Microbio Ch. 11

Microbiology chapter 11 "physical and chemical agents for microbial control".

physical, chemical, and mechanical methods to destroy or reduce undesirable microbes in a given area =

decontamination

microbes with the highest resistance include =

prions, bacterial endospores

microbes with moderate resistance include =

pseudomonas sp, mycobacterium tuberculosis, staph aureus, protozoan cysts

microbes with the least resistance include =

most bacterial vegetative cells, fungal spores and hyphae, yeast, enveloped viruses, protozoan trophozoites

a process that destroys all viable microbes, including viruses and endospores =

sterilization

a process to destroy vegetative pathogens, not endospores; inanimate objects =

disinfection

disinfectants applied directly to exposed body surfaces =

antiseptic

any cleansing technique that mechanically removes microbes =

sanitization

number of microbes, nature of microbes, temp and pH, concentration or dose of agent, mode of action of agent, presence of solvents, organic matter, or inhibitors =

factors that affect death rate

doesnt necessarily kill a microbe, but inhibits growth and or metabolism =

microbiostatic agent

kills a microbe =

microbicidal agent

an antimicrobials mode of action is its =

cellular targets

mode of action where cell wall becomes fragile and cell lyses =

cell wall

examples of antimicrobial agents that target the cell wall include =

some antimicrobial drugs, detergents, alcohol

mode of action where phospholipid bilayer loses its integrity =

cell membrane

examples of antimicrobial agents that target the cell membrane include =

detergent, surfactants

mode of action that prevents replication, transcription, translation, peptide bond formation, protein synthesis =

protein and nucleic acid synthesis

examples of antimicrobial agents that target protein and nucleic acid synthesis include =

chloramphenicol, UV radiation, formaldehyde

mode of action that denatures or disrupts proteins =

proteins

examples of antimicrobial agents that denature or disrupt proteins include =

alcohols, phenols, acids, heat

methods of physical control include =

heat (moist and dry), cold, desiccation, radiation, filtration

lower temperatures and shorter exposure time, coagulation and denaturation of proteins =

moist heat

methods of dry heat disinfection include =

incineration, dry ovens

moderate to high temperatures, dehydration, alters protein structure, incineration =

dry heat

methods of moist heat disinfection include =

steam under pressure, autoclave, boiling

form of moist heat disinfection that sterilizes =

steam under pressure

10-40min of moist heat disinfection in which steam must reach surface of item being sterilized, denatures proteins, destroys membranes and DNA =

autoclave

what is the mode of action for autoclave?

denatures or disrupts proteins

100C for 30min of moist heat disinfection that destroys non-spore forming pathogens =

boiling

heat is applied to kill potential agents of infection and spoilage without destroying food flavor or value, kills non-spore forming pathogens and lowers overall microbe count =

pasteurization

pasteurization at 63C-66C for 30 minutes =

batch method

pasteurization at 71.6C for 15 seconds =

flash method

generally, _____ takes more time and higher temps as compared to _____

dry heat, moist heat

examples of microbiostatic methods include =

refrigeration, freezing

gradual removal of water from cells, leads to metabolic inhibition =

desiccation

desiccation is _____ because many cells retain ability to grow when water is reintroduced

ineffective

freeze drying; preservation =

lyophilization

deep penetrating power that has sufficient energy to cause electrons to leave their orbit, breaks DNA =

ionizing radiation

examples of ionizing radiation include =

gamma rays, x-rays, cathode rays

ionizing radiation is used to =

sterilize food products and medical supplies

little penetrating power so item must be directly exposed =

non-ionizing radiation

_____ creates pyrimidine dimers, which interfere with replication

UV light

non-ionizing radiation is used to =

sterilize air, water or surfaces

physical removal of microbes by passing a gas or liquid through a filter =

filtration

filtration is used for =

sterilize heat sensitive liquids and air

germicides that kill endospores, may be sterilants =

high level

high level germicides are used for =

devices that cannot be heat sterilized, intended to be used in sterile environments

germicides that kill fungal spores, not endospores, tebercle bacillus, and viruses =

intermediate level

intermediate level germicides are used for =

disinfect devices that will come in contact with mucous membranes

germicides that eliminate only vegetative bacteria, vegetative fungal cells, and some viruses =

low level

low level germicides are used for =

to clean surfaces that touch skin only

solutions of 50-95%, act as surfactants dissolving membrane lipids and coagulating proteins of vegetative bacterial cells and fungi, intermediate level =

alcohols

one of the oldest and most effective antiseptics, works against all bacteria and many endospores, fungi, and viruses; alters plasma membranes =

iodine

iodine mixed with alcohol is a =

tincture

iodine mixed with an organic carrier molecule is an =

iodophor

produce highly reactive hydroxyl-free radicals that damage protein and DNA while also decomposing to O2 gas - toxic to anaerobes =

hydrogen peroxide

hydrogen peroxide is an antiseptic at _____ concentrations, and sporicidal at _____ concentration

low, high

act as surfactants that alter membrane permeability of some bacteria and fungi, very low level decontamination =

quaternary ammonia compounds (quats)

mechanically remove soil and grease containing microbes =

detergents and soaps

Unwanted microbes present in a given time, place or amounts; microbes which are present in wrong place or in wrong amounts =

Contaminant

Methods for Decontamination =

physical, chemical, mechanical

growth of microorganisms or presence of toxins in blood or tissues =

Sepsis

practice which prevents entry/infection =

Asepsis

dramatically reduce numbers of microbes on living tissue (skin) typically combined with use of antisepsis =

Determination

dry heat method at 150 to 180 degrees Celsius, coagulate proteins =

dry ovens

_____ radiation disinfects by creating pyrimidine dimers to prevent DNA synthesis at molecular levels

non-ionizing