Chapter 28 - Clinical Microbiology and Immunology

Question 1

obligate anaerobic bacteria

Answer 1

culture of anaerobic microorganisms

Question 2

general-purpose media

Answer 2

support growth of most aerobic facultatively aerobic organisms
-blood agar, chocolate agar (heated blood)

Question 3

enriched media

Answer 3

contain specific growth factors that enhance growth of certain fastidious pathogens

Question 4

a-hemolysis

Answer 4

a partial or “green” hemolysis associated with reduction of red cell hemoglobin

Question 5

alpha hemolysis is caused by..

Answer 5

hydrogen peroxide produced by bacterium, oxidizing hemoglobin

Question 6

beta-hemolysis

Answer 6

complete lysis of red cells surrounding the colony

Question 7

b-hemolysis is caused by

Answer 7

two hemolysis O and S

Question 8

weakly beta-hemolytic species

Answer 8

streptococcus agalactiae, clostridiumperfringens, listeria monocytogenes

Question 9

selective media

Answer 9

inhibits growth of some bacteria while inhibiting others

Question 10

differential media

Answer 10

allow identification based on growth, colour, and appearance

Question 11

thayer martin medium

Answer 11

a selective medium that contains antibiotics vancomycin, nystatin, trimethoprim, costing that inhibit growth of other bacteria

Question 12

non-secretive medium

Answer 12

chocolate agar

Question 13

culture of neisseria gonorrhoeae needs to be incubated in a humid environment at..

Answer 13

35*C with 3-7% CO2

Question 14

oxidase positive

Answer 14

blue colonies in contact with reagent and contain cytochrome c

Question 15

disk diffusion test

Answer 15

method for assessing antimicrobial susceptibility

• specified agar medium is inoculated with culture of bacteria
• inhibition zones measured and interpreted according to a standardized guide

Question 16

etest

Answer 16

-non-diffusion-based antimicrobial susceptibility testing method that uses a preformed and predefined gradient of an antimicrobial agent immobilized on a plastic strip

Question 17

nucleic acid based tests

Answer 17

PCR

Question 18

PCR

Answer 18

presence of amplified gene segment confirms presence of pathogen

Question 19

quantitative and reverse transcriptase PCR

Answer 19

uses pathogen specific RNA to make cDNA

Question 20

qualitative real time PCR

Answer 20

uses fluorescently labelled PCR products

-almost immediate results

Question 21

nucleic acid probes - dipstick assay

Answer 21

• reporter and capture probes used
• capture probe has a polyA tail which hybridized to polyT oligo attacked to dipstick
• binding of target DNA to reporter seem as a colour change

Question 22

serology

Answer 22

the study of antigen-antibody reactions in vitro

Question 23

Usefulness of a serological test for diagnostic purposes is dependent on..

Answer 23

the test’s specificity and sensitivity

Question 24

serological reactions

Answer 24

neutralization, precipitation, agglutination

Question 25

test specificity

Answer 25

probability of having a negative test if the patient is NOT infected

Question 26

test sensitivity

Answer 26

probability of having a positive test when the patient IS infected

Question 27

an infection can be identified by..

Answer 27

measuring the patient’s antibody titer against antigens produced by the pathogen

Question 28

common immunoassays

Answer 28

agglutination, ELISA, radioimmunoassay

Question 29

skin testing

Answer 29

another method for determining exposure to a pathogen-delayed hypersensitivity

Question 30

T/F all pathogens elicit an immune response that can be measured

Answer 30

FALSE

-neisseria gonorrhoeae

Question 31

monoclonal antibodies

Answer 31

bind to a single epitope

Question 32

polyclonal antibodies

Answer 32

multiple antibodies may bind multiple epitopes on an antigen

Question 33

precipitin rxn

Answer 33

a visible antigen-antibody reaction

Question 34

agglutination

Answer 34

visible clumping of a particulate antigen when mixed with antibodies specific for the particulate antigens

Question 35

Which is more sensitive: agglutination or precipitation

Answer 35

agglutination

Question 36

passive/indirect agglutination

Answer 36

agglutination of soluble antigens or antibodies adsorbed or chemically coupled to cells or insoluble particles

Question 37

indirect agglutination can be up to ___more sensitive than direct.

Answer 37

5x

Question 38

neutralization

Answer 38

the interaction of antibody with antigen to clock or distort the antigen sufficiently to reduce or eliminate its biological activity

Question 39

direct fluorescent methods

Answer 39

the antibody targeted against the surface antigen is covalently linked to the fluorescent dye

Question 40

indirect fluorescent method

Answer 40

The presence of a nonfluorescent antibody on the surface of a cell is detected by use of a fluorescent antibody directed against the nonfluorescent antibody

Question 41

immunofluorescence

Answer 41

antibodies can be chemically modified with fluorescent dyes to help detect antigens on intact cells

Question 42

two common fluorescent dyes

Answer 42

rhodamine B and fluorescein isothiocyanate

Question 43

immunoblot/western blot

Answer 43

Electrophoresis of proteins, followed by transfer to a membrane and detection by addition of specific antibodies
-immunoblot detect antibodies to specific antigens or antigens themselves

Question 44

4 different enzyme immunoassay and radioimmunoassay

Answer 44

4 different EIA methodologies frequently used: direct EIA, indirect EIA, sandwich, combination