Fungal infections Flashcards
3 main fungal pathogens
aspergillus - aspergillus fumigus
candida - candida albicans
Cryptococcus - Cryptococcus neoformans
6 groups of patients fungal infections affect and why
opportunistic infection affecting those with impaired immunity
- primary immunodeficiency
- HIV/AIDS
- malignancy and transplant
- premature neonates
- ICU
- chronic lung conditions eg asthma, CF, COPD
4 risk factors for mucocutaneous candidiasis
antibiotic use
inhaled steroids
moist areas
neonates <3 months old
3 presenting symptoms of primary immunodeficiency
neutropenia
low CD4+ T cells
impaired IL-17 immunity
Where is the most common source of invasive candidiasis?
it is a gut commensal so invasive candidiasis is usually endogenous in nature
4 risk factors for invasive candidiasis
broad spectrum antibiotics
intravascular catheters
total parenteral nutrition
abdominal surgery
diagnosing invasive candidiasis
blood culture or culture from usually sterile site
B-d-glucan high NPV to exclude
PCR, assays
Why is diagnosing invasive candidiasis more difficult in children?
sampling issues
List the steps of invasive pulmonary aspergillosis infection
sporulation
inhalation of airborne conidia
conidial germination in absence of sufficient pulmonary defences
Who does acute invasive pulmonary aspergillosis affect?
neutropenic patients post transplant (stem cell> solid organ) defects in phagocytes
how long does chronic pulmonary aspergillosis last and who does it affect?
over 3 months
those with underlying chronic lung conditions
Who does allergic aspergillosis affect?
CF and asthma
Difference between acute and subacute invasive pulmonary aspergillosis
subacute is a non neutropenic host and non angioinvasive with limited fungal growth
How does invasive aspergillosis present as a symptom of primary immunodeficiency?
congenital neutropenia
chronic granulomatous disease
often outside lungs eg brain, spine, abdomen, bone
Briefly describe the presentation and findings of chronic pulmonary aspergillosis
pulmonary exacerbations, resp symptoms, lung function decline
positive sputum cultures for aspergillus
5 findings on investigations in allergic bronchopulmonary aspergillosis
(sub)acute lung function deterioration and resp symptoms
new abnormalities on chest imaging
elevated IgE
increased aspergillus specific IgE or positive skin test
positive aspergillus specific IgG
Pulmonary aspergilloma
a fungal mass that usually grows in the lung cavities
Who does pulmonary aspergilloma affect?
TB, sarcoidosis, bronchiectasis etc
diagnosing pulmonary aspergillosis in a non neutropenic host
sputum culture/bronchoalveolar lavage/biopsy
aspergillus specific IgG and IgE in chronic and allergic pulmonary aspergillosis
What types of pulmonary aspergillosis is aspergillis specific IgG and IgE raised?
chronic and allergic
How to diagnose pulmonary aspergillosis in a neutropenic host
high res CT chest - halo sign
molecular markers in blood
BAL and biopsies
How is Cryptococcus transmitted?
inhalation - bark of trees, bird faeces etc
Danger of Cryptococcus infection in those with HIV
meningoencephalitis
How does meningoencephalitis in those with HIV/AIDS present?
headache, confusion, coma, vision
2 bodily fluids used in the diagnosis of cryptococcal infection
blood and CSF
findings of CSF analysis in Cryptococcus
india ink preparation
culture, increased protein and decreased glucose
Cryptococcus antigen
findings of blood analysis in Cryptococcus
culture and Cryptococcus antigen
List 4 antifungal agents and route of delivery
amphotericin B (IV)
azoles (IV and oral)
echinocandins (IV)
flucytosine (IV and oral)
Action of amphotericin B
act on ergosterol > lysis
Action of azoles
inhibit ergosterol synthesis
Action of echinocandins
inhibit glucan synthesis
Action of flucytosine
inhibit fungal DNA synthesis
Some challenges and needs for future mycology
no vaccines or immunotherapies
new antifungals - toxicity, resistance, cost
diagnostics - sensitivity, specificity
