Physical Methods of Control
Antibiotics
Chemical Methods of Control
Tests/Methods
Resistance
100
What are the three general physical methods used for control?
-Heat
-Filtration
-Radiation
100
What is an antibiotic?
naturally produced antimicrobial agents made by bacteria and molds
100
Which scientist proposed the idea of using phenol to disinfect a room before sugery?
Joseph Lister
100
Which test is considered a Quantitative method?
MIC, Minimum inhibitory concentration
100
What are the two types of resistance?
Intrinsic and Acquired
200
If you needed to get sterilize a liquid that can easily evaporate, what physical method of control would you use?
Filtration
200
What is the difference between synergism and antagonism?
Synergism, works well combined, while antagonism, works worse combined with other things
200
What is the most effective concentration of alcohol, commonly used in hand sanitizers?
60-80%
200
Which method uses a disk diffusion assay?
Kirby-Bauer method
200
True or False: Resistance to antibiotics is a result from exposure to antibiotics
False
300
If you needed to get rid of microbes on the outside of a package of bread before it gets shipped to stores, what physical method of control would you use?
Non-Ionizing Radiation
-Because you are just getting rid of microbes on the outside!
300
What are the 5 targets of antibiotics?
Cell Wall
Protein Synthesis
Nucleic Acid synthesis (can be split into DNA replication and transcription)
Membrane
Metabolic Pathways
300
Which level of control are biguanides part of?
**Extra points if can name an example of a biguanide
Antiseptics
Chlorohexidine
300
What is a disk diffusion assay?
A drug is added to a paper disk and is then placed on a agar plate that is inoculated with lawn, and the drug diffuses away from the disk to generate different concentration rings
300
How can bacteria acquire resistance to something harmful?
Random mutation
Horizontal gene transfer of a previously mutated gene
400
Which physical method of control causes thymine dimers in DNA?
Non-Ionizing Radiation - UV causes thymine dimers in DNA
400
Which two antibiotics affect membrane phospholipids?
Daptomycin and Polymyxin
400
What are the three examples of chemical preservatives?
Nitrate & nitrite
Weak organic acids
Sugar and Salt
400
Which drug is most effective at lower concentrations according to these results?
Tetracyclin because it has the biggest zone of inhibition, meaning that towards the outer edge of the circle is effective in lower concentrations
400
What are the four mechanisms of acquired resistance?
Drug-inactivation
Target alteration
Decreased uptake
Increased elimination
500
What are the 5 heat treatments that we talked about in class and their respective level of control?
Sterilization: Autoclave, Incineration
Disinfection: Boiling, Hot air oven
Preservation: Pasteurization
500
Which two antibiotics affect peptide cross bridge formation?
Bacitracin, Carbapenems
500
What are the 13 chemicals and their respective level of control that we talked about in class?
Sterilant: Glutaraldehyde, Chlorine, Ethylene oxide
Disinfectants: Alcohols, Chlorine, Phenolics, Peroxides, Quats
Antiseptics: Alcohols, Silver, Iodine, Phenolics, Peroxides, Biguanides
Preservation: Sugar & Salts, Weak Organic Acids, Nitrate & Nitrite
500
What is the zone of inhibition and what does it show?
The area around the disk where there is no growth
Larger zone means the drug works at lower concentrations and is more effective
500
Explain one of the four mechanisms of acquired resistance
Drug-inactivation: an enzyme modifies the drug so that it cannot bind to the bacteria or doesn't work anymore
Target alteration: the bacteria change itself so that the drug cannot bind to it
Increased elimination: the drug enters the cell but then is pumped out quickly
Decreased uptake: Proteins prevent entry into the cell