Microbiology - Ch. 5 (Control And Termination)

Front 1

Def: Decontamination

Back 1

The treatment of an object to make it safe to handle

Front 2

Def: Disinfection

Back 2

Directly targets the removal of all pathogens, not necessarily all microorganisms

Front 3

Def: Heat Sterilization

Back 3

The most widely used method of controlling microbial growth.

Front 4

Decimal Reduction Time (D)

Back 4

Amount of time required to reduce viability tenfold.

exponential relationship.

Heat kills faster as temperature rises. Moist heat works better than dry heat.

Endospores can survive heat that would rapidly kill vegetative cells.

Front 5

Def: Thermal Death Time

Back 5

Time to kill all cells at a given temperature; affected by population size.

Front 6

Decimal Reduction Time Visual

Back 6

Front 7

Def: Autoclave

Back 7

The autoclave is a sealed device that uses steam under pressure.

- Allows temperature of water to get

above 100°C.

- Kills endospores.

- Not the pressure but the high

temperature that kills the

microbes.

Front 8

Def: Pasteurization

Back 8

The process of using precisely controlled heat to reduce the microbial load in heat-sensitive liquids.

- Does not kill all organisms, so it is

different from sterilization.

Front 9

Autoclave Structure Visual

Back 9

Front 10

Autoclave Cycle Visual

Back 10

Front 11

Control Method: UV

Back 11

Ultraviolet (UV) radiation (between 220 and 300 nm) has sufficient energy to cause modifications and breaks in DNA.

- UV useful for decontaminating

surfaces.

- Cannot penetrate solid, opaque, or

light-absorbing surfaces.

Front 12

Control Methods: Ionizing Radiation (Part 1)

Back 12

Electromagnetic radiation that produces ions and other reactive molecules upon collision.

Amount of energy required to reduce viability tenfold (D10) is analogous to D value.

Front 13

Control Methods: Ionizing Radiation (Part 2)

Back 13

Some microorganisms more resistant to radiation than others (e.g., endospores vs. vegetative cells, viruses vs. bacteria).

Used for diverse items including surgical supplies, plastic labware, drugs, fresh produce, meat.

Front 14

Back 14

Front 15

UV Survival Rate Visual

Back 15

Front 16

Control Methods: Ionizing Radiation (Part 3)

Back 16

Sources of radiation include cathode ray tubes, X-rays, and radioactive nuclides.

Radiation is used for sterilization in the medical field and food industry.

Front 17

Control Methods: Ionizing Radiation (Part 4)

Back 17

Radiation is approved by the WHO and is used in the United States for decontaminating foods particularly susceptible to microbial contamination.

- Hamburger, chicken, and spices

may all be irradiated.

Front 18

Control Methods: Filtration (Part 1)

Back 18

Filtration avoids the use of heat on sensitive liquids and gases.

- Pores of filter (0.45 and 0.2 μm)

are too small for living organisms

to pass through but do not trap

most viruses.

- pores allow liquid or gas to pass

through.

Front 19

Control Methods: Filtration (Part 2)

Back 19

Depth filters made of overlapping paper or glass fibers.

- HEPA filters Membrane filters

function more like a sieve.

Nucleopore filters for scanning electron microscopy.

Front 20

Antimicrobial Agents

Back 20

Chemicals that kill or inhibit growth.

Front 21

-cidal vs. -static

Back 21

-cidal kills microorganisms (e.g., bactericidal, fungicidal, viricidal).

-static inhibits growth (e.g., bacteriostatic, fungistatic, viristatic).

Front 22

The Three Classification of Antibacterial Agents

Back 22

Classified as Bacteriostatic, Bacteriocidal, and Bacteriolytic.

Front 23

Bacteriostatic Agents w/ Visual

Back 23

Inhibit biochemical processes such as protein synthesis and bind weakly.

Front 24

Bactericidal Agents w/ Visual

Back 24

Bind tightly and kill the cell.

Front 25

Bacteriolytic Agents w/ Visual

Back 25

Kill by lysis (e.g., detergents).

Front 26

Minimum inhibitory concentration (MIC)

Back 26

The smallest amount of an agent needed to inhibit growth of a microorganism.

Front 27

Disc Diffusion Assay

Back 27

Uses solid media.

Antimicrobial agent added to filter paper disc, diffuses into agar.

MIC is reached at some distance.

- Zone of inhibition: area of no

growth around disc.

Front 28

The Control of Growth on Various Surfaces

Back 28

Sterilants, disinfectants, sanitizers, and antiseptics are used to prevent growth on inanimate surfaces and external body surfaces.

Front 29

Def: Sterilants

Back 29

Destroy all microorganisms, including endospores.

Front 30

Def: Disinfectants

Back 30

Used on surfaces to kill microorganisms but not necessarily endospores.

Front 31

Def: Sanitizers

Back 31

Reduce microbial numbers but do not sterilize.

Front 32

Def: Antiseptics (germicides)

Back 32

Kill or inhibit microbial growth but are nontoxic enough to be applied to living tissues.

Front 33

Antiseptic Visual

Back 33

Front 34

Sterilants, Disinfectants, and Sanitizers Visual

Back 34