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MICAB - Exam 1
Lecture 2
Question | Answer |
---|---|
Define virulence | an organism's ability to cause an infection and establish disease (pathogenicity); attributed to differences in genomes |
Define infection | Bacteria capable of causing disease becomes established within the host. |
Define colonization | Persistence within the host of a disease causing bacterium without symptoms (asymptomatic carriers) |
Define disease | Infection that produces symptoms. |
Two categories of virulence factors | Promotion of colonization (invasion into the host) and agents that cause damage to the host (toxins) |
A-B Toxins | Separate peptides that mediate host binding (B) and toxin activity (A), eg. Diphtheriae, cholerae, and tetanus |
Membrane disrupting toxins | Hemolysins and phospholipases, eg. a-toxin of C. perfingens. |
Superantigens | Act by stimulating T-cells to release cytokines. eg. S. aureus -toxic shock protein. |
AB Toxins do this to inactive proteins | Ribosylate |
Bactericidal | Permanent loss of replication |
Bacteriostatic | Temporary loss of replication |
Minimum Inhibitory Concentration (MIC) | Lowest concentration that inhibits growth |
Minimum Bactericidal Concentration (MBC) | Lowest concentration that reduces growth by 99 % |