Fungi

Question 1

Give examples of superficial cutaneous mycoses.

Answer 1

Dermatophytosis

Superficial candidiasis

Malassezia

Question 2

Explain dermatophytosis.

Answer 2

Dermatophyte fungi (group of fungi) digest keratin.

This causes infection of skin and keratinised structures like hair and nails.

Question 3

Presentation of dermatophytosis.

Answer 3

Scale and pruritus.

The skin lesions are usually anular with central healing like ring worm and tinea corporis.

Tinea pedis affects up to 15% of healthy population. Tinea pedis is also known as Athlete’s foot and is a type of dermatophytosis - There are skin erosions and blisters in toe web spaces and dry scale on soles.

Question 4

What is fungal nail disease?

Answer 4

A type of dermatophytosis leading to onchomycosis aka tinea unguium.

Question 5

What is tinea capitis?

Answer 5

Dermatophytosis of the scalp.

It leads to scalp scaling and alopecia

Question 6

Explain superficial candidiasis.

Answer 6

Usually Candida albicans.

This fungi is commensal in the mouth, vagina and GI tract.

However when a patient is immunosuppressed or on antibiotic treatment this commensal can start to take over its environment.

Question 7

Presentation of superficial candidiasis.

Answer 7

Oropharyngeal = white patches on erythematous background, soreness, inflamed areas.

Genitourinary - soreness and white patches + discharge

Skin = Usually in folds/interdigital

Question 8

What is Malassezia?

Answer 8

A fungi that is commensal to greasy skin

Question 9

Presentation of Malassezia.

Answer 9

There are different types;

Pityriasis versicolor - scaly hypo/hyperpigmened rash with scaling

Seborrhoeic dermatitis - scaling of face, scalp and anterior chest.

Malassezia folliculitis - itchy, follicular rash on back and shoulders

Question 10

Diagnosis of superficial/cutaneous mycoses.

Answer 10

Clinical + microscopy of skin scrapings.

Question 11

Treatment of superficial mycoses.

Answer 11

Topical “-azole” antifungal or tebinafine 1-4 weeks.

Also topical nystatin and amphotericin in superficial candidiasis.

Tinea capitis - griseofulvin, terbinafine or itraconazole

Nail infection requires systemic treatment like terbinafine or itraconazole.

Question 12

Give examples of systemic/invasive mycoses.

Answer 12

Invasive candidiasis

Cryptococcus

Histoplasmosis

Blastomycosis

Question 13

Explain invasive candidiasis.

Answer 13

This typically occurs in immunocompromised patients, in comorbidity or in ITU settings.

Question 14

Presentation of invasive candidiasis.

Answer 14

Febrile with no microbiological evidence of infection.

New murmur

Muscle tenderness

Skin nodules

Question 15

Diagnosis of invasive candidiasis.

Answer 15

Repeated blood/tissue cultures

PCR

Candida in respiratory secretions alone is not enough.

Question 16

Treatment of invasive candidiasis.

Answer 16

Remove all possible catheters

Echinocandins, fluconazole, amphotericin.

Consider empirical treatment if persistent fever or unresponsive to other therapy.

Question 17

What might cryptococcus cause?

Answer 17

It is seen in HIV infection and can cause pneumonia or meningitis.

Question 18

Presentation of cryptococcus.

Answer 18

Usually in immunosuppressed like HIV, Sarcoid, Hodgkin’s, haematological malignancy and post-translplant.

Symptoms might be very non-specific.

Headache, confusion, ataxia, focal neurological signs, fever, cough, pleuritic pain and SOB.

Question 19

Diagnosis of cryptococcus.

Answer 19

Indian ink CSF stain

Culture blood/CSF/BAL

Antigen testing in blood/CSF

Question 20

Treatment of cryptococcus

Answer 20

Amphotericin + flucytosine, fluconazole

Question 21

Explain histoplasmosis.

Answer 21

There is worldwide distribution of Histoplasma and it can be found in soil contaminated with bird and bat faeces.

The illness depends on the host’s immunity.

Question 22

Presentation of histoplasmosis.

Answer 22

Flu-like symptoms

Fever

Malaise

Cough

Headache

Myalgia

Pneumonia

Lung nodules/cavitation

Pericarditis

Mediastinal fibrosis and granulomas making it look like sarcoidosis or TB.

Question 23

Diagnosis of histoplasmosis.

Answer 23

Serology and antigen testing

Question 24

Treatment of histoplasmosis.

Answer 24

If tehre is moderate-severe lung disease or any CNS involvment amphotericin and itraconazole is given.

If not - conservative treatment

Question 25

Where can Blastomyces be found?

Answer 25

In Decomposing matter mainly in USA and canada

Question 26

Presentation of blastomycosis.

Answer 26

Fever

Cough

Night sweats

ARDS

There is a risk of extrapulmonary disease as well with immunosuppression such as skin, bone, GU and CNS disease.

Question 27

Diagnosis of blastomycosis.

Answer 27

Culture

Antigen detection

Question 28

Treatment of blastomycosis.

Answer 28

Amphotericin and itraconazole

Question 29

When should you suspect invasive fungal infection?

Answer 29

Any patient with riskfactors for it such as infection, malignancy, critical illness, catheter, transplantation, genetic, surgical or other comorbidity.

Any systemically unwell patient who fails to respond to antibiotic therapy.

Any persistently febrile patient with no microbiological evidence of infection

Question 30

Investigations of invasive fungal infection.

Answer 30

Blood cultures - three samples at different sites in the same sitting.

Microscopy + immunohistochemistry/fluorescence depending on site/risk

Antigen/antibody testing

PCR