MICRO: Fungal infections Flashcards
What are fungi?
Eukaryotic cells - chitinous cell walls, membrane containing ergosterol, 80S ribosomes
What are the main 2 types of fungi?
- Dimorphic = change between yeasts and moulds
![](https://s3.amazonaws.com/brainscape-prod/system/cm/385/832/569/a_image_thumb.png?1634115970)
What is the commonest fungal infection?
Candida spp - this is a yeast
Where can candida be grown in the lab?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/385/832/572/a_image_thumb.png?1634116108)
Where can you grow candida to distinguish between different species?
Chromogenic agar
- Aetiological agents:
- Candida albicans (MOST COMMON)
- Candida glabrata
- Candida krusei
- Candida tropicalis
- Candida auris (newly discovered and very dangerous)
![](https://s3.amazonaws.com/brainscape-prod/system/cm/385/832/574/a_image_thumb.png?1634116166)
What are the types of superficial candida infections?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/385/832/575/a_image_thumb.png?1634116314)
How do you treat superficial candida infections?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/385/832/576/a_image_thumb.png?1634116404)
Which one is yeast?
- Form individual cells (a bit like bacteria but much bigger)
- Replicate by budding
- Grow in colonies (a bit like bacteria)
- Distributed world-wide
- Periodic Acid-Schiff (PAS) stain
Stain gram positive on the gram stain.
![](https://s3.amazonaws.com/brainscape-prod/system/cm/385/832/577/a_image_thumb.png?1634116437)
What are the risk factors for candidaemia?
- malignancy esp haem
- burns
- complicated post-op courses
- long lines
What is the management of candidaemia?
Candida is very sticky so can stick to many different organs hence the many investigations.
![](https://s3.amazonaws.com/brainscape-prod/system/cm/385/832/579/a_image_thumb.png?1634116557)
What is the first line antifungal when you are told that there is a yeast infection in the blood?
Echinocandin e.g. anidulafungin
Give examples of invasive candida infections.
![](https://s3.amazonaws.com/brainscape-prod/system/cm/385/832/582/a_image_thumb.png?1634116642)
What are the main types of cryptococcis?
Characterised by having a large capsule
![](https://s3.amazonaws.com/brainscape-prod/system/cm/385/832/583/a_image_thumb.png?1634116735)
Which animal is cryptococcus associated with?
Pigeons
What is the lifecycle of cryptococcus?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/385/832/585/a_image_thumb.png?1634116805)
What are the risk factors for cryptococcosis?
Impaired T cell immunity e.g. in reduced CD4 helper T cells <200/ml
Taking T cell immunosuppressants for organ transplant - 6% lifetime risk
What is the difference between cryptococcus neoformans and gatti?
-
Cryptococcus neoformans Immunodeficient
- Greatly increased in patients with impaired T-cell immunity (AIDS with very low CD4+ counts)
- Second most common cause of death in AIDS
- Patients taking immunosuppressants for solid organ transplant (6% lifetime risk)
-
Cryptococcus (neoformans var) gattii Immunocompetent
- Affects immunocompetent individuals in tropics (especially SE Asia and Australia)
- High incidence of SOLs in the lung and brain
- Increased resistance to amphotericin B
Which stain is used to identify cryptococcus? What other diagnostic tools are used?
- India ink stain of CSF (seen below with large capsule)
- Imaging
- Lateral flow for cryptococcal antigen
- Culture from body fluids/blood
![](https://s3.amazonaws.com/brainscape-prod/system/cm/385/832/588/a_image_thumb.png?1634117058)