Atypical Clinical Presentation of Sporotrichosis Caused by Sporothrix globosa Resistant to Itraconazole

Bimodal distribution of azole susceptibility in Sporothrix brasiliensis isolates in Brazil

Sporothrix brasiliensis is an emerging zoonotic fungal pathogen that can be difficult to treat. Antifungal susceptibility testing was performed on the mold phase of a convenience sample of 61 Sporothrix spp. isolates from human and cat sporotrichosis cases in Brazil using the Clinical and Laboratory Standards Institute standard M38. A bimodal distribution of azole susceptibility was observed with 50% (28/56) of S. brasiliensis isolates showing elevated itraconazole minimum inhibitory concentrations ≥16 µg/mL. Phylogenetic analysis found the in vitro resistant isolates were not clonal and were distributed across three different S. brasiliensis clades. Single nucleotide polymorphism (SNP) analysis was performed to identify potential mechanisms of in vitro resistance. Two of the 28 resistant isolates (MIC ≥16 mg/L) had a polymorphism in the cytochrome P450 gene, cyp51, corresponding to the well-known G448S substitution inducing azole resistance in Aspergillus fumigatus. SNPs corresponding to other known mechanisms of azole resistance were not identified in the remaining 26 in vitro resistant isolates.

On-site detection of Sporothrix globosa using immunoglobulin Y, magnetic separation and loop-mediated isothermal amplification

BACKGROUND

Sporothrix globosa (S. globosa) is an agricultural activity-related but neglected pathogenic fungus responsible for sporotrichosis. Timely detection is crucial for managing and preventing its spread. However, due to the lack of efficient recognition elements for enriching S. globosa, the current approaches for detecting S. globosa are not simple and/or sensitive enough. This hinders their wider application of fast screening.

RESULTS

Herein, we successfully prepared immunoglobulin Y (IgY) targeting S. globosa, and developed a rapid and accurate detection method, improving upon current limited and inadequate detection approaches. Our method combined the use of IgY and loop-mediated isothermal amplification (LAMP) to enhance detection sensitivity and specificity simultaneously. The IgY was fabricated on magnetic beads to specifically concentrate S. globosa in samples, while LAMP amplified the captured target after simple boiling DNA extraction. By using our method, as low as 4.66 × 102 Cells mL-1S. globosa was accurately detected in soil and corn straw samples. We further integrated this assay into a portable toolbox for sample-to-result detection in resource-limited areas. By using this toolbox, we have colorimetrically detected soil and corn straw samples contaminated by S. globosa, suggesting the promising on-site detection potential.

SIGNIFICANCE AND NOVELTY

A new IgY recognizing S. globosa was prepared. Through the combination of IgY enrichment and LAMP amplification, the detection sensitivity and specificity were improved simultaneously. This method eliminated thermal cycling, simplified the operation, and reduced the analysis time. Compared to existing methods, our approach is more suitable for on-site detection and can significantly improve public health responses to sporotrichosis outbreaks.

Human and Feline Sporotrichosis in a Reference Center of Southeastern Brazil: Genetic Differentiation, Diversity, and Antifungal Susceptibility of Sporothrix Species

Sporotrichosis is a neglected subcutaneous fungal infection that affects humans and animals worldwide caused by species belonging to the genus Sporothrix. This study aims to examine the range of genetic variations, assess molecular epidemiology significance, and explore potential modes of transmission of the Sporothrix species associated with the current sporotrichosis outbreaks in Espírito Santo, Brazil. In this investigation, 262 samples were evaluated, including 142 from humans and 120 from felines, collected between 2016 and 2021. The isolates were identified based on morphological and molecular characteristics. Sexual idiomorphs were determined by mating-type PCR using primers specific to the MAT1-1 and MAT1-2 loci. Amplified fragment length polymorphism (AFLP) was employed to assess the genetic variability of Sporothrix spp. Finally, antifungal susceptibility testing was performed following the CLSI M38-A2 protocol. Of the 142 human samples, 125 were identified as S. brasiliensis and 17 as S. schenckii s. str. The presence of S. brasiliensis was overwhelming (100%) during outbreaks, highlighting the significant role of domestic cats in the emergence of this species. Heterothallism was the only observed mating strategy. However, the MAT1-2 idiomorph was predominant in cases of cat-transmitted sporotrichosis (χ2 = 202.976; p < 0.0001). Our AFLP results show significant intraspecific variability observed among S. brasiliensis isolates in Espírito Santo. Different genotypes forming subgroups within the same population suggest that these isolates do not originate from a single ancestor, indicating multiple emergences. Furthermore, terbinafine was the antifungal with the best results in vitro. However, in clinical practice, itraconazole remains the primary treatment choice. Sporotrichosis continues to advance in the state; therefore, the health system must outline one-health strategies to contain the disease to prevent future epidemics.

Prevalence and Antifungal Susceptibility of Sporothrix species in Guangzhou, Southern China

INTRODUCTION

Sporotrichosis is a subcutaneous and chronic infection caused by traumatic inoculation of pathogenic sporothrix species, usually infecting the skins and subcutaneous tissues of humans and animals. However, the lack of epidemiological data required further molecular identification to describe the distribution of this fungus in our region. In this study, forty-eight clinical sporothrix isolated from Sun Yat-Sen Memorial Hospital were classified, and the susceptibility of each strain to seven antifungal agents was determined.

METHODS

Forty strains of S. globosa and eight strains of S. shenkshii were identified via colony morphology and PCR sequencing of calmodulin gene.

RESULTS

Antifungal susceptibility tests of the mycelial phase in vitro showed terbinafine (TRB) and luliconazole (LULI) were the most effective, followed by itraconazole (ITZ) and amphotericin B (AMB). By contrast, voriconazole (VCZ), 5-flucytosine (5FC) and fluconazole (FCZ) have low efficacy with high MIC.

CONCLUSION

Our results showed a predominantly S. globosa infection trend in southern China. Simultaneously, sporothrix is sensitive to TRB, LULI, ITZ and AMB whereas resistant to FCZ. This study firstly reports antifungal sensitivity test in vitro and epidemiological correlation analysis of sporothrix in southern China, and also the first time to find that sporothrix is sensitive to LULI.

Current Progress on Epidemiology, Diagnosis, and Treatment of Sporotrichosis and Their Future Trends

Sporotrichosis, a human and animal disease caused by Sporothrix species, is the most important implantation mycosis worldwide. Sporothrix taxonomy has improved in recent years, allowing important advances in diagnosis, epidemiology, and treatment. Molecular epidemiology reveals that S. brasiliensis remains highly prevalent during the cat-transmitted sporotrichosis outbreaks in South America and that the spread of S. brasiliensis occurs through founder effects. Sporothrix globosa and S. schenckii are cosmopolitan on the move, causing major sapronoses in Asia and the Americas, respectively. In this emerging scenario, one-health approaches are required to develop a creative, effective, and sustainable response to tackle the spread of sporotrichosis. In the 21st century, it has become vital to speciate Sporothrix, and PCR is the main pillar of molecular diagnosis, aiming at the detection of the pathogen DNA from clinical samples through multiplex assays, whose sensitivity reaches remarkably three copies of the target. The treatment of sporotrichosis can be challenging, especially after the emergence of resistance to azoles and polyenes. Alternative drugs arising from discoveries or repositioning have entered the radar of basic research over the last decade and point to several molecules with antifungal potential, especially the hydrazone derivatives with great in vitro and in vivo activities. There are many promising developments for the near future, and in this review, we discuss how these trends can be applied to the Sporothrix-sporotrichosis system to mitigate the advance of an emerging and re-emerging disease.

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.

Biological and Clinical Attributes of Sporothrix globosa, a Causative Agent of Sporotrichosis

Sporotrichosis is an important subcutaneous mycosis with high prevalence and threat to human and animal health worldwide. Sporothrix schenckii, Sporothrix brasiliensis, and Sporothrix globosa are the main etiological agents of this disease; and even though many efforts have been made recently to understand the Sporothrix-host interaction, little is known about S. globosa, an underestimated species. This organism shows the lowest virulence among the members of the Sporothrix pathogenic clade and represents an important pathogenic agent due to its global distribution. Here, we offer a review with all the known information about S. globosa, including its genome and proteomic information, and compare it with S. schenckii and S. brasiliensis, to explain the differences observed among these species, in terms of virulence, the host immune response, and the antifungal sensitivity. Also, we provide the gene prediction of some S. globosa putative virulence factors.

Uncommon Clinical Presentations of Sporotrichosis: A Two-Case Report

Sporotrichosis is a subcutaneous endemic mycosis caused by species of the Sporothrix schenckii complex. The most common clinical form of the disease is lymphocutaneous, while the fixed cutaneous and disseminated cutaneous forms are rare. Moreover, it is more prevalent in immunocompetent individuals. In this study, we present two cases of sporotrichosis with uncommon clinical forms: fixed cutaneous (Case 1) and disseminated cutaneous (Case 2). Both cases were diagnosed in immunocompetent males from endemic regions in Mexico, who had at least 1 year of evolution without improvement in response to prior nonspecific treatments. The diagnosis of sporotrichosis caused by S. schenckii sensu stricto was established through the isolation of the pathogen and its identification through the amplification of a 331 bp fragment of the gene encoding calmodulin. In both cases, improvement was observed after treatment with potassium iodide. Cases 1 and 2 illustrate the rarity of these clinical forms in individuals residing in endemic areas; hence, it is important to ensure a high index of clinical suspicion for the diagnosis of mycosis, as the differential diagnoses vary widely.

Synergism of Nikkomycin Z in Combination with Diphenyl Diselenide Against Sporothrix spp

We evaluated the in vitro activity of nikkomycin Z (NikZ) in combination with diphenyl diselenide (PhSe)₂, two compounds previously shown to have anti-Sporothrix spp. activity. Eighteen isolates of Sporothrix spp. were tested in checkerboard assays. Synergism for inhibition and killing Sporothrix spp. occurred in 100% and 89% of the isolates, respectively. The anti-Sporothrix spp. activity of this combination provides a rationale for in vivo studies to evaluate the application of both compounds in sporotrichosis treatment.

Diphenyl diselenide alone and in combination with itraconazole against Sporothrix schenckii s.str. and Sporothrix globosa

We evaluated the in vitro susceptibility of Sporothrix schenckii s.str. and Sporothrix globosa to diphenyl diselenide (PhSe)₂ alone and in association with itraconazole (ITZ). Eight clinical isolates were tested in microdilution and checkerboard assays. (PhSe)₂ alone inhibited all isolates in concentration ≤ 8 µg/mL and was effective in killing one S. schenckii isolate. Inhibitory and fungicidal beneficial effects in its interaction with ITZ were shown against 87.5% (7/8) and 50% (4/8) of the isolates tested, respectively. Our study demonstrates the in vitro antifungal activity of (PhSe)₂ against two pathogenic Sporothrix species, suggesting studies of in vivo applications are warranted.

Molecular epidemiology of Sporothrix schenkii isolates in Malaysia

Sporothrix schenkii is a dimorphic fungus that causes infections in both humans and animals. We report on 25 S. schenkii isolates collected in 2017 from humans and cats clinically diagnosed with sporotrichosis, in Malaysia. These isolates were phenotypically identified as S. schenkii sensu lato and further defined as S. schenckii sensu stricto based on partial calmodulin gene sequence. Isolates from both humans and cats were genotypically identical but displayed phenotypic variation. Phylogenetic analyses based on partial calmodulin sequence showed that the Malaysian isolates clustered with global S. schenkii sensu stricto strains, in particular, of the AFLP type E. This analysis also revealed that partial calmodulin sequence alone was sufficient for classifying global S. schenckii sensu stricto strains into their respective AFLP types, from A to E. The genetically conserved S. schenkii sensu stricto species isolated from humans and cats is suggestive of a clonal strain present in Malaysia. To the best of our knowledge, this is the first report on molecular identification of Sporothrix schenkii strains from human infections in Malaysia. Further studies are required in order to elucidate the clonal nature of Malaysian S. schenkii isolates. Our findings indicate the presence of a predominant S. schenkii genotype in the environment, causing infections in both cats and humans in Malaysia.

Rosa NM, Costa LAS, Visbal G, Rozental S, Navarro M. Synthesis, characterization and biological evaluation of zinc and copper azasterol complexes against Sporothrix brasiliensis

Characterized zinc– and copper–azasterol complexes acting as promising antifungal agents against Sporothrix brasiliensis. Metal–drug synergism was effectively applied.

Phenotypic and molecular characterisation of Sporothrix globosa of diverse origin from India

Sporotrichosis is one of the neglected tropical diseases causing subcutaneous chronic granulomatous lesion by thermally dimorphic fungi belonging to Sporothrix species. Sporothrix brasiliensis, Sporothrix mexicana and Sporothrix globosa are the common pathogenic species. In Asian countries, S. globosa constitutes nearly 99.3% of all Sporothrix species. We studied 63 cases of sporotrichosis of geographically diverse origin from India and Sporothrix isolates were characterised for its growth in different media, temperatures, ability to assimilate sugars and antifungal susceptibility profile. Molecular characterization was performed by sequencing of the calmodulin (CAL), beta tubulin (BT) and translational elongation factor 1-alpha (TEF-1α) and typing by fluorescent amplified fragment length polymorphism (FAFLP). In patients who presented with fixed (49.2%), lymphocutaneous lesions (23.8%), in 26.9% the details were not known, none had systemic dissemination. All the isolates tested were Sporothrix globosa and that could grow up to 35 °C and unable to grow at and beyond 37 °C. The assimilation of sucrose, ribitol and raffinose helps in identifying S. globosa. Sequences of CAL or BT or TEF-1α can differentiate S. globosa from other species in the complex. FAFLP results exhibited low genetic diversity. No correlation was noted between genotypes and clinical presentation, or geographic distribution. Itraconazole, terbinafine and posaconazole showed good in vitro antifungal activity against S. globosa whereas fluconazole and micafungin had no activity. S. globosa of Indian origin is relatively less pathogenic than other pathogenic Sporothrix species as it does not cause systemic dissemination and in the diagnostic laboratory, incubation of the cultures below 37 °C is essential for effective isolation.

Potential use of Nikkomycin Z as an anti- Sporothrix spp. drug

Sporotrichosis, the most common subcutaneous mycosis in several countries, is caused by the dimorphic fungus, Sporothrix spp. Given some limitations in the treatment of this disease, and the high potential of nikkomycin Z (NikZ) as an antifungal against dimorphic fungi, this study aimed to evaluate the in vitro susceptibility of Sporothrix spp. to NikZ alone and with the drug of choice, itraconazole (ITZ). Seventeen clinical isolates of three Sporothrix spp. species (10 S. brasiliensis, six S. schenckii sensu stricto and one S. globosa) were tested in microdilution and checkerboard assays. Minimal inhibitory concentration (MIC), minimal fungicidal concentration (MFC), fractional inhibitory and fungicidal concentration indexes (FICi and FFCi) were analyzed. MIC of NikZ alone could be determined against S. globosa (12.5 μg/ml) and against 67% (4/6) and 30% (3/10) of the S. schenckii sensu stricto and S. brasiliensis isolates, respectively (≤ 400 μg/ml). Synergism with ITZ was showed against almost all the isolates tested (94%; 16/17), including reversing resistance to ITZ alone in some isolates. Our study shows the potential of NikZ in sporotrichosis treatment. Further studies in experimental models are needed to understand the possible future application of this drug as an alternative therapy or as an adjuvant in sporotrichosis treatment.

LAY ABSTRACT

Sporotrichosis is a subcutaneous and lymphatic infection, caused by fungi of Sporothrix spp. Our study shows the potential of NikZ to inhibiting Sporothrix species in vitro. Further studies are needed to understand the future application of this drug to sporotrichosis treatment.

In vitro antifungal susceptibility of Sporothrix globosa isolates from Jilin Province, northeastern China: comparison of yeast and mycelial phases

The dimorphic fungus Sporothrix globosa is the predominant etiologic agent causing sporotrichosis in China, particularly in the northeast. It has been demonstrated that the incubation temperature and growth phase can influence in vitro antifungal susceptibility profiles of S. schenckii sensu stricto and S. brasiliensis (sibling species of S. globosa). Few studies have reported on the antifungal susceptibility of S. globosa, especially using large numbers of isolates. In this study, we assessed the susceptibility of 80 isolates of S. globosa originating from Jilin Province, northeastern China, to six antifungal agents (itraconazole, terbinafine, voriconazole, posaconazole, fluconazole, and amphotericin B), at varying incubation temperatures and in different fungal growth phases. The isolates were most sensitive to terbinafine (geometric mean [GM] of the minimum inhibitory concentration [MIC]: 0.0356 μg/ml for the mycelial phase at 30 °C, 0.0332 μg/ml for the mycelial phase at 35 °C, and 0.031 μg/ml for the yeast phase, respectively), followed by posaconazole (GM of the MIC: 4.2501 μg/ml for the mycelial phase at 30 °C, 1.4142 μg/ml for the mycelial phase at 35 °C, and 0.7195 μg/ml for the yeast phase, respectively) and itraconazole (GM of the MIC: 6.8448 μg/ml for the mycelial phase at 30 °C, 3.1383 μg/ml for the mycelial phase at 35 °C, and 1.0263 μg/ml for the yeast phase, respectively). The isolates were relatively resistant to fluconazole (GM of the MIC: 76.7716 μg/ml for the mycelial phase at 30 °C, 66.2570 μg/ml for the mycelial phase at 35 °C, and 24.4625 μg/ml for the yeast phase, respectively) and voriconazole (GM of the MIC: 26.2183 μg/ml for the mycelial phase at 30 °C, 13.6895 μg/ml for the mycelial phase at 35 °C, and 1.3899 μg/ml for the yeast phase, respectively). For all the tested azole drugs, the MICs at 30 °C were significantly higher than those at 35 °C (P < 0.001); for all agents except terbinafine, the MICs of S. globosa in the yeast phase were significantly lower than those of the strains in the mycelial phase (P < 0.001). These results show that the sensitivities of S. globosa to antifungal compounds are dependent on incubation temperature and growth phase. To the best of our knowledge, this is the largest study of antifungal susceptibility of S. globosa isolates reported to date. To establish epidemiological cutoff values for S. globosa, further antifungal susceptibility testing studies by independent laboratories located in different regions and using uniform conditions are required.

Antifungal resistance on Sporothrix species: an overview

INTRODUCTION

The treatment of human and animal sporotrichosis is often performed with antifungal agents; however, the emergence of antifungal-resistant strains of Sporothrix species has been reported. We aimed to discuss the ability of Sporothrix species in developing resistance to the conventional antifungals and mechanisms for this.

METHODOLOGY

Published data on databases (PubMed, Science Direct, Google Scholar) were investigated using a combination of keywords from 2008 to 2019 by the StArt tool.

RESULTS

The minimal inhibitory concentrations values based on the Clinical and Laboratory Standards Institute (CLSI) from eight references were classified according to the epidemiological cutoff values in wild-type or non-wild-type strains. In this way, non-wild-type S. schenckii and, mainly, S. brasiliensis isolates were recognized on itraconazole, amphotericin B, terbinafine, and voriconazole, which are strains that deserve more attention toward antifungal control, with a probable risk of mutation to antifungal resistance. Among the few reviewed studied on antifungal resistance, the melanin production capacity (DHN-melanin, L-DOPA melanin, and pyomelanin), the low genetic diversity due to the abnormal number of chromosomes, and the mutation in cytochrome P450 are some of the factors for developing resistance mechanism.

CONCLUSIONS

The emergence of Sporothrix species with in vitro antifungal resistance was evidenced and the possible mechanisms for resistance development may be due to the melanin production capacity, genetic diversity and mutations in cytochrome P450. Further studies should be carried out targeting gene expression for the development of antifungal resistance on Sporothrix species in order to prospect new therapeutic targets for human and veterinary use.

Terpinen-4-ol inhibits the growth of Sporothrix schenckii complex and exhibits synergism with antifungal agents

Aim: This study investigated the effect of terpinen-4-ol against Sporothrix schenckii complex and its interactions with antifungals. Materials & methods: The antifungal activity of terpinen-4-ol was evaluated by broth microdilution. The potential effect on cellular ergosterol concentration was evaluated by spectrophotometry. The antibiofilm activity was evaluated by violet crystal staining and XTT reduction assay. The potential pharmacological interactions with antifungals were evaluated by the checkerboard assay. Results: terpinen-4-ol (T-OH) showed minimal inhibitory concentrations ranging from 4 to 32 mg/l decreasing cellular ergosterol content and presented a SMIC ranging from 64 to 1024 mg/l for Sporothrix spp. The combinations of T-OH with itraconazole or terbinafine were synergistic. Conclusion: T-OH has antifungal activity against Sporothrix spp. and acts synergistically with standard antifungals.

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.

Prevalence and antifungal susceptibility of Sporothrix species in Jiangxi, central China

Sporotrichosis is a subcutaneous mycosis caused by traumatic inoculation of pathogenic Sporothrix species. Until recently, Sporothrix globosa was considered as the unique Chinese species causing this disorder. In the present study, 33 clinical Sporothrix strains isolated from Jiangxi, China, were classified and antifungal susceptibility for each strain was determined. Thirteen S. globosa strains and 20 S. schenckii strains were identified by morphology and by multilocus analysis using rDNA ITS, CAL, and EF1α (i.e., internal transcribed spacer, calmodulin and elongation factor-1α). In vitro antifungal susceptibility testing of yeast phases indicated that itraconazole, terbinafine, and posaconazole were most effective against both species, followed by amphotericin B and voriconazole, while fluconazole, 5-fluorocytosine had low efficacy with high MICs. Co-occurrence of S. schenckii and S. globosa in central China may indicate different routes of transmission in this area.

Antifungal activity of different molecular weight chitosans against planktonic cells and biofilm of Sporothrix brasiliensis

Sporotrichosis, caused by Sporothrix schenckii complex species, is the most prevalent subcutaneous mycosis in many areas of Latin America. Chitosan has been used as an antifungal agent; however the effects of the molecular weight (MW) of chitosan (i.e. high (HMW), medium (MMW) and low (LMW) molecular weight chitosan) on S. brasiliensis has not been well described, particularly on biofilms. Effects on the planktonic form activity of S. brasiliensis were quantified by broth microdilution, while anti-biofilm activity was quantified by measuring metabolic activity via XTT (2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide and biomass formation (crystal violet). The molecular weight of chitosan modulated its effect on the planktonic form of S. brasiliensis, presenting lower MIC values for LMW chitosan. With regards both the adhesive and mature phases of biofilm, the LMW chitosan reduced biomass and metabolic activity most effectively. This study confirms the effects of the molecular weight and deacetylation degree of chitosan on its antifungal properties for potentially pathogenic fungi.

Sensitivities of periodic acid-Schiff staining, Grocott's silver staining and calcofluor white staining in the diagnosis of human sporotrichosis

OBJECTIVE

This study aimed to investigate the sensitivity of periodic acid-Schiff (PAS) staining, Grocott's silver staining (GSS) and calcofluor white (CFW) staining in the diagnosis of sporotrichosis.

METHODS

Paraffin embedded tissues (n = 100) which were diagnosed with sporotrichosis by fungal culture were subjected to PAS, GSS, and CFW staining, and the detection rate of sporotrichosis was determined.

RESULTS

The sensitivity of PAS, GSS, and CFW staining was 31%, 40% and 74%, respectively, in the diagnosis of sporotrichosis.

CONCLUSION

CFW staining has a high sensitivity in the diagnosis of sporotrichosis, and sections are easily observed and can be repeatedly stained after CFW staining. For patients suspected to have sporotrichosis, CFW staining may be employed for early diagnosis before a fungal culture.

Immunopathogenesis of Human Sporotrichosis: What We Already Know

Sporotrichosis is a subacute/chronic mycosis caused by dimorphic fungus of the genus Sporothrix. This mycosis may affect both human and domestic animals and in the last few years, the geographic dispersion and increase of sporotrichosis worldwide has been observed. The occurrence of cases related to scratching/bites of domestic felines have increased, characterizing the disease as predominantly a zoonosis. In humans, sporotrichosis mainly involves the cutaneous tegument of infected patients, but other tissues may also present the infection. The main forms of clinical presentation are lymphocutanous sporotrichosis (LC) and fixed sporotrichosis (F). Although less common, mucosal, cutaneous disseminated, and extracutaneous forms have also been described. Multiple factors from the fungus and host can play a role in driving the clinical evolution of sporotrichosis to benign or severe disease. In this review, we discuss the immunopathological aspects involved in human sporotrichosis. Putting together the two branches of knowledge—host immune response and fungal evading mechanisms—we may perceive new possibilities in understanding the fungus–host interaction in order to be in a position to go further in the control of sporotrichosis.

Metal–azole fungistatic drug complexes as anti-Sporothrix spp. agents

Metal–antifungal drug complexes were investigated against fungus causing of sporotrichosis. They were more active against fungal cells than to mammalian cells.

Exploring virulence and immunogenicity in the emerging pathogen Sporothrix brasiliensis

Sporotrichosis is a polymorphic chronic infection of humans and animals classically acquired after traumatic inoculation with soil and plant material contaminated with Sporothrix spp. propagules. An alternative and successful route of transmission is bites and scratches from diseased cats, through which Sporothrix yeasts are inoculated into mammalian tissue. The development of a murine model of subcutaneous sporotrichosis mimicking the alternative route of transmission is essential to understanding disease pathogenesis and the development of novel therapeutic strategies. To explore the impact of horizontal transmission in animals (e.g., cat-cat) and zoonotic transmission on Sporothrix fitness, the left hind footpads of BALB/c mice were inoculated with 5×106 yeasts (n = 11 S. brasiliensis, n = 2 S. schenckii, or n = 1 S. globosa). Twenty days post-infection, our model reproduced both the pathophysiology and symptomology of sporotrichosis with suppurating subcutaneous nodules that progressed proximally along lymphatic channels. Across the main pathogenic members of the S. schenckii clade, S. brasiliensis was usually more virulent than S. schenckii and S. globosa. However, the virulence in S. brasiliensis was strain-dependent, and we demonstrated that highly virulent isolates disseminate from the left hind footpad to the liver, spleen, kidneys, lungs, heart, and brain of infected animals, inducing significant and chronic weight loss (losing up to 15% of their body weight). The weight loss correlated with host death between 2 and 16 weeks post-infection. Histopathological features included necrosis, suppurative inflammation, and polymorphonuclear and mononuclear inflammatory infiltrates. Immunoblot using specific antisera and homologous exoantigen investigated the humoral response. Antigenic profiles were isolate-specific, supporting the hypothesis that different Sporothrix species can elicit a heterogeneous humoral response over time, but cross reaction was observed between S. brasiliensis and S. schenckii proteomes. Despite great diversity in the immunoblot profiles, antibodies were mainly derived against 3-carboxymuconate cyclase, a glycoprotein oscillating between 60 and 70 kDa (gp60-gp70) and a 100-kDa molecule in nearly 100% of the assays. Thus, our data broaden the current view of virulence and immunogenicity in the Sporothrix-sporotrichosis system, substantially expanding the possibilities for comparative genomic with isolates bearing divergent virulence traits and helping uncover the molecular mechanisms and evolutionary pressures underpinning the emergence of Sporothrix virulence.