Overview Microbial Flashcards
In the clinic,
where only a very small subset of bacteria will be found, several important features of a clinical isolate are tested to identify the organism. What are they?
Metabolism: test by measuring growth on a particular medium and/or the ability to react with an indicator chemical in the medium.
Requirement for oxygen: test by measuring growth in oxygen.
Sensitivity to antibiotics: test by measuring growth in the presence of
antibiotics.
Gram staining: test by performing the Gram stain.
Morphology: test by examining colony morphology and light microscope appearance.
Define pathogen.
A pathogen is an organism that can cause disease. Microbes are still major pathogens.
Define symbiotic and give an example.
Symbiotic (or mutualistic): An association where the two species are mutually dependent
Example: Human and E. coli (in a healthy individual)
Define commensal and give an example.
Commensal: An association where only one of the two species
benefits, but the other does not suffer
Example: Human and Bacteriodes
Define parasitic and give an example.
Parasitic: An association where one species derives its nutrients
from and at the expense of the other
Example: Human and Mycobacterium tuberculosis
Define obligative.
Obligative: The parasite requires the host to survive
Define facultative.
Facultative: The parasite does not require the host to survive
What is a strict or primary pathogen? Give an example.
Strict or primary pathogens: Are infective to healthy hosts
Example: Mycobacterium tuberculosis
What are opportunistic pathogens? Example?
Opportunistic pathogens: Cause infection when the host is already compromised
Example: Pseudomonas aeruginosa
