Chapter 11 Microbiology Controlling Microbial Growth

Physical and Chemical

Controlling microbial growth can be done through both __________ and ____________ processes.

Decontamination

Removal or destruction of microbes from surfaces

Degermation

Mechanical removal of microbes on living surfaces like the skin. Ex: handwashing or scrubbing the skin.

Disinfection

A chemical that destroys microbes (vegetative cells) on non-living surfaces.

Antisepsis

A chemical technique that destroys microbes on living surfaces

Degermation and Antisepsis

Which decontamination processes can be used on living surfaces?

Disinfection, sterilization, and sanitization

Which decontamination processes are used on non-living or inanimate objects?

Sterilization

Complete removal or destruction of all microbes and viruses.

Sterilization

Which decontamination process is effective against endospores?

Sterilization

Which decontamination process is used on inanimate objects/surfaces because it would likely be harmful or hard to achieve on living tissues

Decontamination

Which decontamination technique uses mostly physical processes?

Sanitization

Techniques that remove microorganisms from inanimate surfaces to reduce the potential for infection and spoilage.

Infection; Spoiling

The purpose of sanitization is to reduce the impact of microorganisms on humans by lowering the chance of _______________ and __________ of products

Pasteurization

A heat treatment used to reduce the number of spoilage organisms and destroy pathogens that can cause illness.

No

Is pasteurization a sterilization process?

Microbicide

A chemical that can kill microbes

Microbistatic

A chemical that inhibits microbial growth.

To Kill

“cide” means what

To inhibit growth

“static” means what?

Gram Positive, Gram Negative, Mycobacteria. Bacterial Endospores

Rank the following based on resistance from low to high:

Gram negative

Gram Positive

Mycobacteria

Bacterial Endospores

Susceptibility

A chart has been designed to show ____________ of microbes to antimicrobial treatments with the types of microbes listed from least to most resistant. This has been done after extensive experimentation to determine the susceptibility of microbes to certain techniques.

Microbial Death

What can show the efficacy of antimicrobial techniques?

Hard

It can be ___________ to observe microbial death because of their small size

Reproductive

Microbial death is detected by a loss of ___________ capability even in optimal growth conditions.

No

If a growth medium with a bacterial strain was treated then incubated and showed turbidity did death occur?

Yes

If a growth medium with a bacterial strain was treated then incubated and was clear did death occur?

No

If a growth medium with a bacterial strain was treated then incubated and showed turbidity was the treatment successful?

Yes

If a growth medium with a bacterial strain was treated then incubated and was clear was the treatment successful?

Decimal Reduction (D)

The time it takes to kill 90% of the microbial population

90%

Decimal reduction is the time it takes to kill _____% of the microbial population

Constant Rate

When a microbial population is exposed to an antimicrobial treatment not all bacteria will die immediately but they will die at a _________ __________.

Logarithmic

Will bacteria die in a linear or logarithmic manner?

Constant

In microbial death a _______ percentage of the population is killed each minute.

Susceptible

The most __________ bacteria will be the first to die

Resistant

The most ____________ bacteria will live the longest.

Number

The starting _________ of microbes can impact the death rate.

Population

The nature of the microbial ____________can impact the death rate. Ex: is it one species or many?

Temperature and pH

The _________ and ____________ of the environment can impact the death rate of microbes

decimal reduction

An increase or decrease in temperature and pH can cause a change in the _________ of a microbial population.

Concentration

The ____________of an agent (dosage and intensity) of an antimicrobial agent can impact the death rate.

Organic Matter

The presence of solvents, ______ ______ or inhibitors can impact the death rate of bacterial populations in the presence of an antimicrobial.

Mode of Action

The ____________ _____ _________ of an antimicrobial agent (what part of the microbe it affects) can impact the death rate.

Heat filtration and radiation

What are the three physical methods of microbial control

Heat

A common method of control that can denature proteins disrupt cell membranes and disrupts nucleic acids, including DNA and RNA

Bactericidal

Are high temperatures bactericidal or bacteriostatic

Bacteriostatic

Are low temperatures bactericidal or bacteriostatic

Moist heat

Which is more effective, moist heat or dry heat

Moist heat

This type of heat is more effective because it can be used at a lower temperature for a shorter time

Moist heat

This type of heat is more efficient because water is a better conductor of heat

Autoclaving

A process using pressurized steam from 121 to 132° c to kill microbes.

Autoclaving

A method of sterilization using pressurized steam. Commonly performed at 121° c

Short

Usually autoclaving only takes a ____ amount of time between 10 to 40 minutes

Pasteurization

Heat treatment used to reduce spoilage and food poisoning causing agents

Pasteurization

A moist heat treatment method that reduces microbial load but does not sterilize

Pasteurization

This method uses temperatures of 63 to 72° c in order to reduce the microbial load without causing adverse product changes

Pasteurization

A moist heat method that inactivates most viruses and vegetative cells to reduce spoilage and food poisoning causing agents

Baking

A dry heat method that involves heating items for 2 to 4 hours at 150 to 180° c

More

Does baking take more or less time than moist heat methods

Incineration

Burning organisms into Ash. Can be done with a Bunsen burner of furnace or an incinerator. This is a dry heat method

Incineration

Using a Bunsen burner to sterilize equipment is an example of which kind of heat method

Dry heat

Hospitals often contain furnaces or incinerators used to dispose of biohazardous waste. Is this a moist or dry heat method

Non-Ionizing

Is UV light ionizing or non-ionizing

No; endospores are usually resistant to UV light

Is UV light sufficient to sterilize a sample

Endospore

This bacterial feature is resistant to UV light because the many layers can block UV radiation and protect DNA

UV light

Radiation that forms thymine dimers and abnormal DNA connections. This can result to DNA breakage or abnormal DNA replication or transcription

Causes thymine dimers

What does UV light do to DNA

Surfaces

Uv radiation is good for _______ but not things under barriers because it is non-penetrating

Non-penetrating

Uv light is _____ meaning that it is blocked by barriers

Thymine dimers

Abnormal DNA connections caused by UV light that can cause bulges in the back bone and potential DNA breakage

Enzymes

Bacteria usually have _______ to repair damage caused by UV light but when it is in excess they are not able to fix the damage

Ionizing

Gamma rays and x-rays are both types of ______ radiation

Ionizing radiation

This type of radiation includes gamma rays and x-rays and these powerful beams of radiation knock electrons off of molecules.

Ionizing radiation

Which type of radiation has shorter wavelengths and more energy

Electrons

Ionizing radiation causes extensive damage to DNA and proteins as it knocks _____ off of molecules

Ionizing radiation

This type of radiation can achieve sterilization if it is used for sufficient amounts of time

Ionizing radiation

This type of radiation can be used to sterilize heat sensitive materials

Ionizing radiation

This type of radiation is penetrating and not blocked by barriers. This means that it can be used to sterilize materials after packaging

Ionizing radiation

This type of radiation has been used to sterilize food and medical products

Filtration

A physical method of microbial control that involves passing air or liquid through membrane filters

Filtration

This process can achieve sterilization if the pore size is small enough

True

True or false: filtration is a good method of microbial control for heat sensitive materials

High efficiency particulate air filter

What does HEPA filter stand for

Pore size

The _____ ______ of a membrane determines what can get through. Small enough pores can block bacteria, viruses, and endospores meaning that this method can be used to sterilize substances

Filtration

This method of microbial control can be used to sterilize air and liquids that cannot be heated

Solid liquid and gas

What forms can chemical methods of microbial control take

Nature

The _____ of the treated material can affect the activity of antimicrobial chemicals. For example, a smooth surface is easier to treat than a porous surface

Contamination

The degree of ________ is a factor that affects the activity of antimicrobial chemicals. For example, the size of the microbial load or the pathogens present

Exposure time

How long you leave the chemical on the material. This is a factor affecting antimicrobial chemical activity

Strength

The _____ and mode of action of the antimicrobial chemical is a factor affecting its activity

High

This level of chemical antimicrobial agents will kill endospores and may sterilize if factors are optimal

Intermediate

This level of antimicrobial agents will kill fungal spores and viruses and vegetative cells

Intermediate

Which level are most chemical antimicrobial agents

False

True or false? Many chemical antimicrobial agents are able to destroy endospores

No, it is often difficult to find chemicals that will destroy endospores

Is it common to find a chemical that will sterilize something

Low

The level of chemical antimicrobial agents that will eliminate only vegetative bacterial and fungal cells and some viruses.

Sterilize

In order for chemical antimicrobial agents to truly ______ something, it often requires high doses and long exposure times

Phenol

An antimicrobial chemical that was first used by Joseph Lister in 1867

Phenols

An antimicrobial chemical that is effective against vegetative bacteria, fungi and most viruses. It is categorized in the intermediate to high category. It functions to disrupt cell membranes and denature proteins

Phenol

The antimicrobial chemical that consists of a hydrocarbon ring and a hydroxyl group. It acts as a good disinfectant

Phenol

This antimicrobial agent is also toxic to humans. However, a derivative called phenolics can function as antiseptics