ID - Fungal Infections

Question 1

Why is fungal infection important in ICU patients?

Answer 1

1. Vulnerable patient group- severity of illness- immunocompromised (HIV, chemo, transplant)- indwelling lines and catheters- increasingly aggressive treatment and surgery- unable to report symptoms2. Strain on ICU- prolonged LOS- prolonged ventilator dependency- multiple changes of lines- worse prognosis

Question 2

What do we mean by the term invasive fungal infection?

Answer 2

Disseminated infection with involvement of three or more deep seated infection sites.or, proven fungaemia

Question 3

Which fungal pathogens are important in ICU patients?

Answer 3

• Candida albicans- Non-albicans candida species (glabrata)- Aspergillus- Crypotococcus- Pneumocystis jerovicii

Question 4

What are the risk factors for the development of fungal infection?

Answer 4

1. Immunocompromise2. Increased age3. Increased severity of illness4. Broad-spectrum antibiotics5. Indwelling catheters6. presence of comorbidities7. Candida colonisation8. Perforated viscus - intrabdominal surgery

Question 5

What are the criteria used to diagnose fungal infection?

Answer 5

Definitive criteria:
1. Single blood culture positive
2. Burn wound invasion
3. Positive tissue/biopsy culture
4. Endophthalmitis
5. Positive culture from ascites or CSF

Invasive fungal infection is suggested by the presence of 3 or more sites.

Question 6

What would lead you to suspect disseminated fungal infection in a ICU patient?

Answer 6

1. Persistent pyrexia despite antibiotic therapy and negative microbiology2. High grade fungiuria in an uncatheterised patient3. Fungus cultured from more than 2 sites4. Confirmed visceral fungal infection

Question 7

How should a patient be investigated for potential fungal infection?

Answer 7

1. Blood cultures2. Urine cultures3. Line cultures (with tip sent for culture if line removed)4. Eye examination5. echo6. Biopsy/other fluid samples e.g. ascites, wound biopsy

Question 8

How would you manage a patient with suspected fungal infection?

Answer 8

1. Assess the patient and stabilise in an A-E approach.
2. Take appropriate microbiological samples (BAL, urine, blood) and liase with medical microbiology team
3. Remove indwelling catheters and line which may have become colonised
4. Echocardiography
5. Eye examination/ophthalmology review
6. Renal imaging CT/US
7. Commence antifungals as advised by microbiology whilst awaiting cultures.

Question 9

What is the overall prognosis of candidaemia?

Answer 9

Candidaemia has a mortality rate of 40-60% with an attributable mortality of 20-40%. Early treatment confers a better prognosis.

Question 10

Tell me about aspergillus?

Answer 10

1. Aspergillus sp. are spore forming moulds found in soil.
2. The most common type infecting humans is Aspergillus fumigatus.
3. Commonest site of infection for aspergillus is the lung.
4. Pulmonary aspergillus can be investigated by:
   - PCR
   - BAL and blood for galactomannan

Question 11

What classes of anti fungal drugs are you aware of?

Answer 11

1. Azoles (fungistatic):
   - fluconazole, itraconazole, voriconazole
   - inhibit ergosterol synthesis
   - good against: albicans (fluconazole), non-albicans, aspergillus (voriconazole)
2. Echinocandin (fungicidal vs candida, fungistatic vs aspergillus)
   - caspofungin, micafungin, anidulafungin
   - Inhibit cell wall glucan synthesis
   - good against: albicans and non-albicans
3. Polyenes (fungicidal)
   - amphotericin
   - fungicidal
   - binds ergosterol in fungal cell wall
   - Good against: candida, cryptococcus, aspergillus