[Isolation of Sporothrix pallida complex in clinical and environmental samples from Chile]

Soil samples from sporotrichosis transmission belt area: Searching for fungal species and their antagonistic activity against Sporothrix brasiliensis

Since 1998, the state of Rio de Janeiro, Brazil, has become a public health problem regarding sporotrichosis, a disease caused by Sporothrix spp. involving contact with infected cats. Efforts to isolate these species from environmental sources are not always successful. In our study, soil from residences situated in cities of Rio de Janeiro where cats with sporotrichosis live was collected and cultured an attempt to isolate Sporothrix spp. but it was not successful. However, other saprophytic fungal species were isolated from soil and identified and among them Purpureocillium lilacinum was the most frequent. From there, we decided to study the in vitro interaction of this species with S. brasiliensis, the principal agent that causes sporotrichosis in this state. The results showed that ten isolates of P. lilacinum inhibited the radial mycelial growth of S. brasiliensis with different percentage of inhibition. The interaction between them revealed the pattern described as overgrowth by antagonist. In conclusion, our data suggest that fungal species with very fast growth and capable of producing metabolites could hinder the growth of Sporothrix spp., it also opens the way for the identification of secondary metabolites with biological activity that could be tested against pathogenic fungi.

Trends in Molecular Diagnostics and Genotyping Tools Applied for Emerging Sporothrix Species

Sporotrichosis is the most important subcutaneous mycosis that affects humans and animals worldwide. The mycosis is caused after a traumatic inoculation of fungal propagules into the host and may follow an animal or environmental transmission route. The main culprits of sporotrichosis are thermodimorphic Sporothrix species embedded in a clinical clade, including S. brasiliensis, S. schenckii, S. globosa, and S. luriei. Although sporotrichosis occurs worldwide, the etiological agents are not evenly distributed, as exemplified by ongoing outbreaks in Brazil and China, caused by S. brasiliensis and S. globosa, respectively. The gold standard for diagnosing sporotrichosis has been the isolation of the fungus in vitro. However, with the advance in molecular techniques, molecular assays have complemented and gradually replaced the classical mycological tests to quickly and accurately detect and/or differentiate molecular siblings in Sporothrix. Nearly all techniques available for molecular diagnosis of sporotrichosis involve PCR amplification, which is currently moving towards detecting Sporothrix DNA directly from clinical samples in multiplex qPCR assays. From an epidemiological perspective, genotyping is key to tracing back sources of Sporothrix infections, detecting diversity in outbreak areas, and thus uncovering finer-scale epidemiological patterns. Over the past decades, molecular epidemiological studies have provided essential information to policymakers regarding outbreak management. From high-to-low throughput genotyping methods, MLSA, AFLP, SSR, RAPD, PCR-RFLP, and WGS are available to assess the transmission dynamics and sporotrichosis expansion. This review discusses the trends in the molecular diagnosis of sporotrichosis, genotyping techniques applied in molecular epidemiological studies, and perspectives for the near future.

Epidemiology of Clinical Sporotrichosis in the Americas in the Last Ten Years

BACKGROUND

Sporotrichosis is a fungal infection caused by species of the Sporothrix genus. Presently, the prevalence of sporotrichosis in the Americas is unknown, so this study aims to analyze the cases reported in the past 10 years.

METHODS

An advanced search was conducted from 2012 to 2022 in English and Spanish in PUBMED, SciELO, and Cochrane, with the terms: "sporotrichosis", "lymphocutaneous sporotrichosis", "fixed sporotrichosis", "mycosis", "Sporothrix spp.", "Sporothrix complex", "S. schenckii sensu stricto", "S. schenckii sensu lato", "S. globose", "S. brasiliensis", "S. luriei". Sporotrichosis is a fungal infection caused by species of the Sporothrix genus associated with "pathogenicity" or "epidemiology".

RESULTS

A total of 124 articles were found in the Americas, corresponding to 12,568 patients. Of these, 87.38% of cases were reported in South America, 11.62% in North America, and 1.00% in Central America and the Caribbean. Brazil, Peru, and Mexico had the highest number of cases. The most prevalent etiological agents were S. schenckii complex/Sporothrix spp. (52.91%), S. schenckii (42.38%), others (4.68%), and Not Determined (ND) (0.03%). The most frequent form of the disease was lymphocutaneous infection; however, the infection type was not determined in 5639 cases. Among the diagnostic methods, culture was the most used.

CONCLUSIONS

There is a high occurrence of cases reported in the literature. South America is the region with the highest number of reports because of its environment (climate, inhalation of spores, etc.), zoonotic transmission (scratches and sneezes from contaminated animals), and possible traumatic inoculation due to outdoor activities (agriculture, gardening, and related occupations). Molecular diagnosis has not been sufficiently developed due to its high cost.

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.

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.

First case report of cutaneous sporotrichosis (Sporothrix species) in a cat in the UK

Case summary

A 12-year-old female neutered indoor-outdoor domestic longhair cat presented with frequent sneezing and a nodular, suppurative lesion on its dorsal nose. Histopathological examination revealed a fungal granuloma. PCR and sequencing of the ribosomal internal transcribed spacers (ITS) regions (ITS-F and ITS-R) confirmed an infection with a Sporothrix species. Further sequencing of the beta-tubulin and calmodulin genes confirmed Sporothrix humicola, which lies within the Sporothrix pallida complex. The cat had concurrent diabetes mellitus, which responded to insulin therapy and diet. Oral itraconazole at 10 mg/kg PO q24h resulted in resolution of the lesions after 12 months. Treatment was well tolerated.

Relevance and novel information

This is the first report of sporotrichosis in a cat in the UK and only the fifth worldwide involving the S pallida complex. Clinicians, pathologists and microbiologists need to be aware of the potential of Sporothrix infections in the UK and the ability of S pallida complex to cause opportunistic infections. Molecular techniques can achieve rapid and accurate identification of rare fungal organisms. A precise diagnosis with molecular testing can provide information regarding prognosis, treatment and zoonotic implications.

The threat of emerging and re-emerging pathogenic Sporothrix species

Sporotrichosis is a neglected subcutaneous mycosis of humans and animals acquired by traumatic inoculation of soil and plant material (classical route) contaminated with infectious propagules of the pathogen or being bitten/scratched by infected cats (alternative route). Within a genus composed of 53 species displaying an essentially environmental core, there are only a few members which have considerable impacts on human or animal health. Infections are typically caused by S. brasiliensis, S. schenckii or S. globosa. Rare mammal pathogens include members of the S. pallida and S. stenocereus complexes. To illustrate the tremendous impact of emerging zoonotic sporotrichosis on public health, we discuss the main features of the expanding epidemics driven by S. brasiliensis in cats and humans. The cat entry in the transmission chain of sporotrichosis, causing epizooties (cat-cat) or zoonosis (cat-human), has contributed to the definition of new paradigms in Sporothrix transmission, reaching epidemic levels, making the disease a serious public health problem. Indeed, S. brasiliensis infection in humans and animals is likely to become even more important in the future, with projections of its expansion in biogeographic domains and host range, as well as greater virulence in mammals. Therefore, lessons from a long-standing outbreak in the state of Rio de Janeiro about the source and distribution of the etiological agents among outbreak areas can be used to create better control and prevention plans and increase awareness of sporotrichosis as a serious emerging zoonotic disease.

An atypical cause of sporotrichosis in a cat

A nine-year-old domestic cat from Melbourne, Australia, presented with a non-ulcerated nodule on its nasal bridge. A fungal infection of the subcutis was diagnosed based on histopathology and culture of a white mould, which was identified as Sporothrix pallida complex by ITS1–5.8S-ITS2 and β-tubulin gene sequencing. The cat was treated by cytoreduction, itraconazole and subsequently posaconazole, which eventually resulted in regression of residual infected tissues and clinical resolution.

Molecular Identification and Antifungal Susceptibility of Clinical Isolates of Sporothrix schenckii Complex in Medellin, Colombia

BACKGROUND

Sporotrichosis is a subcutaneous mycosis that affects humans and other animals. Infection prevails in tropical and subtropical countries. Until a few years ago, it was considered that two varieties of Sporothrix schenckii caused this mycosis, but by applying molecular taxonomic markers, it has been demonstrated that there are several cryptic species within S. schenckii complex which varies in susceptibility, virulence, and geographic distribution.

OBJECTIVE

This study aimed to identify the clinical isolates of Sporothrix spp. from patients with sporotrichosis in Medellin, Colombia, using two markers and to evaluate the in vitro susceptibility to itraconazole.

METHODS

Thirty-four clinical isolates of Sporothrix spp. from Colombia, three from Mexico, and one from Guatemala were identified through sequencing of the noncoding region ITS-1 + 5.8SDNAr + ITS-2 and of the fragment containing exons 3 and 4 of the β-tubulin gene. Clinical isolate sequences were compared with GenBank reference sequences using the BLASTN tool, and then, phylogenetic analysis was performed. Besides, the in vitro susceptibility to itraconazole was evaluated by determining the minimum inhibitory concentrations according to the CLSI M38-A2 method.

RESULTS

Clinical isolates were identified by morphology as Sporothrix spp. Using the molecular markers, ITS and β-tubulin, isolates were identified as S. schenckii sensu stricto (25) and Sporothrix globosa (13). Susceptibility to itraconazole was variable among clinical isolates.

CONCLUSION

This is the first scientific publication that identifies species that cause sporotrichosis in Colombia, along with the antifungal susceptibility to itraconazole.

Ecological Determinants of Sporotrichosis Etiological Agents

Ecological determinants of sporotrichosis etiological agents remain poorly understood. For this reason, we performed explorations using local climate estimates to determine the temperature and humidity ranges of the environment where clinically relevant Sporothrix species occur and to identify what plant species are associated with them, using data collected from the published literature. We performed a literature search to identify all publications on environmental isolations of medically relevant species of Sporothrix in the PubMed, SCOPUS, and EMBASE databases. All those studies were included in the analysis where medically relevant species of Sporothrix have been isolated from soil samples, and described a specific geographical location that could be precisely georeferenced. We approximated temperature and humidity from local climate estimates, integrating geospatial data, temperature, and water vapor pressure from regions or provinces where medically relevant species of Sporothrix have been isolated from soil. Sporothrix spp. were more commonly isolated from soil of different regions or provinces of 16 countries. Most environmental isolates were identified as S. schenckii, whereas S. pallida, S. brasiliensis, S. globosa, and S. mexicana were rare. We estimate that medically relevant Sporothrix spp. grow in the soil at temperatures of 6.6 °C to 28.84 °C and 37.5% to 99.06% relative humidity. These findings indicate that sporotrichosis etiological agents grow in soil in ecological niches from soil with wide ranges of temperature and humidity, but they are also associated with a variety of plants, flowers, woody debris, reed leaves, corn stalks, leaves, and wood crumbs, potentially facilitating its establishment and proliferation in the environment.

Molecular Components of the Sporothrix schenckii Complex that Induce Immune Response

Sporotrichosis is a fungal disease caused by the Sporothrix schenckii complex that includes species such as S. brasiliensis, S. schenckii sensu stricto, S. globosa, S. luriei, S. mexicana, and S. pallida, which exhibit different potentially antigenic molecular components. The immune response of susceptible hosts to control infection and disease caused by these fungi has been little studied. Besides, the fungus-host interaction induces the activation of different types of immune response. This mini-review analyzes and discusses existing reports on the identification and functional characterization of molecules from species of the S. schenckii complex with clinical relevance, and the mechanisms that mediate the type and magnitude of the immune response in experimental models in vivo and in vitro. This knowledge is expected to contribute to the development of protective and therapeutic strategies against sporotrichosis and other mycoses.