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
Explain
Phenol & Phenolics
Kind & MOA
Antiseptic
Mode of Action:
1. Disrupts cytoplasmic membrane
1. Denatures DNA
1. Inactivates enzymes
What chemical group?
Lysol, hexachlorophene, trichlosan
Uses: Soaps, lotions, cosmetics, body deodorants, PineSol
Phenol & Phenolics
Explain
Halogens
Kind & MOA
Sterilant, disinfectant, sanitizer
MOA (Mode of Action)
1. Iodine binds to tyrosine residues of proteins
2. inhibits protein production
1. Iodine oxidizes sulfhydryl groups
2. disrupts protein structure
1. Water + Cl → hypocholorous acid (oxidizing agent)
What chemical group?
Examples
* Iodine, chlorine, mercuric dichloride
* Betadine
* Chlorox
Uses
Topical antiseptic, disinfectant of lab surfaces
Halogens
Explain
Alcohol
Kind & MOA
Antiseptic (most effective at 70%)
MOA
1. Denatures proteins (water must be present
1. Disrupts cellular membrane
1. Lipid solvent
What chemical group?
Examples
Isopropyl alcohol, Ethyl alcohol
Uses
Tropical antiseptic
Alcohol
Explain
Quaternary Ammonium Compounds
Kind & MOA
Disinfectant, antiseptic, sanitizer
MOA:
1. Probably disrupts the membrane
1. Interacts with phospholipids
Quaternary Ammonium Compounds can support the growth of ____.
Pseudomonas sp.
What chemical group?
Examples
Detergents, Lysol, Cepacol, soaps
Uses
* Medical, food and dairy equipment
* Soaps, lotion and topical disinfectant
Quaternary Ammonium Compounds
Explain
Alkylating Agents
Kind & MOA
Disinfectant, sterilant
MOA:
1. Disrupts proteins and structure of nucleic acids
What chemical group?
Examples (examples are carcinogenic)
* Formaldehyde
* Gluteraldehyde (spore killers)
* Ethylene oxide (explosive)
* OPA (ortho- phtaladehyde)
Uses
* Surface disinfectant, sterilant for temp-sensitive materials (plastics, lenses)
* high-level disinfectant for medical instruments
Alkylating agents
Explain
Oxidizing Agents
Kind & MOA
Antiseptic, disinfectant, sterilant
MOA:
1. Disrupt disulfide bonds in proteins
1. Membrane and protein stability
What chemical group?
Examples
* Hydrogen peroxide
* Vapors used in ozone chambers
* Potassium permanaganate
Uses
* Topical antiseptic, medical equipment
Oxidizing Agents
