Paediatric Fungal Infections – Diagnostic Methods

Test Type

Effective for

Exclusions

Problems

Galactomannan assay (Serum)
EIA 
(Fungal cell wall marker)

Found in all Aspergillusspecies. For serum, urine, BAL*, CSF and other. Rapid diagnosis (pre–radiographic signs of infection). [1] [2]

CGD , Jobs syndrome (false negatives)

May be false negatives (see exclusions). Could be low sensitivity in cancer patients.
False positives with contaminating GM  in some b lactam antibiotics  esp. Amoxicillin,piperacillin-tazobactam. Also dietary GM should be considered.

Beta 1-3 glucan
(Fungal cell wall marker)

Testing is limited. Not species specific.
Minimum data in children. (Candida meningoencephalitis in CSF – may be a useful test) [3]

Do paediatric patients have a high baseline for this Antigen?
Possible false negatives from cellulose in surgical gauze.
Need to define cut off values.

Mannan antibodies (serum)

Yeast only – but may be used for exclusion purposes. [4][5]

Preliminary neonate data encouraging.

Fungal DNA -PCR

High specificity and sensitivity. Rapid [6]

Difficult to extract fungal DNA and susceptible to contamination. If using blood samples –several ml of blood required. [7]

Microscopy

Practical and inexpensive

Limited to site

Slow – causing delay in diagnosis

Diagnostic imaging
CT

Halo sign and later sign of air crescent less frequently seen in paediatrics.
Whereas focal bronchopneumonia more often seen. [8] [9]

Risk of CT radiation in children is greater than adults. [10]