Mirco Lab 9- HIV, Strep, and hCG Rapid Tests

Rapid Test

An easy to use test that provides quick results, typically in 20 minutes or less, at the point of care

Rapid tests, also known as rapid _____ tests, are done at the point of care.

diagnostic

How does the accuracy of most rapid tests generally compare to standard lab tests?

Most are highly accurate, but the results are not always as accurate as standard lab tests.

List three examples of infectious diseases that are often diagnosed using rapid tests.

Influenza (flu), strep throat, malaria, HIV, or COVID-19.

What is the first step in the general procedure for using a rapid test?

Providing a sample of body fluid, such as blood, urine, saliva, or nasal secretions.

Pros of a rapid test

• Fast results=faster treatment

• Easy to use as non-medical workers can use it and you can even do it at home

• Useful in areas with limited resources and/or access to labs

• Inexpensive

Cons of a rapid test

• Lower sensitivity, meaning they aren’t as accurate as lab tests

• False negatives that could prolong treatment

Sensitivity

How well a test can identify a disease or condition particularly in its earliest stages

What is a false negative test result?

A result indicating that a person does not have a disease or condition when they actually do

Compared to standard lab tests, rapid tests are more likely to produce which type of erroneous result?

False negatives

What action is often taken by healthcare providers to verify the result of a rapid test?

A second sample is taken and sent to a lab for confirmatory testing

The Rapid HIV Antibody Test is designed to detect the presence of what in a patient's sample?

Anti-HIV antibodies

The Rapid Strep Test is designed to detect the presence of what from a throat swab?

Antigens from Streptococcus pyogenes

The pregnancy hCG Urine Rapid Test is designed to detect the presence of what in urine?

The hormone hCG hhuman chorionic gonadotropin)

The rapid tests for HIV and Strep described in the lab are what specific type of assay?

A lateral flow immunochromatographic assay

The condition known as AIDS (Acquired Immune Deficiency Syndrome) is caused by which virus?

HIV

List three modes of transmission for the Human Immunodeficiency Virus (HIV)

1. Sexual contact

2. Exposure to contaminated blood/blood products

3. Vertical transmission from mother to fetus

Diagnosis of HIV infection relies on testing for the presence of _____ to HIV viral proteins in bodily fluids.

antibodies

Why might a rapid HIV antibody test give a negative result for a person who was very recently infected?

The antibody response may take several months to reach detectable levels

On a rapid test cassette, what result is indicated by a single colored line appearing only at the Control Zone (C)?

a negative result

What visual result on a rapid test cassette indicates a positive result?

Two colored lines appear: one at the Control Zone (C) and one at the Test Zone (T)

A rapid test is considered _____ if a line fails to appear at the Control Zone (C).

Invaild

What is the full name of the bacterium responsible for Group A Streptococcal infections?

Streptococcus pyogenes

What is the source of human chorionic gonadotropin (hCG) during pregnancy?

It is a glycoprotein hormone secreted by the developing placenta shortly after fertilization.

In a normal pregnancy, how early can hCG be detected in urine?

As early as 6 days following conception

The hormone hCG consists of an alpha and a beta subunit; which subunit gives the hormone its specific properties?

The beta subunit

How do HIV antibody tests work?

• They detect antibodies that the body produces in response to having the infection. 

• If antibodies are present then they bind to the antigen on the test strip

• The test is a  lateral flow immunochromatography assay, where a fluid samples mixes with regents on a test strip

How do hCH pregnancy test work?

• This test decreased the presence of the hormone hCG (human chorionic gonadotropin). This hormone is produced by the placenta after fertilization. 

• The antibodies, monoclonal and polyclonal are used to bind to hCG if it is present in the urine (at elevated levels)

How do rapid Strep tests work?

Detects antigens from Group A S. pyogenes that come from a throat swab. The swab is mixed with a reagent. If the antigens are present, the regent extracts the antigens and binds to the antibodies on the strep, producing a colored line