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Miscellaneous fungal infections


1. Penicilliosis

  1. More than 150 known species
  2. Occur as saprophytes in soil and decomposing organic matter
  3. Only dimorphic species is P. marnefii
  4. Causes infection in AIDS patients
  5. Mainly in Southeast Asian countries
  6. India: cases have been reported form northeastern states
  7. Animal reservoir: Chinese bamboo rats
  8. Infection acquired by respiratory route
  9. Infects reticuloendothelial system  

Clinical features: Tuberculosis like illness characterized by fever, weight loss, anaemia, involvement of liver, spleen, lungs

Histologic sections: ellipsoidal yeast cell (2-6
μm in length), divided by transverse septations (fission). Stained well by PAS, methenamine silver

Mold form: SDA at 25°C, brush like arrangement of conidia, produces brick red colored diffusible pigment


2. Pneumocystosis

  1. Pneumocystis carinii/ jIroveci: Interstitial plasma cell pneumonia
  2. Features in favor of fungi: 16s RNA, attacked by chitinase, lack of intracellular or sexual stages not typical of sporozoa, stained with fungal stains
  3. Features in favor of protozoa: 5s-rRNA similar to sporozoa, lacks ergosterol, responds better to antiprotozoal treatment
  4. Greater similarity to fungi than to protozoa therefore classified as fungus
  5. One of the commonest opportunistic infection in AIDS
  6. Morphological forms: Trophozoite, sporozoites & cyst
  • Trophozoites: fill the alveoli of the lungs, pleomorphic, 2-12μm
  • Cysts: most commonly observed, 5-8μm, oval, thick walled, containing upto 8 sporozoites,
    Infection acquired by respiratory route; reactivation of latent infection
    Attaches and damages type I pneumocytes 

a. Clinical features:

  1. Fever; non productive cough, hypoxia, cyanosis, gradual & progressive dyspnoea, alveolar or interstitial infiltrates (usually involves whole lung after beginning in the hilus), CXR - perihilar haziness with diffuse mottling
  2. Nosocomial spread - premature infants, debilitated, malnourished, congenital immunodeficiency 

b. Diagnosis:

  1. Specimens: BAL, Lung Biopsy, Sputum,
  2. Direct microscopic examination by Direct Fluorescent antibody staining, other staining methods
    Cysts: stained by methanamine silver (black), Toludine blue O (red purple), Cresyl etch violet
    Sporozoite: Stained by Wright-Giemsa (basophilic cytoplasm, red-purple nuclei)
  3. No role of culture or serology for diagnosis 

c. Treatment: TMP – SMX, drug of choice


3. OTOMYCOSIS- Subacute/ chronic infection of external auditory canal

  1. Common agents: A. niger
  2. A. fumigates/Penicillium spp./ C. albicans
  3. Diagnosis by microscopic examination and culture 

4. KERATOMYCOSIS- Invasive fungal infection of the cornea

  1. Common agents: A. fumigatus
  2. flavus/A. glaucus/A. niger/Fusarium spp.
  3. Curvularia spp./Candida spp. /Penicillium spp.
  4. Alterneria spp./Drechslera spp.
  5. It usually follows trauma.
  6. Diagnosis by microscopic examination and culture 

5. Mycotoxicosis:

Illness or death of man or domesticated animals following consumption of food contaminated with mycotoxins (secondary metabolites & there affects are not dependant on fungal infection or viability). e.g. aflatoxins produced by Aspergillus flavus (Turkey X disease)

6. Mycetismus: Due to the consumption of fleshy fungi . e.g. ergot poisoning caused by eating bread made of rye flour which is contaminated with Claviceps (St. Anthony’s fire, St. Vitus Dance), mushroom poisoning.


Respiratory allergic diseases caused by fungi and actinomycetes


Allergic disease



Farmer’s lung

Stored hay

Faenia rectivirgula

Thermoactinomyces vulgaris


Sugar cane

T saccharii

Maple bark strippers lung

Maple tree bark

Cryptostroma corticale

Cheese washers lung


Penicillium caseicolum

Maltster’s lung

Barley malt

Aspergillus clavatus


Red wood saw dust

Aureobasidium pullulans



Penicillium frequentans

Wood pulp workers lung

Wood pulp

Alterneria spp.

Humidifier lung


T. vulgaris, T. candidus

Exoantigen Tests
  1. The exoantigens are defined as cell free antigens or soluble immunogenic macromolecules produced by fungi during their growth. These are readily detected in supernatant of culture broths or aqueous extracts of slant cultures. 
  2. The exoantigens test depends on interaction between antigen produced by mycelial phase of fungi in culture and homologous antibodies, which are specifically generated to precipitate them. These can be detected even with contaminated or non-viable fungi. 
  3. The technique reduces potential for exposure to bio-hazardous fungi by eliminating need for in vitro conversion or cultural manipulations used in animal inoculations. 
  4. The principle of exoantigen test is that antibodies developed against particular mycelial antigens react specifically in gel immunodiffusion precipitin test (Ouchterlony's technique). 
  5. The mold form of dimorphic fungi can be identified easily, negating need of conversion to yeast phase within a week time. Monoclonal antibodies are exceptionally useful for characterizing species-specific exoantigens and for elucidating intraspecies antigenic relationship. 
  6. Some of species-specific exoantigens for identification of systemic dimorphic fungal pathogens like Histoplasma capsulatum, Blastomyces dermatitidis, Coccidioides immitis and Paracoccidioides brasiliensis. 

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