antimicrobial bacteria general Flashcards
what are the important things to consider when choosing an antimicrobial
the organism, the host, the treatment
what is characteristic of gram +
they have a much thicker cell wall, explains the retention of gram stain.
what is the gram + wall composed of?
peptidoglycan a complex polymer.
what are the three parts of peptidoglycan
backbone, tatrapeptide chains, peptide cross bridges.
what is the backbone of the peptidoglycan wall composed of
alternating subunits of N-acetylglucosamine NAG and N-acetylmuramic acid NAM connected by beta (1,4) linkages.,
what are the characteristics of the tetrapeptide chains?
they are identical and attached to NAM.
what are the characteristics of the cross-bridges
they are identical and made of protein.
what is the site of action of the beta-lactams
the peptide cross-links. it inhibits the b-lactamase
what is beta-lactamase
a penicillin-binding protein that is secreted outside of the cell. performs the cross-linking for the cell wall
gram negative outer membrane
semipermeable lipid bilayer composed of phospholipids, lipoproteins, LPS, and proteins. prevents toxic substances from entering the cell.
what is lipopolysaccharide?
this is endotoxin and released when the cell is killed.
what are the porins in gram - responsible for?
permit the passive diffusion of low-molecular weight hydrophilic compounds accounts for the inability of larger molecules to enter the cell.
what is the periplasmic space
gelatinous material between the inner and outer membrane of gram (-) contains the peptidoglycan and beta-lactamase.
what is the purpose of peptidoglycan
provides structural stability to prevent osmotic lysis.
gram (+) treat with what?
penicillin, antistaph PCN, aminopenicillin, vancomycin, linezolid, daptomycin
