Antifungal Flashcards
Who is at risk of getting invasive fungal infections?
people who are
- receiving aggressive immunosuppressive therapy
- receive invasive devices = central venous catheters
- receiving new immune modifying drugs
- having prolonged use of broad spectrum antibiotics
- having other co-morbidities = HIV, diabetes, TPN
- affected by environmental factors = building sites, hay
What are the types of invasive fungal infections?
- causative agents
candida
aspergillus
cryptococcus neoformans
moulds - mucormycosis
What is empiric prescribing?
treatment directed against anticipated and likely cause of infectious diseases
- are given before the causative agent is known
can lead to resistance due to lack of gold standard diagnostics
What are the main classes of antifungals? What are examples?
azoles - fluconazole, voriconazole, itraconazole
echinocandins - anidulafungin, caspofungin
polyenes - amphotericin B, nystatin
What is Candidiasis? Why is diagnosing limited for candida infections?
infections caused by Candida spp
- a type of yeast
can affect the bloodstream, heart, brain, kidneys, GIT, eyes, etc
blood cultures are limited for diagnosing invasive candidiasis due to
- its poor sensitivity and slow turn around time
What are signs of candidaemia?
- bloodstream infection caused by candida = most common form
fevers and chills that do not improve with antibiotics
it can cause septic shock
- low blood pressure, fast heart rate, rapid breathing
What is the treatment for invasive candidiasis?
1st line - IV echinocandins
once stable and improving, the patient can be stepped down to
2nd line - oral azoles
What are the challenges associated with candidiasis management?
it can be difficult for anti fungal drugs to reach an adequate and effective concentration at the site of infection
- urine = only fluconazole can reach the urine, amphotericin B and flucytosine could be used but they are limited due to toxicity
drug resistance
What are the types of candidiasis?
C.albicans
- most common type that causes invasive disease and blood stream infection
C.glabrata
- has reduced susceptibility to fluconazole
- preferred treatment is echinocandins
C.parapsilosis
- common in neonates, infants and people with central venous catheters
- more susceptible to azoles than echinocandins
C.tropicalis
- more common in cancer patients
- are susceptible to azoles and echinocandins
C.krusei
- uncommon type and is seen in haematological malignancies
- resistant to fluconazole
- can be treated with echinocandins and step down is voriconazole
C.auris
- all are fluconazole resistant and variably resistant to other azoles, polyenes and echinocandins
What is a biomarker for candidiasis?
beta-D-glucan
- component of fungal cell wall
- high negative predicted value, >97%
What is the candida risk score?
evidence of unexplained infection
antibiotic exposure - >5 days
host risk factors - TPN, decompensated liver failure, diabetes, >72hrs corticosteroids, immunosuppressive therapy
How should candidaemia be managed?
central venous catheters should be removed and a tip line sent for culture
- source control
follow up blood cultures should be taken to confirm clearance of infection
duration of treatment is 2 weeks from the date of the first negative blood culture with no missed doses
ophthalmic examinations should be performed in all non-neutropenic patients within a week of therapy
- to check if endophthalmitis has occurred secondary to candidaemia
echocardiography (ECGs) should be considered to exclude endocarditis
What is aspergillosis?
mould found worldwide in hay, compost, soil, cellars and plants
most common site of infection is the respiratory tract
- lungs, sinuses
recommended treatment for invasive pulmonary aspergillosis is to continue for a minimum of 6-12 weeks
How is aspergillosis infection diagnosed?
most are diagnosed using radiography with confirmatory biomarkers tests
- serum or bronchoalveolar lavage (BAL) fungal biomarkers
= galactomannan (polysaccharide found in the cell wall) or beta-D-glucan
What are the risk groups for invasive aspergillosis infection?
prolonged neutropenia (AML, ALL, MDS)
allogenic stem cell transplant
solid organ transplant
high dose/prolonged steroids
