Fungal Infections

Question 1

What is candida albicans?

Answer 1

A fungus and in the sputum represents colonisation of the resp tract or contamination from oral candida (part of normal oral flora). Candida spp. will usually grow in a standard blood culture bottle > gram positive cocci, however, are much larger than bacteria so are easy to distinguish. Candida can cause sepsis so need to act quickly - mortality: 40-50%

Question 2

What are common sources of candida infections?

Answer 2

• Most common source for candidaemia is gut flora
• Candida can translocate from the gut into the bloodstream if the epithelial lining becomes damaged microscopically (sepsis) or macroscopically (perforation, obstruction, necrosis).
• They can also cause sepsis in patients who have intravascular catheters like central lines by moving from skin and forming biofilms on catheter surface. These should be removed/changed if possible independent if they are the source or not.

Question 3

Where does candida spp. normally colonise?

Answer 3

Normal part of gut flora. Also common colonisers of the oral cavity, vagina and moist areas of skin. Infection is defined by elicitation of inflammation and tissue damage. The most commonly isolated species is candida albicans.

Question 4

What is thrush?

Answer 4

Oral thrush typically in immunocompromised, either systemically (HIV, immunosuppression) or locally (lack of saliva). A single attack of vulvovaginal candidiasis doesn’t require predisposing factors but recurrent disease is associated with diabetes and other immunological deficiencies. Can get thrush if patient has received broad-spectrum abx due to disruption of normal flora.

Question 5

How is candidaemia treated?

Answer 5

• The anti-fungal micafungin (or other echinocandins) is used for treatment and candidaemia requires prolonged treatment: for 2 weeks from when repeat blood cultures are negative.
• If it’s line-associated candidaemia, definitive treatment is by removing line. Replace line if needed. Infected lines = one of most common sources of infection for candidaemia.

Question 6

Describe superficial fungal infections

Answer 6

Occur in anyone and are common. People immunocompromised are more at risk and can have a more severe presentation e.g. HIV and diabetics

• Oral and vaginal thrush
• Tinea e.g. athlete’s foot (tinea pedis) or ringworm (tinea capitis) - dermatophyte group
• Fungal nail infection (onychomycosis) - dermatophyte
• Pityriasis versicolor - malessezia furfur

Question 7

Describe subcutaneous fungal infections

Answer 7

Not common in UK and occur mainly in tropical countries. They affect the dermis, SC tissue and adjacent bones and often some degree of immunocompromise.

Question 8

Describe deep fungal infections

Answer 8

Occur in immunocompromised, may be receiving drugs to suppress immune system e.g. chemo, HIV

• Invasive candida sp. e.g. candidaemia in ICU patients with central line that have bypassed skin barrier
• Invasive aspergillus fumigatus - transplants or chemo patients
• Pneumocystis jiroveci pneumonia (PCP) - HIV or low lymphocytes
• Cryptococcal meningitis - patients who have HIV or other severe immunosuppression, caused by cryptococcus neoformans