Ch 15 - Diagnostic testing

Why is aseptic technique important in specimen collection?

to protect the patient and the sample from contamination

what is collected using a "clean catch"?

urine

what is collected using sterile needle aspiration?

blood

what is collected through deep coughing after swallowing to clear the mouth of saliva?

sputum

What are the phenotypic testing methods?

• immediate direct examination

• colony morphology

• biochemical tests

• phage typing

• Antibiotic sensitivity testing

• Selective and differential media

What is an advantage of immediate direct examination over selective/differential media or colony morphology?

it's faster

A specimen is cultured in phenol red broth. Phenol red broth changes colors based on carbohydrate fermentation. This is:

selective or differential media

S. aureus can be distinguished by testing for the coagulase enzyme using rabbit plasma. This is:

biochemical test

What is not a genotypic test?

ELISA

PCR

makes millions of copies of a small segment of DNA

Microarray

uses single-stranded DNA or RNA probes to bind to known DNA sequences that are present on a slide or chip

DNA sequencing

determining the exact nitrogenous base sequence for a segment of DNA

Multiplex PCR

allow patient samples to be analyzed quickly and detect the possibility of multiple pathogens

Which of the following are immunologic tests?

• agglutination and precipitation

• immunochromatography

• serotyping

• Western Blots

• ELISA

• In vivo testing

agglutination

clumping

a positive agglutination test will:

appear clear with a solid at the bottom of the well

antibody titer

antibody concentration measurement to determine exposure and immunity

What is another name for immunochromatography?

lateral flow test

T/F: The control on the lateral flow test pad is primarily to validate that the test ran as expected.

True

Why is serotyping considered an immunologic test?

it relies on antibody/antigen interactions

Western Blot

identify the presence of a particular protein that is present within a sample

ELISA

uses an enzyme to produce a color change to indicate that antigen or antibody is present

Put the steps of indirect ELISA in order.

1. Known antigen adsorbed to bottom of wells

2. Dilutions of patient serum are added to wells

3. Secondary antibody with enzyme added.

4. Substrate added

antigen test

determine infection

What is another term that describes antibody tests?

Indirect

Which COVID-19 test determines exposure and immunity, but not current infection status?

Antibody test

Which COVID-19 test detects specific viral antigens and is cheaper to run but also less sensitive?

Rapid antigen test

Which COVID-19 test detects viral RNA and is highly specific and sensitive?

PCR test

Immunologic tests rely on antibodies only binding with a single antigen epitope and not to other targets. This is:

specificity

A good diagnostic test will detect the target even if it is only present in small amounts. This is:

sensitivity

A test that is lacking sensitivity will yield false ______

negatives

T/F: Only medical professionals can collect medical specimens.

False

antibody test

determines exposure

A test that is lacking specificity will yield false ___

positive

PCR stands for

polymerase chain reaction