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Applied Pharmaceutical Microbiology > Disinfectants, Antiseptics and Preservatives > Flashcards

Disinfectants, Antiseptics and Preservatives Flashcards

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Biology 101 flashcards
1
Q

What is the definition of disinfection?

A

The process of removing micro-organisms from surfaces of inanimate objects

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2
Q

What are the properties of good Disinfectants?

A 
Broad spectrum
Rapid kill
Non corrosive
Easy to prepare and use
Stable
Inexpensive
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3
Q

What are high-level disinfectants?

A

They destroy ALL micro-organisms

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4
Q

What are intermediate-level disinfectants?

A

They destroy all bacteria, most viruses and fungi

Exclude some viruses, bacterial spores, prions

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5
Q

What are low-level disinfectants?

A

They destroy most bacteria, some viruses, fungi

Excludes TB, some viruses, fungi, bacterial spores, prions

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6
Q

What are examples of high-level disinfectants?

A

Aldehydes
Hypochlorites
Peroxydens

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7
Q

What are examples of intermediate-level disinfectants?

A 
Alcohols
Biguanides
Iodine/Iodophore
Phenolics
QACs
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8
Q

What are examples of low-level disinfectants?

A

Phenolics

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9
Q

What are the main factors affecting choice of disinfectant?

A 
Intended application
No. and type of micro-organisms present
Environmental factors
Safety, Stability and Cost
Properties of chemical agent
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10
Q

What types of disinfectants are critically toxic?

A

Phenolics and Aldehydes (formaldehyde and gluteraldehyde)

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11
Q

Unstable compounds are stored in what form before use?

A

Inactive

Activated before use

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12
Q

How does organic matter (blood, pus, food residues) affect disinfectants?

A

They can decrease antimicrobial capacity

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13
Q

How do divalent cations (Ca and Mg) affect disinfectants?

A

They decrese the activity of them

Stabilize cell well, block adsorption sites

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14
Q

How does dilution affect disinfection?

A

Higher conc. of disinfectant increases efficacy and decreases exposure time.

Dilution doesn’t affect all disinfectants in the same way:
- The higher the N (dilution coefficient) the bigger the decrease in potency by dilution

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15
Q

How does temperature affect disinfection?

A

Cidal activity is increased with increased temperature

Expressed quantitatively by calculating temperature coefficient (Q10)

Dependent on chemical

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16
Q

How does pH affect disinfection?

A

Affects survival and growth of organism

Affects potency

17
Q

The disinfectant must remain ‘___’

A

Wet

18
Q

What is the suspension test?

A

Dilutions of disinfectant added to standardised bacterial suspension in water + albumin at set temp

At a specific time interval:

  • Remove sample
  • Neutralise disinfectant
  • Determine viable count (cfu/ml)

Calculate conc. disinfectant req. to kill 99.999% (5 log kill, 1 in 100,000 bacteria survive)

19
Q

How do you work out the minimum inhibitory concentration (MIC)?

A
  • Prepare doubling dilutions of test agent
  • Inoculate with test organism
  • Incubate at 37C overnight
  • Score for growth

MIC is the lowest conc. showing no growth

20
Q

What is the disc susceptibility test?

A

Zone of growth inhibition indicates antimicrobial activity.

Compare to standards.

21
Q

What do antiseptics do?

A

Destroy or inhibit micro-organisms on living tissue

22
Q

How are antiseptics evaluated?

A

Time Kill.

For each micro-organism and each antimicrobial:

  • Dilute test agent
  • Inoculate with test organism
  • At designated time intervals, remove the sample and determine the viable count (antimicrobial needs to be neutralised)
23
Q

What do preservatives do?

A

Decrease microbial spoilage AFTER product manufacture

- Decrease risk of infection

24
Q

What factors affect the choice of a preservative?

A

Intended application

  • Sterile/Non-sterile
  • Route of admin (affects toxicity)
  • Composition of product/packaging (susceptibility to microbial attack)

No. and type of micro-organisms present

Micro-environment

Safety, Stability, Cost

Properties of chemical agent (interactions with other components)

  • Capacity
  • Conc/dilution
  • Storage temperature
  • pH
25
Q

How are preservatives evaluated?

A

Challenge test.

  • Assess activity with product in final container
  • Inoculate preserved product with 10^6 test organisms per ml
  • Assess viability by VC
  • Preservative adequate if decrease in viability meets criteria of acceptance (diff criteria for diff preservatives)
26
Q

What are the properties of good Preservatives?

A 
Adequate spectrum
Rapid and/or long term action
Good solubility
Effective at product pH
Compatible with formulation/packing
Physically undetectable
Constitute a small proportion of product
Stable, non-toxic and cost effective
27
Q

What are the properties of good Antiseptics?

A 
Adequate spectrum
Rapid Kill
Non-toxic, non-irritant
Immediate, persistent and cumulative activity
Motivation to use
Stable, cost effective

Applied Pharmaceutical Microbiology (15 decks)

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