Chapter 15: Diagnosing Infections

Question 1

Light microscopy aids in the observation of these items.

Answer 1

cell shape, size, and arrangement; Gram stain reaction, acid-fast reaction; endospores, granules, and capsules

Question 2

What can you use to pinpoint harder to see characteristics such as cell wall, flagella, pili, or fimbriae?

Answer 2

Electron Microscopy

Question 3

Name the biochemical characteristics used to diagnose infectious agents. (5)

Answer 3

(1) Enzyme production, (2) fermentation of sugars, (3) capacity to digest complex polymers, (4) production of gas, (5) sensitivity to antibiotics

Question 4

Which method produces more rapid results?

Answer 4

Genotypic (automated)

Question 5

Viable Noncultured (VNC)

Answer 5

microbes that can’t be grown in the laboratory that are identified by genotypic methods

Question 6

Immunological Methods

Answer 6

patient sample is tested for the presence of specific antibodies to a suspected pathogen

Question 7

A Gram stain of a sputum sample from a patient is an example of a ______ method of microbial identification. A. genotypic B. immunologic C. phenotypic D. histologic E. None of the choices is correct.

Answer 7

A. phenotypic

Question 8

“Clean Catch” Urine Sampling (describe the method)

Answer 8

taken by washing the external urethra and collecting the urine midstream

Question 9

How to collect a skin sample

Answer 9

skin can be swabbed or scraped with a scalpel to expose deeper layers; wounds must be cleansed prior to swabbing

Question 10

Sterile Material Sampling

Answer 10

blood, cerebrospinal fluid, and tissue fluids must be taken by STERILE NEEDLE ASPIRATION

Question 11

Signs of microbial infections (4)

Answer 11

(1) fever, (2) wound exudate, (3) mucus production, and (4) abnormal lesions

Question 12

Presumptive Data

Answer 12

place the isolated microbe into a preliminary category

Question 13

Confirmatory Data

Answer 13

pinpoint the microbe’s identity

Question 14

Results are entered into ______

Answer 14

a summary patient chart

Question 15

Tests involved when starting with patient analysis: (3)

Answer 15

(1) immunologic and serologic tests on blood; (2) in vivo tests for reaction to microbe; (3) clinical signs and symptoms

Question 16

Direct Testing (Microscopic) (4)

Answer 16

(1) Gram-stain; (2) Acid-fast stain; (3) Fluorescent Ab stain; (4) Gene probes

Question 17

Direct Testing (Macroscopic) (2)

Answer 17

(1) Direct Antigen; (2) Gene probes

Question 18

Tests on Isolates (6)

Answer 18

(1) Biochemical; (2) Serotyping; (3) Antimicrobial Sensitivity; (4) Gene probes; (5) Phage testing; (6) Animal inoculation

Question 19

Care should be taken to avoid contamination with ______ when taking samples from a patient. air water droplet nuclei normal microbiota None of the choices is correct.

Answer 19

Normal Microbiota

Question 20

Stains most often used when diagnosing

Answer 20

Gram-stain and Acid-fast

Question 21

Specialized Media

Answer 21

used to enrich a pathogen present in small numbers or is easily overgrown

Question 22

Selective Media

Answer 22

to encourage the growth of only the suspected pathogen

Question 23

Differential Media

Answer 23

used to identify definitive characteristics and fermentation patterns

Question 24

pure cultures must be obtained from___________so that subsequent steps in identification will be accurate

Answer 24

isolation media

Question 25

Physiological reactions of bacteria to nutrients and other substrates indicates what?

Answer 25

Enzymes are present in bacteria

Question 26

Enzyme-mediated metabolic reactions often visualized by what?

Answer 26

a color change

Question 27

Carbohydrate Fermentation shows...?

Answer 27

production of acid and/or gas

Question 28

Enzyme actions (biochemical tests):

Answer 28

catalase, oxidase, and coagulase

Question 29

Dichotomous keys

Answer 29

Flow charts based on easily recognizable characteristics (motility, gram-stain, morphology) that helps identify bacteria

Question 30

Phage Typing

Answer 30

Test used when morphological and biochemical tests are insufficient; infects bacteria with bacteriophage to identify certain kinds

Question 31

Probes

Answer 31

small fragments of single-stranded DNA or RNA complementary to the specific DNA sequence of a particular microbe

Question 32

Fluorescent in situ hybridization (FISH)

Answer 32

rapidly identifies 16s RNA sequences without first culturing the organism;

Question 33

Ribosomal subunit suitable for identifying bacteria

Answer 33

16s rRNA (part of 30s)

Question 34

Polymerase Chain Reaction

Answer 34

Amplifies minute quantities of DNA in samples into billion of copies & greatly improving the quality of the test

Question 35

Kary Banks Mullis

Answer 35

Won a nobel prize for improving on the polymerase chain reaction

Question 36

Fluorescent in situ hybridization (FISH) requires a pure culture of organisms obtained from a patient sample. True False

Answer 36

False

Question 37

Serology

Answer 37

involves in vitro testing of serum based on the principle that antibodies have an extreme specificity for antigens

Question 38

Specificity

Answer 38

property of a test to focus only on a certain antibody or antigen, and not react with an unrelated or distantly related antigen

Question 39

Sensitivity

Answer 39

detection of even minute quantities of antibodies or antigens in a specimen;

Question 40

These samples can be analyzed for the presence of specific & sensitivity antibodies

Answer 40

urine, cerebrospinal fluid, whole tissues, and saliva

Question 41

Fluorescent Antibodies (Direct)

Answer 41

unknown test specimen or antigen is fixed to a slide and exposed to a Fluorescent antibodies (Fab) solution;

Question 42

Antigen-Antibody (Ab-Ag)

Answer 42

Complexes that will remain bound to the Fab sample and will be visualized by fluorescence microscopy

Question 43

Fluorescent Antibodies testing is used to...? (Direct)

Answer 43

valuable for identifying and locating microbial antigens on cell surfaces or tissues; also ID's agents for syphilis, gonorrhea, and meningitis

Question 44

Fluorescent Antibodies (Indirect)

Answer 44

In the indirect FAB method, known antigen is added to the test serum (not onto slide as direct method); binding of the antibody is seen under microscope

Question 45

Fluorescent Antibodies testing is used to...? (Indirect)

Answer 45

used to diagnose syphilis and various viral infections

Question 46

Radioimmunoassay (RIA)

Answer 46

antibodies or antigens labeled with a radioactive isotope used to pinpoint minute quantities of a corresponding antigen or antibody

Question 47

RIA is used to...?

Answer 47

used to detect hormone levels in samples and diagnose allergies

Question 48

Enzyme-Linked Immunosorbent Assay (ELISA)

Answer 48

uses an enzyme-linked indicator antibody to visualize Ag-Ab reactions

Question 49

ELISA is used to...?

Answer 49

common test used for antibody screening for HIV, hepatitis A and C, and Helicobacter

Question 50

Tuberculin test for Mycobacterium tuberculosis

Answer 50

small amount of purified protein derivative (PPD) from Mycobacterium tuberculosis is injected into the skin

Question 51

Indicator of mycobacterium tuberculosis

Answer 51

appearance of a red, raised, thickened lesion in 48 to 72 hours can indicate previous exposure to tuberculosis