Chapter 5- Control Of Microbial Growth

Front 1

Describe Joseph Lister's importance in the history of microbiology

Back 1

He revolutionized surgery by introducing methods that prevented wounds from being infected.

He poured Carbolic acid directly onto wounds and found it prevented infections.

Front 2

Sterilization

Back 2

Completely destroy all microbes in or on material including endospores

Front 3

Disinfection

Back 3

elimination of most or all pathogens on or in material. Endospores survive.

Front 4

Disinfectants

Back 4

antimicrobial chemicals used for disinfecting, kill bacteria, not to use on skin

Front 5

Antiseptics

Back 5

safe enough for use on living tissue

Front 6

Pasteurization

Back 6

brief heat treatment that reduces number of spoilage organisms and destroys pathogens

Front 7

Decontamination

Back 7

reduces number of pathogens to a level that is considered safe to handle

Front 8

Sanitization

Back 8

Substantially reduces microbial population, meets health standards

Front 9

Preservation

Back 9

process of delaying spoilage of foods or other perishable products

Front 10

Why are healthcare products and facilities important to consider when choosing methods of microbial growth control

Back 10

Important because of healthcare associated infections

People's immune systems are compromised because they are ill, therefore much more susceptible to an infection.

They may undergo invasive procedures where they are very exposed, and they are constantly shedding pathogens in their feces, urine, etc. So sterilization is important.

Front 11

Why is daily life important to consider when choosing methods of microbial growth control

Back 11

Washing and scrubbing hands with soap is efficient enough to control microbial growth. Cooking foods, cleaning surfaces and refrigeration.

Front 12

Why is food production important to consider when choosing methods of microbial growth control

Back 12

Foods retain quality longer when contaminating microbes are removed. Heat if most common. Chemical additives (but risk of toxicity)

Food facilities need to keep surfaces clean

Front 13

Why water treatment important to consider when choosing methods of microbial growth control

Back 13

Chlorine has been used to kill microbes in water.

Front 14

Explain types of microorganisms and why it is important to consider when choosing methods of microbial control

Back 14

Endospores, Mycobacterium, Naked viruses

These all require rigorous treatment, such as use of toxic chemicals, boiling (heat treatment)

Front 15

Explain number of microorganisms and why it is important to consider when choosing methods of microbial control

Back 15

The time it takes for heat or chemicals to destroy a population depends on the number of microbes present.

Washing and scrubbing can reduce time to sterilize.

Front 16

Explain environmental conditions and why it is important to consider when choosing methods of microbial control

Back 16

Dirt, grease and body fluid can interfere with heat treatment and chemical disinfectants.

Temperature and pH levels can too.

Example: hypochlorite solution can be more effective at low pH. Higher temps can kill faster too.

Front 17

Explain Risk for infection and why it is important to consider when choosing methods of microbial control

Back 17

Medical instruments must be cleaned appropriately for surgical/medical procedures

Critical instruments: must be sterile for they come in contact with/penetrate body tissues

Semicritical instruments: Come into contact with mucous membranes, but don't penetrate such as gastrointestinal endoscopes. So must be disinfected, because few endospores can remain

Non critical instruments: Countertops, stethoscopes should be sanitized.

Front 18

Explain appropriateness of the method and why it is important to consider when choosing methods of microbial control

Back 18

Sterilization and disinfection can be inappropriate for certain types of materials, for example, heat treatment can damage many types of plastics.

Moist heat (boiling) cannot be used to treat moisture sensitive material.

Front 19

How does heat kill microorganisms? which is faster, dry heat or moist?

Back 19

Moist is faster.

It denatures their proteins

Front 20

Boiling

Back 20

Boiling for 5 minutes destroys most microorganisms and viruses, except endospores.

Example of use: Boiling for at least 5 minutes can be used to treat drinking water

Front 21

Pressurized Steam

Back 21

121*C for 15 mins or longer, destroys endospores

Sterilizes microbiological media

Used for canning foods-commercially sterile.

Front 22

Dry Heat oven

Back 22

Destroys cell components and denatures proteins.

Takes longer than moist heat

Laboratory glassware is sterilized.

So are powders, oils and other dry materials.

Front 23

Incineration

Back 23

Burns cell components to ashes. Flaming of wire inoculating loops

Front 24

High Temp Short time Pasteurization

Back 24

Milk is heated to 72*C and held for 15 secs.

Front 25

Ultra violet radiation

Back 25

Destroys all microorganisms that can grow under normal storage conditions.

Heats milk to 140*C, holding temp for a few secs, then cooled rapidly.

Front 26

Explain process of filtration and methods of use

Back 26

Yes it is sterile????

Membrane filters have microscopic pores that allow liquid to flow through while trapping particles too large to pass.

Filters of .2 micrometers in size are commonly used.

Used for beer and wine, and for some heat sensitive medications.

Front 27

Ionizing radiation

Back 27

Destroys DNA and possibly cytoplasmic membranes.

Produces reactive molecules that damage other cell components.

Items can be sterilized even after packaging.

Examples of use: used to sterilize heat-sensitive materials including medical equipment, disposable surgical supplies and drugs such as penicillin.

Also, microbes in spices, herbs and approved types of produce and meats.

Front 28

Ultraviolet radiation

Back 28

Damages DNA. Penetrates poorly.

Bacterial endospores are the most UV resistant.

Cannot be used to destroy microbes in solid substances or turbid liquids.

Most effective when used at close range.

Examples: destroys microbes in the air, drinking water, and disinfects surfaces.

Front 29

Alcohols

Back 29

Easy to obtain, inexpensive.

60-80% isopropyl alcohol.

Used as antiseptics to clean skin before procedures.

Does not sterilize, does not destroy endospores and some naked viruses.

Front 30

Aldehydes

Back 30

Capable of destroying all microbes

Irritating to skin

Glutaraldehyde and orthophthaladehyde

Used to sterilize medical instruments.

Formalin used in vaccine production and preserve specimens.

Front 31

Biguanides

Back 31

Low toxicity, destroys wide range of microbes, adheres to skin

Chlorhexidine used in antiseptic soaps, used in catheters and surgical mesh

Front 32

Ethyline Oxide Gas

Back 32

Toxic, explosive, and could be carcinogenic

Easily penetrates hard to reach places

Commonly used to sterilize medical devices

Front 33

Halogens

Back 33

Chlorine and Iodine

Disinfects inanimate objects, surfaces, drinking water.

Iodine can be used as antiseptics and disinfectants

Front 34

Metals

Back 34

High concentrations are too toxic to human tissue.

Silver can be used as disinfectant and used in topical dressings.

Front 35

Peroxygens

Back 35

Hydrogen peroxide because catalase breaks it down.

Peracetic acid is more potent.

Can be used as sterilants under controlled conditions.

HP for milk and packaged juices;

PA to disinfect AND sterilize medical devices

Front 36

Phenolic Compounds

Back 36

Triclosan is used in soaps and lotions

Kills most vegetative bacteria and denature proteins.

Hexachlorophene is highly effective against S. aureus, but use is limited.

Front 37

Quaternary Ammonium Compounds

Back 37

Non toxic enough to be used on food preparation surfaces.

Widely used to disinfect inanimate objects and preserve non food substances.

Front 38

Chemical Preservatives

Back 38

Must be non-toxic for safe ingestion

Benzoic, sorbic and propionic acids are weak organic acids sometimes added to foods such as breads and cheeses.

Nitrite is used in processed meats- if not, C. botulinum could grow.

Front 39

How does low temperature effect microorganisms?

Back 39

Inhibits growth of many pathogens and spoilage organisms by slowing or stopping critical enzyme reactions.

Freezing preserves food by stopping microbial growth

Front 40

How does reducing available water effect microorganisms?

Back 40

Salting and drying decrease the availability of water in food below the limits required for growth of most microbes.