Exam 3 -Chapter 12 Flashcards
the killing or removal of all microorganisms in a material or an object
sterilization
it is impossible to do this to skin without burning it
sterilization
an environment or procedure that is free from contamination by pathogen
asepsis
process of reducing or inhibiting microbial growth by applying chemicals to inanimate objects
antisepsis
removal of microbes from a surface by scrubbing
degerming
lowering the number of pathogens of objects to safe public health level
sanitization
minimizing disease transmission by washing tableware in scalding water
sanitization
the use of heat to kill pathogens and lower the number of spoilage organisms in food or beverages
pasteurization
“-static” agents when controlling microbial growth
is the inhibition but not complete destruction
“-cidal” agents when controlling microbial growth
is the complete destruction or death
permanent loss of reproductive ability under ideal environment conditions
microbial death rate
Ex. if temp kills 20% of bacteria in one minute it will kill 20% of the surviving bacteria in the second minute, and so on
microbial death rate
significance of microbial control in death rate
is to control the amount of microbial exposer to the public
what are the targets for microbial control agents
cell walls, cytoplasmic membrane, proteins, nucleic acids
what does cytoplasmic membrane do considering microbial control
susceptibility, chemical agents that damage membrane by altering permeability
how are proteins targets from microbial control
damage proteins, enzymes, structural components, heat or chemicals denature proteins and cause cell death
how nucleic acids are targets fro microbial growth
heat, radiation, chemical can cause mutations in DNA
disrupt cellular function and stop protein synthesis
Ex. gamma rays. UB light, X-Rays
factors to consider when selecting microbial control agent
- inexpensive
- fast-acting
- stable during storage or shelf life
- harmless to humans, animals, and objects
- nature of sites to be treated
- degree of susceptibility of the microbes involved
- environmental conditions
nature of site to be treated when considering selecting microbial control agent
- harsh chemical and extreme heat cannot be used on humans, animals or fragile objects
- instruments that penetrate the body must be sterilized
- items contacting the mucous membranes or skin must be disinfected unless immunocompromised
degree of susceptibility of microbes when considering selecting microbial control agent
- actively growing microbes more susceptible to treatment than stationary cells
- select method to kill the hardiest microorganisms present
environmental conditions to consider when selecting microbial control agent
- temperature-enhanced by increased temp
- pH disinfectant activity can be enhanced or inhibited by a change in pH
- organic materials - fat, feces, blood, pus interfere with penetration of heat
5 types of physical methods of microbial control
heat, low temperature, filtration, osmotic pressure, and radiation
what does heat do to control microbial growth
denature enzymes, affect plasma membrane, and disrupt function of nucleic acid
types of heat to control microbial growth
moist heat - boiling or autoclave
dry heat - direct flaming, hot-air sterilization, incineration
low temperature to control microbial growth
freezing - slow; inhibit microbial metabolism
refrigeration - bacteriostatic; halts growth of most pathogens (mesophiles)
*rate and intensity determine effectiveness
filtration to control microbial growth
passage of liquid or gas through a filter with pores small enough to retain microbes
*used to sterilize heat sensitive materials (antibiotics, vitamins)
HEPA filters used by lab and healthcare workers to prevent airborne contamination
osmotic pressure to control microbial growth
- using high concentrations of sugar or salt
- removal of water inhibits cellular respiration
- food reservation
- molds and yeast have higher tolerance
radiation to control microbial growth
Gamma rays; X-rays (ionizing)
Ultraviolet (nonionizing)
gamma rays to control microbial growth
Ionization
- high penetration
- destroys DNA
- used to sterilize medical and dental supplies
ultraviolet radiation to control microbial growth
Nonionizing
- low penetration
- damages DNA
- Germicidal lamps used in hospitals
to destroy pathogens without altering flavor of food or beverage
pasteurization
importance of refrigeration
halts the growth of most pathogens
importance of freezing
inhibit microbial growth
- helminthes die in days
- bacterial endospores, vegetative bacteria and viruses can survive for years
inhibit cellular metabolism and microorganism undergo plasmolysis in high salt and sugar
hypertonic solutions
high penetration, destroys DNA, and sterilizes medical and dental supplies
Ionizing radiation
low penetration, damages DNA, and germicidal lamps used in hospitals
Nonionizing radiation
why 70% alcohol is more effective than 90%
water has a lower evaporation rate than alcohol and will stay on surface longer and kill more bacteria
actions of alcohols as antimicrobial agents
- denature proteins
- dissolve lipids
- kill bacteria, enveloped viruses and fungi, but not endospores and non-envelope viruses
- ethanol/isopropanol disinfectant
types of halogen-containing antimicrobial agents
- iodine
- chlorine
- bromine
- fluorine
iodine as an antimicrobial agent
- inactivates enzymes and cellular respiration
- control of microbes in pools, drinking water, and food utensils
- surgical scrubs and incision sites
chlorine as an antimicrobial agent
- forms hypochlorous acid in water
- swimming pools, drinking water, sewage treatment
- calcium hypochlorite, sodium hypochlorite, chloramines
types of oxidizing agents
hydrogen peroxide and peracetic acid
what are the uses of oxidizing agents
to inhibit metabolism and oxidize molecules inside cells
when do you oxidizing agents
deep puncture wounds
surface acting i.e. soaps and detergents
surfactants
antibmicrobial action of soap
limited germicidial action through scrubbing
antimicrobial action of detergents
hydrocarbons, acid-anionic sanitizers important in dairy industry
low levels of bacteriostatic agents
heavy metals
list of heavy metals
silver, mercury, zinc, copper, selenium, mercuric chloride and copper sulfate
heavy metals are what when considering their microbial control
germicidial or antiseptic
heavy metals do this to cells
denature enzymes
used in eyes of newborns and surgical dressing
1% silver nitrate
most effective antimicrobial that inactivate proteins and denature DNA
formaldehyde and glutaraldeyde
2% solution if glutataldehyde is used in
hospitals and dental offices
Glutaraldehyde is more expessive than formaldehyde but is
less irritating and more effective
where is formaldehyde is used for
to embalm, disinfect reusable kidney dialysis machines, isolation rooms, surgical instruments
formaldehyde irritates
mucous membranes
advantage of using gaseous agents of microbial control
penetrates most material and kills microorganisms by denaturation and can be used on heat sensitve material
disadvantage of using gaseous agents of microbial control
explosive, poisonous, carcinogenic
examples of gaseous agents used for microbial control
ethylene oxide and propylene oxide
antibacterial and antifungal agent found in numerous consumer products
triclosan
liquid antiseptic/antimicrobial skin soap
hibiclens
denatures enzymes, ologodynamic action
silver
inactive enzymes and cellular proteins
iodine
used on surgical scrubs and incisions
iodine
topical antiseptic used for minor cuts and scrapes
mercurochromes
really kills 99% of bacteria viruses
lysol
what are the phenols and phenolics
triclosan, hibiclens, lysol
