Fungal infections Flashcards
What are fungi?
Eukaryotic organisms with chitinous cell wall and ergosterol containing plasma membranes
How to categorise fungi?
Yeasts - Sing cell that reproduces by budding (Candida, cryptococcus)
Moulds - Grow by branching and extension (Dermatophytes, apergillus)
Commonest cause of fungal infections in humans?
Candida
When does oral candida usually present?
If you are immunocompromised or if you have broad spectrum abx
How does superficial candida infection present?
Oral thrush, candida oesophagitis, vulkvovaginit or even cutaneous
How to treat superficial candida?
Topical:
Nystatin - Oral
Cotrimazole - Vulvovaginitis, localised cutaneous
Oral:
Fluconazole
How does microscopy of yeast look like?
Large clusters
Gram +ve
Which patients have a high risk of candidaemia?
(Haem) malignancies
Burns patients
Post op
Long lines
What investigations would you do for candida?
Imaging
Beta D glucan serology
Echo to look for endocarditis
Fundoscopy for candida endophthalmitis
What is the management for candida?
Echinocandin - Anidulafungin
Remove line or prosthetic materials
How to treat candida infection in the CNS?
Ambisome or voriconazole
How to treat candida infection in the bones and joints?
Ambisome or voriconazole
How to treat candida infection in endocarditis?
Ambisome or voriconazole
How to treat candida infection in the urinary tract?
Fluconazole
How to treat intra abdominal candida infection?
Peritoneal dialysis with echinocandin or fluconazole
What is cryptococcus?
Encapsulated yeast
What are the different serotypes of cryptococcus?
A and D - C Neoformans (Immunodeficient)
B and C - C Gattii (Immunocompetent)
How is cryptococcus transmitted?
Inhalation of aerosolised organisms
Which animal is cryptococcus associated with?
Pigeons
What is a risk factor for cryptococcus?
HIV
Organ transplant - Patients taking T cell immunosuppresants (Tacrolimus) - May have menegitis due to this
What does a C Gatti infection commonly cause?
Space occupying lesions in brain and lungs
Meningitis
What ink is used for cryptococcus stain?
India
What serum test / CSF would you do for cryptococcus?
Cryptococcal antigen
How to treat cryptococcal meningitis?
Amphotericin B + Flucystosine - 2 weeks
High does fluconazole - 8 weeks
Low does fluconazole - 1 year
Due to high opening CSF pressure, need to repeat lumbar punctures to relieve the pressure
On a side note, what can you find on a CSF sample in sub arachanoid haemorrhage?
Xanthochromia - break down of blood products
Why do you ask patients to lie down after lumbar puncture?
You may have low CSF pressure so you can get a headache
How to test for Aspergillosis
Aspergillus antibodies - Galactomannan
How to treat aspergillus
Voriconazole
Ambisome
What is pneumocystis jiroveci?
Lacks ergosterol in cell wall
Who is at risk of getting pneumocystis jiroveci?
Debilitated infants
Severe protein malnutrition
How to diagnose pneumocystis jiroveci?
Microscopy
PCR
Serum Beta D Glucan
How to treat pneumocystis jiroveci?
High dose cotrimoxazole
Steroids if hypoxia is present
Who is at risk of getting mucormycoses?
Immunosuppresed and diabetic patients
How does mucormycoses present?
Rhinocerebral - Cellulitis of orbit and face, black pus form palate and nose, opthalmoplegia, low GCS
Pulmonary
Cutaneous
How to treat mucormycoses?
Broad spectrum anti fungals
Surgery
How do dermatophytes invade?
Invades dead keratin of skin, hair and nails
Name some sites where dermatophytes grow and what the condition is called?
Tinea pedis - Feets
Tinea capitis - Scalp
Tinea cruris - groin
Tinea corporis - abdo
What is onichomycosis commonly caused by?
Trichophyton spp
What is pitrriasis versicolor caused by?
Malassezia furfur
How to treat pityriasis and onichomycosis?
Topical - clotrimazole, ketoconazole
What side effects do azoles cause?
Abnormal LFTs
What side effects do polyenes cause?
Nephrotoxicity - Potassium, sodium and magnesium wasting
What side effects do echinocandins cause?
Relatively innocuous
What side effects do pyrimidine analogues cause?
Blood disorders
Which part od the fungal cell do polyenes and azoles attacks?
Cell membrane
Are azoles P450 inducers or inhibitors?
Inducers
Which part of the fungal cell do echinocandins attack?
cell wall - inhibits Beta 1-3 d glucan synthase enzyme
Which fungi does echinocandins cover?
Candida
Aspergillus
Does NOT cover cryptococcus
Which part of the fungal cell does pyrmidine analogues such as Flucytosine attack?
DNA RNA synthase
What is Flucytosine used for?
Candida and cryptococcal meningitis in combination with ambisome/fluconazole
When do you need to monitor Flucytosine blood levels?
When used in conjunction with amphotericin
