The emergence of zoonotic Fusarium oxysporum infection in captive-reared fingerlings of golden mahseer, Tor putitora (Hamilton, 1822) from the central Himalayan region of India

Emergence of Aeromonas salmonicida subsp. masoucida MHJM250: unveiling pathological characteristics and antimicrobial susceptibility in golden mahseer, Tor putitora (Hamilton, 1822) in India

Aeromonas salmonicida subsp. masoucida, designated as laboratory strain MHJM250, was characterized from a naturally infected farmed golden mahseer, Tor putitora. The infected fish exhibited clinical signs of erosion at the caudal fin and hemorrhage onx the ventral body surface. Molecular identification through 16 S rDNA and phylogenetic analysis revealed 100% similarity with a known strain A. salmonicida subsp. masoucida (MT122821.1). MHJM250 exhibited positive reactions for oxidase, catalase, esculin, MR-VP, O/F and utilized arginine and lysine. It also demonstrated siderophore activity, thrived at various NaCl concentrations, hydrolyzed gelatinase, skimmed milk and casinase. In vitro studies exhibited its hemolytic nature, significant biofilm production in glucose-rich tryptone soya broth and beta-hemolysis. MHJM250 didn't produce slime and was non-precipitated upon boiling. It showed crystal violet binding characteristics and auto-agglutination with relatively weak hydrophobicity (25%). In the challenge assay, intraperitoneal administration of MHJM250 to T. pitutora fingerlings at 108 CFU mL-1 resulted in pathogenicity with 3% mortality and mild hemorrhagic symptoms. Histopathological analysis revealed degenerative changes in gill, kidney, liver, muscle, and intestine samples. The bacterium displayed resistance to several antibiotics (µg/disc); ampicillin (10 µg), ampicillin/ sulbactam (10/10 µg), clindamycin (2 µg), linezolid (30 µg), penicillin G (10 µg) and rifampicin (5 µg) and varied minimum inhibitory concentrations against oxytetracycline, erythromycin and florfenicol. Transmission electron microscopy showed its rod-shaped structure with single polar flagellum and lophotrichous flagella. An investigation on the molecular basis for virulence factors of A. salmonicida subsp. masoucida MHJM250 may offer crucial understandings to formulate disease prevention and control strategies in aquaculture.

Identification and antifungal sensitivity of Fusarium species isolated from piscine hosts

Fusarium is a huge genus of filamentous fungi that has the potential to cause emerging diseases. Members of this genus can cause infections in plants, animals and humans. Here, we report the isolation of F. oxysporum and F. equiseti from 2 important fish species, Oncorhynchus mykiss (rainbow trout) and Tor putitora (golden mahseer), respectively. F. oxysporum has emerged as a significant fungal pathogen causing infection in many fish. However, F. equiseti has been isolated mainly from plants. As far as the available literatures are concerned, this is the first report on the isolation of F. oxysporum and F. equiseti from these hosts. The isolates were identified based on growth morphology and microscopic observation. F. oxysporum produced violet pigmentation on potato dextrose agar, while F. equiseti had yellow colouration. F. oxysporum produced 1- to 2-celled microconidia along with straight or curved macroconidia having 3 to 4 septa. F. equiseti produced abundant macroconidia with 4 or more septa. Species were further confirmed based on the nucleotide sequences of the internal transcribed spacer region. In a molecular phylogeny analysis, F. oxysporum and F. equiseti formed 2 different clades. In an antifungal sensitivity assay, F. oxysporum was found to be susceptible to clotrimazole with a minimum inhibitory concentration of 1.0 µg ml-1, whereas F. equiseti was susceptible to clotrimazole, ketoconazole and fluconazole. Overall, the main findings of this study are the infection of new hosts by Fusarium species and the limited activity of many antifungal drugs against these pathogens.

A novel case of cutaneous, nasal and systemic fusariosis in a goat

The clinical findings associated with nasal, cutaneous and systemic fusariosis in a 3-year-old billy Boer goat are summarised. The clinical features, treatment, postmortem findings and laboratory diagnostics are reported and discussed in the context of existing knowledge on mycoses of small ruminants. The goat presented primarily for respiratory signs (inspiratory dyspnoea) with unilateral left-sided mucopurulent nasal discharge, and multifocal variably ulcerative and necrotic cutaneous nodules. Histopathology of nasal and cutaneous biopsies revealed necrotising pyogranulomatous inflammation with intralesional septate hyphal elements that correlated with culture of Fusarium oxysporum. The patient continued to deteriorate clinically during treatment with oxytetracycline and meloxicam, with the addition of sodium iodide and potassium iodide, and was humanely euthanased. Postmortem examination revealed multifocal nodular lesions throughout the kidneys, abdominal lymph nodes and lungs. These lesions were consistent with those identified antemortem from which F. oxysporum was cultured. Although treatment was unsuccessful, to the author's knowledge, no instance of rhinofacial or systemic caprine infection with Fusarium spp. has been documented in the veterinary literature, making this the first recognised instance of this form of infection in small ruminant species.

Diversity and Antimicrobial Activity of Intestinal Fungi from Three Species of Coral Reef Fish

Although intestinal microbiota play crucial roles in fish digestion and health, little is known about intestinal fungi in fish. This study investigated the intestinal fungal diversity of three coral reef fish (Lates calcarifer, Trachinotus blochii, and Lutjanus argentimaculatus) from the South China Sea using a culturable method. A total of 387 isolates were recovered and identified by sequencing their internal transcribed spacer sequences, belonging to 29 known fungal species. The similarity of fungal communities in the intestines of the three fish verified that the fungal colonization might be influenced by their surrounding environments. Furthermore, the fungal communities in different intestines of some fish were significantly different, and the number of yeasts in the hindgut was less than that in fore- and mid-intestines, suggesting that the distribution of fungi in fishes' intestines may be related to the physiological functions of various intestinal segments. In addition, 51.4% of tested fungal isolates exhibited antimicrobial activity against at least one marine pathogenic microorganism. Notably, isolate Aureobasidium pullulans SCAU243 exhibited strong antifungal activity against Aspergillus versicolor, and isolate Schizophyllum commune SCAU255 displayed extensive antimicrobial activity against four marine pathogenic microorganisms. This study contributed to our understanding of intestinal fungi in coral reef fish and further increased the library of fungi available for natural bioactive product screening.

Biosynthesis of Novel Tellurium Nanorods by Gayadomonas sp. TNPM15 Isolated from Mangrove Sediments and Assessment of Their Impact on Spore Germination and Ultrastructure of Phytopathogenic Fungi

The biosynthesis of nanoparticles using green technology is emerging as a cost-efficient, eco-friendly and risk-free strategy in nanotechnology. Recently, tellurium nanoparticles (TeNPs) have attracted growing attention due to their unique properties in biomedicine, electronics, and other industrial applications. The current investigation addresses the green synthesis of TeNPs using a newly isolated mangrove-associated bacterium, Gayadomonas sp. TNPM15, and their impact on the phytopathogenic fungi Fusarium oxysporum and Alternaria alternata. The biogenic TeNPs were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Raman spectroscopy and Fourier transform infrared (FTIR). The results of TEM revealed the intracellular biosynthesis of rod-shaped nanostructures with a diameter range from 15 to 23 nm and different lengths reaching up to 243 nm. Furthermore, the successful formation of tellurium nanorods was verified by SEM-EDX, and the XRD pattern revealed their crystallinity. In addition, the FTIR spectrum provided evidence for the presence of proteinaceous capping agents. The bioinspired TeNPs exhibited obvious inhibitory effect on the spores of both investigated phytopathogens accomplished with prominent ultrastructure alternations, as evidenced by TEM observations. The biogenic TeNPs impeded spore germination of F. oxysporum and A. alternata completely at 48.1 and 27.6 µg/mL, respectively. Furthermore, an increase in DNA and protein leakage was observed upon exposure of fungal spores to the biogenic TeNPs, indicating the disruption of membrane permeability and integrity. Besides their potent influence on fungal spores, the biogenic TeNPs demonstrated remarkable inhibitory effects on the production of various plant cell wall-degrading enzymes. Moreover, the cytotoxicity investigations revealed the biocompatibility of the as-prepared biogenic TeNPs and their low toxicity against the human skin fibroblast (HSF) cell line. The biogenic TeNPs showed no significant cytotoxic effect towards HSF cells at concentrations up to 80 μg/mL, with a half-maximal inhibitory concentration (IC50) value of 125 μg/mL. The present work spotlights the antifungal potential of the biogenic TeNPs produced by marine bacterium against phytopathogenic fungi as a promising candidate to combat fungal infections.

A One Health Perspective to Recognize Fusarium as Important in Clinical Practice

Any strategy that proposes solutions to health-related problems recognizes that people, animals, and the environment are interconnected. Fusarium is an example of this interaction because it is capable of infecting plants, animals, and humans. This review provides information on various aspects of these relations and proposes how to approach fusariosis with a One Health methodology (a multidisciplinary, and multisectoral approach that can address urgent, ongoing, or potential health threats to humans, animals, and the environment). Here, we give a framework to understand infection pathogenesis, through the epidemiological triad, and explain how the broad utilization of fungicides in agriculture may play a role in the treatment of human fusariosis. We assess how plumbing systems and hospital environments might play a role as a reservoir for animal and human infections. We explain the role of antifungal resistance mechanisms in both humans and agriculture. Our review emphasizes the importance of developing interdisciplinary research studies where aquatic animals, plants, and human disease interactions can be explored through coordination and collaborative actions.