Flashcards in antimicrobial chemotherapy Deck (16):
what are antimicrobial agents?
chemicals that are routinely used to control microbial growth
what is selective toxicity?
the exploitation of differences between host and invading organism, it has unique target sites
what does broad spectrum mean?
it's effective on gram positive and gram negative bacteria
what does narrow spectrum mean?
it is effective on a single group of bacteria only
what are bacteriostatic agents?
frequently inhibitors of protein synthesistttttt, they bind to ribosomes, if the conc of the agent is lowered, growth resumes
what are bacteriocidal agents?
they bind tightly to cells and kill them. dead cells are not destroyed and total cell numbers remain constant
what are bacteriolytic agents?
they kill by cell lysis, they decrease cell number, e.g. cell wall synthesis inhibitors aka penicllin
what are the 2 common used assays for measuring antimicrobial activity?
1. minimum inhibitory concentration and disc diffusion assay
the mic determines the smallest amount of agent needed to inhibit the growth of a test bacterium
the disc diffusion assay determines the zone of inhibition
what are some target sites?
cell wall, protein synthesis, nucleic acid, cell membrane
what are disinfectants and antiseptics used on?
disinfectants are used on inanimate objects, they are important in infection control.
antiseptics can be used on living tissue
what do preservatives do?
maintain microorganisms at low level
what do biocides do? and hat does their efficacy depend on?
they do not sterilise, their efficacy depends on concentration, microbial load, presence of organic matter
what are the 2 ways of resistance?
intrinsic and extrinsic
what is intrinsic resistance?
the bacteria may lack target structure, or bacteria is impermeable e.g. biofilm formation
what is extrinsic resistance?
the bacteria produces degradative enzymes, modification of target site, pumping agent out of cell