Physical and Chemical Control of Microbes Flashcards
Microbes with least level of resistance
vegetative bacterial; most likely to be killed
Microbes with moderate levels of resistance
protozoan cyst and fungal spores
Microbes with high levels of resistance
bacterial endospores and prions
Sterilization
any process that destroys all life and inactivates all viruses and prions
Sterile
everything dead
Inactivated
mostly/partly sterile
-icide
to kill (fungicide)
-statics
prevent growth; killing is not the goal (bacteriostatics, fungistatic)
Disinfectant
process of destroying vegetative pathogens/endospores and remove toxic products of organisms
Sanitization
removes microorganisms and debris; physical removal
Sepsis
state of having microbes present (in body tissues)
Asepsis
practice that prevents the entry of a microbe into tissue, body, areas
Microbial death
whether or not they are capable of undergoing cell division in their optimal conditions
How to decide method to kill microbe
number of organisms, nature of the organism, environmental conditions, concentration of antimicrobial agent, mode of action of the antimicrobial agent, presence of interfering organic matter or solvents things
Number of organisms
more = thicker = longer time to destroy microbes
Nature of organisms
microbes ability to survive
Environmental conditions
temperature and pH in which you’re trying to kill the microorganisms can affect the activity of the disinfectant
Concentration of antimicrobial agent
higher the concentration the better the antimicrobial agent is (except alcohol)
Mode of action of the antimicrobial agent
how that antimicrobial agent attacks the microbe and knowing whether or not the microbe actually contains the structure that’s being attacked
Presence of interfering organic matter or solvents things
can inhibit the action of antimicrobial agents
Mode of action
against cell wall, surfactants, cellular synthesis, protein structure and function
Action against bacterial cell wall
target the cell wall; compromised cell wall can allow attack of cell membrane
Action of surfactants
disrupts the structural integrity of phospholipid membrane causing release of important molecules and toxins to come into cell
Action of targeting cellular synthesis
targeting anything that can affect the ability for a microbe to reproduce and survive
Action of targeting protein structure and function
destroys function of protein; cell wont be able to release waste, bring in nutrients, etc.
Moist heat
heat that includes the use of steam (60-135C)
Mode of action of moist heat
coagulates and denatures protein
How to have steam @ temps above 100C?
add pressure
Eg. of moist heat
autoclave, pasteurization (60-70C @ short periods), fasteurization, boiling water
Dry heat
removes water needed for metabolism, denatures, incinerates (160C+)
Eg. of dry heat
flame, oven
Moist v dry heat
moist heat is more effective at same temps (coagulation and denaturing of proteins)
Thermal death point
lowest temperature required to kill all microbes in 10 minutes
Lyophilization
freeze-drying microbes/chemicals
Lyophilized chemical
rehydrating freeze-dried chemicals
Ionizing radiation
transmitting enough energy molecule is able to eject out of orbital and create chemical changes
(gamma rays and x-ray)
Effect of ionizing radiation
break covalent bonds in DNA leading to mutations
Non-ionizing radiation
causes electron to enter slightly higher energy state (not creating ions)
Effect of non-ionizing
lead to the formation of abnormal bonds
Ionizing radiation mutations
large scale
Non-ionizing radiation mutations
point mutations
Mechanical removal of microbes
using filters to remove microbes from a fluid (liquid/air/water)
Chemical agents
keep microbes from growing and surviving (eg. disinfectants, antiseptics, sterilizers, preservatives)
Aqueous solution
pure water or water-based liquid chemical agent
Tincture
antimicrobial agent that is alcohol or water alcohol-based dilution
Ideal antimicrobial chemical agents
glutaraldehyde, chlorhexidine, hydrogen peroxide
common antimicrobial chemical halogens
chlorine, iodine
Mode of action for halogens
break disulfide bonds
Disulfide bonds
bonds between two sulfur atoms that are found in proteins between two cysteine amino acids
Amino acids that contain sulfur
methionine, cysteines
What kind of bond is a disulfide bond?
covalent; causes permanent denaturation
Chlorine
OCl-
Hypochlorite (most common chlorine)
OCl
Iodine
free iodine and iodophors
Iodophors
iodine complexed with neutral polymers
What do large molecules in iodophors allow?
slow release of the iodine into solution; allow for function and lasting effects
Phenol
six carbon ring structure with double bonds in the ring structure with an attached hydroxide functional group
Mode of action phenol
disrupts cell walls and it disrupts cell membranes and also precipitates proteins
Chlorhexidine chlorexodyne
combination of chlorine and two phenolic rings
Ethanol
two carbons with a hydroxide
Isopropanol
three carbon alcohol with the hydroxide alcohol; more effective
Mode of action for alcohols
concentrations 50 or higher dissolve membrane lipids and denature proteins by coagulation
Why does 80% alcohol not coagulate?
not enough water
What does alcohol do to the cell?
dehydrates the cell, does not kill
Oxidizing agents
hydrogen peroxide and ozone
Cationic detergents include
quaternary ammonium/quats
Quats (cationic)
attracted to the phospholipids and be very effective at causing leaks in the cell membrane
Mode of action metallic elements
bind to functional groups of proteins and inactivate them bringing metabolism
Aldehydes
organic substance that contains a c-h-o functional group or an aldehyde functional group
Eg. aldehydes
glutaraldehyde, formaldehyde
Ethylene oxide
sterilizer when binds to DNA molecules and proteins
Chlorine dioxide
strong alkylating agent reacting with functional groups in DNA and protein
