDNA is essential for the identification of environmental, but not clinical, isolates of S. schenckii. Isolates of Sporothrix schenckii were classified into 23 mtDNA types (Types l-23) based on mtDNA RFLP patterns with HaeIII and clustered into two major groups by phylogeny, Group A (Types 1-3, 11, 14-19, 22 and 23) and Group B (Types 4-10, 12, 13, 20 and 21). Group A isolates are predominant in South Africa, North America, Central America and South America, while Group B isolates are predominant in Australia and Japan. In Japan, the relative distribution of the mtDNA types varied with geographic region: Types 4, 6 are comparatively abundant in West Japan (Kansai and Kyushu districts), Type 5 is comparatively abundant in East Japan (Tokai, Kanto and Tohoku districts) and Type 2 is abundant in the Hokuriku district. Type 1 is found only in the Hokuriku district.