Pre-Health Microbiology Chapter 20

Finals

What is classification?

Placing organisms in groups of related species, lists of characteristics of known organisms

What is identification?

Matching characteristics of an “unknown” organisms to lists of known organisms, clinical lab identification

Why take the time to identify an infectious agent?

Many bacteria are resistant to certain antibiotics and specific pathogens are associated with disease complications, so tracking the spread can lead to its source and prevention

What are problem-solving algorithms to identify bacteria?

Several tests at once to seep up identification by using step by step procedures and interpret results in a set sequence

What are the steps to problem-solving algorithms?

Isolate, create a pure culture, gram stain, and discover biochemical pathways/properties

What is restriction fragment length polymorphism (RFLP) analysis?

DNA is digested with restriction enzymes then run on a gel to observe the digestive patterns with fluorescent staining or radioactive probe to identify a specific gene or DNA sequence

What is polymerase chain reaction (PCR)?

A lab technique used to amplify a specific segment of DNA exponentially in vitro by performing denaturation, annealing, and elongation

Why is PCR the most widely used molecular method in the clinical lab?

DNA primers can be made for specific pathogens, so multiple sets of DNA primers can identify individual genes from a pathogen for more specific typing; useful for pathogens that are hard/slow to grow

Polyclonal antibodies typically recognize…

Many different epitopes on the same antigen

Monoclonal antibodies typically recognize…

One epitope

What is serotyping?

Used to identify and classify microorganisms based on the specific antigens present on their surface

What does ELISA do? (enzyme-linked immunosorbent assay)

Detects antigens in a sample by capturing the conjugated antibody if an antigen is present and will yield a colored product

What are point of care lab tests (rapid antigen test)?

Used directly at the site of patient care, the result is obtained quickly in order to make appropriate treatment decisions; involve immunochromatographic assays (ICT)

What makes a good POC lab test?

High specificity and high sensitivity; important to make sure tests are accurate and reliable

What is sensitivity?

How small of a sample a test can detect

What is specificity?

How well a test can distinguish positives and negatives

What is a sample application?

A drop of specimen; if present, it contains C-ps antigen from S. pneumoniae (red diamonds)

What happens when labeled antibodies are binded?

The sample moves along the strip then meets gold-labeled antibodies and this antibodies bind specifically to the pneumococcal antigen —> antigen-antibody complex

What is the test line (detection zone)?

The complex reaches the line, which has fixed antibodies against the same antigen, then the complex gets captured here and gold particles accumulate visible colored lines

What is the control line (validity check)?

Excess labeled antibodies continue to the control line then bind to anti-rabbit IgG antibodies to form a line if working properly