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MLT-Serological
Microbiology
| Question | Answer |
|---|---|
| What is serological technique? | Involve the use of antigen & antibody reactions |
| What is the example of know antibody against unknown antigens/microbe? | Streptex |
| What are the examples of known antigen against unknown antibody? | 1.Widal test (test for Salmonella typhi infection) 2. ELISA for anti hepatitis B antibodies |
| What are the examples of serological assays? | 1.Immunofluoresence 2.ELISA |
| What is direct immunofluoresence? | 1.For antigen detection 2.use fluorescent dye labelled ab 3.Non specific reaction may occur |
| What is indirect immunofluoresence? | 1.For antibody detection 2.require a fluorescent dye labelled second antibody 3.Increase in sensitivity 4.decrease in specificity |
| Why indirect immunofluoresence will decrease in specificity? | fluorescent 2nd antibody may also bind to unreacted ag & ab |
| What is the full name of ELISA? | Enzyme Linked ImmnunoSorbent Assay |
| What is the drawback of immunofluoresence? | Both direct & indirect IF rely on experienced staff, interpretation can be subjective |
| Why ELISA is a heterogenous enzyme assay? | Either Ag or Ab is attached on solid phase |
| How to measure the enzyme activity of ELISA? | 1.Enzyme activity is measured by specific substrate 2.using a machine 3.Quantitative, so more objective interpretation |
| What is agglutination? | Cross linking of microorganisms, cells or particles by antibody against surface antigen |
| Whats the requirement for effective agglutination? | Requires large amount of antigenic determinants & antibody binding sites |
| Which antibody is more effective in agglutination? | IgM |
| What are the 3 types of agglutination and its example? | 1.direct, clumping Ag by Ab, eg. slide test for Salmonella 2.Indirect(passive), known Ag linked to latex particles or RBC, eg.Treponema pallidum hemagglutination test) 3.reverse passive, know Ab attached on latex particles, eg. Streptex |
| What is Widal test? | 1. An agglutination test 2.Test Ab during tyhpoid fever 3.Ab against flagellar (H) Ag & somatic (O) Ag 4.eg. Samonella typhi, S. paratyphi A, B, C |
| A STD, syphillis is caused by ? | 1.Treponema pallidum 2.Gram negative, spirochetes |
| What is the non-specific test for syphillis? | VDRL(venereal disease research laboratory) test |
| What are the non-specific Ab detected in VRDL test? | They called Reagins |
| Whats so special about the Treponema pallidum Ag? | cardiolipin coated on cholesterol particles |
| How to examine the VRDL test result? | Under 10x objective lens |
| What is the alternative for VDLR test? | Rapid Plasma Reagin (RPR) test 1.Antigen cardiolipin coated on charcoal 2.no need heat treatment 3. agglutination can be observed by naked eyes 4.Plasma is the sample |
| What is the high sensitivity and high specific test for syphillis? | Fluorescent Treponemal Antibody Absorption (FTA ABS) test |
| What is Fluorescent Treponemal Antibody Absorption (FTA ABS) test? | 1. Uses type specific treponema pallidum antigen 2. Detects antibody in patient's serum by indirect IF |