Control of Microbes including antibiotics Flashcards
Bacteriostatic
Stop/inhibit bacterial growth (reversible/does not kill bacteria)
Bactericidal
Kills bacteria (irreversible)
Sterilization
destruction of all forms of microbial life and acellular entities, such as endospores.
Disinfection
destruction of vegetative cells (doesn’t impact endospores) (bleach is an example of disinfection)
Antsepsis
disinfection of living tissue, ex: hydrogen peroxide (and not all disinfections are antisepsis)
Degerming
removal of microbes from a limited area (quick cleaning of bacteria)
Sanitization
lowering microbial counts to safe public health levels.
What is D-value/decimal reduction time?
decimal reduction time (D-value) is time required to kill 90% of microbes or spores in a sample under the conditions.
Death of a microbe equals the loss of the ability to grow and reproduce (which gradually happens over a period of time).
Autoclave
steam under pressure increases temperature and also kills endospores and viruses that survive boiling.
Pasteurization
reduces microbial load, kills pathogens (doesn’t kill of all microbes just a large amount) and does not sterilize.
Incineration
direct flaming of the loop in the laboratory and disposal of biological materials.
Hot air oven
for materials unable to withstand steam (used to prevent exposure to steam and need a linger time for sterilization).
Autoclave is not preferred to use than hot air oven, True or False?
False autoclave is preferred over hot air oven.
What are the two common pore sizes for membrane filtration of liquid samples?
the two common pore sizes for membrane filtration of liquid samples are 0.2Mm and 0.45Mm which helps to get rid of bacteria.
Filtration
separates bacteria from liquid, filter sample through a membrane and is used for liquids that can’t be autoclaved
Ultrafiltration
a gram-negative microbes killed by autoclaving.
What is the difference between the use of ionizing and non-ionizing radiation in control of microbial growth?
Ionizing and non-ionizing both damage DNA. But ionizing has a stronger penetration power (wavelength <1nm (gamma rays, X-rays)) while has a poor penetrating power used for surface sterilization/used to sterilize petri plate (wavelength >1nm (UV light))
What are containing compounds and alcohols that are used in chemical control of microbes?
Halogen (Bromine Br, Chlorine Cl, Astatine At, Iodine I, Fluorine F, Tennessine Ts) and chlorine and iodine are halogens used in chemical to control microbes.
Chlorine-traditionally for disinfecting drinking water (can kill spores)
Iodine-very effective germicide (antiseptic)
Ethanol and isopropyl alcohols are alcohol used in chemical control of microbes.
What is the difference between natural, synthetic, and, semisynthetic antibiotics?
Natural antibiotics- compete with other microbes.
Synthetic antibiotics- human made, synthesize to use as treatment.
Semisynthetic- makes changes to chemical structure.
What are narrow spectrum vs broad spectrum antibiotics?
Narrow spectrum-effective only against a few types of microbes.
Broad spectrum- effective against many types.
Minimal inhibitory concentration (MIC)
lowest concentration of an antibiotic that inhibits growth of a test organism.
Minimal bactericidal concentration (MBC)
lowest concentration of antibiotic that kills a test organism.
List the mode of action for these antibiotics: Penicillin, Polymyxin, Quinolones, Rifampin, Actinomycin, Tetracycline, Isoniazid, and Trimethoprim.
Inhibition of cell wall synthesis- penicillin, cephalosporins, bacitracin, vancomycin.
Inhibition of protein synthesis- tetracyclines, chloramphenicol, erythromycin, and streptomycin.
Inhibition of nucleic acid replication and transcription- quinolones, actinomycin, and rifampin.
Cell membrane inhibitors- polymyxins
Enzyme inhibitors- trimethoprim and isoniazid
List some ways in which antibiotics are overused/misused.
Overuse of antibiotics for non-medical purposes.
Overuse of antimicrobial compound containing products.
What are the 4 mechanisms of antibiotic resistance discussed in class?
- Inhibitors of DNA replication- resistance is due to efflux pumps, which membrane proteins that expel/pumps antibiotic out of the cell (expel the antibiotic before it reaches its target).
- Inhibitors of protein synthesis- bugs may modify antibiotic-binding site on ribosome to become resistant and some bugs prevent penetration of drug (drug is block from entering the microbial cell).
- Bacteria quickly modify the target enzyme to become triclosan-resistant.
- These resistance mechanisms may render the organisms resistant to other antibiotics with a similar target.
