1,3-Beta-D-Glucan and Galactomannan Testing Sensitivity Specificity and False Positives
1,3-Beta-D-Glucan
• Cell wall component of many fungi
• Routine use: Candida, Aspergillus. Other +s: PCP, Histo
• Almost always negative with Crypto, Mucormycosis
• Neg (<60 pg/mL), Indet (60-79), Pos (>80)
• Sens 55-9536, spec 77-96%
• Higher specificity for IFI in hem malignancies (cut-offs defined in clinical context of breakthrough IFI in HM pts); from BAL samples
• False positives: IVIG, IV penicillin formulations (eg amox-clav, not available in US), HD with cellulose membranes (many dialyzer membranes synthetic and do not TBDG), Use of cellulose filters with IVs
Gauze packing of serosal surfaces, Albumin, Infections with certain bacteria with cellular beta-glucans
Galactomannan Ag
• Major polysaccharide constituent of Aspergillus cell walls
• Routine use: Aspergiflus. Other +s: Fusarium, Penicilfium, Histo
• OD >= 0.5 considered positive with:
Sens 82%. Spec 81% for dx of IA
PPV NPV >90% (In most clinical situations, low pretest probability limits the use of this test)
• Most useful in high risk pts with hem malignancies
• Detection in BAL does not differentiate colonization vs invasive dz
• Sensitivity ↓ w/concurrent admin mold-active AF
• False positives: Pip/Tazo, Amox/Clav (may result in + as long as 5d after stopping abxs, but newer formulations post-2010 almost never +), IVIg, +GM more likely in first 100d following HCT and in pts with GIT mucositis or GVHD (leaky gut, translocation), Contamination of foods with Aspergillus or closely related fungi (Penicillium), Frozen ice-pops (iso GVHD), Certain blood products
#BetaDGlucan #Galactomannan #Fungal #Testing #FalsePositives #Laboratory #sensitivity
