Cell Wall/ Membrane Acting Agent (Pre work- KAUR)

the cell wall of gram positive bacteria is what kind of layer?

peptidoglycan

what kind of sugars does gram positive bacteria contains?

N-acetylglucosamine (NAG) & N-acetylmuramic acid (NAM)

in gram positive, the staph aureus the link is Gly 5-D-Ala between lysines. The cross linked is catalyzed by what ?

transpeptidase (also known as PBP)

some amino amcids of the peptigolycan layer are of what? which protects the peptidoglycan

D-stereochemistry

beneath the peptidoglycan layer is what ?

lipoidal cytoplasmic (or plasma ) membrane

among these proteins are the B-lactam targets which is what

penicillin bind proteins (PBPs)

in gram positive, inner membrane and its protein components provide what

principal barrier to uptake of antibiotics

PBPs are enzymes that are important in cell wall formation and repair (t/f)

true

there are number of different types of PBP and their function dependent on species of bacteria (t/f)

true

B-lactam antibiotics bind to PBPs and kill bacteria by preventing the biosynthesis of a functional cell wall (t/f)

true

with gram negative bacteria, the cell wall is more complex and more lipoidal (t/f)

true

in gram negative bacteria, cell contain an additional outer lipid membrane that differs considerably from inner membrane

true

the outer layer contains complex lipopolysaccharides (LPS) in gram negative (t/f)

true

LPS that encodes antigenic responses, causes septic shock in gram negative

true

in gram negative, exterior layer also contains a number of enzymes and proteins which are what?

porins

porins are super molecules made up of two or three monomeric proteins that allow many kinds of small molecules to pass and other contain specific receptors that allow only certain molecules to come in (t/f)

true

in gram negative, periplasmic space containing less impressive and thinner, compared to gram positive which is a layer of peptidoglycan (t/f)

true

in gram negative, periplasmic space (plasma membrane) where the B-lactam targets are found in

true

selective and irreversible inhibition of enzymes (PBP) processing the developing peptidoglycan layer is MOA of what

B-Lactam Antibiotics

B-Lactam bind to PBPs followed by cell lysis and are bactericidal (t/f)

true

the peptide pendant from the lactate carboxyl of a muramic acid unit (NAM) terminates in a D-Alanyl-D-Alanine unit (t/f)

true

in gram negative, terminal D-alanine unit is enchanted for a glycine unit on adjacent stand in a reaction catalyzed by PBPs. (t/f)

true

PBP uses what group to attack the penultimate D-alanyl unit forming a covalent ester bond

serine hydroxyl group

Enzyme-peptidoglycan ester bond is attacked by free amino end of a pentaglycyl unit of a adjacent strand, regenerating the transpeptidase active site for further catalytic action and producing a new amide bond.

true

penicillins and b-lactam antibiotics have structure that closely resembles that of what ?

acylated D-alanyl D-alanine

the enzyme mistakenly accepts the penicillin as though it were its normal substrate

true

a cyclic amide with four atoms in its ring

b-lactam

penicillin subclass of b-lactam antibiotics is characterized by presence of substituted five membered what?

thiazolidine ring

first penicillin was what ?

penicillin G be

penicillin G also called what?

benzylpenicillin

the sodium and potassium salts of penicillin are what?

crystalline, hydroscopic and water soluble

best stability of B-lactam is noted at pH between what ?

pH 6.0-7.2

there are 4 types of b-lactam antibiotics

penicillin

cephalosporins

cabapenems

monobactam

five membered thiazolidine ring is what b-lactam antibiotic

penicillins

six membered dihydrothiazine ring is what b-lactam antibiotics

cephalosporins

five membered pyrroline ring is what type of b-lactam antibiotics

carbapenems

which b-lactam antibiotics is no ring

monobactam

replace enzymes targeted by b-lactam antibiotics with alternative enzymes that carry out the same function. MRSA produces a mutated PBP-2 that does not efficiently bind methicillin any long is what resistance mechanism

target alteration

what resistance mechanism is due to lack of porins; decreased cellular uptake of drug

inability to penetrate

which resistance mechanism increased production of efflux pumps to spit antibiotics back out of the cell

active efflux pumps

which resistance mechanisms is production of B-lactamases. B-lactamases are enzymes produced by microorganism that catalyze hydrolysis of B-lactam bond and inactivate B-lactam antibiotics to penicilloic acids before they can reach the PBPs.

B-lactamases

which four main resistance mechanisms that pathogenic bacteria have evolved to neutralize B-lactam antibiotics

target alteration

inability to penetrate

active efflux pumps

B-lactamases

which bacteria has thick peptidoglycan

gram positive

which one has more detailed bacteria

gram negative