Controlling microbial growth in the enviroment CH 9

Question 1

What are 2 external target of antimicrobial agents as well as 2 intent targets

Answer 1

• 2 external targets are Cells walls and cell memebranes burst due to osmotic effect and contents leak out if the plasma is damaged
• 2 internal targets are Denaturation of the proteins and mutation of the nucleic acid

Question 2

What are 3 general characteristics of an ideal control agent

Answer 2

Inexpensive, fast acting, stable during storage

Question 3

Selective toxicity

Answer 3

capable of controlling microbial growth while being harmless to humans animal and objects.

Question 4

Which 3 factors influence the effectiveness of antimicrobial control agents? Which single factor is the most important?

Answer 4

Site to be treated, Environmental conditions and Relative suseptibility is the most important

Question 5

Know the meanings of all basic terms for microbial control agents (Table 9.1), including germicides, prefixes, and suffixes.

Answer 5

prefixes are- cide and cidal are destruction in all types of microbes
Also Stasis, and Static they slow growth

Question 6

What are the 3 infectious agents that are most resistant to chemical control?

Answer 6

Prions
Bacterial endospores
Mycobacterial wax in cell wall.
Cysts of protozoa

Question 7

What type of general medical applications require use of a high level germicide, an intermediate level germicide, and a low level germicide?

Answer 7

High level is oxidizing agents (peroxides)
Intermediate halogens and alcohols (iodine, chlorine)
Low level phenolics and phenol (chemicals)

Question 8

Which are more common control methods – chemical means or physical means?

Answer 8

Chemical

Question 9

What is the general level of activity of phenolics? Why are they often very useful antimicrobial compounds?

Answer 9

Intermediate to Low they denature proteins

Question 10

What are 2 examples of alcohols used in microbial control? What is the primary issue for how effective an alcohol is as a germicide?

Answer 10

isopropenal issue is it drys too fast.

Question 11

What are 2 more common halogens used as control agents? Give a couple of examples of the use of chlorine to control microbial growth.

Answer 11

Iodine tablets, chlorine treatment

Chlorine in pools and Drinking water.

Question 12

How effective are oxidizing agents as antimicrobials? Give 2 examples of useful products in this category.

Answer 12

Oxidizing agents (peroxide, peracetic acid) are very effective and kill anaerobes in deep puncture wounds

Question 13

What are surfactants? What is the difference between soaps and detergents as antimicrobial agents? What are quats?

Answer 13

• surfactants are soaps that don’t have degerming agents and detergents decease surface tension of water and disrupt cell membranes
  QUATS are composed of ammonium( NH4+) cation in which hydrogen atoms are replaced by other functional groups or hydrocarbon chains and are colorless, tasteless and harmless to humans except in high concentrations.

Question 14

What are 2 examples and uses of heavy metals to control microbial growth? How is it that we are able to use these toxic molecules in some cases without damaging our own cells?

Answer 14

zinc,mercury,silver,copper arsenic. they denature proteins

Because they combine with sulfur atoms in molecules of cysteine’s an amino acid.

Question 15

What level of effectiveness are aldehydes for controlling microbial growth. Give an example of one of these chemicals.

Answer 15

very effective high level examples are glutaraldehyde and formaldahyde.

Question 16

What is ethylene oxide and how is it used?

Answer 16

is a gas used in hospitals to sterilize

Question 17

What are the 4 methods for evaluating the effectiveness of a chemical for control of microbial growth? Which method is the one currently approved for use in the US?

Answer 17

1- Phenolcoelfficent (cconcentration test)
2- Dilution test
3- kelsey -sykes capacity test
4- in use test (more comprehensive)

Question 18

Describe the in-use test for evaluating chemical control agents. Why is this the best method currently available?

Answer 18

you take an actual swab of the object such as hospital room equipment

Question 19

How does refrigeration restrict growth of most microbes, and can freezing kill microbes?

Answer 19

because the rates of bio chemical reactions are slower because its colder no freezing does not kill microbes

Question 20

What are 3 methods of microbial control that use moist heat?

Answer 20

1. Boiling
2. autoclaving
3. pasteurization

Question 21

Why is moist heat more effective than dry heat to kill microbes

Answer 21

because boiling kills vegetative cells of bacteria and fungi protozoan trophozoites and most viruses

Question 22

What is an autoclave and for what general purpose is it used?

Answer 22

Autoclave standard way to kill pathogens. uses steam heat under pressure to sterilize chemicals and objects that can tolerate moist heat
-to sterilize chemicals and objects

Question 23

What is incineration? Why is it the ultimate means for sterilization of medical waste

Answer 23

incineration is to burn to ash

-to make sure all pathogens are destroyed

Question 24

Why is desiccation effective in limiting growth of bacteria

Answer 24

means to dry

-because motabolism requires water and drying slows the spread of most pathopgens including bacterial syphilis

Question 25

What type of non-ionizing radiation can be used to kill bacteria and fungi?

Answer 25

UV rays

Question 26

What is the general principle by which filtration can purify liquids or air?

Answer 26

the filter catches the microbes

Question 27

What are HEPA filters and in what type of applications are they commonly used?

Answer 27

1- high efficency particles

2- filteration for cars and airplanes.

Question 28

Why did the CDC establish biosafety levels for handling microbes?

Answer 28

to protect against suspect able pathogens

Question 29

What are the 4 biosafety levels? How are these distinguished? Know an example of the type of organism associated with different BSL protocols.

Answer 29

Biosafety level 1 - NON HAZARDOUS E Coli
BSL2-POTENTIAL PATHOGENIC HIV
BSL3 -FATAL AGENTS YELLOW FEVER, TB
BSL4 - EBOLA, Unknown

Question 30

What biosafety level are most teaching labs?

Answer 30

BSL 1

Question 31

What are 2 concerns in using so many products in our daily lives that contain antimicrobial chemicals?

Answer 31

Antibiotic resistance and New Mutations.

Question 32

describe the in use test for evaluating disinfectants and antiseptics. What are the other 3 tests for evaluating chemical control agents? why is the in use test more useful than are the other test

Answer 32

In use test methods of evaluating the effectiveness of a disinfectant of antiseptic which test efficacy under specific real life conditions.
The other 3 are-
Phenol Coefficient
Use dilution test
kelsey-sykes capacity test
in use is the best because it takes swabs taken before and after then incubated an monitoring for growth from the actual object such as operating room equipment

Question 33

Explain why antibiotics are most effective against cells that are actively growing and reproducing. Support this explanation by listing 3 mechanisms of antibiotic action and give an example of a specific antibiotic for each mechanism.

Answer 33

Because antibiotics inhibit the synthesis and when a cell is not growing rapidly its not creating synthesis or cell walls or cell membranes

Question 34

What re reservoirs of infection? describe types of reservoirs of infection in humans. Give an example disease for each type of reservoir.

Answer 34

Reservoirs of infection are sites where pathogens are maintained as a source we discuss 3 types of reservoirs. Animals reservoirs. Human carriers, and nonliving Aids TB syphilis Botulism tetanus yellow fever Anthrax, bubonic plaque and rabies