fungitell aka beta d glucan testing
- related: Infectious Disease
- tags: #literature #pulmonary
BDG is a polysaccharide component of the cell wall of fungi, including Pneumocystis. This test has become important in the suspected/presumptive diagnosis of PJP in both patients with HIV and patients without HIV, and in those too unstable to undergo bronchoscopy, with good sensitivity and a high negative predictive value, making it unlikely that a patient with a negative BDG result has PJP. Values used are usually greater than 80 pg/mL, which shows a good sensitivity of 91% and specificity of 81% for PJP. Values less than 60 pg/mL are considered negative, and values between 60 and 80 pg/mL are considered indeterminate. The BDG assay result is also positive in infections with Aspergillus species and Candida species, and may be positive with Histoplasma, Fusarium, and coccidioidomycosis. The BDG result is typically negative in patients with mucormycosis, cryptococcosis, and blastomycosis infections. False-positive results can occur with some bacterial infections (some strains of Pseudomonas aeruginosa), hemodialysis using cellulose membranes, IV immunoglobulin, some albumin compounds, use of cellulose filters for IV administration of certain infusions, and gauze used to pack serosal surfaces.
β-d-glucan assays can detect the presence of several different fungi, including Aspergillus, Candida, and Pneumocystis jirovecii. Unfortunately, cross-reactivity also extends to β-lactam antibiotics (eg, piperacillin) and immunoglobulins, which raises the concern for false-positive test results.1
Cross reacts except for Mucor, cocci, and cryptococcus.2