Outbreaks of clinical mastitis caused by Trichosporon beigelii in dairy herds

Nasal trichosporonosis in 2 mixed-breed ewes

Two adult mixed-breed ewes were presented with a 2-wk history of upper respiratory disease. Both animals were depressed, with bilateral serosanguineous nasal discharge and harsh bronchovesicular sounds accompanied by crackles and wheezes on auscultation. One animal was recumbent and was euthanized at presentation. The other animal with similar signs, as well as exophthalmos, was euthanized because of a mass in the nasal passages. On autopsy, severe pyogranulomatous and necrotizing ethmoidal rhinitis with focal pyogranulomatous pneumonia was diagnosed in both animals. An intralesional fungal organism was identified in the nares and lungs of both animals. The organism could not be isolated via fungal culture but was identified as Trichosporon sp. by a PCR assay. Trichosporon spp. are rarely associated with disease in veterinary medicine. This ubiquitous fungus might cause disease following trauma to the nasal passages or secondary to immunocompromise.

Systemic Trichosporon loubieri infection in a cat

Our study describes a case of systemic Trichosporon loubieri infection in a cat with acute dyspnea, anorexia, and aggressiveness. Physical examination revealed multiple ulcerative cutaneous lesions on the abdomen, neck, and thorax. Thoracic radiographs and ultrasound showed multiple mediastinal nodules and marked pleural effusion, respectively. A cutaneous biopsy from the ulcerated wounds revealed necrogranulomatous dermatitis and panniculitis with numerous intralesional fungal hyphae. Fungal culture on fresh swab samples from the cutaneous lesions yielded growth of a fungal organism that was further identified as Trichosporon loubieri by PCR and DNA sequencing. The cat was subsequently euthanized and submitted to autopsy. Gross pathology changes consisted of multifocal to coalescing white nodules ranging from 5 to 10 mm in diameter that expanded the mediastinal fat, intrathoracic lymph nodes, lungs, and costal pleura. These lesions consisted of areas of necrogranulomatous inflammation with numerous intralesional fungal hyphae morphologically similar to those observed in the cutaneous biopsy sample. Gross and histologic changes were consistent with a systemic fungal infection, and the etiologic diagnosis was supported by fungal culture. Fungal identity was confirmed by DNA sequencing of D1-D2 and TS1 regions.

Effects of temperature and incubation time on the in vitro expression of proteases, phospholipases, lipases and DNases by different species of Trichosporon

Fungi produce a broad spectrum of enzymes capable of degrading different substrates in nature. When the substrate is the tissue of a vertebrate host, these enzymes acts as a fungal virulence factor that increases the pathogenicity of the fungus. Trichosporon yeasts are emerging pathogens that infect immunocompromised patients. Little is known about the virulence characteristics of these fungi. The aim of this research was to characterize the behavior of protease, phospholipase, lipase and DNase production in different species of Trichosporon, with a focus on the influence of incubation temperature on the expression of these enzymes. Classical methodologies were used in all of the experiments, and the results were statistically analyzed. The proportions of the samples that produced each type of enzyme were as follows: lipases (95.5%), phospholipases (56.8%), proteases (50,0%) and DNases (38.6%). The incubation temperature was an important factor in the expression of enzymatic activity, and it influenced the incubation period of each species. Although these data concerning the enzymatic activity expressed by isolates of Trichosporon are valuable, further research is warranted to completely characterize this new pathogen, as well as in vivo studies to determine the roles of these enzymes in the pathogenesis of trichosporonosis.

Adaptation of Microstix®-Candida Slide-test for Diagnosis of Bovine Mastitis Due to Anascogenic Yeasts

Although a large diversity of mastitis-causing bacteria (150 species, subspecies or biovars) have been documented, an adequate and simple mycological screening for yeast-related mastitis has not been developed. Since yeast incubation normally lasts longer than the majority of bacteriological ones, usually a treatment is administered before the results of microbial cultures are obtained. Therefore, a simple test has been needed for detection of yeast-related mastitis, the results of which can be read in parallel to bacteriological screening. Application of Microstix®-Candida assay was first checked for its specificity in standard Candida albicans (Oxford strain) cultures (phase I) and then in the other 36 strains of yeasts isolated from clinical mastitis cases during field investigations (second phase). Next, a test was implemented for identification of pathogens in 9 cohorts (1,200 cows) from red-white Polish- Friesian breed in which the dynamics of mastitis were traced by bacteriological and mycological assays along year-long observations. The data obtained showed that apart from frequent infections (~50-70%) proved by using pure microbial cultures, also mixed (bacterial-fungal) infections (0-25%) appeared as well as negative sieves (in the range of 0-45%). Mycological assays revealed a significant fraction of mixed infections during both lactation and the dry period. Strepto-staphylococcal infection was thus identified, however, its proportion strongly decreased after the introduction of antibiotics (after sensitivity to microbial agents was determined). Microbial monitoring was improved in these herds by parallel application of bacteriological and mycological (particularly Microstix®- Candida) tests. Microstix®-assay appears to be useful for mycological diagnosis in field conditions of infected (mastitis) herds. Its advantages include easy performance and short incubation time that is only 24 h at 37 °C (72-96 h at room temperature). This allowed demonstrating the cow’s udder yeast infection simultaneously with the first reading of bacterial cultures. Its specificity was confirmed against standard Candida Oxford strain, and sensitivity (100%) was confirmed in mycological cultures (36 strains) and biochemical assays.

Rhizopus oligosporus and yeast co-cultivation during barley tempeh fermentation—Nutritional impact and real-time PCR quantification of fungal growth dynamics

Barley tempeh was produced by fermenting barley kernels with Rhizopus oligosporus. The potential of the yeasts Saccharomyces cerevisiae (three strains), S. boulardii (one strain), Pichia anomala (one strain) and Kluyveromyces lactis (one strain) to grow together with R. oligosporus during barley tempeh fermentation was evaluated. All yeast strains grew during the fermentation and even during cold storage of tempeh (P<0.01). The growth of yeasts slightly increased the ergosterol contents, but did not influence amino acid contents and compositions, and did not reduce phytate contents. Slight increases of vitamins B(6) and niacinamide, and slight decreases of B(1) and biotin were observed. Quantification of fungal growth is difficult during mixed species fermentations because ergosterol is found in all fungal species, and colony-forming-unit (cfu) estimations are not reliable for R. oligosporus and other sporulating fungi. Therefore, we developed a quantitative real-time PCR method for individually quantifying S. cerevisiae and R. oligosporus growth in barley tempeh. The PCR results were highly correlated with the ergosterol content of R. oligosporus and with the number of cfu of S. cerevisiae. Thus, real-time PCR is a rapid and selective method to quantify yeasts and R. oligosporus during mixed species fermentation of inhomogenous substrate such as barley tempeh.

Mycotic bovine nasal granuloma

A case of mycotic bovine nasal granuloma in a 10 year-old Jersey cow, produced by Drechslera halodes is presented. Histopathological sections showed abundant hyaline and pigmented extra and intracellular fungal structures together with a polymorphic cellular granuloma formed by neutrophils, lymphocytes, plasmocytes, histiocytes and giant cells of the Langhans type. It is the first case of mycotic bovine nasal granuloma recognized in Uruguay although this disease seems to be frequent according to the opinion of veterinarian specialists. Another similar clinical case also in a Jersey cow from the same dairy house with an intense cellular infiltrate rich in eosinophils without granulomatous image, together with extracellular hyaline and fuliginous fungal forms, is also referred for comparative purposes. Geotrichum sp. was isolated. The need of an early diagnosis and treatment of the disease is stressed.