Fusarium solani species complex infection in elasmobranchs: A case report for rough-tail stingray with valid antifungal therapy

Voriconazole Pharmacokinetics Administered at 4 mg/kg IM and IV in Nursehound Sharks (Scyliorhinus stellaris) Under Human Care

Fungal diseases, despite their low incidence in sharks and rays, are considered emerging diseases in this group of animals and can lead to high mortality rates despite treatment. The information available related to the treatment of fungal diseases in elasmobranchs is limited and is frequently based on the empirical knowledge provided by the professionals and clinicians working with these species. The use of azole antifungal drugs, especially voriconazole, has shown promise as a potential treatment option for fungal infections in elasmobranchs, with favorable outcomes in some registered cases. However, scientific knowledge regarding azole pharmacokinetics (PK) in fish remains limited, and despite the recent publication of a PK study with voriconazole in rays, there are still no published PK studies for azoles in sharks. In this study, voriconazole was administered at 4 mg/kg intravenously (IV) and intramuscularly (IM) to nursehound sharks (Scyliorhinus stellaris) (n = 6). Blood samples were collected before administration and at nine predetermined time intervals afterwards (0.25, 0.5, 1, 1.5, 2, 4,8,12, 24, and 36 h). Plasma concentrations were determined using a validated high-performance liquid chromatography (HPLC) method, and pharmacokinetic (PK) parameters were estimated using a non-compartmental model. The mean peak plasma concentrations (Cmax) ± SEM after IM administration was 3.00 ± 0.23 µg/mL. The volume of distribution (Vd) after IV and IM administration resulted in 1.39 ± 0.09 L/kg and 1.50 ± 0.18 L/kg, respectively, showing no statistically significant differences between the two routes. Clearance (Cl) values were 0.12 ± 0.01 mL/min after IV administration and 0.29 ± 0.05 mL/min after IM administration. No adverse effects were detected during the study or four weeks after administration. These results support the administration of IV and IM voriconazole in sharks; however, additional studies on toxicity and pharmacodynamics are necessary. Moreover, further research on the susceptibility of fungal pathogens affecting elasmobranchs is needed to establish an optimal dosing regimen for IM voriconazole in the treatment of mycosis in sharks.

Updates on antifungal pharmacotherapy in elasmobranchs: pharmacokinetics of 4 mg/kg voriconazole after IM and IV administration in undulate skates (Raja undulata) maintained under human care

Introduction

Fungal diseases are frequently associated with elevated mortality rates in elasmobranchs. Currently, there is a notable absence of scientifically validated therapeutic medications that can ensure both effectiveness and safety when administered to this group of animals. The empirical prescription of azole antifungal agents, particularly voriconazole, has been posited as a potentially efficacious treatment approach for addressing most common mycoses in sharks and rays. However, there are still no published pharmacokinetic studies supporting its use in elasmobranchs and there is a lack of scientific base for its utilization in elasmobranchs.

Methods

For this study, voriconazole was administered intravenously (IV) and intramuscularly (IM), at a single dose of 4 mg/kg to six adult undulate skates (Raja undulata). A washout period of 8 weeks was left between each route of administration. Blood samples were collected both before and at ten predetermined intervals after each dosing (0.25, 0.5, 1, 1.5, 2, 4, 8, 12, 24, and 36 h after drug administration). Plasma concentrations were quantified using a validated high-performance liquid chromatography method, and pharmacokinetic (PK) data was analyzed through non-compartmental methods.

Results

The mean extrapolated concentration at 0 h (C0) after IV administration was 27.19 ± 7.15 μg/mL and the mean peak plasma concentrations (Cmax) ± SEM after IM administration resulted 2.98 ± 0.28 μg/mL at a mean time to maximum concentration (T max) of 1.33 ± 0.17 h. Terminal half-lives were calculated and resulted 11.18 ± 1.32 h for IV injections and 9.59 ± 1.38 h for IM injections. The area under the curve extrapolated to infinity was determined as 58.14 ± 2.79 h·μg/ml following IV injections and 37.60 ± 6.67 h·μg/ml following IM injections. The IM-administered voriconazole exhibited a mean absolute bioavailability of 64.67 ± 11.47%.

Discussion

These discoveries provide backing for the possible application of voriconazole through the intramuscular route in undulate skates and support using lower dosage regimens compared to those required for oral administration, emphasizing the importance of conducting further pharmacokinetic studies with antifungals in elasmobranchs.

Fungal Diseases in Elasmobranchs and Their Possible Treatment with a Special Mention to Azole Antifungal Agents

INTRODUCTION

Elasmobranchs currently constitute an important part of the animal collection of many aquariums worldwide. Their maintenance under human care has allowed us to describe and identify new pathogens and diseases affecting them, as well as to determine different treatments for these diseases. Great advances in elasmobranch husbandry have been developed.

METHODS

A search was performed on scientific databases as PubMed and other specialized sources (IAAAM archive).

RESULTS

Little information on pharmacotherapeutics is available in this taxonomic group, and treatments lack a scientific base and instead are frequently dependent on empirical knowledge. Pharmacokinetic studies are the first step to determining therapeutic protocols that are safe and effective. The available bibliography shows that a majority of the mycoses recorded in cartilaginous fish are severe, aggravated by the fact that the antifungal treatments administered, following the guidelines used for teleost species, are ineffective in elasmobranchs. Azoles appear to be a promising group of antifungals for use in treating systemic mycoses in sharks and rays.

CONCLUSIONS

Based on the findings of this review, it is essential to investigate the pharmacokinetics of the different antifungals in these species in order to provide therapeutic options for fungal infections in cartilaginous fish.

Comparative genomic and transcriptomic analyses of trans-kingdom pathogen Fusarium solani species complex reveal degrees of compartmentalization

BACKGROUND

The Fusarium solani species complex (FSSC) comprises fungal pathogens responsible for mortality in a diverse range of animals and plants, but their genome diversity and transcriptome responses in animal pathogenicity remain to be elucidated. We sequenced, assembled and annotated six chromosome-level FSSC clade 3 genomes of aquatic animal and plant host origins. We established a pathosystem and investigated the expression data of F. falciforme and F. keratoplasticum in Chinese softshell turtle (Pelodiscus sinensis) host.

RESULTS

Comparative analyses between the FSSC genomes revealed a spectrum of conservation patterns in chromosomes categorised into three compartments: core, fast-core (FC), and lineage-specific (LS). LS chromosomes contribute to variations in genomes size, with up to 42.2% of variations between F. vanettenii strains. Each chromosome compartment varied in structural architectures, with FC and LS chromosomes contain higher proportions of repetitive elements with genes enriched in functions related to pathogenicity and niche expansion. We identified differences in both selection in the coding sequences and DNA methylation levels between genome features and chromosome compartments which suggest a multi-speed evolution that can be traced back to the last common ancestor of Fusarium. We further demonstrated that F. falciforme and F. keratoplasticum are opportunistic pathogens by inoculating P. sinensis eggs and identified differentially expressed genes also associated with plant pathogenicity. These included the most upregulated genes encoding the CFEM (Common in Fungal Extracellular Membrane) domain.

CONCLUSIONS

The high-quality genome assemblies provided new insights into the evolution of FSSC chromosomes, which also serve as a resource for studies of fungal genome evolution and pathogenesis. This study also establishes an animal model for fungal pathogens of trans-kingdom hosts.