Antimicrobial Modes of Action Flashcards
what are the requirements for antimicrobial activity
adsorption to cell surface, passage into cell, interaction with target
what antiinfectives undergo oxidation
peroxygen compounds, halogens
what antiinfectives undergo x-linking
aldehydes
what antiinfectives undergo coagulation
aldehydes, chlohexidine, phenols, ethanol, mercurials
what happens during oxidation mode of action
strand breakage, binding to DNA or RNA, degredation of unsaturated fatty acids, modification of S-S bonds
what happens during the x-linking mode of action
NH2 groups of surface-exposed lysine residues
what happens during the coagulation mode of action
extensive x-linking and protein precipitation
what happens when biocide concentration and exposure time are increased
bacteriostatic = sub-lethal, bacteriocidal=lethal
permeability changes, reversible enzyme inhibition, structural damage, leakage, autolysis, lysis, cytoplasm coagulation
what disinfectants act on the cell wall of bacteria
low conc phenol, fomaldehyde
what disinfectants work on -SH groups in DNA
glutaraldehyde, hydrogen peroxide, iodine
what disinfectants work on -NH2 groups
formaldehyde, glutaraldehyde
what disinfectants work on ribosomes
H2O2
what disinfectants work on nucleic acid
acridine dyes, cimetidine
what disinfectants work on coagulation
high conc chlorhexidine, phenol, Hg salts
what disinfectants work on proton motive force
parabens, some phenols
what disinfectants work on cell membrane permeability
cetrimidine, chlorhexidine, phenol
what disinfectants work on membrane ATPase
chlorhexidine
what disinfectants work on electron transport systems
hexachlorophane
what disinfectants work on enzymes with-SH groups
Hg, Ag agents
what is intrinsic/innate resistance
natural chromosomally encoded property
what is extrinsic or acquired resistance
organism becomes resistant
what is phenotypic extrinsic resistance
response to mode of growth
what is genetic extrinsic resistance
requires mutation/ genetic transfer
includes co-resistance
what type of resistance are efflux pumps
innate resistance
what happens with efflux pumps
antimicrobials pumped out of cell via pumps in the cell wall
what barriers to penetration do bacteria have
spore coat, waxy fatty acids, presence of OM/structure/porins, peptidoglycan
what decreased accumulation mechanisms do bacteria have to disinfectants
efflux pumps, degredation/modification of biocide
what adaptations do bacteria have toward disinfectants
altered/absence f metabolic pathway
what bacteria has acquired phenotypic resistance
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
what are biofilms
acquired phenotypic resistance
provide barrier to biocide, facilitates cell-cell communication, allows 3D community to develop, increased genetic exchange
how does acquired genetic resistance occur (chromosomal mutation)
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
how does acquired resistance via efflux upregulation occur
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
