Veterinary Microbiology (3110301) Systemic mycoses 1 Dimorphic fungi รศ.สพ.ญ.อรวรรณ นว ภาพ ภาคว ชาจ ลช วว ทยา คณะส ตวแพทยศาสตร จ ฬาลงกรณ มหาว ทยาล ย 2547
Systemic mycoses แบ งเป น 3 group 1. เก ดจาก true pathogenic fungi ซ งส วนใหญ จะเป น Dimorphic fungi ได แก Bastomyces, Coccidioides, Paracoccidioides, Histoplasma etc. 2. เก ดจาก Yeast-like fungi ได แก Candida, Cryptococcus, Malassezia, Trichosporon, Geotrichum. 3. เก ดจาก Opportunistic pathogenic fungi ได แก Aspergillus, Mucor, Rhizopus, Penicillium etc.
Systemic mycoses caused by Dimorphic fungi
Yeast and yeast like fungi
(Dimorphic fungi) (Yeast and yeast like fungi)
Dimorphic fungi Blastomycosis (North American Blastomycosis) Agent : Blastomyces dermatitidis (perfect stage as Ajellomyces dermatitidis) Clinical characteristic : mild respiratory infections - ---> Bronchopnemonia or lobar pneumonia ---> chronic or disseminate ---> skin lesion, other organs (percutaneous infection is rare) Geography : Central America, Central eastern sea coast state, Africa Therapy : Amphotericin B, Hydroxystilbamidine
Blastomycosis
37 o c : thick walled yeast cells (8-10 mm in diameter) daughter cells bud on a broad base
Blastomyces dermatitidis (Yeast phase)
25 o c : oval or pear shaped conidia (2-10 mm in diameter) ore born either on conidiophore or directly on the septate hyphae
Blastomyces dermatitidis (Mycelial phase)
Mycelial phase Yeast phase
Fig.1 The mould and yeast forms of Blastomyces dermatitidis.
Blastomyces dermatitidis Usual habitat : acid soil rich in organic matter Clinical infection : dog and human, other species (cat uncommon) Geography : North America, Africa, Middle east, India
Canine Blastomycosis Infection by inhalation Pulmonary Blastomycosis Symptom : chronic debilitating condition, coughing, exercise intolerance, dyspnoea, lymph node enlargement Dissemination to skin, eye, bone, central nervous system, urogenital tract in male dog (primary cutaneous Blastomycosis is uncommon)
Severe lesion : granulomatous or pyogranulomatous (yeast cells are numerous in this lesion) Treatment : Amphotericin B + Ketoconazole Hydroxystilbamidine
Paracoccidioidomycosis (South American Blastomycosis) Agent : Paracoccidioides brasiliensis Clinical characteristic : Pulmonary infection (lung involvement) ---> hematogenous and lymphatic route ---> mucous membrane and mucocutaneous junction ---> papules develop into vessels ---> ulcer, granulomatous ---> draining sinus ---> lymphatic system ---> spleen, intestine etc. (percutaneous is rare)
Geography : South America, Brazil Predisposing factors : malnutrition, exposure to soil or plant Therapy : Self limiting, Amphoteracin B
(intercalary) Single or multiple budding cell
Paracoccidioides brasiliensis Mycelial phase Yeast phase
Paracoccidioides brasiliensis Mycelial phase
Paracoccidioides brasiliensis Yeast phase
Coccidioidomycosis Agent : Coccidioides immitis Clinical characteristic : respiratory infection ---> inhalation of arthroconidia (from mold form of fungus in soil) ---> pulmonary lesion (tuberculosis like lesion), acute pneumonia (skin reaction may occur) Usual habitat : soil of arid or semiarid, dust (heavily contaminated with arthroconidia)
Geography : South Western America, Mexico, Central and South America (human, dog, horse) Predisposing factors : malnutrition, expose to soil (dust) or plant (contaminated arthroconidia), inhalation of mass of spores
Colony : 25 o -30 o c (mycelial form), colony are shiny, moist and grey becoming white and cottony Microscopic : thick walled, barrel shaped arthroconidia (fragmentation)
Canine Coccidioidomycosis Dog with mild pulmonary coccidioidomycosis, cough, fever, anorexia, may recover spontaneously Disseminated form pulmonary lesion ---> immunosuppression ---> osteomyelitis, lameness, bone destruction Treatment : Ketoconazole therapy for at least 6 months
Equine Coccidioidomycosis Non specific, intermittent fever, abdominal pain, loss of weigh, musculoskeletal involvement, musculoskeletal pain, osteomyelitis
Coccidioides immitis
Coccidioides immitis Spherule with endospores in lung tissue
Coccidioides immitis Spherule with endospores in lung tissue
Fig.3 The mould form and spherule of Coccidioides immitis.
Histoplasmosis, Darling s disease, Reticuloendotheliosis Agent : Histoplasma capsulatum (found in soil, bird or bat feces) Histoplasma farciminosum (soil saprophyte) Clinical characteristic : mild respiratory infection ---> lung (calcification lesion in lung) ---> lymph node enlargement ---> reticuloendothelial cell (leukemia, lymphoma) ---> many organs and tissues (percutaneous is rare)
Geography : North America, Central America, Africa Predisposing factors : inhalation of mass of spores (infected bat caves, chicken crop, staring nest)
Histoplasma capsulatum Mycelial phase
Histoplasma capsulatum Yeast phase
Histoplasma capsulatum Mycelial phase Yeast phase
Histoplasma capsulatum
Histoplasma capsulatum
Histoplasma capsulatum
Fig.2 The mould and yeast forms of Histoplasma capsulatum.
Canine and Feline Histoplasmosis Agent : Histoplasma capsulatum Clinical characteristic : asymptom at first ---> inhalation---> pulmonary alveolar macrophage (microconidia, yeast form), pulmonary lesion, dyspnoea depression, fever, loss of weigh ---> granulomatous lesion in lung of dog and cat (in dog may occur intestinal lesion but not in cat) ---> chronic cough, diarrhea, emalciation, skin ulcerative, skin nodule, lymphadenitis, eye lesion, lameness and neurological dysfunction Treatment : Amphoteracin B, ketoconazole
Epizootic lymphangitis Agent : Histoplasma farciminosum (contagious disease of equine) Clinical characteristic : skin abrasion on the limbs, ocular and pulmonary involvement, lymphocutaneous lesion (lympoidinopathy in any organs, occur yeast cell of Histoplasma farciminosum in macrophage) Treatment : excision of skin, sodium iodide therapy
Sporotrichosis Agent : Sporothrix (Sporotrichum) schenckii Clinical characteristic : chronic cutaneous or lymphocutaneous lesion (generalized are rare) Sporadic cases in horse, cat, dog, cattle, goat, pig, human
Sporothrix (Sporotrichum) schenckii Mycelial phase
Sporothrix (Sporotrichum) schenckii Yeast phase
Fig.4 The mould and yeast forms of Sporothrix schenckii.
Equine Sporotrichosis Agent : Sporotrix schenkii Clinical characteristic : lymphocutaneous in horse skin abrasion on the lower limb superficial lymnphatic vessel of nodule ulceration discharge (yellow exudate) subcutaneous edema cause by lymphatic obstruction Treatment : - inorganic iodide - excision of skin lesion
Feline Sporotrichosis Agent : Sporotrix schenkii Clinical characteristic : nodular skin lesion on limbs extremities, head, tail lymphadenitis nodule ulcerate and disease seropurulent exudate ulceration of muscle, bone to another animals by grooming to human by handle infected animals Treatment : - sodium iodide mix in feed, continue 30 days after recover - ketoconazole + sodium iodide
Canine Sporotrichosis Agent : Sporotrix schenkii Clinical characteristic : ulceration and crusted, alopecia, cutaneous lesion at head, trunk of dog lymphocutaneous infection (disseminated form is rare) Treatment : - sodium iodide mix in feed, continue 30 days after recover - ketoconazole + sodium iodide
Dimorphic fungi and disease production
Table 1 Dimorphic fungi which are associated with disease in animals and humans.