Systemic mycosis

• Systemic mycoses are diseases caused by fungi that affect animals.
• Dimorphic fungi have different morphologies between their saprophytic and parasitic phases.
• Coccidioides, Histoplasma, Blastomyces, and Paracoccidioides are examples of dimorphic fungi that grow as molds in their inanimate habitat and produce sporangia or budding yeasts in tissue.
• Infection in systemic mycoses is usually by inhalation.
• Some mycoses are seen primarily in immunocompromised animals.
• Lesions in systemic mycoses tend to be granulomatous to pyogranulomatous (lung) and then dissemination may occur to bone, skin, central nervous system, or abdominal viscera.
• Systemic mycoses are noncontagious.
• Dogs are most frequently affected by systemic mycoses, with horses occasionally affected.
• Adhesins SOWgp (for spherule outer wall glycoprotein) have affinity for extracellular matrix proteins (laminin, fibronectin, and collagen).
• β- Glucosidase 2 (for β- glucosidase 2) is an enzyme secreted by the endospores of Coccidioides that most likely plays a role in endospore morphology.
• Antibodies (IgM isotype) to Bgl2 are made early in the infectious process.
• Most cases of Pneumocystis carinii in domestic animals have occurred in horses and dogs.
• Rhizopus spp., Rhizomucor spp., Absidia spp., Mucor spp., and Mortierella spp. cause respiratory and hematogenous infections in various viscera and the central nervous system.
• Pneumocystis carinii is an opportunist pathogen capable of causing severe pneumonia in immunocompromised individuals.
• Rhizopus spp., Rhizomucor spp., Absidia spp., Mucor spp., and Mortierella spp. cause marked by ulcerative lesions and mesenteric lymphadenitis in gastrointestinal infections in animals.
• Rhizopus spp., Rhizomucor spp., Absidia spp., Mucor spp., and Mortierella spp. are examples of fungi that cause gastrointestinal infections in animals.
• Rhizopus spp., Mucor spp., Absidia spp., Mortierella spp. are examples of fungi that cause mycotic bovine abortion.
• Itraconazole has been beneficial in treating disseminated aspergillosis.
• Rhizopus spp., Rhizomucor spp., Absidia spp., Mucor spp., and Mortierella spp. cause mycotic bovine abortion, gastrointestinal infections, marked by ulcerative lesions and mesenteric lymphadenitis, in ruminants, swine, and dogs, as well as respiratory and hematogenous infections affecting various viscera and the central nervous system.
• Chitinase 1 (for chitinase 1) is one of several chitinases that are involved with the formation of, and release of, endospores from the spherule.
• Histoplasma capsulatum is found in the topsoil layers, especially in the presence of bird (mainly starlings in North America and chickens in South America) and bat guano.
• Histoplasmosis is genetically divided into six classes: class1 and class 2 are found in North America; class 3 is found in Central and South America; class 4 is found in Florida (North America); and class 5 and class 6 are found in human patients with acquired immunodeficiency syndrome from New York (North America) and Panama (Central America), respectively.
• Blastomyces dermatitidis is a dimorphic fungus existing as a mold in the soil (saprophytic stage) and as a yeast in tissue (parasitic stage).
• Blastomyces dermatitidis produce conidiophores with spherical or oval smooth-walled conidia.
• Histoplasma capsulatum forms large, spherical tuberculate (i.e., spiked) macroconidia.
• Melanin reduces the toxicity of hydroxy radicals, superoxides, and singlet oxygen radicals found within the phagolysosome.
• Normal phagolysosomes have a pH <5, a pH that optimizes the activity of many of the digestive enzymes found in this environment.
• M-antigen, found in yeast phase of phagolysosome, is a catalase enzyme that plays a role in the survival of the yeast phase within the phagolysosome.
• Histoplasma capsulatum raises the pH of the phagolysosome to 6.0 – 6.5, thereby reducing the activity of these lysosomal enzymes.
• Transmission of Histoplasmosis is mostly by inhalation of microconidia or hyphal fragments, possibly by ingestion, and, rarely, by wound infection.
• Antibodies (IgG isotype) to Cts1 are made late in the infectious process (in disseminated disease), and are useful diagnostically (detected by the complement fixation, CF test).
• β- 1,3- glucanosyltransferase (for glucan elongating glucanosyltransferase) is located on the surface of endospores.
• In pulmonary infections, following spore inhalation, suppurative exudates accumulate in the bronchioles.
• Canine nasal aspergillosis occurs especially in young dogs of dolichocephalic breeds.
• Pigment (Melanin) is a free radical scavenger that reduces the toxicity of hydroxy radicals, superoxides, and singlet oxygen radicals found within the phagolysosome.
• Cell-mediated immunity is believed to be the major factor in limiting the dissemination of infection in Aspergillosis spp.
• Itraconazole (given orally) has been successfully used to treat nasal aspergillosis when topical treatment is not possible.
• Aspergilli grow on all common laboratory surfaces and thrive in the environment.
• Aspergillus is an opportunistic pathogen that depends on impaired, overwhelmed, or bypassed host defense to permit hyphal invasion of tissues.
• Bovine abortion outbreaks are often related to moldy fodder.