systemic and oppurtunistic fungal infection

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Systemic and Opportunistic
Mycoses

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Systemic Mycoses
• Systemic mycoses are caused by fungi that
are mostly soil saprophytes.
• Fungi causing systemic mycoses are
dimorphic:
 Blastomyces dermatitidis,
 Paracoccidioides brasiliensis,
 Coccidioides immitis and
 Histoplasma capsulatum

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Blastomycosis
• North American blastomycoses
• Caused by Blastomyces dermatitidis
• Source of infection is the soil
• Acquired by inhalation
• Suppurative granulomatous lesion in any
part of the body with predilection for lungs
and skin

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Blastomycosis
• culture is filamentous with septate hyphae
and many round/oval conida.

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Paracoccidioidomycosis
• South American blastomycosis
• Caused by Paracoccidioides brasiliensis
• Chronic, granulomatous disease of the skin,
mucosa, lymph nodes and internal organs
• Infection acquired by inhalation
• Causes pulmonary infection and spread is
by hematogenous route, leading to
ulcerative granulomas of buccal and nasal
mucosa

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Paracoccidioidomycosis
• At 37°C in tissues and culture, large, round,
oval cells with multiple budding, Mariner’s
wheel

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Coccidioidomycosis
• Caused by Coccidioides immitis
• Acquired by Inhalation of dust with
arthrospores
• Manifests as fever
• culture, mycelial forms fragment into
arthrospores
• Confirmation may be by DNA probes
• Culture must be handled with special care in
Biological Safety Cabinet as laboratory
infections are common

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Histoplasmosis
• Intracellular infection of reticuloendothelial
system
• Caused by Histoplasma capsulatum
• Fever, anemia, lymphadenopathy, hepato
splenomegaly, granulomatous ulcerative
lesions develop in skin and mucosa
• culture:
white cottony mycelial growth with large thick-
walled, spherical spores with tubercles or
finger-like projections

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H.capsulatum: Mycelial and yeast forms

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Opportunistic mycosis

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Opportunistic Mycoses
• Seen in immunocompromised
• Caused by fungi which are normal
commensal,
• like Candida albicans,
• Aspergillus fumigatus

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Aspergillosis
• Caused by
• Aspergillus fumigatus,
• Aspergillus niger and
• Aspergillus flavus

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Aspergillosis
• Invasive aspergillosis: Pneumonia and
dissemination to other organs
• Superficial infections: Otomycosis, mycotic
keratitis and infection of nasal sinuses
Laboratory diagnosis
• Direct microscopy: Hyaline septate hyphae

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Aspergillosis
• Culture on Sabouraud’s dextrose agar:
colonies –
• A. fumigatus, dark green velvety;
• A. flavus, powdery yellowish green;
• A. niger, powdery black colonies
• Serology: Antibody and antigen can be
demonstrated by ELISA and CIEP

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Aspergillus spp. (a) A.fumigatus; (b) A.flavus and (c) A.niger

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Penicillosis
• caused by Penicillium
• Colonies are powdery bluish green, white
border
• Microscopy: Septate hyaline hyphae with
branched conidiophore,
- bearing chains of conidiospores
resembling brush border.

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Penicillium. Chains of conidia are produced by phialides, which are
supported by branched conidiophores. Terminal conidium is oldest.

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MUCOR MYCOSIS:
• Caused by Rhizopus, Mucor and Absidia.
• Spread – respiratory tract or nasal cavity.
• Associated with
- diabetes
- immunocompromised state.

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• Caused by candida albicans.
• Normal inhabitants of skin and mucosa.
Pathogenesis:
• Cutaneous candidiasis – sweaty regions.
• Vaginitis
• Oral thrush
• Intestinal candidiasis
• Bronchopulmonary candidiasis
• Systemic infection - sepsis

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• Gram stain: gram positive cells
• SDA agar: cream white smooth colonies.
• Formation of germ tube – when incubated in human
serum at 37 degree celsius.
TREATMENT
• Amphotericin B
• Imidazole
• Itraconazole
• fluconazole

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Gram stain
SDA agar