Fungal diagnostics

Antigen detection

1,3-β-D glucan (Se 75%, Sp 85%): 可以在哪些 fungus 看得到？

• Candida, Aspergillus, Histo, Coccidio, PCP, for invasive infxn in immunocomp host.
• Cannot detect Mucor, Rhizopus, Blasto, Crypto.
• Use of 1,3-β-D-glucan in invasive fungal diseases in hematology patients

Galactomannan (Se 71%, Sp 89%)

• Aspergillus. BAL preferred.
• Test serum only if heme malig or HSCT.
• Not for screening or Rx monitoring in solid organ Tx, chronic granulomatous disease (false ⊕ w/ colonization).

Histo urine/serum Ag

• Se of urine Ag 90% (serum 80%) if disseminate;
• Sp limited by X-react

Crypto Ag (serum, CSF)

• sAg >90% Se & Sp in invasive, less for pulm. only unless HIV+

Blastomyces

urine >serum Ag, high Se but modest Sp given X-react w/ other fungi

• Culture: Candida grows in blood/urine Cx, but ↓ Se of BCx in deep tissue infection; others (eg, Crypto, Histo) ↓↓ Se of BCx; if suspect Coccidio alert lab (biohazard)
• Antibody detection: useful for Coccidio (serum IgG and IgM 7–21 days post exposure)
• Biopsy: no grinding of tissue if Zygomycetes suspected