Info
🌱 來自: Huppert’s Notes
Systemic Fungal Infections🚧 施工中
Systemic Fungal Infections
• Pathogens:
- See Tables 8.7 and 8.8 for organisms that cause systemic and opportunistic fungal infections
• Diagnostic tests to evaluate for fungal infections:
- 1,3-Beta-D-glucan (BDG): Tests for a cell-wall polysaccharide that is present in most, but not all, fungi. It is 75–85% sensitive and specific for a fungal infection.
• Relevant fungi for which it tests include:
• Candida
• Aspergillus
• Histoplasma
• Coccidioides
• It does not detect mucormycosis (e.g., Rhizopus spp. and Mucor spp.), Cryptococcus spp., and Blastomyces spp.
• False positives can occur with administration of IVIG, albumin, and some hemodialysis filters
- Galactomannan: Tests for a specific component of the cell wall in Aspergillus. Sensitivity of ~70% in serum. More sensitive on BAL samples (~80%). Rarely, false positives can occur in patients receiving TPN. Piperacillin/tazobactam causes false positives, but less commonly now due to new formulations of the antibiotic
- Cryptococcal antigen (CrAg): Tests for an antigen associated with Cryptococcus. The serum test is useful in patients with HIV/AIDS and CD4 counts <100 cells/μL.
• If serum CrAg is negative, there is a very low likelihood that the patient has cryptococcal meningitis (especially in HIV, may not be as sensitive in other types of immunocompromise)
• If serum CrAg is positive, get an LP to rule out cryptococcal meningitis in all patients
• If LP demonstrates crypto meningitis, treatment includes induction therapy with amphotericin B + flucytosine, followed by consolidation and maintenance therapy with fluconazole once repeat LP demonstrates clearance of the organism from CSF
- Histoplasma antigen: Tests for an antigen associated with histoplasmosis. Can be tested off of serum or urine; >90% sensitivity (urine) and 80% sensitivity (serum). Urine Histoplasma antigen is very sensitive for disseminated histoplasmosis in HIV infection.
- Cocci immunofixation and complement fixation: Used to evaluate for coccidioidomycosis. Different sensitivity/specificity for these tests in blood vs. CSF.
• Treatment: Antifungal agents – see Table 8.24