Advances and challenges in the management of feline sporotrichosis

Case report: Severe ulcerative dermatitis leading to sepsis in a cat with sporotrichosis by Sporothrix brasiliensis

Sporotrichosis caused by Sporothrix brasiliensis is an emerging zoonotic mycosis of great clinical relevance in South America. This case highlights its severe systemic presentation, reported for the first time in a feline patient from Chile. A 1-year-old neutered male cat presented with severe ulcerative dermatitis, developing a dysoxic phenotype of sepsis. Diagnosis was made by cytology, histopathology, fungal culture, and polymerase chain reaction, confirming S. brasiliensis as the pathogen. Treatment included itraconazole associated with potassium iodide. Despite aggressive antifungal therapy and intensive care, based on fluid resuscitation, optimization of analgesia, and administration of vasoactive drugs, the cat developed refractory hypotension and persistent hyperlactatemia, which ultimately led to euthanasia. This report highlights the high pathogenic potential of S. brasiliensis to cause severe systemic disease, even in hosts negative to retroviral infections, and emphasizes the importance of promoting responsible animal management practices to prevent the spread of this infectious agent.

Sporothrix davidellisii : A new pathogenic species belonging to the Sporothrix pallida complex

Sporothrix species (Ascomycota, Ophiostomatales) are dimorphic fungi with diverse ecological niches, ranging from mammalian, plant, and insect pathogens to fungicolous organisms. Here, we describe Sporothrix davidellisii (CBS 147636T), a novel pathogenic species within the S. pallida complex isolated from a case of feline sporotrichosis in Melbourne, Australia. Phylogenetic analyses based on ITS, β-tubulin (BT2), calmodulin (CAL), and translation elongation factor 1-α (EF1-α) sequences confirmed its distinctiveness, with ITS sequence identity to its closest relative (S. chilensis) not exceeding 97.6%. The assembled genome is 39.02 Mb (eight contigs) with a 27.2 kb mitochondrial genome and a total of 12,631 predicted genes. Genetic diversity analyses revealed moderate nucleotide variation in the ITS region (π = 0.055), greater diversity in BT2 (π = 0.098), and CAL (π = 0.118), supporting its status as a unique species. Morphological studies revealed distinctive characteristics differentiating S. davidellisii from its nearest relatives, including elongated clavate sympodial conidia and sessile conidia. Notably, S. davidellisii exhibits yeast-like growth at 37°C, forming ellipsoid to ovoid budding cells in liquid media, although cigar-shaped yeasts, characteristic of highly virulent Sporothrix species, are rarely observed. This ability to transition to a yeast-like form, combined with its high-temperature tolerance (growth up to 40°C), underscores its opportunistic pathogenic potential. The pathogenic role of S. davidellisii highlights the importance of monitoring atypical Sporothrix infections in feline hosts, which may serve as environmental sentinels for emerging fungal pathogens. These findings expand the taxonomy of Sporothrix, contributing to our understanding of the evolutionary complexity and zoonotic potential of species within the S. pallida complex.

The Emergence of Cat-Transmitted Sporotrichosis Driven by Sporothrix brasiliensis in Piauí, Brazil

INTRODUCTION

In Brazil, the emergence of feline sporotrichosis, a neglected subcutaneous mycosis primarily transmitted by cats and caused by the fungus Sporothrix brasiliensis, has been monitored via molecular tools. This approach underscores the geographic expansion of this disease and highlights the critical role of molecular surveillance in understanding its epidemiology and guiding public health interventions.

METHODS

We investigated three domestic cats (Felis catus) with multiple skin lesions in Picos, Piauí, Brazil. The cats were examined, and samples were collected for laboratory diagnosis, including cytological evaluation, fungal culture, and molecular characterisation. The molecular analysis involved a one-tube multiplex probe-based qPCR assay for the diagnosis of Sporothrix species, mating-type determination, and amplified fragment length polymorphism (AFLP, EcoRI-GA/MseI-AG) to assess genetic similarity and potential origin.

RESULTS

All three cats were diagnosed with sporotrichosis caused by the hypervirulent S. brasiliensis. A probable case of zoonotic transmission has been reported in a 12-year-old girl who developed Parinaud oculoglandular syndrome after contact with one of the cats with sporotrichosis. The molecular analysis revealed that the cat isolates were MAT 1-2 and formed a single cluster according to the AFLP analysis, suggesting direct transmission (cat-cat) and a potential founder effect. The isolates were also closely related to strains from Pernambuco and Southeast Brazil, indicating a possible introduction from these regions.

CONCLUSIONS

Identifying S. brasiliensis in Piauí emphasises the need for increased awareness and control measures to prevent further spread. The predominance of the MAT1-2 idiomorphs and the genetic similarity among outbreak isolates suggest clonal expansion, which could have significant implications for public health and veterinary practices. Considering its zoonotic potential and environmental adaptability, a One Health approach is crucial for managing and controlling the spread of cat-transmitted sporotrichosis.

Therapeutic alternatives for sporotrichosis induced by wild-type and non-wild-type Sporothrix schenckii through in vitro and in vivo assessment of enilconazole, isavuconazole, posaconazole, and terbinafine

This study explores the effectiveness of various antifungal drugs in treating sporotrichosis caused by Sporothrix schenckii, especially in non-wild-type (non-WT) strains. The drugs tested include enilconazole (ENIL), isavuconazole (ISA), posaconazole (POS), terbinafine (TER), and itraconazole (ITC). The study involved in vitro and in vivo tests on 10 WT isolates and eight ITC non-WT isolates. Two isolates were assessed using time-kill assays, checkerboard assays, and Galleria mellonella infection models. In vitro studies have shown that all of these drugs were more effective than or equal to ITC against WT and non-WT isolates. No ITC resistance was observed with other azoles. All drugs inhibited fungal growth of WT and non-WT strains within 24 h at all incubations. ENIL and TER showed fungicidal effect against types at over 2x minimum inhibitory concentrations with no regrowth. POS was fungicidal against WT at high concentrations but not against non-WT. ISA was only fungicidal for non-WT. ITC did not exhibit any fungicidal activity. In checkerboard experiments, the combination of POS or ISA with TER showed enhanced activity against WT and non-WT strains, surpassing the combination of ITC with TER. In vivo model experiments demonstrated significantly reduced mortality rates with ENIL, POS, and TER against WT and with ENIL, ISA, POS, and TER against non-WT. The study concludes that monotherapy with ENIL, ISA, POS, and TER, and combinations of POS/TER or ISA/TER, show promise as effective antifungal treatments against S. schenckii, including ITC-non-WT isolates.

Zoonotic feline sporotrichosis: a small case cluster in Perth, Western Australia, and a review of previous feline cases from Australia

Sporotrichosis is caused by species of the fungus Sporothrix that affect human and several animal species. The transmission of sporotrichosis is classically from an environmental source following penetrating injury. The alternative zoonotic route has gained attention due to the rapid and significant spread of cat-transmitted sporotrichosis in South America and Malaysia, resulting in several thousand human and feline cases in recent decades, especially in Brazil. In Australia, sporotrichosis is sporadic and mainly related to environmental sources. Although feline sporotrichosis is rare in Australia, zoonotic transmission occurred in two of five reported cases, including a recent case cluster, which is reported in this article. The investigation of such cases in Australia is important, as cats not only represent a source of infection living in close proximity with humans, but also, they may represent sentinels for the environmental presence of the fungus. To encourage the investigation and reporting of new veterinary cases, we have reviewed Australian sporotrichosis cases in humans and cats and report a new case cluster of feline sporotrichosis in Perth, WA, Australia, with zoonotic transmission. The index case was a kitten who developed severe facial sporotrichosis with prominent involvement of the nasal planum. Two human cases - one suspected and one confirmed - are also described in the owner, who was a veterinary nurse, and the attending veterinarian, respectively, probably from handling the kitten while not wearing gloves. Later, another mature cat in the same household also became infected. The affected cats were successfully treated using combination of itraconazole and terbinafine. To the best of our knowledge, this is only the second case of cat-transmitted sporotrichosis reported from Australia.

The rising incidence of feline and cat-transmitted sporotrichosis in Latin America

INTRODUCTION

Sporotrichosis is a subcutaneous mycosis caused by different species of thermodimorphic fungi belonging to the genus Sporothrix. These fungi may affect a wide range of warm-blooded animals, including humans, dogs and, mainly, cats.

METHODS

In this article, we conducted a narrative literature review about the status of feline and cat-transmitted sporotrichosis in Latin American countries, with emphasis on Brazil.

RESULTS

From a global perspective, Latin America is one of the main foci of human and feline sporotrichosis. In humans, the disease has been reported in several countries, with endemic transmission occurring in Brazil, Colombia, Costa Rica, Guatemala, Mexico and Uruguay. Sporothrix brasiliensis is the most common species identified in human cases in Brazil, whereas Sporothrix schenckii predominates in other countries.

CONCLUSION

Domestic cats are the main source of infection in the zoonotic transmission cycle of sporotrichosis in Latin America. Cases of feline sporotrichosis have been reported in several countries, including Argentina, Brazil, Chile, Colombia, Mexico, Panama, Paraguay and Peru.

Plasma itraconazole concentrations during treatment of feline sporotrichosis

Itraconazole (ITZ) is the most used drug to treat feline sporotrichosis; however, little is known about its pharmacokinetics in cats with this mycosis. The aim of this study was to determine plasma ITZ concentrations in cats with sporotrichosis treated with ITZ as monotherapy or in combination with potassium iodide (KI). Cats diagnosed with sporotrichosis received orally ITZ (100 mg/cat/day) or combination therapy with ITZ (100 mg/cat/day) and KI (2.5-5 mg/kg/day) in the case of worsening or stagnation of the clinical condition. At each monthly visit, blood samples were collected at an interval of 4 h for analysis of trough and peak plasma ITZ concentrations by HPLC. Clinical features and laboratory parameters were evaluated during follow-up. Sixteen cats were included in the study. The median plasma ITZ concentration of all cats was 0.75 µg/mL. The median plasma ITZ concentration was 0.5 µg/mL in cats that received ITZ monotherapy (n = 12) and 1.0 µg/mL in those treated with ITZ + KI (n = 4). The clinical cure rate was 56.3% (n = 9) and the median treatment duration was 8 weeks. Nine cats (56.3%) developed adverse clinical reactions, and hyporexia was the most frequent (n = 8; 88.9%). Serum alanine aminotransferase was elevated in four cats (25%). The median plasma ITZ concentration detected in cats was considered to be therapeutic (>0.5 µg/mL) and was reached after 4 weeks of treatment. Plasma ITZ concentrations were higher in cats that received ITZ + KI compared to those treated only with ITZ, suggesting pharmacokinetic synergism between these drugs.

Effect of proton pump inhibitors on susceptibility and melanogenesis of Sporothrix species

Introduction. Sporotrichosis is a subcutaneous infection caused by dimorphic Sporothrix species embedded in the clinical clade. Fungi have virulence factors, such as biofilm and melanin production, which contribute to their survival and are related to the increase in the number of cases of therapeutic failure, making it necessary to search for new options.Gap statement. Proton pump inhibitors (PPIs) have already been shown to inhibit the growth and melanogenesis of other fungi.Aim. Therefore, this study aimed to evaluate the effect of the PPIs omeprazole (OMP), rabeprazole (RBP), esomeprazole, pantoprazole and lansoprazole on the susceptibility and melanogenesis of Sporothrix species, and their interactions with itraconazole, terbinafine and amphotericin B.Methodology. The antifungal activity of PPIs was evaluated using the microdilution method, and the combination of PPIs with itraconazole, terbinafine and amphotericin B was assessed using the checkerboard method. The assessment of melanogenesis inhibition was assessed using grey scale.Results. The OMP and RBP showed significant MIC results ranging from 32 to 256 µg ml-1 and 32 to 128 µg ml-1, respectively. Biofilms were sensitive, with a significant reduction (P<0.05) in metabolic activity of 52% for OMP and 50% for RBP at a concentration of 512 µg ml-1 and of biomass by 53% for OMP and 51% for RBP at concentrations of 512 µg ml-1. As for the inhibition of melanogenesis, only OMP showed inhibition, with a 54% reduction.Conclusion. It concludes that the PPIs OMP and RBP have antifungal activity in vitro against planktonic cells and biofilms of Sporothrix species and that, in addition, OMP can inhibit the melanization process in Sporothrix species.

Neutrophil Oxidative Burst Profile Is Related to a Satisfactory Response to Itraconazole and Clinical Cure in Feline Sporotrichosis

Despite the central role of cats in the transmission and amplification of Sporothrix, studies regarding immune response in feline sporotrichosis are scarce. In cats with sporotrichosis, neutrophil-rich lesions are usually associated to good general condition and lower fungal burden. However, the role of neutrophils in anti-Sporothrix immunity has been little explored in cats. Thus, the aim of this study was to evaluate the neutrophil oxidative burst in the blood of cats with sporotrichosis. Cats with sporotrichosis included in the study were treated with itraconazole (ITZ) alone or combined with potassium iodide (KI). The neutrophil oxidative burst was evaluated through a flow-cytometry-based assay using dihydrorhodamine 123 (background) and stimulation with Zymosan and heat-killed Sporothrix yeasts. The cure rate was 50.0% in cats under treatment with ITZ monotherapy and 90.9% in cats treated with ITZ + KI (p = 0.014), endorsing the combination therapy as an excellent alternative for the treatment of feline sporotrichosis. Higher percentages of Sporothrix-stimulated neutrophils were associated with good general condition (p = 0.003). Higher percentages of Sporothrix- (p = 0.05) and Zymosan-activated (p = 0.014) neutrophils before and early in the treatment were related to clinical cure in ITZ-treated cats. The correlation between oxidative burst and successful use of KI could not be properly assessed given the low number of failures (n = 2) in this treatment group. Nasal mucosa involvement, typically linked to treatment failure, was related to lower percentages of activated neutrophils in the background at the treatment outcome (p = 0.02). Our results suggest a beneficial role of neutrophils in feline sporotrichosis and a positive correlation between neutrophil activation and the cure process in ITZ-treated cats.

Combination therapy of itraconazole and an acylhydrazone derivative (D13) for the treatment of sporotrichosis in cats

Acylhydrazone (AH) derivatives represent a novel category of anti-fungal medications that exhibit potent activity against Sporothrix sp., both in vitro and in a murine model of sporotrichosis. In this study, we demonstrated the anti-fungal efficacy of the AH derivative D13 [4-bromo-N'-(3,5-dibromo-2-hydroxybenzylidene)-benzohydrazide] against both planktonic cells and biofilms formed by Sporothrix brasiliensis. In a clinical study, the effect of D13 was then tested in combination with itraconazole (ITC), with or without potassium iodide, in 10 cats with sporotrichosis refractory to the treatment of standard of care with ITC. Improvement or total clinical cure was achieved in five cases after 12 weeks of treatment. Minimal abnormal laboratory findings, e.g., elevation of alanine aminotransferase, were observed in four cats during the combination treatment and returned to normal level within a week after the treatment was ended. Although highly encouraging, a larger and randomized controlled study is required to evaluate the effectiveness and the safety of this new and exciting drug combination using ITC and D13 for the treatment of feline sporotrichosis.

IMPORTANCE

This paper reports the first veterinary clinical study of an acylhydrazone anti-fungal (D13) combined with itraconazole against a dimorphic fungal infection, sporotrichosis, which is highly endemic in South America in animals and humans. Overall, the results show that the combination treatment was efficacious in ~50% of the infected animals. In addition, D13 was well tolerated during the course of the study. Thus, these results warrant the continuation of the research and development of this new class of anti-fungals.

Sporotrichosis in Argentina: clinical and epidemiological analysis

Introduction

Sporotrichosis is an implantation mycosis caused by Sporothrix spp. It is distributed worldwide and can be found in vegetation and soil. The most frequent route of infection is by trauma with elements contaminated with fungal propagules. Since domestic cats are the most affected animals and can transmit this infection to humans, sporotrichosis is considered a zoonosis. Clinical presentations include nodular lymphangitis, fixed cutaneous, pulmonary (rare), and disseminated (exceptional).

Objectives

To analyze the epidemiology of sporotrichosis in Argentina during 2010 and 2022. To describe the clinical presentation, diagnostic methods, and treatment of cases diagnosed during this period. To know the circulating genotypes and to observe possible associations with the geographic location where the infection was acquired.

Materials and methods

Analytical, retrospective, and observational study. We analyzed the medical records of patients with sporotrichosis from 12 health institutions in Argentina, between 2010 and 2022.

Results

We present 54 cases in which the most frequent clinical form was nodular lymphangitis, and the treatment of choice was itraconazole. Conventional diagnosis was made in all cases. Culture of clinical samples was more sensitive than direct examination because it allowed the isolation of Sporothrix spp. in all 54 cases. Molecular identification was performed in 22 cases, with Sporothrix schenkii sensu stricto being the most frequently isolated species.

Conclusions

This study allowed to know the epidemiology of this mycosis in Argentina, as well as the availability of diagnostic methods and the treatment of choice.

Sporotrichosis Outbreak Due to Sporothrix brasiliensis in Domestic Cats in Magallanes, Chile: A One-Health-Approach Study

Sporotrichosis is an implantation mycosis with subcutaneo-lymphatic or, more rarely, a viscerally disseminated affection; it can be acquired through traumatic percutaneous inoculation of the fungus present in soil or plant matter, or by feline scratching. Among the causative agents, Sporothrix brasiliensis is considered the most virulent species with a high prevalence in Brazil and recently in Argentina.

OBJECTIVE

To describe a S. brasiliensis outbreak in domestic and feral cats detected in the Magallanes region of southern Chile.

MATERIALS AND METHODS

Between the months of July and September 2022, three cats presented with suppurative subcutaneous lesions located mainly on the head and thoracic limbs. The cytology revealed the presence of yeasts with morphological characteristics suggestive of Sporothrix spp. The histopathology confirmed pyogranulomatous subcutaneous lesions associated with the presence of the same yeasts. The fungal culture followed by the partial gene sequence and analysis of the ITS region confirmed the diagnosis of the S. brasiliensis as the causative agent. The cats were treated with itraconazole associated in one case with potassium iodide. The evolution of the patients was favorable in all cases.

CONCLUSIONS

An outbreak caused by S. brasiliensis was detected in domestic and feral cats in austral Chile. The correct identification of this fungus and antifungigram is essential for treatment decisions and for designing dissemination control and prevention programs under a one health approach that consider the health of people, animals, and the environment.

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.