Microbiology 18: Fungal Infections Flashcards
Name 3 yeasts ?
Candida (most common)
Cryptococcus
Histoplasma
Name 2 Moulds ?
Aspergillus
Dermatophytes
What does it mean if a fungi is dimorphic?
It can change between yeasts and moulds depending on environmental conditions
Which groups of people are particularly at risk of systemic candidiasis ? (5)
- Very low birth weight infants
- Immunocompromised
- Patients on ITU
- Patients receiving TPN
- Pts on ABx - antibiotics will kill the commensals
How do you differentiate Candida Albicans from other Candidas ?
They form Germ tubes
What is the candida infection that affects skin folds in children called ?
Intertrigo
Which yeast infection is particularly more common in HIV +ve patients ?
Cryptococcus - since impaired T cell immunity
NB second most common cause of death in AIDS
Which yeast shows capsules when stained on India ink ?
What is now preferred to Ix this organism instead of India Ink?
Cryptococcus - The ink will stain everything black EXCEPT for the capsule around the yeast
enzyme immunoassay (EIA) - to look for components of the capsule
Name the Cryptococcus Neoformans variant which causes meningitis in immunosupressed people especially around SE asia and Australia where there are Eucalyptus trees ?
Cryptococcus Neoformans var. gatii
Which antigen if detected in serology can suggest aspergillus infection ?
Galactomannan
Name an aggressive disease caused by a mould which is considered a surgical emergency and requires debridement ?
Which 2 groups does it mainly affect?
What is Tx?
Mucormycosis - Characterised by cellulitis of the orbit and face which progresses with discharge and black pus from the palate and nose - eventually involves the brain (rhinocerebral mucormycosis)
- Immunocompromised patients
- Poorly controlled diabetics
Tx: ENT team + Amphotericin (HIGH DOSE)
A hyper pigmented lesion on the back which has a “spaghetti and meatballs” appearance on microscopy and orange fluorescence under Wood’s light.
Most likely organism ?
Malassezia furfur
This is pityriasis versicolour
A rose gardener gets pricked by a rose thorn on his arm. This leads to small nodular lesions on the surface which start to ulcerate.
Most likely organism ?
Sporothrix schenkii (rose gardener’s disease)
This fungus causes loss of hair and scaly red lesions on the scalp.
Most likely organism ?
Tinea capatis
List 4 types of infections caused by Tinea ?
- Athletes foot (Tinea pedis)
- Ringworm (Tinea Corporis) - body
- Tinea capatis - head
- Tinea cruris - groin
What is the main treatment for Aspergillus infection ?
Amphotericin - 6 weeks
1st line antifungal in each situation
- Skin- imidazole
- Female genital area- clotrimazole
- Oral- miconazole or if extensive, PO fluconazole
PLEASE CLOZE DELETE EACH DRUG (AND DO ALL AS C1)
Which drug is still effective for candida albicans but is slowly losing sensitivity?
(ANSWER TO SECOND Q): fluconazole
Which anti fungal is used to treat Cryptococcus infection ?
amphotericin B +/- flucytosine
NB echinocandins are used as empirical therapy for Candida infections, however Cryptococcus is RESISTANT to echinocandins
Fungus causing systemic infection or meningitic disease
Cryptococcus neoformans
Which organism causes Pityriasis versicolour ?
Malassezia. FurFur
Which organism causes seborrheic dermatitis ?
Malassezia globosa
Which fungus can grow on Sabouraud agar?
What Ix are done for this infection?
Candidiasis
- swabs
- blood culture
- Serology: beta-D Glucan assay
features of cryptococcus
acute pulmonary, systemic or meningitic disease cause by inhalation of a fungus
ambisome treatment
AIDS and T cell impaired patients more susceptible
cryptococcal meningitis can cause hydrocephalus
Antifungal used for non-albican candida
Echinocandins
