Antimicrobial Resistance Flashcards
What are the 3 ways of physical sterilization?
Heat
Radiation
Filter
What “metric” quantitfies antimicrobial effectiveness?
- Decimal Reduction time - time it takes to reduce microbial population by 90%
- D = -t / log Nf - log No
- T = Tfinal - Tinitial
- What is the most widely used method of controlling microbial growth?
- How does this method work against microbes?
- Heat sterilization
- High temperatures denature macromolecules
What are some things you can’t kill/sterilize in an autoclave?
- spores
- Anything you want to keep living
- Scrubs, electronics, etc.
How does an autoclave work?
- Sealed device that use steam under pressure
- allows temps of water to get above 100 C
- Pressure doesnt kill, but high temperature does.
What is pasteurization?
Is pasteurization a form of sterilization?
- process of using precisely controlled heat to reduce the microbial load in heat-sensitive liquids
- Does not kill all organisms - so technically it is not sterilization.
What types of surfaces can/can’t be affected by UV radiation?
- Can
- tops of surfaces
- Can’t
- solid, opaque, or light-absorbing surfaces
Is radiation sterilization approved by the WHO for the decontamination of foods susceptible to microbial contamination?
Yes
What is filter sterilization good for?
- Allow liquid and gas to fit through but catches very small microbes
- Good for heat sensitive things that need to be sterilized.
Most bacteria are [] - [] microns long, but HEPA filters catch anything greater than [] um….
- 3-5 microns
- >.3 um
What is the MAIN target for most antimicrobials?
essential proteins and cell membrane
What species of bacteria make 2/3 of the useful antibiotics?
Streptomyces species
What are the 3 main compounds produced to stop the growth of microbes?
Antibacterials
Antivirals
Antifungus
What is the minimum inhibitory concentration?
- Smallest amount of an agent needed to inhibit growth of a microorganism
- Varies between organism, not real precies
How are viable cell counts used to quantify chemical growth control of microbes?
What is the draw back to viable cell count?
- Gives information about bacteriostatic / cidal /lytic
- since you actually look at the plates and shit
- Can be used to calculate decimal reduction times
- However, can be very laborious
- Stopping growth of cell and disrupting viability =
- Stopping growth and destroying cells =
- Stopping growth/reproduction without distupting the viability of cells =
- bacteriocidal
- Bacteriolytic
- Bacteriostatic
What are the 2 categories of chemical agents?
- Products use to control microbes for external use
- Industrial settings, chemicals in food, sterilants, disinfectants antiseptics, etc….
- Chemical sdesigned for internal use
- antibiotics - antibacterials, antivirals, antifungals, antiparasitics
What chemical antimicrobial agent is ok to use on human and living tissues?
Antiseptics
Ex: Ethanol, soap, iodine
What antimicrobial agent destorys all microbial life, including spores?
- Sterilants
- Hydrogen peroxide, ethylene oxide gas, bleach
- 6-7 log reduction
What chemical antimicrobial agent kills most microbes, except for spores, on surfaces?
- Disinfectants
- Ex: Ethanol, ozone, chlorine gas, Pine-Sol
- 4-5 log reduction
What chemical antimicrobial agent reduces the total number of microbes?
- Sanitizers
- Ex: Alcohol gels
- 2-3 log reduction
How do synthetic antibiotics generally attack microbes?
- Analogs similar to vitamins, amino acids, and other compounds
- Adding a bromine or fluorine to nucleic acid base and amino acid analogs
How do sulfa - synthetic drugs work?
- They are a competitive inhibitor to the enzyme dihydropteroate synthase (DHPS)
- Enzyme involve din foalte synthesis
How do Isoniazid antibiotics work?
- It is a growth analog effective against mycobacterium
- interferes with synthesis of mycolic acid
What are the major naturally occuring antimicrobial drugs created by…Streptomyces?
- tetracyclines
- aminoglycosides
- macrolides
- chloramphenicol
- 60-80% of naturally occuring antibiotics
What are the major naturally occuring antimicrobial drugs created by…Fungi?
- Penicillium
- Cephalosporium
- B-lactams
What are the major naturally occuring antimicrobial drugs created by…Bacillus?
- Polymixins
- Bacitracin
What do B-lactams inhibit?
What specific protein do they inhibit and which type of bacterial cell are they most effective against?
- transpeptidation - final step of inserting NAG-NAM into peptid
- PBPs that crosslink peptidoglycan
- Most effective against against G+ since they have a large peptidoglycan layer
What does Daptomycin inhibit?
What is it produced by?
Use to treat [] bacterial infections
How does it effect the membrane?
- Membrane function
- Streptomyces
- Treats G+ infection
- Forms pores in cytoplasmic membrane
What are polymixins made by?
What do they distrupt and how?
- Paneibacillus polymyxa
- Bind to LPS of G- and disrupt inner membrane and outer membrane
What new class of broad-sprectrum antibiotics inhibit fatty acid biosynthesis?
Platensimycin
