IC2 Flashcards

1
Q

what is sterilisation

A

process that destroy/eliminate all form of microbial life

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2
Q

what is disinfection

A

process that eliminate many/all microorganism except bacterial spores or inanimate objects

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3
Q

cleaning

A
  • removal of visible soil
  • manual/mechanical w water & detergent/enzymatic product
  • required before disinfection/sterilisation
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4
Q

biocides

A
  • fight microorganisms on non living surfaces & human skin
  • broader spectrum of activity than antibiotics
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5
Q

factors affecting efficacy of disinfection & sterilisation - number of microbes

A
  • larger number = longer time
  • prioir cleaning = reduce no. of microorganisms = increase margin of safety & shorten exposure time to kill microbial load
  • location of microbes: direct contact, not effective if crevice/hinge
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6
Q

factors affecting efficacy of disinfection & sterilisation - innate resistance of microorganism

A
  • spores more resistant to disinfectant (spore coat & cortex act as barrier
  • mycobacteria waxy cell wall = prevent disinfectant entry
  • gram -ve bacteria outer membrane = act as barrier to uptake of disinfectant
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7
Q

factors affecting efficacy of disinfection & sterilisation - concentration & potency of disinfectant

A
  • more concentrated = greater efficacy = shorter time to achieve disinfection
  • process X linear: 1/2 disinfectant concentration doesn’t mean double time required
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8
Q

factors affecting efficacy of disinfection & sterilisation - physical & chemical factor

A

1) temp increase

  • increase activity but possible degradation

2) pH increase

  • alter disinfectant molecule/cell surface
  • improve activity for some (glutaraldehyde, quat ammonium compounds)
  • decrease activity for some (phenol, hypochlorite, iodine)

3) humidity

  • important for gaseous disinfectant (ethanol, chlorine dioxide, formaldehyde)

4) water hardness

  • divalent cations interact w disinfectant -> form insoluble precipitate -> reduce rate of kill
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9
Q

factors affecting efficacy of disinfection & sterilisation - organic & inorganic matter

A
  • chemical reaction between germicide
  • protection by occlusion into salt crystals
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10
Q

factors affecting efficacy of disinfection & sterilisation - duration of exposure

A

exposed for appropriate minimum contact time

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11
Q

factors affecting efficacy of disinfection & sterilisation - biofilms

A
  • microbial communities that are tightly attached to surfaces, X be easily removed
  • mechanisms of biofilm development:
    1) old layers
    2) genotype variation
    3) neutralising enzyme
    4) physiologic condition
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12
Q

factors affecting efficacy of disinfection & sterilisation - general list of all the factors

A

1) number of microbes
2) innate resistance
3) concentration & potency of disinfectant
4) physical & chemical factor
5) organic & inorganic matter
6) duration of exposure
7) biofilms

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13
Q

types of active ingredients in disinfectant - alcohol - general

A

rapid broad spectrum antimicrobial activity against vegetative bacteria (mycobacteria), viruses, fungi BUT not sporicidal

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14
Q

types of active ingredients in disinfectant - alcohol - uses

A

1) hard-surface disinfection
2) skin antisepsis (+/- other excipients/biocides cuz alcohol irritant)

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15
Q

types of active ingredients in disinfectant - alcohol - MOA

A

1) Denaturation of protein

  • increased by water (dehydrogenase of E coli, lag phase of enterobacter aerogenes

2) bacteriostatic by inhibition of metabolites essential for rapid cell division

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16
Q

types of active ingredients in disinfectant - alcohol - types

A

1) isopropyl alcohol
- greater lipophilic properties than ethyl alcohol & less active against hydrophilic viruses (polio)

2) ethanol

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17
Q

types of active ingredients in disinfectant - alcohol - disadvantages

A

1) not sporicidal
2) microbial activity affected by organic matter
3) volatile (may affect contact time)(

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18
Q

types of active ingredients in disinfectant - ammonia - function

A

general purpose cleaner for many surfaces (Glass, stainless steel)

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19
Q

types of active ingredients in disinfectant - ammonia - MOA

A

-saponifying liquids within envelopes of microorganisms
- equilibrium: in 1 mole of ammonia, 0.42% ammonia converted to ammonium

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20
Q

types of active ingredients in disinfectant - ammonia - disadvantages

A
  • household ammonia irritant for eyes & gastric system
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21
Q

types of active ingredients in disinfectant - aldehyde - MOA

A

alkylation of sulfhydryl, hydroxyl, carboxyl, amino groups of microorganisms -> alter RNA, DNA, protein synthesis

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22
Q

types of active ingredients in disinfectant - aldehyde - actions against different microorganism

A

1) bacterial spore

  • low concentration: inhibit germination
  • high concentration: sporicidal (interact w outer cell layer)

2) mycobacteria

  • probably involve mycobacterial cell wall

3) other nonsporulating bacteria

  • strong association with outer layers of gram pos & neg bacteria, cross linking of protein amino groups, inhibition of transport processes into cell

4) fungi

  • fungal cell wall: interaction w chitin

5) viruses

  • protein DNA cross link
  • capsid changes
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23
Q

types of active ingredients in disinfectant - aldehyde - general uses

A
  • when require strong disinfection
  • antisepsis, sterilisation
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24
Q

types of active ingredients in disinfectant - aldehyde - disadvantages

A
  • toxicity (need PPE)
  • odour
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25
types of active ingredients in disinfectant - aldehyde - types
1) paraformaldehyde: solid polymer, vaporised by heat for gaseous decontamination 2) glutaraldehyde: LAST RESORT
26
types of active ingredients in disinfectant - ortho-phthalaldehyde (OPA) - general
clear blue liquid, pH 7.5
27
types of active ingredients in disinfectant - ortho-phthalaldehyde (OPA) - MOA
- OPA interact w amino acid, protein, microorganism - OPA less potent cross-linking agent but compensated for by lipophilic aromatic nature of OPA that assist uptake through outer layers of mycobacteria & gram -ve bacteria - kill spores by blocking spore germination process
28
types of active ingredients in disinfectant - ortho-phthalaldehyde (OPA) - advantages
- stability over wide pH range (3-9) - X irritant to eyes and nasal passage - X odour - excellent material compatibility
29
types of active ingredients in disinfectant - ortho-phthalaldehyde (OPA) - disadvantages
handled with caution: stain proteins gray (including unprotected skin)
30
types of active ingredients in disinfectant - biguanides - components
1) chlorhexidine 2) alexidine
31
types of active ingredients in disinfectant - biguanides - chlorhexidine - general
- broad spectrum bactericidal agent - activity pH dependent, greatly reduced in presence of organic matter - used in mouthwash
32
types of active ingredients in disinfectant - biguanides - chlorhexidine - MOA
1) Damage membrane 2) cross cell outer membrane (passive diffusion) 3) Attacks: - bacterial cytoplasmic (coagulation, gelling) - inner membrane - yeast plasma membrane (partition into cell wall, plasma membrane, cytoplasm of cells)
33
types of active ingredients in disinfectant - biguanides - alexidine
- contain ethylhexyl end groups - faster onset of bactericidal activity - significantly faster alteration in bactericidal permeability - reduce lipid phase separation & domain
34
types of active ingredients in disinfectant - chlorine - general
- liquid (sodium hypochlorite), solid (calcium hypochlorite) - broad spectrum antimicrobial activity
35
types of active ingredients in disinfectant - chloride - advantages
1) no toxic residues 2) cheap 3) fast acting 4) remove dried/fixed organisms & biofilms from surfaces 5) low incidence of serious toxicity 6) effective because works on different places of microorganisms
36
types of active ingredients in disinfectant - chloride - MOA
- attributed to undissociated hypochlorous acid (HOCI) - oxidation of sulfhydryl enzymes & amnio acid - ring chlorination of amino acids - loss of intracellular contents - decreased uptake of nutrients - inhibition of protein synthesis - decreased oxygen uptake - oxidation of respiratory components - decreased ATP production - DNA breaks - depressed DNA synthesis
37
types of active ingredients in disinfectant - chloride - factors affecting efficacy
- pH ** HOCL dissociate to less microbiocidal form ** increase pH = decrease efficacy
38
types of active ingredients in disinfectant - chloride - disadvantages
- household bleach cause ocular irritation, oropharyngeal/esophageal/gastric burn - corrosiveness to metal in high concentration - inactivation by organic matter - discolouring of fabrics - release of toxic chlorine gas when mixed w ammonia/acid (household cleaning agents) - relative stability
39
types of active ingredients in disinfectant - chloride - alternative compounds
- types: 1) demand-release chlorine dioxide 2) sodium dichloroisocyanurate 3) chloramine-T - advantages 1) retain chlorine longer = exert prolonged bactericidal effect 2) sodium hychloroisocyanurate tablets stable & higher activity than sodium hypochlorite because more free chlorine available
40
types of active ingredients in disinfectant - iodine - usage
antiseptic on skin/tissue
41
types of active ingredients in disinfectant - iodine - MOA
penetrate cell wall of microorganism quickly = disrupt protein & nucleic acid structure & synthesis
42
types of active ingredients in disinfectant - iodophor - general
- iodine + solubilising agent/carrier - sustained-released reservoir of iodine - release small amount of free iodine in aq solution
43
types of active ingredients in disinfectant - iodophor - advantages
- non staining - free of toxicity & irritancy
44
types of active ingredients in disinfectant - iodophor - usage
antiseptic & disinfectant
45
types of active ingredients in disinfectant - iodophor - MOA
free iodine contribute to bactericidal activity
46
types of active ingredients in disinfectant - iodophor - factors contributing to efficacy
- dilute iodophor = more rapid bactericidal activity - potentially weaken iodine linkage to carrier polymer = increase in free iodine in solution
47
types of active ingredients in disinfectant - peroxygens (h2o2) - uses
- disinfection, sterilisation, antisepsis - broad spectrum efficacy against virus, bacteria, yeast, bacterial spore - high concentrations & longer contact time for sporicidal activity (increased efficacy in gaseous phase)
48
types of active ingredients in disinfectant - peroxygens (h2o2) - general
- greater activity against gram pos than neg - presence of catalase/other peroxidase in organisms increase tolerance
49
types of active ingredients in disinfectant - peroxygens (h2o2) - advantages
- environmentally friendly (Rapidly degrade into water and oxygen) - relatively stable + contain stabilisers to prevent decomposition
50
types of active ingredients in disinfectant - peroxygens (h2o2) - MOA
oxidant - produce free radicals (.OH) - attack essential cell components
51
types of active ingredients in disinfectant - peroxygens (h2o2) - alternatives
accelerated hydrogen peroxide - enhance bactericidal efficacy by: 1) surfactant 2) organic acid 3) emulsifier acid - uses 1) disinfectant/cleaning agent - stabilise h2o2 for extended use in med/vet device
52
types of active ingredients in disinfectant - peracetic acid (CH3COOOH) - uses
- more potent biocide than h2o2 - sporicidal, bactericidal, virucidal, fungicidal at low conc - low temperature liquid sterilant for medical device, flexible scope, HD - environmental surface sterilant
53
types of active ingredients in disinfectant - peracetic acid (CH3COOOH) - advantages
- decompose to safe to use by products (Acetic acid & o2) - free from decomposition by peroxidases - remain active in presence of organic loads
54
types of active ingredients in disinfectant - peracetic acid (CH3COOOH) - MOA
- denature proteins & enzymes - increase cell wall permeability by disrupting sulfhydryl (-SH) & sulfur (S-S) bond
55
types of active ingredients in disinfectant - phenol - uses
- antiseptic, disinfectant, preservative - antifungal (Damage to plasma membrane) - antiviral (X effect on capsid unless treatment > 20 min)
56
types of active ingredients in disinfectant - phenol - MOA
- membrane-active properties - induce progressive leakage of intracellular constituents ** release of K+: first index of membrane damage
57
types of active ingredients in disinfectant - chloroxylenol (halophenol) - uses
- antiseptic - disinfectant formulation - bactericidal ** P. aeruginosa & many moulds highly resistant - excipient in topical products
58
types of active ingredients in disinfectant - chloroxylenol (halophenol) - advantages
- non toxic, non irritant ** but toxic upon oral consumption or eye contact
59
types of active ingredients in disinfectant - diamidines - uses
- anti bacteriostatic agent for topical treatment of wound - disinfection, antisepsis
60
types of active ingredients in disinfectant - diamidines - MOA
inhibition of oxygen uptake & leakage of amino acid
61
types of active ingredients in disinfectant - silver compounds - silver nitrate
1) uses - antimicrobial, antifungal 2) MOA - interaction w thiol in enzymes & proteins - affect microbial plasma, cytoplasmic membrane, nucleic acid
62
types of active ingredients in disinfectant - diamidines - silver sulfadiazine
1) General - combination of 2 antibacterial agent & sulfadiazine - broader spectrum 2) MOA - induce membrane bleb in susceptible bacteria
63
types of active ingredients in disinfectant - mercuric chloride (HgCl2) - uses
broad range disinfectant
64
types of active ingredients in disinfectant - mercuric chloride (HgCl2) - MOA
affect microbial peptide synthesis
65
types of active ingredients in disinfectant - mercuric chloride (HgCl2) - disadvantages
1) highly toxic both acutely & cumulative poison (AKI if accumulate in kidney) 2) corrosive
66
types of active ingredients in disinfectant - quaternary ammonium compounds - uses
1) environmental sanitation of non critical surfaces (floor, wall, furniture) 2) fungicidal, bactericidal, virucidal against lipophilic (enveloped) viruses 3) X sporicidal, tuberculocidal, virucidal against hydrophilic (non-enveloped) viruses
67
types of active ingredients in disinfectant - quaternary ammonium compounds - disadvantages
skin irritant
68
types of active ingredients in disinfectant - quaternary ammonium compounds - MOA
1) adsorption & penetration into cell wall 2) Reaction w cytoplasmic membrane (lipid/protein) -> membrane disorganisation 3) leak of intracellular low MW material 4) degradation of proteins & nucleic acid 5) wall lysis caused by autolytic enzymes
69
types of active ingredients in disinfectant - vapour-phase sterilant - uses
sterilise heat-sensitive medical devices & surfical supplies
70
types of active ingredients in disinfectant - vapour-phase sterilant - types
1) Ethylene oxide, formaldehyde 2) hydrogen peroxide, peracetic acid