Fungal infections Flashcards
Fungal infections are opportunistic and can affect patients with certain chronic lung diseases such as…?
Asthma
CF
Chronic obstructive lung disorders
Name some specific fungal diseases caused by cryptococcus or candida species?
Candida - Thrush and Canidemia
Cryptococcus - Meningitis
Name some specific fungal diseases caused by Pneumocystis or Aspergillus species
Pneumocystis - Pneumocystis pneumonia
Aspergillus - Allergic and invasive pulmonary aspergillosis and Aspergilloma
What is candidiasis?
Candidiasis is skin and mucous membrane (mucocutaneous) infection withCandidaspecies
Infections can occur anywhere and are most common in moist areas like in skinfolds, digital web spaces, genitals, cuticles, and oral mucosa.
Can be a side effect of overuse of inhalation steroids
What is invasive candidiasis?
Candida colonises in the gut and gets into the bloodstream (this could be by peritonitis, surgical anastomotic leakage or translocation or an IV catheter).
It spreads to other organs including the eyes, kidneys, liver and brain etc
Mortality is up to 40%
What sorts of things can put you at risk of invasive candidiasis in hospital? (4)
Broad-spectrum antibiotics
Intravascular catheters
Total parenteral nutrition
Abdominal surgery
How is invasive candidiasis diagnosed?
A blood culture or tissue culture
PCR
β-d-glucan test
Where/ in whom are you likely to see invasive candidiasis infections?
Immunocompromised
Patients with co-morbidities
ITU/ICU
Risk factors of invasive aspergillosis
Immunocompromised e.g HIV, leukaemia, burns or broad spectrum antibiotic use
How does aspergillosis become invasive?
Inahlation of airborn spores
The spores germinate in absence of sufficient pulmonary defences
What are the 5 ways that aspergillus affects the lungs?
Asthma
Allergic bronchopulmonary aspergillosis
Aspergilloma
Invasive aspergillosis
Extrinsic allergic alveolitis
What is aspergilloma?
A fungus ball/mass within a pre-existing cavity (often caused by TB or sarcoidosis)
It is usually asymptomatic but can have cough, haemoptysis, weight loss etc
What is Allergic bronchopulmonary aspergillosis?
Immunological responses to a variety of A. fumigatus antigens in the CF host
Results from type 1 and 3 hypersensitivity reactions to aspergillus fumigatus.
It affects Asthmatics and CF patients
Initially causes bronchoconstriction then permanent damage occurs causing bronchiectasis
Chronic pulmonary aspergillosis
Pulmonary exacerbations with a decline in lung function >3 months
Increased respiratory symptoms such as cough, decreased exercise tolerance and dyspnoea
Positive sputum cultures for Aspergillus
Affects Asthmatics, CF and COPD patients
How is pulmonary aspergillosis diagnosed in non-neutropenic patients?
Cultures of sputum and/or bronchoalveolar lavage, and/or biopsy
Aspergillus specific IgG and IgE in chronic and allergic pulmonary aspergillosis
How is pulmonary aspergillosis diagnosed in neutropenic patients?
High resolution CT-chest - looking for halo sign or air-crescent sign
Molecular markers in blood
Bronchoalveolar lavage, and/or biopsy where possible
How is cryptococcus transmitted?
Inhalation - it can be found on the bark of a variety of trees, bird faeces and organic matter
What can a cryptococcus infection progress into?
- Pneumonia
- Dissemination into the brain causing Meningoencephalitis in HIV/AIDs patients
How does cryptococcosis present?
Headache
Confusion
Altered behaviour
Visual disturbances
Coma due to raised ICP
How is cryptococcal disease diagnosed?
CSF: Indian Ink preparation, culture, high protein and low glucose
Cryptococcus antigen
Blood: culture, cryptococcus antigen test
Cryptococcal menignitis has a high mortality rate in Africa.
What are some factors that are associated with mortality in this case?
Delay in presentation and diagnosis
Lack of access to antifungals
Inadequate induction therapy
Delays in starting antiretroviral therapy
Immune reconstitution syndrome
Name some antifungal agents used to treat invasive fungal infections
Amphotericin B formulations (iv) - acts on ergosterol (in cell membrane) = broadest anti-fungal
Azoles (iv, oral)
Echinocandins (iv)
Flucytosine (iv, oral) - inhibits DNA synthesis
Which anti-fungals are opted for in invasive candidiasis?
Echinocandins
Fluconazole
Which anti-fungals are opted for in invasive aspergillosis?
Voriconazole
Lsavuconazole
