Lecture 1 Overview Flashcards
What is the only indirect approach to microbial identification
Appearance of antibodies against the antigen
Name the four direct methods of microbial identification
- Direct Microscopic Analysis
- Microbial Culture, physiology, and morphology
- Antigenic Analysis
- Genetic Analysis
Infectious microbial agents of disease can be divided into what three groups?
- Normal Flora
- Opportunistic
- Pathogenic (Frank)
Define Opportunistic microorganisms
Are typically normal flora that can become pathogenic under certain circumstances
Define “frank” or pathogenic microorganisms
Typically cause disease when present and are not generally normal flora
Can the normal flora be helpful to the body? Explain
Yes, for example some normal flora can often out-compete frank pathogens, limiting their ability to colonize
What is the usual reason for opportunistic infections
Some impairment of the innate and/or adaptive immune systems
Are viruses normally considered part of the normal microbial flora?
No.
Explain the reasoning behind acute vs. convalescence in a clinical sample.
This is simply measuring the antibodies during the acute illness vs after the illness has either passed or is aged. The antibodies are different and usually indicative of the stage of the illness.
What are the 6 ways to prepare a bug to be visualized?
- Gram Stain
- Acid-fast stain
- India Ink stain
- KOH prep
- FITC Serology
- PCR (Polymerase Chain Reaction)
What organism does Acid-Fast staining help visualize?
Mycobacterium
What staining technique is used to visualize Capsules?
India Ink Stain
What does a KOH prep visualize?
Fungi
The purpose of PCR in visualization?
To help genetically identify sequences of DNA or RNA that helps determine the organism
What does the FITC Serology help us visualize?
Antibodies
Which method of microbial identification is most prone to operator error?
Genetic Analysis (PCR?)
Describe how the KOH prep works
Because Fungi are resistant to this staining, if fungi are present they will outlast the staining. If there is nothing left after the prep, there are no fungi present.
FITC serology is similar to what other type of test to determine antibodies?
ELISA test where a flourescent dye is added to the end of the antibody
What is the purpose of the enriched media?
If one is not sure what the bacteria is, this is an agar that makes sure the bacteria will grow so that it can be further tested. Blood agar is a good example of this type of media
What does a selective media do
It is specific to bacteria strains with specific nutrients and conditions for that specific bacteria to grow
Name 6 ways of identifying a microorganism after an in vitro isolation or culture
- Microscopic visualization (gram stain, etc.)
- Enzyme tests (catalase, oxidase, etc.)
- Physiology (Metabolic pathways)
- Ab detection (ELISA, FITC)
- DNA/RNA characterization (PCR)
- Antibiotic Susceptibility
Name three ways to detect a virus from culture or colonization
- Cell lytic assay
- DNA/RNA characterization
- Ab detection
