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Infection & Immunity > Antimicrobial Modes of Action > Flashcards

Antimicrobial Modes of Action Flashcards

1
Q

what are the requirements for antimicrobial activity

A

adsorption to cell surface, passage into cell, interaction with target

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2
Q

what antiinfectives undergo oxidation

A

peroxygen compounds, halogens

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3
Q

what antiinfectives undergo x-linking

A

aldehydes

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4
Q

what antiinfectives undergo coagulation

A

aldehydes, chlohexidine, phenols, ethanol, mercurials

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5
Q

what happens during oxidation mode of action

A

strand breakage, binding to DNA or RNA, degredation of unsaturated fatty acids, modification of S-S bonds

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6
Q

what happens during the x-linking mode of action

A

NH2 groups of surface-exposed lysine residues

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7
Q

what happens during the coagulation mode of action

A

extensive x-linking and protein precipitation

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8
Q

what happens when biocide concentration and exposure time are increased

A

bacteriostatic = sub-lethal, bacteriocidal=lethal

permeability changes, reversible enzyme inhibition, structural damage, leakage, autolysis, lysis, cytoplasm coagulation

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9
Q

what disinfectants act on the cell wall of bacteria

A

low conc phenol, fomaldehyde

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10
Q

what disinfectants work on -SH groups in DNA

A

glutaraldehyde, hydrogen peroxide, iodine

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11
Q

what disinfectants work on -NH2 groups

A

formaldehyde, glutaraldehyde

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12
Q

what disinfectants work on ribosomes

A

H2O2

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13
Q

what disinfectants work on nucleic acid

A

acridine dyes, cimetidine

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14
Q

what disinfectants work on coagulation

A

high conc chlorhexidine, phenol, Hg salts

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15
Q

what disinfectants work on proton motive force

A

parabens, some phenols

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16
Q

what disinfectants work on cell membrane permeability

A

cetrimidine, chlorhexidine, phenol

17
Q

what disinfectants work on membrane ATPase

A

chlorhexidine

18
Q

what disinfectants work on electron transport systems

A

hexachlorophane

19
Q

what disinfectants work on enzymes with-SH groups

A

Hg, Ag agents

20
Q

what is intrinsic/innate resistance

A

natural chromosomally encoded property

21
Q

what is extrinsic or acquired resistance

A

organism becomes resistant

22
Q

what is phenotypic extrinsic resistance

A

response to mode of growth

23
Q

what is genetic extrinsic resistance

A

requires mutation/ genetic transfer

includes co-resistance

24
Q

what type of resistance are efflux pumps

A

innate resistance

25
Q

what happens with efflux pumps

A

antimicrobials pumped out of cell via pumps in the cell wall

26
Q

what barriers to penetration do bacteria have

A

spore coat, waxy fatty acids, presence of OM/structure/porins, peptidoglycan

27
Q

what decreased accumulation mechanisms do bacteria have to disinfectants

A

efflux pumps, degredation/modification of biocide

28
Q

what adaptations do bacteria have toward disinfectants

A

altered/absence f metabolic pathway

29
Q

what bacteria has acquired phenotypic resistance

A 
legionella pneumophila (legionnaire's disease)
exists as parasite inside protozoa, isolated from water sources where outbreaks have occurred, intracellular bacteria more resistant to biocides than planktonic bacteria
30
Q

what are biofilms

A

acquired phenotypic resistance
provide barrier to biocide, facilitates cell-cell communication, allows 3D community to develop, increased genetic exchange

31
Q

how does acquired genetic resistance occur (chromosomal mutation)

A 
changes in protein, fatty acid or phospholipid composition decreases efficacy
changes in lentgth of O-chain of LPS
changes in number and/or size of porins
modified target, altered pathway
increased efflux
32
Q

how does acquired resistance via efflux upregulation occur

A

widespread resistance to multiple solvents, detergents and antibiotics
partly under control of mar operon (marA=activator, marR=repressor)
inactivation of marR or over-expression of marA induces mar phenotype

Infection & Immunity (22 decks)

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