SEROLOGICAL TEST Flashcards
Provides enough information to name the species of the fungal organism
SEROLOGICAL TEST
key elements that needed to improve management of invasive fungal infections
Rapid diagnosis
Early initiation of antibiotic fungal therapy
- Time consuming; mold cultures grow after several weeks.
- It has low sensitivity due to the low concentration of the organism in the samples infested.
Culture methods
- Detection of specific host immune responses to fungal antigens using immunological reagents
- Detection and quantitation of specific fungal metabolite byproducts
Non-culture methods
Targets for serological tests:
● Antigen
● Antibody
● Metabolites
Types of serological tests
Agglutination
Immunodiffusion
Complement Fixation Test
Enzyme Linked Immunosorbent Assay
Lateral Flow Assay
Good for Cryptococcosis
Detect polysaccharide antigen
Qualitative & semi-quantitative
LATEX AGGLUTINATION
Detection of Heat labile glycoprotein, Mannan antigen and anti–Mannan antibody
Invasive Candidiasis
is a component of cell wall
mannan
latex agglutination should be treated with
Sodium metaperiodate
latex agglutination should be pretreating serum with
2 beta mercaptoethanol
Look for antibodies of specific antigens
IMMUNODIFFUSION
Active infection
(+) M and H
Early/Chronic Infection
(+) M only
COMPLEMENT FIXATION TEST: Detection of IgE antibodies
Aspergillosis
COMPLEMENT FIXATION TEST:
◆ Ab detected against M & H Ags
◆ high sensitivity, low specificity
Histoplasmosis
ELISA: Qualitative or Screening assay
Cryptococcosis/ Blastomycosis/ Histoplasmosis/Coccidioidomycosis
COMPLEMENT FIXATION TEST: Detects IgG Ab to Coccidioides culture filtrate
Coccidioidomycosis
Presumptive diagnosis of Invasive candidiasis by Mannan Ag & Anti-Mannan Ab Assay
Candidiasis
ELISA: Allergic = detection of IgE Ab
◆ Invasive = Screening test; detects
galactomannan
Aspergillosis
➔ Adjunct in diagnosis of invasive fungal infections
➔ Pan fungal marker
1,3 β D-Glucan Assay
Detection of metabolites
D-Arabinitol
Secreted Aspartyl Proteinase
Rapidly eliminated by immune complexes & endocytosis by Kuppfer cells
Mannan
makes use of several different target genes to identify an organism
Multiplex PCR
Screening test & determination of endpoint titres
Cryptococcosis
component in majority of fungal cell walls
Exo antigen
makes use of two sets of primers
Nested PCR
○ Widely used for Candida albicans
○ Microbroth dilution MIC test
○ Tests several species of Candida against different antifungal agents
○ Reliable sensitivity test
Sensititre Yeast One
Allows the physician to choose the right antifungal agent not really required
E-TEST Agar MIC Method
○ Microbroth dilution breakpoint test
○ Allows us to identify which concentration of
drugs is susceptible
FungiTest
