Fungal Infections
  • Aspergillus Fumigatus

This is a moulid which affects the lungs both directly and indirectly. It is a systemic opportunist and so typically affects those who are immunocompromised or more susceptible to infection.

– Can indirectly cause Asthma and also Extrinsic Allergic Alveolitis as well as direct pathologies:

 

– Allergic Bronchopulmonary Aspergillosis (ABPA)

Aspergillus Fumigatus causes type I and III hypersensitivity reactions, which is particularly seen in people with Asthma and Cystic Fibrosis. This leads to acute bouts of inflammation and bronchiectasis.

– It initially causes bronchoconstriction giving asthma symptoms then permanent damage giving bronchiectasis

Symptoms:

– Wheeze and Dyspnoea

–  Cough with sputum containing fungal hyphae

– Bronchiectasis

– Recurrent chest infections

Investigations:

– High resolution CT – shows bronchiectasis

– Radioallergosorbent (RAST) Aspergillus test

– Positive IgG Precipitins

– Raised IgE and eosinophilia

Management – 1st line Oral steroids –> 2nd line Itraconazole

 

– Aspergilloma

This is when the mould forms a fungal clump within a body cavity.

Risk factors – TB, Sarcoidosis, Lung cancer

Symptoms: Asymptomatic in most people, however can resemble a lung cancer

Cough with blood, weight loss

Investigations: CXR shows lung cavity, High titres of IgG                                                         Aspergillus Precipitins

– CT shows air-crescent sign

 

Management – Treat with Itraconazole + Amphotericin –> Consider surgical excision

 

– Invasive Aspergillosis

This occurs in people with a severe neutrophil deficiency. The mould becomes invasive and starts to penetrate the lungs and paranasal sinuses and has a high mortality.

 

Risk factors: HIV, Leukhaemia, Immunocompromised

 

Diagnosis: Made by a lung biopsy                                        Treatment: IV Voriconazole + Amphotericin

 

  • Cryptococcus Neoformans

This is a yeast found in bird droppings which is the most common fungal infection of the CNS.

– It is a systemic opportunist which typically causes infections in immunocompromised patients + IVDU

– Usually causes infections in the lung, but most serious infection is meningitis infection in AIDS patients

 

Symptoms – Commonly seen in patients with AIDS with CD4 count <100cells/mm3

– Meningitis (fever, headache, seizure, vomiting)                      – Focal neurological deficit

 

Tests – CT –> shows cerebral oedema

– Lumbar puncture –> CSF has high opening pressure, India ink test positive

– High Lymphocytes, low neutrophils, raised protein, low glucose (therefore atypical)

 

Management – IV Amphotericin + flucytosine

 

  • Pneumocystis Jirovecci/Carinii

A fungal infection that is an AIDS defining disease, typically causing a pneumonia in HIV positive patients.

 

Symptoms – Atypical Pneumonia (SOB, dry cough, fever) but very few chest signs

– Can lead to pneumothorax + hepatosplenomegaly and lymphadenopathy

– Gives typical desaturations of SpO2 during exercise

 

Tests – CXR shows bilateral interstitial pulmonary opacifications

– Sputum culture –> this is stained using the Grocott (silver stain) to identify the fungi

 

Management – 1st line is Co-trimoxazole –> 2nd line is IV pentamidine

– Prophylaxis with co-trimoxazole is recommended in all patients with a CD4 count of less than 200/mm³

1. Yale Rosen from USA / CC BY-SA (https://creativecommons.org/licenses/by-sa/2.0)

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