Fungi Flashcards
Give examples of superficial cutaneous mycoses.
Dermatophytosis
Superficial candidiasis
Malassezia
Explain dermatophytosis.
Dermatophyte fungi (group of fungi) digest keratin.
This causes infection of skin and keratinised structures like hair and nails.
Presentation of dermatophytosis.
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.
What is fungal nail disease?
A type of dermatophytosis leading to onchomycosis aka tinea unguium.
What is tinea capitis?
Dermatophytosis of the scalp.
It leads to scalp scaling and alopecia
Explain superficial candidiasis.
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.
Presentation of superficial candidiasis.
Oropharyngeal = white patches on erythematous background, soreness, inflamed areas.
Genitourinary - soreness and white patches + discharge
Skin = Usually in folds/interdigital
What is Malassezia?
A fungi that is commensal to greasy skin
Presentation of Malassezia.
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
Diagnosis of superficial/cutaneous mycoses.
Clinical + microscopy of skin scrapings.
Treatment of superficial mycoses.
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.
Give examples of systemic/invasive mycoses.
Invasive candidiasis
Cryptococcus
Histoplasmosis
Blastomycosis
Explain invasive candidiasis.
This typically occurs in immunocompromised patients, in comorbidity or in ITU settings.
Presentation of invasive candidiasis.
Febrile with no microbiological evidence of infection.
New murmur
Muscle tenderness
Skin nodules
Diagnosis of invasive candidiasis.
Repeated blood/tissue cultures
PCR
Candida in respiratory secretions alone is not enough.
Treatment of invasive candidiasis.
Remove all possible catheters
Echinocandins, fluconazole, amphotericin.
Consider empirical treatment if persistent fever or unresponsive to other therapy.
What might cryptococcus cause?
It is seen in HIV infection and can cause pneumonia or meningitis.
Presentation of cryptococcus.
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.
Diagnosis of cryptococcus.
Indian ink CSF stain
Culture blood/CSF/BAL
Antigen testing in blood/CSF
Treatment of cryptococcus
Amphotericin + flucytosine, fluconazole
Explain histoplasmosis.
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.
Presentation of histoplasmosis.
Flu-like symptoms
Fever
Malaise
Cough
Headache
Myalgia
Pneumonia
Lung nodules/cavitation
Pericarditis
Mediastinal fibrosis and granulomas making it look like sarcoidosis or TB.
Diagnosis of histoplasmosis.
Serology and antigen testing
Treatment of histoplasmosis.
If tehre is moderate-severe lung disease or any CNS involvment amphotericin and itraconazole is given.
If not - conservative treatment
Where can Blastomyces be found?
In Decomposing matter mainly in USA and canada
Presentation of blastomycosis.
Fever
Cough
Night sweats
ARDS
There is a risk of extrapulmonary disease as well with immunosuppression such as skin, bone, GU and CNS disease.
Diagnosis of blastomycosis.
Culture
Antigen detection
Treatment of blastomycosis.
Amphotericin and itraconazole
When should you suspect invasive fungal infection?
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
Investigations of invasive fungal infection.
Blood cultures - three samples at different sites in the same sitting.
Microscopy + immunohistochemistry/fluorescence depending on site/risk
Antigen/antibody testing
PCR
