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BN541 Topic 2 > Unit 5 > Flashcards

Unit 5 Flashcards

1
Q

What is antisepsis?

A

The non-toxic disinfection of the skin, mucous membranes or other living tissues

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2
Q

what is a germicide?

A
  • A chemical agent that can kill micro-organisms but not necessarily their endospores;
  • bactericide - kills bacteria
  • fungicide - kills fungi
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3
Q

What is disinfection?

A

The reduction or elimination of pathogenic micro-organisms; disinfection does not sterilise.

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4
Q

What is disinfectant?

A

A chemical agent applied to an object or material to reduce or inhibit microbial growth.

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5
Q

What is sterilisation?

A
  • The complete destruction of all living organisms on an object or in a material
  • this includes even the most resistant stages such as endospores
  • sterilisation is absolute, there are no degrees of sterilisation.
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6
Q

What is bacteriostasis?

A

Inhibition of bacterial growth, but the bacteria are not killed; if the bacteriostatic agent is removed, then bacterial growth may resume.

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7
Q

What is sanitisation?

A

The reduction of pathogens on objects to safe public health levels by mechanical cleansing or chemicals.

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8
Q

What is asepsis?

A

“without infection”; refers to techniques that prevent or minimise the entry of living micro-organisms.

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9
Q

What are the 5 sites that are targeted during microbial control?

A
  1. The cell wall
  2. The cell membrane
  3. Cellular enzyme activity
  4. Proteins other than enzymes
  5. Nucleic acids
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10
Q

What are the 3 physical methods of microbial control that may achieve sterilisation?

A
  1. Heat
  2. Radiation
  3. Filtration
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11
Q

What are the 4 physical methods of microbial control that may NOT achieve sterilisation?

A
  1. drying
  2. osmostic pressure
  3. freezing
  4. freeze drying
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12
Q

What happens to micro-organisms when moist heat is applied?

A

.Cellular proteins are denatured and enzyme activity destroyed

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13
Q

what are 3 applications of moist heat?

A
  1. boiling
  2. pasteurisation
  3. autoclaving
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14
Q

What effect does pasteurisation have on micro-organisms?

A
  • Kills non-spore forming pathogenic bacteria in milk and other liquids
  • Does not sterilise
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15
Q

What effect does boiling have on micro-organisms?

A

At 100 degrees C for 10-30 mins kills all micro-organisms except heat resistant bacterial endospores and viruses.

Does not sterilise

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16
Q

What does dry heat do to micro-organisms and what are 2 examples?

A

Leads to death of micro-organisms by oxidation of cell components

  • Hot air ovens
  • Incinerators
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17
Q

What is an advantage and a disadvantage of hot air ovens?

A

Adv: Effective for sterilisation of materials that can withstand high temperature

Dis: Does not penetrate well, requires longer period of time (minimum of 1hr at 160-170 degrees)

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18
Q

What is the effect of incineration on micro-organisms?

A

Rapid and complete destruction of microorganisms

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19
Q

How does an autoclave destroy micro-organisms?

A
  • Pressure is controlled to produce about twice normal atmospheric pressure (200KPa)
  • Temp of steam is thereby increased from 100-121 degrees C
  • All microorganisms are killed with 15 minutes
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20
Q

What is the latent heat of vaporization?

A
  • The energy that is required to achieve the change of state from liquid to gas.
  • The same amount of energy required for this change of state is released (as heat) when the steam condenses back to water
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21
Q

Why is hydration important in sterilisation?

A

Process of denaturation of enzymes and proteins occurs much more readily when cell is in hydrated state

22
Q

What are the 2 types of radiation used for sterilisation?

A
  • gamma = Uses: sterilising plastics, pharmaceuticals, heat sensitive material, food preservation. Short wavelength (0.001-.1nm), high energy ionising radiation
  • ultraviolet - Uses: sterilisation of smooth, clean surfaces and air (hospital theatres, nurseries, food prep areas, labs
23
Q

How does drying effect micro-organisms?

A

Absence of water inhibits enzyme activity but not usually killed. Can resume normal activity when moisture is present

24
Q

How does refrigeration effect micro-organisms?

A
  • slowing rate of enzyme-controlled reactions but does not kill them
  • Microorganisms will resume growth one normal temps are restored
25
Q

How is filtration used to sterilise micro-organisms?

A
  • Can be used to reduce number of microorganisms present or eliminate them completely
  • Only works on fluids (liquids and gas)
  • Passes through screen with pores small enough to filter out microorganisms
26
Q

What are factors influence the effectiveness of disinfectants/antiseptics?

A
  1. Number of microorganisms present
  2. Type of microorganisms present
  3. Concentration of disinfectant/antiseptic
  4. Inactivation of the chemical
27
Q

What is the difference between disinfectants and antiseptics?

A

Disinfectant: chemical agent applied to an inanimate object or material to reduce or inhibit microbial growth
Antiseptic: non-toxic disinfectant for use on living tissue (skin, mucous membranes or exposed tissue)

28
Q

How does osmotic pressure effect micro-organisms?

A

High concentration of salt, sugar or other solutes can create a hypertonic solution which draws water from inside cell to the outside by osmosis causing the cell membrane to pull away from cell wall (plasmolysis)

29
Q

How do soaps work to aid in microbial control?

A

Remove oily substances, dirt and microbes from surfaces by acting as surfactant and reducing surface tension making them miscible (mixable) with water

30
Q

What are 2 chemical agents used in sterilisation of micro-organisms?

A

Ethylene oxide: denatures proteins. Used for sterilisation of pre-wrapped heat sensitive plastic material and heat sensitive equipment

Glutaraldehyde: Sterilising heat-sensitive equipment such as endoscopes.
- toxic and allergenic

31
Q

What is chemotherapy and what is a chemotherapeutic agent?

A
  • Chemotherapy is a treatment of disease by means of chemical taken into the body
  • Chemotherapeutic agent applies to any drug used for any disease
32
Q

What are the 5 desirable properties of an antimicrobial agent?

A
  1. selective toxicity
  2. soluble in body fluids
  3. Not produce allergic reactions
  4. Rate of breakdown should be low enough drug remains in the tissues for long enough to have effect
  5. Micro-organisms should not readily become resistant to drug
33
Q

What is the difference between antibiotics and synthetic drugs?

A

Antibiotics: produced naturally by bacteria and fungi

Synthetic drugs: manufactured by chemical synthesis

34
Q

What is an antibiotic?

A

chemical substance produced by micro-organisms which has the capacity to inhibit the growth or kill other microorganisms.

35
Q

What is an example of a broad spectrum drug?

A

Broad = tetracycline (attacks gram neg and pos bacteria)

36
Q

What is an example of a narrow spectrum drug?

A

Narrow = penicillin (only attacks gram pos)

37
Q

What are 5 main modes of microbial action?

A
  1. Inhibition of bacterial cell wall synthesis
  2. Interference with cell membrane function
  3. Interference with bacterial metabolism
  4. Inhibition of protein synthesis
  5. Interference with nucleic acids
38
Q

What are 2 drugs that inhibit cell wall synthesis?

A
  1. penicillin
  2. vancomycin (last resort for MRSA as has high toxicity)

drugs work to inhibit synthesis of peptidoglycan (only in bacterial cell wall) by preventing cross linking between chains leading to lysis and death (only works on growing cells)

39
Q

What are 2 drugs that interfere with cell membrane function?

A

-polymyxin B and nystatin

Drugs cause disorganisation of phospholipid bilayer = loss of control of molecular traffic = leakage of cell contents = death

40
Q

What is a drug that interferes with bacterial metabolism?

A
  • sulphonamides work by inhibiting folic acid synthesis which produces DNA components
  • work by competing for space on enzyme as structure is similar
41
Q

What are 3 drugs that inhibit protein synthesis?

A
  • tetracycline, erythromycin, chloramphenicol

- selective toxicity inhibits protein synthesis and therefore enzyme synthesis = cessation or death of bacterial cell

42
Q

What are 2 drugs that interfere with nucleic acids?

A
  • Quinolones inhibit DNA enzyme gyrase

- Rifampin prevents mRNA synthesis

43
Q

What is the difference between bactericidal and bacteriostatic drugs?

A

Bactericidal: causes irreversible and lethal changes to cell (e.g, penicillin on cell wall)

Bacteriostatic: interfere with metabolism without causing death of cell, prevent replication and allow immune system to get rid of infection. (e.g. tetracycline)

44
Q

What are 3 potential dangers of using anti-microbial drugs?

A
  1. toxicity
  2. allergic reactions
  3. interference with normal flora
45
Q

What is synergism in relation to drug combination?

A

The effect is greater than the anticipated sum of individual effects (penicillin and streptomycin combined to treat bacterial endocarditis)

46
Q

What is antagonism in relation to drug combinations?

A

The action of one or both drugs is compromised (penicillin and tetracycline to treat pneumococcal meningitis. Tetra interferes with action of penicillin)

47
Q

What is Anti-microbial prophylaxis?

A

Admin of drug before there is any evidence of infection but where risk of infection is high. (Rheumatic heart disease patients given penicillin after dental surgery to prevent Streptococcus viridans infection in blood stream.

48
Q

What is surgical treatment of a localised infection?

A

when localised infection is not responsive to drugs and prevents antibiotics in body fluids, surgical removal or drainage may be required.

49
Q

What is natural resistance to a drug?

A

intrinsic property of the organism and unrelated to contact with drug

50
Q

What is acquired resistance to a drug?

A

Changes in the genetic constitution of the organism

- antibiotics do NOT induce mutations but can create favourable environments for survival of mutant resistant organisms

51
Q

What are the 4 mechanisms of resistance to anti-microbial agents?

A
  1. Development of enzyme that can destroy or inactivate the antibiotic
  2. Alteration of cell membrane permeability
  3. Alterations to the drug’s binding site within the cell
  4. Alteration of metabolic pathways
52
Q

What are 4 methods of reducing resistance to anti-microbial drugs?

A
  1. should not be used indiscriminately
  2. sensitivity testing carried out (except in life threatening situations)
  3. should be used until all target organism have been destroyed
  4. Coupled antibiotics should be used

BN541 Topic 2 (9 decks)

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