1
Q
what is sterilisation
A
process that destroy/eliminate all form of microbial life
2
Q
what is disinfection
A
process that eliminate many/all microorganism except bacterial spores or inanimate objects
3
Q
cleaning
A
- removal of visible soil
- manual/mechanical w water & detergent/enzymatic product
- required before disinfection/sterilisation
4
Q
biocides
A
- fight microorganisms on non living surfaces & human skin
- broader spectrum of activity than antibiotics
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
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
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
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
9
Q
factors affecting efficacy of disinfection & sterilisation - organic & inorganic matter
A
- chemical reaction between germicide
- protection by occlusion into salt crystals
10
Q
factors affecting efficacy of disinfection & sterilisation - duration of exposure
A
exposed for appropriate minimum contact time
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
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
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
14
Q
types of active ingredients in disinfectant - alcohol - uses
A
1) hard-surface disinfection
2) skin antisepsis (+/- other excipients/biocides cuz alcohol irritant)
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
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
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)(
18
Q
types of active ingredients in disinfectant - ammonia - function
A
general purpose cleaner for many surfaces (Glass, stainless steel)
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
20
Q
types of active ingredients in disinfectant - ammonia - disadvantages
A
- household ammonia irritant for eyes & gastric system
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
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
23
Q
types of active ingredients in disinfectant - aldehyde - general uses
A
- when require strong disinfection
- antisepsis, sterilisation
24
Q
types of active ingredients in disinfectant - aldehyde - disadvantages
A
- toxicity (need PPE)
- odour
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
