Chapter 9: Microbial Control

Give the conditions, action, and uses for refrigeration.

0-7 degrees C; Inhibits metabolism

Give the conditions, and action for incineration.

1 second at 1,000 degrees C; Sterilization

Give the conditions, and action for ultra-high-temperature sterilization.

1-3 seconds at 140 degrees; Sterilization

Give the conditions and action for boiling.

10 minutes at 100 degrees C; Disinfection and sanitization

Give the conditions and action for autoclaving.

15 minutes at 121 degrees C; Sterilization

Give the conditions and action for Pasteurization.

15 seconds at 72 degrees C; Denatures proteins

Give the conditions, and action for hot air.

2 hours at 160 degrees C; Denatures proteins and Sterilization

Give the actions and uses for antimicrobials.

Acts against cell walls; Disinfectants

Which chemical methods do not denature proteins?

Antimicrobials and surfactants

Which physical method of moist heat takes the most time?

Autoclaving

Which of the physical methods sterilize?

Autoclaving, Ultra-high-temperature-sterilization, hot air, incineration, filtration, and both ionizing and nonionizing radiation

What are psychrophilic bacteria?

Bacteria that like cold temperatures and can still produce in a refrigerator, like listeria

What are mesophilic bacteria?

Bacteria that like room temperatures and slow down in a refrigerator

What are the 4 most resistant groups of microbes/infectious particles? Why are they resistant to many antimicrobial agents?

Bacterial endospores, species of mycobacterium, prions, and protozoa cysts because they are protected by a wide variety of outer coverings that antimicrobial agents cannot penetrate

Why is refrigeration considered bacteriostatic?

Because the bacterial cells cannot multiply under such low temperatures

Give the conditions and action for freezing.

Below 0 degrees C; Inhibits metabolism

Which physical methods of control can be classified as moist heat?

Boiling, autoclaving, pasteurization, and ultra-high-temperature sterialization

What causes hydrogen peroxide to bubble on the skin?

Catalase

What are the 4 microbial structures that most microbial control methods target?

Cell walls, cell membranes, proteins and nucleic acids

What is a hypertonic solution and why does exposure to such a solution harm microbes (Osmotic Pressure)?

Cells in a hypertonic solution lose water and will shrink. This removal of water will decrease or stop their metabolism and they will no longer be able to reproduce.

Give the actions and uses for aldehydes.

Denature proteins; Disinfectant and embalming fluid

Give the actions and uses for enzymes.

Denature proteins; Removal of prions on medical instruments

Give the actions and uses for gaseous agents.

Denature proteins; Sterilization

Give the actions and uses for heavy metals.

Denature proteins; collodial silver, silver nitrate in baby's eyes

Give the actions and uses for halogens.

Denatures proteins; Disinfectants and antiseptics

Give the actions and uses for phenolics.

Denatures proteins; Disinfectants and antiseptics

Give the actions and uses for phenol.

Denatures proteins; Original surgical antiseptic

Give the actions and uses for alcohols.

Denatures proteins;Disinfectants and antiseptics

Give the actions and uses for surfactants.

Disrupts cell membranes; Soaps for degerming

What type of microbe is the most susceptible to control methods?

Enveloped viruses

_________ _______ are the easiest to get rid of.

Enveloped viruses

Which physical methods of control can be classified as dry heat?

Hot air and incineration

How can prions be killed?

Incineration

How is the correct BSL determined?

It depends on method of transmission and resistance of microbe to sterilization methods

Distinguish between the 4 biosafety levels.

Level One is meant for the handling of microbes not known to infect healthy hosts. Level Two is regimented for handling moderately dangerous microbes, such as flu. Level Three requires that all procedures be performed inside safety cabinets with HEPA filters and specifies that labs must have certain safety features. Level Four is designed for exotic microbes that can cause fatal disease in humans.

This enzyme breaks down peptidoglycan in bacteria.

Lysozyme

Which is a BSL 2? What is an example?

Moderate hazard. MRSA is an example.

Which is more efficient: moist heat or dry heat?

Moist heat

Why are none of the physical methods used for antisepsis?

None of the physical methods are used for antisepsis because antisepsis involves chemical contact with the skin.

Both ionizing and nonionizing radiation effect which biological molecule?

Nucleic acids

What are the differences between sterilization, disinfection, and antisepsis?

Sterilization is removal and destruction of all microbes, disinfection uses physical or chemical agents to inhibit or destroy pathogens, and antisepsis is the killing of microbes on the skin using a chemical agent.

Give the actions and uses for oxidizing agents.

Sterilize through chemical reactions; Hydrogen peroxide

Give the conditions and action for desiccation.

Temperature varies depending on amount of water being removed; Inhibits metabolism

What are the similarities between the 4 control methods in the previous question?

Temperature, time, and pressure

Give the conditions and action for lyophilization.

-196 degrees C while drying; Inhibits metabolism;

What is the difference between the suffixes -cidal and -static?

-Static refers to a chemical or physical agent that can stop microorganisms from growing, but does not kill them. -Cidal refers to an agent that permanently destroys a microorganism.

If a sterilizing agent can remove endospores, what else can it remove?

Everything except prions

Give the conditions and action for osmotic pressure.

Exposure to hypertonic solutions, Inhibits metabolism

Give the conditions and action for filtration.

Filter retains microbes; Physically separates microbes from air and liquids

Which chemicals can be used for sterilization?

Gaseous agents

Which of the chemical methods sterilize?

Gaseous agents and oxidizing agents

Which precautions are taken for BSL 1? What is an example?

Hand washing and disinfection of instrument and surfaces. E. coli is an example.

What is the most resistant biological molecule?

Prions

This enzyme cleans prion contaminated equipment.

Prionzyme

Some types of _______ can cut up prions.

Proteins

Which physical method targets DNA?

Radiation

Give the conditions, action, and uses for ionizing radiation.

Rays; Destroys DNA; Sterilization

What is degerming?

Removal of microbes from a surface by scrubbing them away

What is the difference between sanitization and disinfection?

Sanitation is the process of disinfecting places and utensils used by the public to make them acceptable by public health standards, while disinfection is the use of physical or chemical agents to inhibit or destroy pathogens.

Which precautions are taken for BSL 4? What is an example?

Separate buildings, airlocks, UV light rooms, air and water must be filtered. Examples are Ebola and Smallpox.

What are 3 factors that affect a control method's efficacy?

The nature of the sites to be treated, the degree of susceptibility of the microbes involved, and the environmental conditions

Which three factors help one to choose the proper method of microbial control?

The site to be treated, the susceptibility of microorganisms, Environmental conditions

Give the conditions, action, and uses for nonionizing radiation.

UV light; Inhibits DNA; sterilization of surfaces

Which physical method of moist heat takes the least time?

Ultra-high-temperature sterilization

Which precautions are taken for BSL 3? What is an example?

Work within safely cabinets, HEPA filters for air, air moves into room and not out . Examples are TB and Anthrax.

Does moist heat denature proteins?

Yes

Is refrigeration bacteriostatic?

Yes