Mycology Virology Short And Long Essay Question And Answers

Mycology Important Notes

1. Classification of fungi

  • Phycomycetes or zygomycetes
  • Ascomycetes
  • Basidiomycetes
  • Fungi imperfect

2. Types of spores.

  • Sexual spores – oospore, ascospore, zygospore and basidospore
  • Vegetative or asexual spore- blastospore, arthrospores, chlamydospores

3. Lab diagnosis used for fungal infection

  • KOH mounts
  • Wood’s lamp
  • Sabouraud’s glucose agar and cornmeal agar culture media
  • Microscopic examination

4. Types of hair infection

  • Endothrix
  • Ectothrix

5. Candidiasis

  • Causative agent – Candida albicans
  • Classification
  • Acute
    • Pseudomembranous
    • Acute atrophic
  • Chronic
    • Chronic hyperplastic
    • Chronic atrophic
  • Complications
    • Intestinal Candidiasis
    • Bronchopulmonary Candidiasis
    • Septicemia
    • Endocarditis
    • Meningitis

Read And Learn More: Microbiology Question and Answers

6. Aspergillosis

  • It is the most opportunistic pathogen
  • Caused by inhalation
  • Diseases caused by it are
    • Aspergillus asthma
    • Bronchopulmonary aspergillosis
    • Colonizing aspergillosis
    • Invasive or disseminated aspergillosis
    • Superficial infections

Mycology Long Essays

Question 1. Give an account of infections caused by Can¬dida albicans. Describe the laboratory diagnosis of Candida.

Infections Caused by Candida:

Lesions caused by Candida are as follows.

Mycology Infections Caused By Candida

1. Oral thrush Features:

  • The lesions appear soft, white, and slightly elevated plaques
  • Sites:
    • Buccal mucosa
    • Tongue
    • Gingiva
    • Palate
    • The floor of the mouth
    • The entire oral cavity is involved in severe cases
  • Person affected are
    • HIV patients
    • Cancer patients undergoing chemotherapy or radiotherapy
    • Neonates and infants
    • Debilitated and chronically ill patients

2. Chronic oral candidiasis

  • Caused by denture-induced stomatitis or chronic hypertrophic candidiasis

Mycology Chronic Oral Candidiasis

3. Chronic mucocutaneous candidiasis

  • Integral lesions are similar to other types
  • Extraoral lesions involve skin, nails, and mucous

4. Angular stomatitis

  • Effects lips
  • Common in immunocompromised patients

5. Circumoral candidal dermatitis

  • Involves lips and area around lips

Candida Laboratory diagnosis:

1. Direct microscopy:

  • Gram-stained smears and KOH mounts from le¬sions of skin, nail (or) mucous membrane are used
  • These show budding Gram-positive yeast cells.

2. Culture:

  • Sabouraud’s dextrose agar media (SDA)
    • SDA is inoculated and incubated at 25 – 37° C for 24 hours.
    • Cream-coloured smooth pasty colonies appear.
    • On gram staining of it shows gram positive bud¬ding yeast cells.

3. Identification:

Candida albicans can be identified by

  • Germ tube test:
    • When incubated in human serum at 37oC, C. al-beans form germ tubes within two hours. – This is called Reynolds braude phenomenon
  • Chlamydospores.
    • Chlamydospores develop in cornmeal agar at; 20 degrees C.

Mycology Germ tube formation

4. Biochemical reactions:

  • C. albicans can be identified by the assimilation and fermentation of sugar.

5. Serology: 

  • C. Albicans can also be identified by the precipita¬tion test with a carbohydrate extract of group A an¬tigens.

Mycology Short Essays

Question 1. Mycetoma/Madhura foot.

  • Mycetoma is a chronic granulomatous infection of the subcutaneous tissue
  • It usually affects the foot but rarely even other parts of the body
  • Commonly seen in tropical countries.

Mycetoma Synonyms:

  • Madhura foot as it was first described from Madurai South India.
  • Madhuramycosis.

Mycetoma Etiology:

Causative agents are

  • Eumycetoma
    • Madhuvella mycetomi
    • Acremonium falciforme.
    • Actinomycetoma.
  • Actinomadura Madurai
    • Nocardia
    • Streptomyces.

Mycetoma Pathogenesis:

Mycology Candida pathogenesis

Mycetoma Treatment:

Mycology Causative organism treatment

Question 2. Actinomycosis.

It is a chronic granulomatous disease

Actinomycosis Causative Organism:

Mycology Actinomycosis Causative Organism

Actinomycosis Forms:

Mycology Actinomycosis Forms

Actinomycosis Features:

It is characterized by

  • Multiple abscesses
  • Tissue destruction
  • Fibrosis
  • Formation of multiple sinuses
  • Painless indurated swelling
    • It may cause gingivitis and periodontitis

Actinomycosis Diagnosis:

1. Microscopy

  • Steps
    • Dilute the pus with saline in a test tube
    • Allow it to settle
    • Sulfur granules are obtained from it
    • These granules are crushed between slides
    • Smears are prepared
    • One of them is Gram stained and the other is acid-fast stained
    • Observe these smears
  • Observations
    • Gram-stained smear shows Gram-positive filaments surrounded by peripheral radiating Gram-negative clubs
    • This results in a sun-ray appearance
    • Acid-fast smears show the central part of non-acid fast clubs surrounded by acid-fast clubs

2. Culture

Cultural media used are

  • Thioglycollate broth
  • Brain heart infusion agar
  • Blood agar
    • They are incubated anaerobically and aerobically with 5% CO2 at 37 degrees C for 2 weeks
    • It results in spider colonies

Actinomycosis Treatment:

  • It involves surgical removal of affected part
  • The antibiotic used in such cases is penicillin

Question 3. Pathogenesis of Candida albicans.

  • Candidiasis is an opportunistic endogenous infection
  • Predisposing factors are:
    • Diabetes
    • Immunodeficiency
    • Malignancy
    • Prolonged administration of antibiotics
    • Patients on immunosuppressive drugs and intra¬venous catheters
  • Lesions caused by it:

Mycology Short Question And Answers

Question 1. Ray fungus

  • Actinomyces are known as ray fungus
  • They are
    • Gram-positive
    • Non-motile
    • Non-sporing
    • Non arid fast organism
  • They appear as granules in the pus.
  • When these granules are crushed between two slides and Gram stained, they show a central filamentous mycelium surrounded by a peripheral zone of swollen radiating club-shaped structures
  • This gives it a sun-ray appearance
  • They cause actinomycosis

Question 2. Rhinosporidiasis.

Rhinosporidiosis is a chronic granulomatous disease.

Rhinosporidiasis Causative Organism:

  • Rhinosporidium seeberi.

Rhinosporidiasis Mode of Infection:

  • Frequent contact with stagnantwater.

Rhinosporidiosis Features:

  • Friable polyps
  • Sites involved- nose, mouth, and eye
  • Oral manifestations are Oropharyngeal lesions
  • They appear as soft red polypoid growth and spread to the pharynx and larynx.
  • These lesions contains mucoid discharge and are vascular.

Rhinosporidiosis Diagnosis:

  • H and E stained tissue sections show a large number of endospores within the sporangia
  • These are embedded in a stroma of connective tissue, and capillaries

Question 3. Cryptococcosis?

It is caused by a Cryptococcus neoformans, a capsu- lated yeast

Cryptococcosis Morphology:

  • A spherical budding cell having a prominent polysaccharide capsule.
  • It is a true yeast and gram-positive.

Cryptococcosis Pathogenesis:

  • Occurs through inhalation

Mycology Cryptococcosis pathogenesis

Sites Involved:

  • Skin
  • Lymph nodes
  • Bones
  • Cutaneous lesions characterized by small ulcers to large granuloma

Laboratory diagnosis:

  • Laboratory diagnosis is done by direct microscopy, culture, latex agglutination test, and animal inoculation test

Question 4. Aspergillosis?

Aspergillosis Etiology:

  • Aspergillosis is caused by inhalation of aspergillus co- nidia (or) mycelia fragments which are present on the decaying matter, soil (or) air.

Aspergillosis Forms:

3 clinical forms of aspergillosis are

Mycology Clinical forms of aspergillosis

Aspergillosis Laboratory Diagnosis:

  • KOH smears show non-pigmented septate hyphae with characteristic dichotomous branching.


  • The clinical specimen is inoculated on SDA without cycloheximide and incubated at 25oC.
  • Colonies appear within 2 days


  • It shows a velvety to powder surface and are colored.

Mycology Colonies

Question 5. Name three opportunistic fungi.

  • Some saprophytic fungi usually do not produce disease but may cause infection under special conditions such as immune-compromised individuals and terminal stages of chronic disease.
  • These are called as opportunistic fungi.

Examples are:

Mycology Fungi Examples

Predisposing conditions:

  • Widespread use of antibiotics, corticosteroids
  • Immunosuppressive drugs
  • Immunosuppressive diseases like AIDS.

Question 6. Mention two important media for culturing fungi.

  • Sabouraud’s dextrose agar (SDA)
  • SDA medium with antibiotics
  • Brain heart infusion (BHI) agar with blood and antibiotics.
    • Fungi are incubated at 37 degrees C and 25 degrees C for 3 weeks in SDA medium
    • Chloramphenicol is added in the culture medium to suppress the growth of contaminating bacteria while cyloheximide is incorporated to suppress the contaminating fungi.

Question 7. Fungus affecting hair

  • Dermatophytes are the group of fungi affecting hair.
  • Favus is a chronic type of ringworm involving the hair follicles

Fungus affecting hair Features:

  • Alopecia
  • Scarring
  • Sparse hyphal growth
  • Formation of air spaces within the hair shaft

Fungus affecting hair Types:

Mycology Fungus affecting hair types

Mycology Ectothrix and endothrix

Question 8. A quick method of diagnosing Cryptococcus neoformans.

  • The latex agglutination test is a quick method for diagnosing Cryptococcus neoformans
  • In this test, polystyrene latex particles are employed to absorb the antigen
  • Latex agglutination tile is used in it
  • The antigen detected is Cryptococcal capsular polysaccharide antigen
  • The specimen used is CSF, serum or urine.

Question 9. Mention two oral fungal infections

  • Oral fungal infections are:
    • Rhinosporidiosis
    • Sporotrichosis
    • Histoplasmosis
    • Blastomycosis
    • Candidiasis

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