Susceptibility of Sporothrix brasiliensis isolates to amphotericin B, azoles, and terbinafine

Evidence of Clinical and Laboratory Correlation of Itraconazole Resistance in Sporothrix brasiliensis Infection: Case Report

Sporotrichosis is a subcutaneous infection caused by fungi from the genus Sporothrix, among which Sporothrix brasiliensis displays high virulence and transmissibility. So far, classical antifungal agents have been efficient against S. brasiliensis, but here we describe the first case of therapeutic failure and a high minimum inhibitory concentration (MIC) in relation to itraconazole.

Milteforan, a promising veterinary commercial product against feline sporotrichosis

Sporotrichosis, the cutaneous mycosis most commonly reported in Latin America, is caused by the Sporothrix clinical clade species, including Sporothrix brasiliensis and Sporothrix schenckii sensu stricto. Due to its zoonotic transmission in Brazil, S. brasiliensis represents a significant health threat to humans and domestic animals. Itraconazole, terbinafine, and amphotericin B are the most used antifungals for treating sporotrichosis. However, many strains of S. brasiliensis and S. schenckii have shown resistance to these agents, highlighting the importance of finding new therapeutic options. Here, we demonstrate that milteforan, a commercial veterinary product against dog leishmaniasis, whose active principle is miltefosine, is a possible therapeutic alternative for the treatment of sporotrichosis, as observed by its fungicidal activity in vitro against different strains of S. brasiliensis and S. schenckii. Fluorescent miltefosine localizes to the Sporothrix cell membrane and mitochondria and causes cell death through increased permeabilization. Milteforan decreases S. brasiliensis fungal burden in A549 pulmonary cells and bone marrow-derived macrophages and also has an immunomodulatory effect by decreasing TNF-α, IL-6, and IL-10 production. Our results suggest milteforan as a possible alternative to treat feline sporotrichosis.

IMPORTANCE

Sporotrichosis is an endemic disease in Latin America caused by different species of Sporothrix. This fungus can infect domestic animals, mainly cats and eventually dogs, as well as humans. Few drugs are available to treat this disease, such as itraconazole, terbinafine, and amphotericin B, but resistance to these agents has risen in the last few years. Alternative new therapeutic options to treat sporotrichosis are essential. Here, we propose milteforan, a commercial veterinary product against dog leishmaniasis, whose active principle is miltefosine, as a possible therapeutic alternative for treating sporotrichosis. Milteforan decreases S. brasiliensis fungal burden in human and mouse cells and has an immunomodulatory effect by decreasing several cytokine production.

Is terbinafine an effective treatment for feline sporotrichosis?

BACKGROUND

Terbinafine has been successfully used in the treatment of human sporotrichosis; however, its effectiveness in the treatment of feline sporotrichosis is unknown. Therefore, this study aimed to describe the use of terbinafine in the treatment of feline sporotrichosis.

METHODS

A cohort study was conducted in cats with sporotrichosis to assess the effectiveness and safety of terbinafine (30‒60 mg/kg/day). Clinical examination and analysis of laboratory parameters were performed monthly until clinical signs resolved or terbinafine treatment was discontinued.

RESULTS

Of the 54 cats with sporotrichosis included in the study, 19 were lost during follow-up and five were withdrawn from the study due to switching to treatment with another prescription drug. Of the remaining 30 cats, 10 achieved clinical cure, with a median treatment time of 18.5 weeks. Treatment failed in 18 cases, and two cats died. Twenty-two cats had adverse reactions to terbinafine treatment, and 10 cats showed elevation of serum transaminases.

LIMITATION

Loss during follow-up was high, which makes it difficult to draw accurate conclusions regarding clinical outcomes.

CONCLUSION

The low rate of clinical cure observed suggests that terbinafine does not represent an effective treatment option for cases of feline sporotrichosis.

Strategies of Pharmacological Repositioning for the Treatment of Medically Relevant Mycoses

Fungal infections represent a worldwide concern for public health, due to their prevalence and significant increase in cases each year. Among the most frequent mycoses are those caused by members of the genera Candida, Cryptococcus, Aspergillus, Histoplasma, Pneumocystis, Mucor, and Sporothrix, which have been treated for years with conventional antifungal drugs, such as flucytosine, azoles, polyenes, and echinocandins. However, these microorganisms have acquired the ability to evade the mechanisms of action of these drugs, thus hindering their treatment. Among the most common evasion mechanisms are alterations in sterol biosynthesis, modifications of drug transport through the cell wall and membrane, alterations of drug targets, phenotypic plasticity, horizontal gene transfer, and chromosomal aneuploidies. Taking into account these problems, some research groups have sought new therapeutic alternatives based on drug repositioning. Through repositioning, it is possible to use existing pharmacological compounds for which their mechanism of action is already established for other diseases, and thus exploit their potential antifungal activity. The advantage offered by these drugs is that they may be less prone to resistance. In this article, a comprehensive review was carried out to highlight the most relevant repositioning drugs to treat fungal infections. These include antibiotics, antivirals, anthelmintics, statins, and anti-inflammatory drugs.

In vitro activity of the anthelmintic drug niclosamide against Sporothrix spp. strains with distinct genetic and antifungal susceptibility backgrounds

The drugs available to treat sporotrichosis, an important yet neglected fungal infection, are limited. Some Sporothrix spp. strains present reduced susceptibility to these antifungals. Furthermore, some patients may not be indicated to use these drugs, while others may not respond to the therapy. The anthelmintic drug niclosamide is fungicidal against the Sporothrix brasiliensis type strain. This study aimed to evaluate whether niclosamide also has antifungal activity against Sporothrix globosa, Sporothrix schenckii and other S. brasiliensis strains with distinct genotypes and antifungal susceptibility status. Minimal inhibitory and fungicidal concentrations (MIC and MFC, respectively) were determined using the microdilution method according to the CLSI protocol. The checkerboard method was employed to evaluate niclosamide synergism with drugs used in sporotrichosis treatment. Metabolic activity of the strains under niclosamide treatment was evaluated using the resazurin dye. Niclosamide was active against all S. brasiliensis strains (n = 17), but it was ineffective (MIC > 20 µM) for some strains (n = 4) of other pathogenic Sporothrix species. Niclosamide MIC values for Sporothrix spp. were similar for mycelial and yeast-like forms of the strains (P = 0.6604). Niclosamide was fungicidal (MFC/MIC ratio ≤ 2) for most strains studied (89%). Niclosamide activity against S. brasiliensis is independent of the fungal genotype or non-wild-type phenotypes for amphotericin B, itraconazole, or terbinafine. These antifungal drugs presented indifferent interactions with niclosamide. Niclosamide has demonstrated potential for repurposing as a treatment for sporotrichosis, particularly in S. brasiliensis cases, instigating in vivo studies to validate the in vitro findings.

Milteforan, a promising veterinary commercial product against feline sporotrichosis

Sporotrichosis, the cutaneous mycosis most commonly reported in Latin America, is caused by the Sporothrix clinical clade species, including Sporothrix brasiliensis and Sporothrix schenckii sensu stricto. In Brazil, S. brasiliensis represents a vital health threat to humans and domestic animals due to its zoonotic transmission. Itraconazole, terbinafine, and amphotericin B are the most used antifungals for treating sporotrichosis. However, many strains of S. brasiliensis and S. schenckii have shown resistance to these agents, highlighting the importance of finding new therapeutic options. Here, we demonstrate that milteforan, a commercial veterinary product against dog leishmaniasis whose active principle is miltefosine, is a possible therapeutic alternative for the treatment of sporotrichosis, as observed by its fungicidal activity in vitro against different strains of S. brasiliensis and S. schenckii, and by its antifungal activity when used to treat infected epithelial cells and macrophages. Our results suggest milteforan as a possible alternative to treat feline sporotrichosis.

A Randomized Clinical Trial Comparing Itraconazole and a Combination Therapy with Itraconazole and Potassium Iodide for the Treatment of Feline Sporotrichosis

Feline sporotrichosis is an endemic disease with high occurrence in Brazil. Itraconazole (ITZ) remains the drug of choice for treating this disease in cats, despite the increasing reports of therapeutic failure. A controlled, randomized clinical trial was performed on 166 naive cats with sporotrichosis to assess the effectiveness and safety of the combination therapy with ITZ and potassium iodide (KI) compared with ITZ monotherapy. Cats were randomly allocated into two treatment groups: G1-ITZ 100 mg/cat/day-and G2-ITZ 100 mg/cat/day + KI 2.5-20 mg/kg/day. Cats treated in G2 presented 77% more risk of reaching a clinical cure (a positive effect) than those treated in G1, even when controlled by negative predictors. The survival curves of the two treatment protocols indicate that a clinical cure was achieved faster in G2. An increase in the KI dose was necessary in 28 cats due to the persistence of clinical signs. Adverse reactions were equally frequent in both groups and manageable with a temporary drug suspension and/or a hepatoprotective therapy. The combination therapy was associated with a higher cure rate and a shorter treatment time, suggesting that ITZ+KI arises as a better option for treating feline sporotrichosis and should be considered the first-line treatment, especially in the presence of negative predictors.

Invasive fungal infections and oomycoses in cats 2. Antifungal therapy

CLINICAL RELEVANCE

Invasive fungal infections (IFIs) and oomycoses (hereafter termed invasive fungal-like infections [IFLIs]) are characterised by penetration of tissues by fungal elements. The environment is the most common reservoir of infection. IFIs and IFLIs can be frustrating to treat because long treatment times are usually required and, even after attaining clinical cure, there may be a risk of relapse. Owner compliance with medication administration and recheck examinations can also decline over time. In addition, some antifungal drugs are expensive, have variable interpatient pharmacokinetic properties, can only be administered parenterally and/or have common adverse effects (AEs). Despite these limitations, treatment can be very rewarding, especially when an otherwise progressive and fatal disease is cured.

AIM

In the second of a two-part article series, the spectrum of activity, mechanisms of action, pharmacokinetic and pharmacodynamic properties, and AEs of antifungal drugs are reviewed, and the treatment and prognosis of specific IFIs/IFLIs - dermatophytic pseudomycetoma, cryptococcosis, sino-orbital aspergillosis, coccidioidomycosis, histoplasmosis, sporotrichosis, phaeohyphomycosis, mucormycosis and oomycosis - are discussed. Part 1 reviewed the diagnostic approach to IFIs and IFLIs.

EVIDENCE BASE

Information on antifungal drugs is drawn from pharmacokinetic studies in cats. Where such studies have not been performed, data from 'preclinical' animals (non-human studies) and human studies are reviewed. The review also draws on the wider published evidence and the authors' combined expertise in feline medicine, mycology, dermatology, clinical pathology and anatomical pathology.

ABBREVIATIONS FOR ANTIFUNGAL DRUGS

AMB (amphotericin B); FC (flucytosine); FCZ (fluconazole); ISA (isavuconazole); ITZ (itraconazole); KCZ (ketoconazole); PCZ (posaconazole); TRB (terbinafine); VCZ (voriconazole).

In vitro isavuconazole activity against Sporothrix brasiliensis suggests its efficacy in some severe sporotrichosis cases

Background: Sporothrix brasiliensis causes sporotrichosis, an important infection in some groups of patients. Aims: This work was designed to investigate the effects of isavuconazole against this species. Methods: An antifungal susceptibility test was performed to compare MIC values with other antifungal drugs used to treat sporotrichosis. A checkerboard assay was performed to understand isavuconazole interactions. Furthermore, isavuconazole growth inhibition on an itraconazole-resistant strain was tested. Results: Isavuconazole had similar MICs to other azoles against S. brasiliensis, presenting fungistatic activity. Isavuconazole did not interact in vitro with antifungals or immunosuppressive drugs and inhibited the growth of an itraconazole-resistant strain. Conclusion: Isavuconazole inhibits S. brasiliensis, its pharmacologic characteristics make it a candidate for patients with sporotrichosis and it may be useful to combat sporotrichosis caused by resistant isolates.

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.

Ethyl acetate fractions of Myrciaria floribunda, Ocotea pulchella, and Ocotea notata exhibit promising in vitro activity against Sporothrix brasiliensis isolates with low susceptibility to itraconazole

Sporothrix brasiliensis with low susceptibility isolates were described from the Brazilian zoonotic sporotrichosis hyperendemics. The aim of this work was to evaluate distinct fractions of Ocotea pulchella, Ocotea notata, Myrciaria floribunda, and Hypericum brasiliense plant extracts against itraconazole-sensitive and low susceptibility S. brasiliensis isolates. Crude extracts were tested against clinical isolates and the ATCC MYA4823 to determine the minimum inhibitory concentrations (MICs) and fungicidal or fungistatic activities (MFC). A high MICs and MFCs amplitude (1 - > 128 µg/mL) were obtained for seven extracts. The highest antimicrobial activities against sensitive S. brasiliensis were displayed by the ethyl acetate extracts of O. notata (MIC = 2-128 μg/mL) and M. floribunda (MIC = 1-8 μg/mL). A fungicidal effect was observed for all fraction extracts. Ocotea spp. and M. floribunda ethyl acetate extracts provide promising profiles against itraconazole-sensitive or low susceptibility S. brasiliensis. Future studies will determine if these extracts can contribute as alternative therapies to this neglected zoonosis.

Laser therapy in the treatment of feline sporotrichosis: A case series

Sporotrichosis is the most prevalent subcutaneous mycosis in Latin America and is an important zoonosis in expansion throughout all the brazilian territory. Domestic cats are highly susceptible to the disease and play an important role in the spread of the agent to both other animals and humans. Sporothrix brasiliensis, the predominant species in the country, has greater virulence and some isolates also showed resistance to azoles, the class of antifungals of choice for treatment. Because it is a long-duration treatment, of high cost, and oral use, sick animals are often abandoned, which contributes to the spread and permanence of the infection as an important public health problem. Therefore, new therapeutic alternatives or adjuncts to treatment with antifungals may contribute to combating this zoonotic agent. In this work we describe the result of the treatment with laser therapy of eight Sporothrix spp infected cats. Our findings show the efficacy of the laser treatment even in different clinical forms. This technique has the potential to decrease the time length and costs of conventional treatment as well as the improvement of the treatment results.

Feline sporotrichosis caused by Sporothrix schenckii sensu stricto in Southern Thailand: phenotypic characterization, molecular identification, and antifungal susceptibility

Feline sporotrichosis caused by the Sporothrix schenckii complex is a global subcutaneous mycosis, having higher prevalence in Latin America and Malaysia. However, its etiological agents have not been elucidated in Thailand, a neighboring country of Malaysia, where the cases are increasing. This study identified 38 feline isolates of S. schenckii from Southern Thailand, collected between 2018 and 2021, using phenotypic characterization and molecular identification using polymerase chain reaction (PCR)-sequencing of partial calmodulin (CAL) and ß-tubulin (Bt2) genes. Phenotypic characteristics proved that the isolates were S. schenckii sensu lato, with low thermotolerance. Based on partial CAL and Bt2-PCR sequencing, all isolates were identified as S. schenckii sensu stricto. Phylogenetic analyses revealed that the isolates were clustered with S. schenckii sensu stricto isolated from the cats in Malaysia. A low degree of genetic diversity was observed among the Thai feline isolates. The antifungal susceptibility of these isolates to antifungal agents, including itraconazole (ITC), ketoconazole (KTC), fluconazole (FLC), and amphotericin B (AMB), was investigated according to the M27-A3 protocol of the Clinical and Laboratory Standards Institute. Results showed low ITC, KTC, and AMB activities against S. schenckii sensu stricto isolates, with high minimum inhibitory concentration (MIC) ranges of 1-8, 1-8, and 2-16 µg/ml, respectively, whereas FLC exhibited MICs of 64 and > 64 µg/ml. This study indicated that S. schenckii sensu stricto is the causative agent responsible for feline sporotrichosis in Southern Thailand. Their phenotypic characteristics and in vitro antifungal susceptibility profiles will help to improve our understanding of this mycosis in Thailand.

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.

Withania somnifera (L.) Dunal whole-plant extracts exhibited anti-sporotrichotic effects by destabilizing peripheral integrity of Sporothrix globosa yeast cells

Chronic topical cases of Sporotrichosis, a chronic fungal infection caused by the ubiquitously present cryptic members of the Sporothrix species complex, are treated with oral administrations of itraconazole. However, severe pulmonary or disseminated cases require repeated intra-venous doses of amphotericin B or even surgical debridement of the infected tissue. The unavoidable adverse side-effects of the current treatments, besides the growing drug resistance among Sporothrix genus, demands exploration of alternative therapeutic options. Medicinal herbs, due to their multi-targeting capacity, are gaining popularity amidst the rising antimicrobial recalcitrance. Withania somnifera is a well-known medicinal herb with reported antifungal activities against several pathogenic fungal genera. In this study, the antifungal effect of the whole plant extract of W. somnifera (WSWE) has been explored for the first time, against an itraconazole resistant strain of S. globosa. WSWE treatment inhibited S. globosa yeast form growth in a dose-dependent manner, with IC₅₀ of 1.40 mg/ml. Minimum fungicidal concentration (MFC) was found to be 50 mg/ml. Sorbitol protection and ergosterol binding assays, revealed that anti-sporotrichotic effects of WSWE correlated well with the destabilization of the fungal cell wall and cell membrane. This observation was validated through dose-dependent decrease in overall ergosterol contents in WSWE-treated S. globosa cells. Compositional analysis of WSWE through high performance liquid chromatography (HPLC) exhibited the presence of several anti-microbial phytochemicals like withanone, withaferin A, withanolides A and B, and withanoside IV and V. Withanone and withaferin A, purified from WSWE, were 10–20 folds more potent against S. globosa than WSWE, thus, suggesting to be the major phytocompounds responsible for the observed anti-sporotrichotic activity. In conclusion, this study has demonstrated the anti-sporotrichotic property of the whole plant extract of W. somnifera against S. globosa that could be further explored for the development of a natural antifungal agent against chronic Sporotrichosis.

Sporotrichosis, commonly known as ‘rose gardener’s disease’ is a rare but chronic fungal infection caused by several pathogenic members of Sporothrix. Although rare, Sporotrichosis can spread to the lungs or whole body, and thus, could be fatal. However, due to low frequency of its occurrence, scientific research on Sporotrichosis has been rather limited. To exacerbate the situation, many Sporothrix members have developed resistance against the common anti-fungal agents used to treat fungal infections. Many medicinal herbs are being explored for their effectiveness against drug-resistant microorganisms. In this connection, the well-known medicinal plant, Withania somnifera, commonly known as Winter cherry in English and Ashwagandha in Hindi, has been explored for its anti-fungal potentials against several pathogenic fungi. However, to the best of our knowledge, anti-fungal effect of W. somnifera against Sporothrix has not been assessed yet. Therefore, this study was conducted to investigate the anti-fungal potentials of Withania somnifera whole plant extract (WSWE) against Sporothrix globosa, known to cause Sporotrichosis in Asia. This study demonstrated significant anti-sporotrichotic effect of WSWE, which could be further explored for developing an alternative natural treatment for Sporotrichosis.

A novel naphthoquinone derivative shows selective antifungal activity against Sporothrix yeasts and biofilms

Sporotrichosis is a subcutaneous mycosis that affects humans and animals, with few therapeutic options available in the pharmaceutical market. We screened the in vitro antifungal activity of fourteen 1,4-naphthoquinones derivative compounds against Sporothrix brasiliensis and Sporothrix schenckii, the main etiological agents of sporotrichosis in Latin America. The most active compound was selected for further studies exploring its antibiofilm activity, effects on yeast morphophysiology, interaction with itraconazole, and selectivity to fungal cells. Among the fourteen 1,4-naphthoquinones tested, naphthoquinone 5, a silver salt of lawsone, was the most active compound. Naphthoquinone 5 was able to inhibit Sporothrix biofilms and induced ROS accumulation, mitochondrial disturbances, and severe plasmatic membrane damage in fungal cells. Furthermore, naphthoquinone 5 was ten times more selective towards fungal cells than fibroblast, and the combination of itraconazole with naphthoquinone 5 improved the inhibitory activity of the azole. Combined, the data presented here indicate that the silver salt naphthoquinone 5 exerts promising in vitro activity against the two main agents of sporotrichosis with important antibiofilm activity and a good toxicity profile, suggesting it is a promising molecule for the development of a new family of antifungals.

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.

Old and New Insights into Sporothrix schenckii Complex Biology and Identification

Sporothrix schenckii is a worldwide-distributed thermally dimorphic fungus, which usually causes a subacute to chronic infection through traumatic implantation or inoculation of its infectious propagules. The fungus encompasses a group of phylogenetically closely related species, thus named the S. schenckii complex, of which S. schenckii sensu stricto and S. brasiliensis are main causative species of sporotrichosis. Owing to a multifaceted molecular dynamic, the S. schenckii complex can switch between the mycelium and the yeast form. This characteristic along with a varying cell wall composition account for significant species-specific differences in the host range, virulence, and susceptibility to antifungal drugs. While culture remains the gold standard to diagnose sporotrichosis, polymerase chain reaction (PCR) or matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry-based methods have become an essential for accurate species identification in many clinical laboratories. If directly applied on tissue samples, molecular methods are helpful to improve both sensitivity of and time to the etiological diagnosis of sporotrichosis. This mini-review aims to put together the old and new knowledge on the S. schenckii complex biology and identification, with particular emphasis on the laboratory diagnosis-related aspects of disease.

Human sporotrichosis: recommendations from the Brazilian Society of Dermatology for the clinical, diagnostic and therapeutic management

BACKGROUND

The increase in the zoonotic epidemic of sporotrichosis caused by Sporothrix brasiliensis, which started in the late 1990s in Rio de Janeiro and is now found in almost all Brazilian states, has been equally advancing in neighboring countries of Brazil. Changes in the clinical-epidemiological profile, advances in the laboratory diagnosis of the disease, and therapeutic difficulties have been observed throughout these almost 25 years of the epidemic, although there is no national consensus. The last international guideline dates from 2007.

OBJECTIVES

Update the clinical classification, diagnostic methods and recommendations on the therapeutic management of patients with sporotrichosis.

METHODS

Twelve experts in human sporotrichosis were selected from different Brazilian regions, and divided into three work groups: clinical, diagnosis and treatment. The bibliographic research was carried out on the EBSCOHost platform. Meetings took place via electronic mail and remote/face-to-face and hybrid settings, resulting in a questionnaire which pointed out 13 divergences, resolved based on the opinion of the majority of the participants.

RESULTS

The clinical classification and laboratory diagnosis were updated. Therapeutic recommendations were made for the different clinical forms.

CONCLUSION

Publication of the first national recommendation, carried out by the Brazilian Society of Dermatology, aimed at the Brazilian scientific community, especially dermatologists, infectologists, pediatricians, family medicine personnel, and laboratory professionals who work in the management of human sporotrichosis.

Synthetic Derivatives against Wild-Type and Non-Wild-Type Sporothrix brasiliensis: In Vitro and In Silico Analyses

Recently, the well-known geographically wide distribution of sporotrichosis in Brazil, combined with the difficulties of effective domestic feline treatment, has emphasized the pressing need for new therapeutic alternatives. This work considers a range of synthetic derivatives as potential antifungals against Sporothrix brasiliensis isolated from cats from the hyperendemic Brazilian region. Six S. brasiliensis isolates from the sporotrichotic lesions of itraconazole responsive or non-responsive domestic cats were studied. The minimum inhibitory concentrations (MICs) of three novel hydrazone derivatives and eleven novel quinone derivatives were determined using the broth microdilution method (M38-A2). In silico tests were also used to predict the pharmacological profile and toxicity parameters of these synthetic derivatives. MICs and MFCs ranged from 1 to >128 µg/mL. The ADMET computational analysis failed to detect toxicity while a good pharmacological predictive profile, with parameters similar to itraconazole, was obtained. Three hydrazone derivatives were particularly promising candidates as antifungal agents against itraconazole-resistant S. brasiliensis from the Brazilian hyperendemic region. Since sporotrichosis is a neglected zoonosis currently spreading in Latin America, particularly in Brazil, the present data can contribute to its future control by alternative antifungal drug design against S. brasiliensis, the most virulent and prevalent species of the hyperendemic context.

Nanostructured Lipid Carriers as a Novel Strategy for Topical Antifungal Therapy

Nanostructured lipid carriers (NLC) were developed as an alternative carrier system optimizing limitations found in topical treatments for superficial fungal infections, such as limited permeation through the skin. However, few published studies are focused on standardization and characterization of determinant variables of these lipid nanosystems' quality. Thus, this systematic review aims to compile information regarding the selection of lipids, surfactants, and preparation method that intimately relates to the final quality of this nanotechnology. For this, the search was carried with the following descriptors: 'nanostructured lipid carriers', 'topical', 'antifungal' separated by the Boolean operators 'and', present in the titles of the databases: Science Direct, Scopus and Pubmed. The review included experimental articles focused on the development of nanostructured lipid carriers targeted for topical application with antifungal activity, published from 2015 to 2021. Review articles, clinical studies, and studies on the development of other nanocarriers intended for other routes of administration were excluded from the study. The research included 26 articles, of which 58% were developed in India and Brazil, 53% published in the years 2019 and 2020. As for the selection of antifungal drugs incorporated into NLCs, the azole class had a preference over other classes, voriconazole being incorporated into 5 of the 26 developed NLC studied. It was also observed a predominance of medium chain triglycerides (MCT) as a liquid lipid and polysorbate 80 as a surfactant. Among other results, this review compiles the influences of each of the variables discussed in the quality parameters of NLCs, in order to guide future research involving the development of this technology. Graphical Abstract.

Clinical and epidemiological aspects of feline sporotrichosis caused by Sporothrix brasiliensis and in vitro antifungal susceptibility

Sporotrichosis is a subcutaneous mycosis resulting from the traumatic implantation of pathogenic Sporothrix species. In Brazil, zoonotic transmission plays an important role in the epidemiology of the disease, involving especially cats. The objective of this study was to isolate Sporothrix spp. from cats with signs of sporotrichosis, determining the causative species, clinical and epidemiological aspects, and the in vitro susceptibility profile of the isolates against antifungal drugs. From September 2017 to February 2019, 245 samples of lesions were collected from symptomatic cats in São José do Rio Preto, Brazil. Identification of the isolates was performed by morphophysiological parameters and species-specific polymerase chain reaction. The susceptibility profile of the isolates was determined for five drugs (amphotericin B, itraconazole, ketoconazole, potassium iodide and terbinafine), using the broth microdilution method. Clinical and epidemiological aspects were analyzed based on data contained on investigation forms filled by the veterinarians at moment of collection. Sporothrix spp. were isolated in 189 (77.2%) of the samples. Phenotypic and molecular analyses revealed S. brasiliensis as the only causative agent. In vitro susceptibility testing showed lower MIC values for terbinafine (MIC = 0.03-2 μg/ml), ketoconazole (MIC = 0.03-2 μg/ml), and itraconazole (MIC = 0.03-4 μg/ml). Most of the animals were male (73.5%), adults (96.3%), stray (53.5%), and uncastrated (69.8%). Our results show the expansion of the S. brasiliensis epidemic to an area nearly 840 km apart from the epicenter of the long-lasting outbreak of cat-transmitted sporotrichosis in Rio de Janeiro.

Antifungal activity of Acylhydrazone derivatives against Sporothrix spp

Sporotrichosis is an emerging mycosis caused by members of the genus Sporothrix The disease affects humans and animals, particularly cats, which plays an important role in the zoonotic transmission. Feline sporotrichosis treatment options include itraconazole (ITC), potassium iodide and amphotericin B, drugs usually associated with deleterious adverse reactions and refractoriness in cats, especially when using ITC. Thus, affordable, non-toxic and clinically effective anti-Sporothrix agents are needed. Recently, acylhydrazones (AH), molecules targeting vesicular transport and cell cycle progression, exhibited a potent antifungal activity against several fungal species and displayed low toxicity when compared to the current drugs. In this work, the AH derivatives D13 and SB-AF-1002 were tested against Sporothrix schenckii and Sporothrix brasiliensis Minimal inhibitory concentrations of 0.12 - 1 μg/mL were observed for both species in vitro D13 and SB-AF-1002 showed an additive effect with itraconazole. Treatment with D13 promoted yeast disruption with release of intracellular components, as confirmed by transmission electron microscopy of S. brasiliensis exposed to the AH derivatives. AH-treated cells displayed thickening of the cell wall, discontinuity of the cell membrane and an intense cytoplasmic degeneration. In a murine model of sporotrichosis, treatment with AH derivatives was more efficient than ITC, the drug of choice for sporotrichosis. The results of the preliminary clinical study in cats indicate that D13 is safe and has potential to become a therapeutic option for sporotrichosis when associated to ITC. Our results expand the antifungal broadness of AH derivatives and suggest that these drugs could be exploited to combat sporotrichosis.

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.

Sporothrix Brasiliensis: A Review of an Emerging South American Fungal Pathogen, Its Related Disease, Presentation and Spread in Argentina

Sporotrichosis, caused by Sporothrix schenckii and related species, is the most frequent implantation mycosis in Latin America. In Argentina, over the last 8 years, there have been 0.16 new cases per month of feline sporotrichosis in 2011, increasing to 0.75 cases per month in 2019 and involving zoonotic transmission to humans. Molecular identification by polymerase chain reaction (PCR) detected Sporothrix brasiliensis in these feline and zoonotic outbreaks. This study will focus on different feline and human sporotrichosis outbreaks caused by S. brasiliensis in Argentina during 2011–2019. We will address the sources of infection and environmental hotspots, as well as the application of several treatment strategies for improving the pharmacotherapy of the different clinical forms of the disease. Finally, we will provide a detailed summary of the clinical aspects and new advances in host–pathogen interactions, virulence factors and immune response, focusing on state-of-the-art diagnostic tools and potential vaccine candidates.

A One Health Approach to Combatting Sporothrix brasiliensis: Narrative Review of an Emerging Zoonotic Fungal Pathogen in South America

Cat-transmitted sporotrichosis caused by Sporothrix brasiliensis has become a major public health concern and presents a distinct divergence from the traditional epidemiology of sporotrichosis. This emerging fungal pathogen spreads readily among cat populations, and human infections occur exclusively via zoonotic transmission. While sporotrichosis is an implantation mycosis that typically manifests as cutaneous lesions in humans and cats, severe extracutaneous manifestations are more common with S. brasiliensis than other Sporothrix species infections. Rapid diagnosis and appropriate treatment regimens are critical for successful clinical resolution of sporotrichosis in both cats and humans. Species-level identification of Sporothrix is possible with molecular diagnostics and necessary for tracking the geographic expansion of S. brasiliensis and better understanding its epidemiology. Combatting cat-transmitted sporotrichosis requires a One Health approach to successfully implement public health control measures.

Identification of two potential inhibitors of Sporothrix brasiliensis and Sporothrix schenckii in the Pathogen Box collection

Sporotrichosis is a neglected endemic mycosis with a high incidence in Latin America, mainly in Brazil. Sporothrix schenckii is the most frequent species in Latin America, whereas Sporothrix brasiliensis is the predominant species observed in Brazil and is associated with both human and animal sporotrichosis. Sporotrichosis treatment remains restricted to a few options, itraconazole being the first choice for human and animal therapy. In this work, we screened the molecular library Pathogen Box (Medicines for Malaria Venture [MMV], Switzerland) in search of compounds with anti-Sporothrix activity. Our initial screen of the 400 compounds identified five compounds that inhibited more than 80% of S. brasiliensis and S. schenkii growth. Among those, three compounds (MMV675968, MMV102872, and MMV002817 (known as iodoquinol)) not previously described as antifungals or agrochemicals, were selected for further evaluation. MMV102872 and iodoquinol showed the most promising combination of antifungal activity (lower inhibitory concentration) and fungal selectivity (lower cytotoxicity in LLC-MK2 cells). Scanning electron microscopy and flow cytometry analyses revealed that MMV102872 and iodoquinol induced changes in cell morphology, membrane integrity, and the presence of neutral lipids, impairing fungal survival. Our results indicate that MMV102872 and iodoquinol are promising molecules for use as scaffolds for the development of new antifungal agents.

Diagnosis of Breakthrough Fungal Infections in the Clinical Mycology Laboratory: An ECMM Consensus Statement

Breakthrough invasive fungal infections (bIFI) cause significant morbidity and mortality. Their diagnosis can be challenging due to reduced sensitivity to conventional culture techniques, serologic tests, and PCR-based assays in patients undergoing antifungal therapy, and their diagnosis can be delayed contributing to poor patient outcomes. In this review, we provide consensus recommendations on behalf of the European Confederation for Medical Mycology (ECMM) for the diagnosis of bIFI caused by invasive yeasts, molds, and endemic mycoses, to guide diagnostic efforts in patients receiving antifungals and support the design of future clinical trials in the field of clinical mycology. The cornerstone of lab-based diagnosis of breakthrough infections for yeast and endemic mycoses remain conventional culture, to accurately identify the causative pathogen and allow for antifungal susceptibility testing. The impact of non-culture-based methods are not well-studied for the definite diagnosis of breakthrough invasive yeast infections. Non-culture-based methods have an important role for the diagnosis of breakthrough invasive mold infections, in particular invasive aspergillosis, and a combination of testing involving conventional culture, antigen-based assays, and PCR-based assays should be considered. Multiple diagnostic modalities, including histopathology, culture, antibody, and/or antigen tests and occasionally PCR-based assays may be required to diagnose breakthrough endemic mycoses. A need exists for diagnostic tests that are effective, simple, cheap, and rapid to enable the diagnosis of bIFI in patients taking antifungals.

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.

In vitro inhibitory effect of statins on planktonic cells and biofilms of the Sporothrix schenckii species complex

Introduction. Sporotrichosis, caused by species of the Sporothrix schenckii complex, is the most prevalent subcutaneous mycosis in many areas of Latin America. Statins are a class of drugs widely used for lowering high sterol levels through their action on 3-hydroxy-3-methylglutaryl-CoA reductase, a key enzyme in the synthesis of sterol.Aim. In this study, the antifungal activity of statins (simvastatin, atorvastatin, pravastatin) against planktonic cells and biofilms of S. schenckii complex species was evaluated, as well as the interaction of pravastatin with classical antifungals (amphotericin B, itraconazole, terbinafine).Methodology. Eighteen strains of Sporothrix species were used. The antifungal susceptibility assay was performed using the broth microdilution method. Mature biofilms were exposed to statins and metabolic activity was measured by the XTT reduction assay.Results. MICs of statins ranged from 8 to 512 μg ml^-1 and from 8 to 256 μg ml^-1 for filamentous and yeast forms, respectively. Regarding mature biofilms, MICs of 50 % inhibition (SMIC50) were 128 μg ml^-1 for simvastatin and atorvastatin and >2048 μg ml^-1 for pravastatin. MICs of 90 % inhibition (SMIC90) were 512 μg ml^-1 for simvastatin and >2048 μg ml^-1 for atorvastatin and pravastatin.Conclusion. These results highlight the antifungal and antibiofilm potential of statins against S. schenckii complex species.

Feline sporotrichosis: a case series of itraconazole-resistant Sporothrix brasiliensis infection

The treatment of feline sporotrichosis is a challenge for veterinary clinicians since refractory cases may occur, due either to patient and/or to pharmacological management errors or due to the development of antifungal resistance. Thus, we aimed to describe the therapeutic history of feline cases infected by itraconazole-resistant Sporothrix brasiliensis in an endemic region of Southern Brazil. Medical records of cats attended at the Veterinary Clinic Hospital (Pelotas/RS, Brazil) between 2016 and 2017 were reviewed. Twelve cases of infection by S. brasiliensis with that showed high minimum inhibitory concentration (MIC) values (≥ 4 μg/mL) to itraconazole by M38-A2 of CLSI were selected. At the hospital consultation, disseminated (cats 1-l0, 12) and localized (cat 11) skin lesions remained in the cats, even after treatment with fluconazole, ketoconazole (02/12), and itraconazole (ITZ, 09/12) performed before this study. High doses (25-100 mg/kg/day) of ITZ for up to 4 months (03/12, cats 2, 6, 12) or over 12 months (05/12, cats 1, 5, 7, 8, 11) did not provide a clinical cure, except for the association of ITZ plus potassium iodide (01/12, cat 12) for 3 months, which proved useful in infections with itraconazole-resistant S. brasiliensis. However, the combined issues of abandonment of therapy by owners for financial reasons, difficulties surrounding therapy administration (03/12, cats 6, 11, 12), and the inappropriate choice of medication (01/12, cat 6), together reflect the reality of this endemic region, which greatly compromises clinical healing. This study highlighted the occurrence of refractory cases by itraconazole-resistant S. brasiliensis in cats from Southern Brazil, as well as the abandonment of treatment and therapeutic errors. We warn of the need for antifungal susceptibility tests to adapt therapeutic protocols in feline sporotrichosis.

Susceptibility and resistance of Sporothrix brasiliensis to branded and compounded itraconazole formulations

Itraconazole is the first drug of choice for the treatment of sporotrichosis and it is available at different concentrations for veterinary patients. However, therapeutic failure has been reported, limiting clinical treatment. This study evaluated the in vitro efficacy of brand-name and compounded itraconazole formulations against Sporothrix brasiliensis and estimated the itraconazole content in each tested formulation. Oral capsules were acquired from two brand-name products for human (H-IND) and veterinary (V-IND) uses, and three from compounding pharmacies in Pelotas, RS, for human (H-COMP1/H-COMP2) and veterinary (V-COMP) uses. Capsule purity was analyzed by liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS). Antifungal activity was determined against 29 Sporothrix brasiliensis by the M38-A2 guideline of CLSI. H-IND/H-COMP1/H-COMP2 had high efficacy against S. brasiliensis (approximately 70% of total isolated susceptible), V-COMP showed moderate efficacy (51.7%), and V-IND was the least effective formulation (37.9%). Thirty-four percent of the total isolates were resistant to all formulations. Furthermore, itraconazole content did not match the concentration indicated by the manufacturers, ranging from 387.70 to 7.81 μg/mg (H-COMP2 > V-COMP > H-IND > H-COMP1 > V-IND). Therefore, it is possible that the formulations showed different in vitro efficacy due to the difference in their itraconazole contents. Given the emergence of antifungal resistance for all formulations, the choice product to be used must follow susceptibility testing. Stringent quality control measures are recommended for product manufactures to assure drug content uniformity.

Coinfection of domestic felines by distinct Sporothrix brasiliensis in the Brazilian sporotrichosis hyperendemic area

Microbial interactions may impact patient's diagnosis, prognosis and treatment. Sporotrichosis is a hyperendemic neglected zoonosis in Brazil, caused by Sporothrix brasiliensis. Four pairs of clinical isolates of Sporothrix were recovered from four diseased cats (CIM01-CIM04, two isolates per animal) raising the possibility of coinfection in a sporotrichosis hyperendemic area, Brazil. Each isolate of the pair had distinct pigmentation in mycological culture, and was designated as "Light" or "Dark", for low and high pigmentation, respectively. Dark isolates reacted strongly with monoclonal antibodies to melanin (p ≤ 0.05) by both ELISA and FACS quantitation, and displayed a ring pattern with some regions exhibiting higher punctuated labeling at cell wall by immunofluorescence. In turn, Light isolates reacted less intensely, with few and discrete punctuated labeling at the cell wall. PCR identified all isolates as S. brasiliensis, MAT1-2 idiomorph. Sequencing of β-tubulin and calmodulin genes followed by phylogenetic analysis placed all eight isolates within the same cluster as others from the Brazilian hyperendemic area. The ability of these strains to stimulate cytokine production by human PBMCs (Peripheral blood mononuclear cells) was also analyzed. CIM01 and CIM03 Light and Dark isolates showed similar cytokine profiles to the control strain, while CIM02 and CIM04 behaved differently (p < 0.001), suggesting that differences in the surface of the isolates can influence host-fungus interaction. MICs for amphotericin B, terbinafine, caspofungin, micafungin, itraconazole, fluconazole, and voriconazole were obtained (CLSI M38-A2/M27-A3). Pairwise comparisons showed distinct MICs between Sporothrix Light and Dark isolates, higher than at least two-fold dilutions, to at least one of the antifungals tested. Isolates from the same pair displayed discrepancies in relation to fungistatic or fungicidal drug activity, notably after itraconazole exposure. Since S. brasiliensis Light and Dark isolates show disparate phenotypic parameters it is quite possible that coinfection represents a common occurrence in the hyperendemic area, with potential clinical implications on feline sporotrichosis dynamics. Alternatively, future studies will address if this specie may have, as reported for other fungi, broad phenotypic plasticity.

Development, skin targeting and antifungal efficacy of topical lipid nanoparticles containing itraconazole

Considering the increased incidence of sporotrichosis and other fungal infections in rural and urban areas, and the limitations and adverse effects of oral itraconazole therapy, we studied nanostructured lipid carriers (NLC) as topical delivery systems to increase itraconazole localization in skin lesions and associate efficacy with reduced systemic exposure. Unloaded and itraconazole-loaded NLC showed nanometric size (~216-340 nm), negative zeta potential (~ -17 mV), and high entrapment efficiency (~97%). NLC treatment decreased transepidermal water loss, an index of cutaneous barrier function, in intact skin and in tissues damaged with a linear incision (to mimic lesions) by 23-36%, and reduced drug transdermal delivery by ~2-fold, demonstrating its ability to localize itraconazole within the skin. The unloaded and itraconazole-loaded NLC were considered safe, as indicated by scores of 0.5 and 0.6 in HET-CAM models, respectively, and lack of toxicity (measured by survival and health index) on the Galleria mellonella larvae. The values obtained for minimum inhibitory concentration and minimum fungicidal concentration on Sporothrix brasiliensis yeasts were 0.25 and 32 μg/mL, respectively. The drug in solution displayed similar values, indicating that encapsulation does not hinder itraconazole antifungal effect. NLC treatment improved the survival rate and health index of G. mellonella larvae infected with S. brasiliensis yeasts and C. albicans, demonstrating antifungal efficacy. Taken together, itraconazole encapsulation in NLC represents a viable strategy to optimize cutaneous localization without compromising its efficacy against fungal infections.

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.

Investigation of a Microemulsion Containing Clotrimazole and Itraconazole for Transdermal Delivery for the Treatment of Sporotrichosis

The aim of this study was to develop a microemulsion (ME) formulation containing an association of itraconazole (ITC) and clotrimazole (CLT) as a transdermal delivery system for the treatment of sporotrichosis. Pseudoternary phase diagrams were constructed to optimize the ME formulation. The ME formulation selected contained 1% (w/w) ITC and 1% (w/w) CLT and was composed of 23.07% Tween® 60 (surfactant), 23.07% propylene glycol (cosurfactant/cosolvent), 30.77% benzyl alcohol (oil), and 21.09% water. The ITC/CLT-loaded ME (ITC/CLT-ME) had a droplet size value of 217 ± 0.9 nm, with a polydispersity index of 0.5 ± 0.1. Permeation experiments on pig ear skin were conducted for ITC/CLT-ME, and the results indicated that the drug permeation performance was influenced by CLT, indicating that CLT acts as a promoter enhancer. In the in vitro antifungal activity assay using Sporothrix brasiliensis yeast, the inhibition halo produced by ITC/CLT-ME exhibited a mean diameter of 43.67 ± 2.31 mm. The ITC/CLT-ME formulation did not cause skin irritation in mice. The results suggest that ITC/CLT-ME is a promising tool for the transdermal treatment of sporotrichosis.

Efficacy of a poly-aggregated formulation of amphotericin B in treating systemic sporotrichosis caused by Sporothrix brasiliensis

In severe cases of sporotrichosis, it is recommended to use amphotericin B deoxycholate (D-AMB) or its lipid formulations and/or in association with itraconazole (ITC). Our aim was to evaluate the antifungal efficacy of a poly-aggregated amphotericin B (P-AMB), a nonlipid formulation, compared with D-AMB on systemic sporotrichosis caused by Sporothrix brasiliensis. In vitro assays showed that Sporothrix schenckii sensu stricto and S. brasiliensis yeast clinical isolates were susceptible to low concentrations of P-AMB and D-AMB. Although P-AMB presented a higher minimal inhibitory concentration (MIC) compared to D-AMB, its cytotoxic effect on renal cells and erythrocytes was lower. For the in vivo assays, male BALB/c mice were intravenously infected with S. brasiliensis yeasts, and P-AMB or D-AMB was administered 3 days post-infection. The efficacy of five therapeutic regimens was tested: intravenous monotherapy with P-AMB or D-AMB, intravenous pulsed-therapy with P-AMB or D-AMB, and intravenous therapy with P-AMB, followed by oral ITC. These treatments increased murine survival and controlled the fungal burden in the liver, spleen, lungs, and kidneys. However, only D-AMB monotherapy or the pulsed-therapies with D-AMB or P-AMB led to 100% survival of the mice 45 days post-infection; only pulsed administration of D-AMB was able to control the fungal load in all organs 45 days post-infection. Accordingly, the histopathological findings showed reductions in the fungal burden and inflammatory reactions in these treatment regimens. Together, our results suggest that the P-AMB formulation could be considered as an alternative drug to D-AMB for treating disseminated sporotrichosis.

Immunity and Treatment of Sporotrichosis

Species of the Sporothrix complex are the etiological agents of sporotrichosis, an important subcutaneous mycosis with several clinical forms and an increasing incidence around the world that affects humans and other mammals. The immunological mechanisms involved in the prevention and control of this mycosis are not entirely understood. Many reports have suggested that cell-mediated immunity has an essential role in the development of the disease, being the primary response controlling it, while only recent data supports that the humoral response is essential for the appropriate control. This mycosis is a challenge for diagnosis since the culture and isolation of the organism are time-consuming and complicated; reasons that have led to the study of fungus antigenic molecules capable of generating a detectable humoral response. The treatment for this disease includes the use of several antifungal drugs like itraconazole, amphotericin B, caspofungin, fluconazole, and the combination between them among others such as the extract of Vismia guianensis.

In vitro susceptibility of Sporothrix brasiliensis: Comparison of yeast and mycelial phases

Sporothrix brasiliensis has emerged as an important cause of sporotrichosis, particularly associated with feline and zoonotic cases. Owing to the paucity of data on antifungal activity against this species, the present study aimed to evaluate the in vitro susceptibility of clinical isolates of S. brasiliensis in the mycelial and yeast phases to itraconazole (ITZ), terbinafine (TRB), and amphotericin B (AMB). Thirty-five isolates from an outbreak of feline sporotrichosis in Southern Brazil were used. All of them were assessed in the yeast and filamentous phases using the broth microdilution technique in accordance with the respective reference protocols M27-A3 and M38-A2 of the Clinical and Laboratory Standards Institute (CLSI). In our study, TRB was the most active antifungal against both the filamentous and yeast phases, showing GM of the MIC of 0.343 μg/ml and 0.127 μg/ml, respectively. In the yeast phase, the GM of the MIC for TRB was significantly lower than that for both ITZ (P = .009) and AMB (P < .001). However, in the filamentous phase, the GM of the MIC for TRB was significantly lower than that of AMB (P < .001), but not different from that of ITZ (P = .091). AMB was the antifungal with the highest GM of the MIC for both phases (1.486 μg/ml for the filamentous phase and 0.660 μg/ml for the yeast). Our results may contribute to a better understanding of antifungal susceptibility profiles of clinical isolates of S. brasiliensis in the mycelial and yeast phases in further studies.

Refractory sporotrichosis due to Sporothrix brasiliensis in humans appears to be unrelated to in vivo resistance

Sporotrichosis is a subacute to chronic infection caused by members of the Sporothrix schenckii complex. Itraconazole is the first choice antifungal drug for treating this infection, with terbinafine and potassium iodide as alternatives and amphotericin B used in cases of severe infections. Correlation of antifungal susceptibility data with the clinical outcome of the patients is scarce. The aim of this study was to correlate clinical and mycological data in patients with refractory sporotrichosis. In this work, antifungal susceptibilities, determined according to the reference M38-A2 CLSI protocol, of 25 Sporothrix strains, isolated from seven human cases of sporotrichosis with adversities in the treatment, are presented. Tested drugs included itraconazole, ketoconazole, posaconazole, voriconazole, terbinafine, and amphotericin B. Fungi were identified using the T3B PCR fingerprinting. This method identified all strains as Sporothrix brasiliensis and also demonstrated a high degree of similarity between the strains. In general, voriconazole was ineffective against all strains, and elevated minimal inhibitory concentrations (MICs) were observed for amphotericin B. High itraconazole and terbinafine MICs were not observed in S. brasiliensis isolates from patients of this study. Moreover, a significant increase in itraconazole and terbinafine MIC values from strains isolated from the same patient in different periods was not observed. The results suggest that the antifungal susceptibility to terbinafine and itraconazole determined by the reference method does not play an important role in therapeutic failure of sporotrichosis and that acquisition of resistance during prolonged antifungal treatment is not likely to occur in S. brasiliensis.

Cell walls of the dimorphic fungal pathogens Sporothrix schenckii and Sporothrix brasiliensis exhibit bilaminate structures and sloughing of extensive and intact layers

Sporotrichosis is a subcutaneous mycosis caused by pathogenic species of the Sporothrix genus. A new emerging species, Sporothrix brasiliensis, is related to cat-transmitted sporotrichosis and has severe clinical manifestations. The cell wall of pathogenic fungi is a unique structure and impacts directly on the host immune response. We reveal and compare the cell wall structures of Sporothrix schenckii and S. brasiliensis using high-pressure freezing electron microscopy to study the cell wall organization of both species. To analyze the components of the cell wall, we also used infrared and 13C and 1H NMR spectroscopy and the sugar composition was determined by quantitative high-performance anion-exchange chromatography. Our ultrastructural data revealed a bi-layered cell wall structure for both species, including an external microfibrillar layer and an inner electron-dense layer. The inner and outer layers of the S. brasiliensis cell wall were thicker than those of S. schenckii, correlating with an increase in the chitin and rhamnose contents. Moreover, the outer microfibrillar layer of the S. brasiliensis cell wall had longer microfibrils interconnecting yeast cells. Distinct from those of other dimorphic fungi, the cell wall of Sporothrix spp. lacked α-glucan component. Interestingly, glycogen α-particles were identified in the cytoplasm close to the cell wall and the plasma membrane. The cell wall structure as well as the presence of glycogen α-particles varied over time during cell culture. The structural differences observed in the cell wall of these Sporothrix species seemed to impact its uptake by monocyte-derived human macrophages. The data presented here show a unique cell wall structure of S. brasiliensis and S. schenckii during the yeast parasitic phase. A new cell wall model for Sporothrix spp. is therefore proposed that suggests that these fungi molt sheets of intact cell wall layers. This observation may have significant effects on localized and disseminated immunopathology.

Design of Two Alternative Routes for the Synthesis of Naftifine and Analogues as Potential Antifungal Agents

Two practical and efficient approaches have been implemented as alternative procedures for the synthesis of naftifine and novel diversely substituted analogues 16 and 20 in good to excellent yields, mediated by Mannich-type reactions as the key step of the processes. In these approaches, the γ-aminoalcohols 15 and 19 were obtained as the key intermediates and their subsequent dehydration catalyzed either by Brønsted acids like H₂SO₄ and HCl or Lewis acid like AlCl₃, respectively, led to naftifine, along with the target allylamines 16 and 20. The antifungal assay results showed that intermediates 18 (bearing both a β-aminoketo- and N-methyl functionalities in their structures) and products 20 were the most active. Particularly, structures 18b, 18c, and the allylamine 20c showed the lowest MIC values, in the 0.5-7.8 µg/mL range, against the dermatophytes Trichophyton rubrum and Trichophyton mentagrophytes. Interesting enough, compound 18b bearing a 4-Br as the substituent of the phenyl ring, also displayed high activity against Candida albicans and Cryptococcus neoformans with MIC₈₀ = 7.8 µg/mL, being fungicide rather than fungistatic with a relevant MFC value = 15.6 µg/mL against C. neoformans.

Fungal Musculoskeletal Infections

Fungi are rare but important causes of osteoarticular infections, and can be caused by a wide array of yeasts and molds. Symptoms are often subacute and mimic those of other more common causes of osteoarticular infection, which can lead to substantial delays in treatment. A high index of suspicion is required to establish the diagnosis. The severity of infection depends on the inherent pathogenicity of the fungi, the immune status of the host, the anatomic location of the infection, and whether the infection involves a foreign body. Treatment often involves a combination of surgical debridement and prolonged antifungal therapy.