Swim bladder mycosis in farmed rainbow trout Oncorhynchus mykiss caused by Phoma herbarum and experimental verification of pathogenicity.

In this study, spontaneous swim bladder mycosis was documented in a farmed fingerling rainbow trout from a raceway culture system. At necropsy, the gross lesions included a thickened swim bladder wall, and the posterior portion of the swim bladder was enlarged due to massive hyperplasia of muscle. A microscopic wet mount examination of the swim bladder contents revealed abundant septate hyphae, and histopathological examination showed periodic acid-Schiff-positive mycelia in the lumen and wall of the swim bladder. Histopathological examination of the thickened posterior swim bladder revealed muscle hyperplasia with expansion by inflammatory cells. The causative agent was identified as Phoma herbarum through morphological analysis and DNA sequencing. The disease was reproduced in rainbow trout fingerlings using intraperitoneal injection of a spore suspension. Necropsy in dead and moribund fish revealed extensive congestion and haemorrhages in the serosa of visceral organs and in liver and abdominal serosanguinous fluid. Histopathological examination showed severe hepatic congestion, sinusoidal dilatation, Kupffer cell reactivity, leukostasis and degenerative changes. Fungi were disseminated to the liver, pyloric caeca, kidney, spleen and heart. Although infections caused by Phoma spp. have been repeatedly reported in fish, species identification has been hampered by extensive taxonomic changes. The results of this study confirmed the pathogenicity of P. herbarum in salmonids by using a reliably identified strain during experimental fish infection and provides new knowledge regarding the course of infection.

Fungal Keratitis Caused by Colletotrichum dematium: Case Study and Review.

Colletotrichum species are known as important pathogens of plants with an impact on crop production. Some of these species are also known as a cause of rare ophthalmic infections in humans. A case of keratitis caused by Colletotrichum dematium after corneal trauma in a 56-year-old woman is presented. Infection was diagnosed based on positive microscopy and culture. The fungal isolate was identified by morphological characteristics and DNA sequencing of the ITS rDNA region, ß-tubulin (tub2) and glyceraldehyde-3-phosphate dehydrogenase (gapdh) genes. The patient responded well to topical therapy with amphotericin B combined with intravenous amphotericin B but improvement was associated with the corneal collagen cross-linking. The review of the literature revealed another 13 cases of C. dematium keratitis, all but one patient having at least one keratitis risk factor in their history. Almost all patients (n = 12) were treated with topical polyene antibiotics (natamycin or amphotericin B), improvement and cure were achieved in eight of them.

Coelomycetous Fungi in the Clinical Setting: Morphological Convergence and Cryptic Diversity.

Human infections by coelomycetous fungi are becoming more frequent and range from superficial to systemic dissemination. Traumatic implantation of contaminated plant material is the most common cause. The typical morphological feature of these fungi is the production of asexual spores (conidia) within fruiting bodies called conidiomata. This study aimed to determine the distribution of the coelomycetes in clinical samples by a phenotypic and molecular study of a large set of isolates received from a U.S. reference mycological institution and by obtaining the in vitro antifungal susceptibility pattern of nine antifungals against a selected group of isolates. A total of 230 isolates were identified by sequencing the D1 and D2 domains of the large subunit (LSU) nuclear ribosomal RNA (nrRNA) gene and by morphological characterization. Eleven orders of the phylum Ascomycota were identified: Pleosporales (the largest group; 66.1%), Botryosphaeriales (19.57%), Glomerellales (4.35%), Diaporthales (3.48%), Xylariales (2.17%), Hysteriales and Valsariales (0.87%), and Capnodiales, Helotiales, Hypocreales and Magnaporthales (0.43% each). The most prevalent species were Neoscytalidium dimidiatum, Paraconiothyrium spp., Phoma herbarum, Didymella heteroderae, and Epicoccum sorghinum The most common anatomical site of isolation was superficial tissue (66.5%), followed by the respiratory tract (17.4%). Most of the isolates tested were susceptible to the majority of antifungals, and only flucytosine showed poor antifungal activity.

A visceral mycosis in farmed rainbow trout (Oncorhynchus mykiss) caused by Neopyrenochaeta submersa.

A mycotic infection manifesting as abdominal distension with free serous fluid accumulation in the coelomic cavity is documented in farmed rainbow trout. Histological examination using PAS and silver staining revealed the presence of numerous fungal hyphae in the spleen and gastrointestinal wall. The isolated fungus was sterile and identified by using phylogenetic analysis based on four loci as Neopyrenochaeta submersa. This is the first time this fungus has been reported as pathogen.