Ch.9: Controlling Microbial Growth In The Environment

Question 1

what is antiseptic?

Answer 1

antimicrobial chemical used to kill microbes on tissues

Question 2

what is antisepsis?

Answer 2

reduction of the number of potential pathogens

Question 3

what is disinfectant?

Answer 3

antimicrobial chemical used to kill microbes on surfaces

Question 4

Describe microbial agents

Answer 4

-Do NOT simultaneosuly kill all cells
-some microbes require longer exposure to an agent before death

Question 5

what is micorbial death?

Answer 5

-permanent loss of reproductive ability under ideal conditions
-constant

Question 6

what are actions of antimicrobial agent alteration of cell wall?

Answer 6

-cell wall helps to maintain cellular integrity

-disrupt its structure, leading to cell rupture and death.

Question 7

what are exceptions of alteration of cell wall?

Answer 7

viruses
-viruses tolerance depends on structure

Question 8

what is a nonenveloped virsus

Answer 8

have greater tolerance to harsh chemicals

Question 9

what is a enveloped virus

Answer 9

are enveloped by a portion of plasma membrane from host cells

Question 10

what are ways to damage proteins and nucleic acids

Answer 10

-chemicals, radiation, and heat can damage nucleic acids

Question 11

how to choose an antimicrobial agent?

Answer 11

-inexpensive
-fast-acting
-stable during storage
-controls microbial growth while being harmless to humans/animals/objects

Question 12

site to be treated

Answer 12

not to be used on humans, animals, fragile objects
-harsh chemicals
-extreme heat

Question 13

site of medical procedure

Answer 13

-Surgical (penetrates skin, major protection for inner tissues, steralized)
-Topical (skin or mucous membranes, disinfected)

Question 14

what are the factors that affect efficiency of antimicrobial?

Answer 14

1.) Site to be treated
2.) Relative susceptibility of microbe to an antimicorbial method
3.) Environmental conditions

Question 15

Low-level germicide

Answer 15

vegatative bacteria, fungi, protozoa, some viruses

Question 16

intermediate-level germacides

Answer 16

kills fungal spores, protozoan cysts, viruses, pathogenic bacteria

Question 17

High-level germicide

Answer 17

kills all pathogens and endospores

Question 18

What are endospores

Answer 18

most resilient form of life

Question 19

what are myobacterium

Answer 19

cell wall contains large amounts of waxy lipid survive drying, protection from water-based chemicals

Question 20

what are protozoan cysts

Answer 20

protects from dessication, shield from radiation and heat, dormant

Question 21

what are prions

Answer 21

cause degenerative brain disease, more resistance than any living thing

Question 22

environmental conditions

Answer 22

temperature and pH
-affect death rate
-affect efficacy
-warm better than cool

Question 23

what does acidic pH do

Answer 23

enhance effect of high temp.

Question 24

what does organic material do

Answer 24

-these interfere with the penetration of antimicrobial agents
ex:-feces, vomit, blood, biofilms

Question 25

What is a Biosaftey Level 1 (BSL-1)?

Answer 25

Handling pathogens that do not cause disease in healthy humans ex: opportunistic pathogens

Question 26

what is a Biosafety Level 2 (BSL-2)?

Answer 26

Handling moderately hazardous agents ex:our lab

Question 27

what is a Biosafety Level 3 (BSL-3)?

Answer 27

Handling microbes in safety conditions ex:enhanced PPE

Question 28

what is a Biosafety Level 4 (BSL-4)?

Answer 28

Handling microbes that cause severe or fatal disease ex: we dont know how to treat it

Question 29

what are physical methods of microbial control?

Answer 29

-extreme temperatures (hot or cold) -desiccation -filtration -osmotic pressure -radiation

Question 30

what is thermal death point?

Answer 30

lowest temperature to kill all cells in 10 minutes in a broth culture

Question 31

what is thermal death time?

Answer 31

time to sterilize a volume of liquid at a set temperature

Question 32

what does moist heat do?

Answer 32

Disinfects, sanitizes, sterilizes, pasteurizes * Denature proteins * Destroy plasma membrane * MORE effective than dry heat

Question 33

what are the methods in use for moist heat?

Answer 33

* Boiling * Autoclaving * Pasteurization * Ultrahigh-temperature sterilization

Question 34

what does boiling do?

Answer 34

Kills vegetative cells (bacteria/fungi), protozoan trophozoites, most viruses * TIME IS CRITICAL * Different elevations require different time limits * CDC recommends a roiling boil for 1 minute

Question 35

who can survive boiling

Answer 35

-endospores -protozoan cysts -some viruses

Question 36

what is autocalving?

Answer 36

Pressure applied to boiling water prevents steam from escaping * Boiling temperature increases as pressure increases * Autoclave conditions: 121oC; 15psi, 15 minutes

Question 37

what is pasteurization?

Answer 37

Heating to high temperature that kills most of the bacteria * Used for milk, ice cream, yogurt, fruit juices * NOT sterilization * Heat-tolerant microbes survive

Question 38

what are dry heat methods

Answer 38

Used for material that cannot be sterilized with moist heat * Denatures proteins and oxidizes metabolic and structural chemicals * Requires higher temperatures for longer time than moist heat * Incineration is ultimate means of sterilization

Question 39

Why is slow freezing better than quick freezing?

Answer 39

Slow freezing causes less cell damage and preserves quality.

Question 40

Why do some organisms survive freezing?

Answer 40

Not all enzymes denature during freezing.

Question 41

Why cook frozen food fully?

Answer 41

Some bacteria survive freezing and need to be killed by cooking.

Question 42

what is dessication in physical methods

Answer 42

Ancient method of microbial control * Drying out * Inhibits growth due to the removal of water

Question 43

what is Lyophilization in physical methods?

Answer 43

Freeze-drying * Used for long-term preservation of microbes * Prevents formation of ice crystals