the removal/ destruction of all living organisms

(Heating is the most common way of killing microbes including thoughs with endospores

sterilization gas ethylene oxide or steam under pressure

the destruction of most microbial life on a control directed at destroyng harmful microorganisms

(Usually refers to no endosporic microbes or pathogens / uses chemicals, ultravioletradiation, boiling water or steam

the destruction of most microbial life on living tissue

(Chemicals, ultraviolet radiation, boiling water or steam are all disinfectants however some disinfectants can be antiseptics such as the same chemical however some may be to harsh for the skin

scrubbingand/or swabbingthe skin in chemicals to remove or reduce the number of microorganisms by mechanical removal

(Usually removal rather than the killin go most microbes in a limited area

a cleaning technique that _reduces or lowers__ the number of  microbes to reducecontamination and maintain safe public health levels  

(Usually accomplished by  high temp washing or washing in a sink folowed by a dip in chemical disinfectant- which are used in bars)

the permanentLOSSof reproductive capabilities (growth)

Bactericide

Biocide

Germicide all mean?

 They all mean the killing of microorganisms

(Usually with certain excepteions such as endospores

Stasis-to stop or steady

Bacteriostasis-

a chemical that preventsbacterialgrowth but does not  kill the bacteria

( Its an inhibitor and once it is removed growth might resume

Bacteria population to die at a constant rate 

(ex autoclaving)

What can influence the rate at which a bactericidal agent kills a bacterium? 

1. Time-•the longerthe time the bacteria are exposed to the agent the the more bacteria killed
2. Agent Concentration-the higher the concentration of the agent the the faster it is to kill more bacteria /?
3. #of Microbes- the more microbes the longer it takes to eliminate the population
4. Evironmental influences- Instruments with organic debris (blood, feces, tissue, etc) will take longer to disinfect or inhibit bacteriacidal agent disinfection. ex microbes in biofilm
5.  Resistance level of microbes (endospores versus non-endospores): More time will be required to treat microbes that have high levels of resistance. For example, endospore-forming bacteria will take longer to kill than non-endospore forming bacteria.

5) Activity level of the method or agent (cidal versus static): Agents that are cidal will be more effective at reducing microbial contamination than agents that are static

ü  Name the three key bacterial components/structures that a bactericidal agent may target.

1. Inner Plasma Membrane-disruption of the inner plasma membrane causes cytoplasmic contents to leak out of the bacterium why- because the plasma membrane inside cell wall transports nutrients and lets out waste interfering with growth of the cell
2. Bacterial Proteins- Enzymes are bacterial protiens/ damage to the structrue of an enzyme can inactivate them- specifically breakage of hydrogen bonds that holds the shape of the protein leading to denaturing
3. Nucleic acids-Dna and Rna that carry the bacteria cells genetic information / damage can  effect replication and transcription/ translation to create enzymes killing bacteria due to metablic functions

ü  What is the best way to graphically represent microbial death from a bactericidal agent and why is this approach the most appropriate?

Logarithmically

Why- because the death rate is constant (results in a straight line

- side note- Impractical- the population of the cells would be only one hundreth of the distance between the 100,000 and the base line(3 min and 1000 cells

ü  What are the two main methods for controlling microbial growth?

1. Physical Method- heat, lowtemp, Dessication, high pressure, osmotic pressure, filtration
2. Chemical Method

ü  List seven physical methods for controlling microbial growth.

1. Heat
2. Low temp
3. Dessication
4. High Pressure
5. Osmotic Pressure
6. Filtration
7. Radiation

Heat

1. Thermal Death Point(tdp)-lowest temperature at which all the bacteria in a liquid suspension will be killed in 10minutes
2.  Thermal Death Time-(Tdt)   minimum length of time for all bacteria in a liquid suspension to be killed at a given temperature  
3. Decimal Reduction Time (drt)-•time (in minutes) in which 90% of a bacterial population will be killed at a given temperature
    
   

ü  What two types of heat can be used to control microbial growth and what happens to proteins/enzymes when exposed to high heat?

Two types of heat

1. Moist HEAT
2. Dry heat

What happens when enzymes are exposed to heat

Denaturing occurs-(breaking of hydrogen bonds that hold the shape of the protein 

ü  Why is moist heat more effective in killing microbes compared to dry heat?

Moist heat is more penatrating

More effective taht dry at a given temp or length of ex exposure/ requires equiptment (ex autoclave)

Dry heat- requires higher temps and is less penatrating requiring longer exposure/ but it is cheap and easy

ü  List three methods that employ moist heat to control microbial growth.  Which of these three methods is the only reliable means of sterilization?

1. Boiling (not reliable)- greater than 20 hrs to kill endosporer, mycobacteria, garamnegative, gram positive take 10 min to kill( vegetative bacteria/ least resistant)
2. Steam Under Pressure (Reliabl)- kills all organisms and endospores within 15 min at 15 psi 121C (time, temp, & pressure)/ sterilize culture media,solutions, medical instruments and ect withstand high temp and pressure/Retort (industrial autoclave- used in Commercial sterilization (canned foods)
3. Pasteurization- mild heating to kill food spoiling microbes without damaging the taste. - High temp short time-(HTST) pasteurization of milk involves exposure at 72°C for 15 SECONDS (no pressure) / Ultra High temp-•(UHT) involves exposure at 134°C for 1-2 sec (no pressure)- stored for several months
    
   

    

ü  What is the general relationship between pressure and the temperature of steam?

Dry heat Sterilization

Direct flaming and inceineration does what?

 Destroys micobes by denaturing, oxidation effects and dehydration 

( Fire burns o2)

Dry heat sterilization

Hot air Sterilization

Dry Heat Sterilization

Dessiccation

Removal of water

without water the microbes can't grow but remain viable or dormant for years

(when the water is finally present they can resume growing)

Base of Lyophilization- freeze drying a process ued to perserve bacteria samples 

Dry heat sterilization

 High Pressure

Can it be used for sterilization 

the pressure alters the protein structures

can destroy vegetative bacteria but endospores are resistant to pressure alone (temp must be added)

NO

Dry Heat Sterilization

Osmotic Pressure

can it be used for sterilization ?

Hypertonic environment

Prevents growth and destroy bacteria

Mold yeasts and endospores more resistant to high osmotic pressure

No

Dry heat sterilization

Filtration

Can it be used for sterilization ?

Mechanical means of removing microbes from a sample works best for bacteria, fungi, protozoa

Used to sterilize heat sensative material enzymes, vaccine, antibiotics

High efficiency particulate air (Hepa)-filters air borne microbes removing all microbes larger than .3 micrometers in diameter

Yes

ü  What are the three critical parameters that must be monitored during autoclaving?

Time

Temperature

Pressure

ü  What industry are canning retorts used in?  What does commercial sterilization mean with respect to the food canning industry?

Food Industry

Commercail Sterilization- by steam under pressure in a retort

1. Washing, sort, blanch to reduce microbes which may alter color
2. cans filled to capacity
3. steam used to drive out dissolved air
4. cans sealed
5. pressurized and steamed in retort
6. cooled by water
7. Labeled stored delivered

ü  Is pasteurized milk sterile?  What does pasteurization achieve?

No its not sterile - theroduric heat resistant microbes survive but are unlikely to make ppl sick or cause milk to spoil

kills microbes that cause spoilage without damaging the taste

ü  What does the HTST pasteurization process involve?  What does HTST stand for?

High Temperature short time (HTST)- 72 C & 15 Sec ( no pressure)

Lower bacteria count good for refrigeration

Applied while milk is flowing through an heat exchanger

ü  What does the UHT pasteurization process involve?  What does UHT stand for?

Ultra High Temperature

The milk is sprayed through a nozzle ( to perserve a non cooked taste) into an under pressure steam chamber- it is then cooled in a vacuum chamber and then packaged

ü  List the two forms of dry heat sterilization.  Aside from denaturation how else dose dry heat destroy microbes?

1. Direct flaming or incineration
2. Hot air sterilization

Dehydration

Oxidation Effect

ü  Can low temperature be used for sterilization?  What does low temperature achieve?

No can't be used for sterilization

Slow microbe growth

Does not kill the microbe

ü  What are the two types of sterilizing radiation?  Which type has a longer wavelength, which type has a higher energy emission and which type is more penetrable?  Give an example of each type of sterilizing radiation. 

1. Ionizing- shorter wavelength higher energy-Gamma rays (penatrates deeply)x rays are similar- Ionization of water- the ionized particles pass through vital portions of the cell causing mutation to kill the cell
2. Nonionizing- longer wavelength less energy- ultraviolet light or rays- damges exposed cells combing or bonding  adjacent pyrimidine bases to thymines

ü  How does nonionizing radiation destroy microbes?  What are the disadvantages of using nonionizing radiation to disinfect/sterilize items?

Uv light damages Dna of exposed cell causing bonds to form between pyrimidine base and thymine

Disadvantage- not very penatrable

damage human eyes

long exposure can cause burs and skin cancer in humans

ü  List what needs to be considered before purchasing a disinfectant.

1. What organisms the disinfectant effects
2. The concentreation of disinfectant-( it can effect the action of the disinfectant
3. Nature of material being disinfected- ex organic mater might interfere with action
4. Ph of medium for greater effect on activity
5. will the disinfectant easiy make contact with the microbe
6. how long the disinfectant needs to be left on a surface

ü  Name and briefly describe the two types of tests than can be used to evaluate disinfectants.

ü   

1. Use- Dilution Test- Glass cylinders or metal is dipped into bacteria, removed, and dried at 37 C . Then they are placed in a concentration of disinfectant recommended by the manufacturer and left for 10 min ar 20 c. Then they are transfered to medium that permits bacteria growth or sterile broth which are incubated. Effectiveness determined by how much bacteria grows
2. Disk diffusion- soked disks are placed on a agar plate filled with bacteria. they are then incubated and a zone of clearing indicated disinfectant effectivness

ü  Name two common halogen disinfectants.

Chlorine

Iodine

ü  Chlorine combined with water produces what common disinfectant?  How does this disinfectant destroy microbes and how effective is this disinfectant against bacterial endospores?

Hypochlorous Acid (Bleach)

oxidizing agent that make the compound loose electrons and disrupts the enzyme functioning

Effectiveness of bleach against endospores is fair

used in disinfectining drinking water, pools, household items and utensils

ü  What type of halogen was used to decontaminate the Hart Senate Offices after the 2001 anthrax attacks?

Chlorine

Specifically Chlorine dioxide

ü  How does iodine destroy microbes and how effective is this type of disinfectant against bacterial endospores?

Oxidizing agent that inhibits protein and enzyme functioning

- Speciffically impairs protien synthesis and cell membrane by creating complex amino acids and unsatruated faty acids

Effectiveness agains endospores is POOR

ü  Explain the difference between tincture of iodine and an iodophor.  Which of these two types of disinfectants is more likely to be used in hospitals today and why?

Tincture-(mixed with alcohol)used in the past as antiseptic/ likely irritates skin and prone to stain/ used for disinfecting water when camping

Iodophors-(mixed with organic molecule) does not stain and less irritating to skin/ commonly used for medical antisepsis/ used to prepare skin for surgery and surgical hand scrubbing

MORE LIKELY TO BE USED IN HOSPITALS 

ü  Who is the father of modern antisepsis and what type of disinfectant did he employ?

Dr. Joseph Lister

Phenol (carbolic acid) to control surgical infections in the operating room

ü  What is phenol?  How does phenol destroy microbes and how effective is it against bacterial endospores?  Why is phenol seldom used in hospitals today?

Carblic Acid- a toxic acid

Denatures enzymes and disrupts or injures lipid containing plasma membrane resulting in leakage of cellular content.

Phenol is not used  due to foul ordor and irritating skin

ü  What are phenolics?  How do phenolics destroy microbes and how effective are they against bacterial endospores?  Name a product that uses a phenolic compound as its active ingredient.

Derivatives of phenol

Destroy microbes by denaturing enzymes and disrupting the plasma membrane causing leakage

Effectivness against endospores POOR

Lysol- uses active phenol ingrediant

ü  What are bisphenols?  How do bisphenols destroy microbes and how effective are they against bacterial endospores?

Derivatives of phenol  containing two phenolic groups

Destroys by triclosan inhibiting enzymes need to create fatty acid lipids for plasma membrane

Effectivness against endospore INEFECTIVE

Name a common biguanide used in many hospital operating rooms