Chemical Growth Control Flashcards
Differentiate
Cidals vs statics
Cidals
* Kills microorganisms completely
* Bacteriocidal/Fungicidal/viricidal
Statics
* Inhibits growth
* Bacteriostatic/Fungistatic/viristatic
Effects of Antimicrobial Agents on Growth
3
- Bacteriocidal
- Bacteriostatic
- Bacteriolytic
- inhibitors of protein synthesis (does not kill)
- binding to ribosomes
- viable cells = total cells
Bacteriostatic
- Binds to cellular target, kills
- Dead cells are not destroyed
- Viable cells are killed, but turbidity is constant
- Ex. bleach/betadine
Bacteriocidal
- Kills by cell lysis; release of cytoplasmic contents
- When you do spectrophotometry, no cells will be detected
- Decreased viable and total cell number
- Example: Penicillin, Detergents, Lysozymes
Bacteriolytic
Differentiate
Viable cell count and Total cell count of each
Effect of Antimicrobial Agents on Growth
- static: same viable & total
- cidal: ↓ viable, same total
- lytic: ↓ viable, ↓ total
lysis destroys dead cells, while cidal kills cells but keeps them there
What do we do to measure antimicrobial activity?
- Minimum Inhibitory Concentration
- Disc Diffusion Technique
- Smallest amount of agent needed to inhibit microbial growth
- Looking at specific concentrations of a single antibiotic
- clear test tube = Most effective concentration of antibiotic
Minimum Inhibitory Concentration
Technique used for Minimum Inhibitory Concentration
Tube dilution technique
Factors that affect Minimum Inhibitory Concentration
- Bacterial species
- Inocoulum size
- Culture medium
- Incubation conditions
the clearer the tube = antibiotic is [more/less] effective
more
- Looking at several antibiotics to see which is the best to kill the organism
- Kirby-Bauer Antimicrobial Assay
- Observe for the zone of inhibition
Disc Diffusion Technique
List
Kinds of Chemical Microbial Agents
- Antiseptics AND Germicides
- Disinfectants
- Sanitizers
- Sterilant
Differentiate
Kinds of Chemical Microbial Agents
What do they do? What are they used on?
Antiseptics AND Germicides
* Nontoxic agents that can kill or inhibit growth of organisms
* Use on living tissues
Disinfectants
* Kills organisms (not necessarily endospores)
* Use on inanimate objects (surfaces, glassware)
Sanitizers
* Reduce, not eliminate, microbial numbers
Sterilant
* Destroy all forms of microorganisms, including endospores
List
Chemical Groups that can be Chemical Microbial Agents
6
- Phenol and Phenolics
- Halogens
- Alcohol
- Quaternary Ammonium Compounds
- Alkylating Agents
- Oxidizing Agents
