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Questions and Answers
Questions and Answers
What breakpoint indicates resistance for E.coli against Ampicillin?
What breakpoint indicates resistance for E.coli against Ampicillin?
- 18 mm
- 16 mm
- 14 mm (correct)
- 22 mm
Which test can be used to detect unknown antibodies?
Which test can be used to detect unknown antibodies?
- By known antigen detection (correct)
- By known antibody detection
- Epidemiological research
- Complete biochemical identification
What is considered a sensitive breakpoint for E.coli using Imipenem?
What is considered a sensitive breakpoint for E.coli using Imipenem?
- 14 mm
- 16 mm
- 18 mm
- 22 mm (correct)
What is the function of the 'K antigen' in cellular components?
What is the function of the 'K antigen' in cellular components?
Which antibiotic shows a breakpoint of 18 mm for resistance in P.aeruginosa?
Which antibiotic shows a breakpoint of 18 mm for resistance in P.aeruginosa?
For E.coli, what is the breakpoint indicating sensitivity of Cefixime?
For E.coli, what is the breakpoint indicating sensitivity of Cefixime?
Which serological test function involves determining the spreading of serotypes?
Which serological test function involves determining the spreading of serotypes?
The 'O antigen' is a component of which cellular structure?
The 'O antigen' is a component of which cellular structure?
What is the effect of heat on complement in serum?
What is the effect of heat on complement in serum?
Which cytokines stimulate the production of C reactive protein?
Which cytokines stimulate the production of C reactive protein?
What is the normal concentration of C reactive protein in serum?
What is the normal concentration of C reactive protein in serum?
What type of test is used for the detection of antibodies?
What type of test is used for the detection of antibodies?
Which of the following is NOT a method of detecting agglutination?
Which of the following is NOT a method of detecting agglutination?
What characteristic is true of quantitative serological tests?
What characteristic is true of quantitative serological tests?
When does C reactive protein reach its maximum concentration after production?
When does C reactive protein reach its maximum concentration after production?
Which category of serological tests includes both visible and invisible methods?
Which category of serological tests includes both visible and invisible methods?
What is the main characteristic of slide agglutination?
What is the main characteristic of slide agglutination?
In tube agglutination, what does the titer indicate?
In tube agglutination, what does the titer indicate?
What role does Protein-A play in co-agglutination with Staphylococcus aureus?
What role does Protein-A play in co-agglutination with Staphylococcus aureus?
Which test is an example of tube agglutination used for typhoid fever diagnosis?
Which test is an example of tube agglutination used for typhoid fever diagnosis?
What type of agglutination uses latex granules as carriers?
What type of agglutination uses latex granules as carriers?
What characterizes precipitation reactions?
What characterizes precipitation reactions?
In which medium does ring precipitation occur?
In which medium does ring precipitation occur?
Which agglutination test specifically involves Rickettsia prowazekii?
Which agglutination test specifically involves Rickettsia prowazekii?
What experiment utilizes a known artificial antigen to detect unknown antibodies in patient serum?
What experiment utilizes a known artificial antigen to detect unknown antibodies in patient serum?
In the Quellung reaction, what is the observable change if the test is positive?
In the Quellung reaction, what is the observable change if the test is positive?
What type of antigen is used in the Elek test?
What type of antigen is used in the Elek test?
Which component of the ELISA test is labeled with an enzyme?
Which component of the ELISA test is labeled with an enzyme?
What is the primary purpose of ring precipitation in immunological testing?
What is the primary purpose of ring precipitation in immunological testing?
Which test specifically indicates the presence of toxin-producing strains of bacteria?
Which test specifically indicates the presence of toxin-producing strains of bacteria?
In the context of the Quellung reaction, what does a positive result indicate about the unknown bacteria?
In the context of the Quellung reaction, what does a positive result indicate about the unknown bacteria?
Which of the following statements correctly describes the role of antibodies in the ELISA technique?
Which of the following statements correctly describes the role of antibodies in the ELISA technique?
What is the role of labeled antibodies in the immunofluorescent method?
What is the role of labeled antibodies in the immunofluorescent method?
In the indirect immunofluorescent method, which component is unlabeled?
In the indirect immunofluorescent method, which component is unlabeled?
Which type of antigen is specifically mentioned in the context of direct immunofluorescence?
Which type of antigen is specifically mentioned in the context of direct immunofluorescence?
What is one characteristic of the direct immunofluorescent method?
What is one characteristic of the direct immunofluorescent method?
What is the primary use of the immunofluorescent method?
What is the primary use of the immunofluorescent method?
Which of the following best describes the 'indirect' method of immunofluorescence?
Which of the following best describes the 'indirect' method of immunofluorescence?
What characteristic distinguishes direct immunofluorescence from indirect immunofluorescence?
What characteristic distinguishes direct immunofluorescence from indirect immunofluorescence?
In the immunofluorescent method, what kind of dye is mentioned for labeling antibodies?
In the immunofluorescent method, what kind of dye is mentioned for labeling antibodies?
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Study Notes
Study Notes
Antibiotic Sensitivity Tests
- EUCAST is the European Committee on Antimicrobial Susceptibility Testing
- Standardized test for sensitivity to antibiotics, reported as:
- S: Susceptible
- R:Resistant
- S. aureus: Staphylococcus aureus
- E.coli: Escherichia coli
- P. aeruginosa: Pseudomonas aeruginosa
Serological Reactions
- Serological tests are used to identify antibodies (Ab), antigens (Ag) or previous infections
- Antigens are proteins or molecules that trigger an immune response, including:
- O antigen: cell wall
- H antigen: flagella
- K antigen: capsule
- F antigen: fimbria
- Complement aids in the destruction of foreign invaders, and involves:
- Lysis: The breakdown of cells
- Opsonization: The coating of microbes for better phagocytosis
- C-reactive protein (CRP) is a type of protein that increases during infection:
- Normal levels: 10 mg/l
- Viral infection: 30-40 mg/l
- Bacterial infection: 200-250 mg/l
- Fungal infection: 250-300 mg/l
- Serological Tests can be used to detect:
- Ag: Directly or from a culture
- Ab: To demonstrate the presence of a disease or the effect of vaccines
Classification of Serological Tests
- Qualitative tests distinguish between the presence or absence of substances
- Quantitative tests give a numerical value of the concentration of a substance in a sample.
- Visible Tests include:
- Agglutination: The clumping of particles
- Precipitation: The formation of a solid in a solution
- Invisible Tests require further detection methods, including:
- Immunofluorescence (IF): Using fluorescent dyes
- Complement Fixation Test (CFT): Identifying the presence of antibodies by their ability to fix complement
- Radioimmunoassay (RIA): Using radioactive isotopes
- Enzyme-Linked Immunosorbent Assay (ELISA): Using enzymes
Agglutination
- Slide agglutination is a qualitative test using:
- Unknown Ag
- Known Ab (specific sera)
- Tube agglutination is a quantitative test, using:
- Known Ag
- Unknown Ab (diluted from patient serum)
- Examples:
- Gruber-Widal test for typhoid fever
- Wright reaction for brucellosis
- Weil-Felix reaction for Rickettsia prowazekii
- Titer is the highest dilution fold, where agglutination is still visible
Indirect Agglutination
- Latex agglutination uses Ab bound to a carrier:
- Carrier:
- Red blood cells (hemagglutination)
- Latex granules (latex agglutination)
- Staphylococcus aureus (co-agglutination)
- Protein A produced by S. aureus can bind to the Fc receptor of IgG
- Carrier:
Precipitation
- Precipitation involves soluble Ag forming a solid with Ab in a solution
- Ring precipitation is the formation of a ring at the junction of Ag and Ab
- It is a quantitative test
- Elek test uses filter paper with Ab against a toxin
- Detects toxin production by a strain
- If the strain is a toxin producer, a precipitation arch will be visible
- Ring precipitation is the formation of a ring at the junction of Ag and Ab
Quellung Reaction
- Quellung reaction is used to identify bacteria with capsules
- Unknown capsule-bearing bacteria (Ag)
- Ab against the capsule
- If positive, the capsule appears larger and more opaque
ELISA
- ELISA is a quantitative test that utilizes:
- Known artificial Ag
- Unknown Ab from patient sera
- Ab*: Anti-human globulin labeled with an enzyme
- Procedure:
- Artifical Ag is adhered to a surface
- Patient sera (containing Ab) is added
- Ab (labeled)* is added and will bind to patient Ab
- Substrate (enzyme specific) is added and will bind to the enzyme of Ab*
Immunofluorescent Method (IF)
- Direct IF:
- Ag: Unknown (unlabeled)
- Ab: Known, labeled with fluorescent dye
- Indirect IF:
- Ag: Known
- Ab: Unknown
- Ab*: Labeled antiglobulin
- Procedure:
- Ag and Ab interact
- Viewed under UV light, fluorescence indicates positivity
Vaccines
- Vaccines are used to stimulate the immune system to produce antibodies against a pathogen
- Live-attenuated: Contain weakened versions of the pathogen
- Inactivated: Contain killed versions of the pathogen.
- Subunit: Contain only specific parts of the pathogen.
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