inhibitors of cell wall synthesis part 1 Flashcards
importance of bacterial cell wall? (4points)
Surround and protect the cell Provides rigidity Act as an attachment site Resist pressure changes If cell wall is lost, the cell will burst and will die
what is the role of the R group in penicillins?
determines stability to enzymes and acids, the antibacterial spectrum and hypersensitivity.
Name the enzyme that penicillins activate, which is responsible for the breakdown of peptidoglycans
autolysin
name the components of gram - bacterial cell wall
lipopolysaccharide
outer membrane
peptidoglycan
cytoplasmic membrane
name the components of gram + bacterial cell wall
peptidoglycan
cytoplasmic membrane
Are penicillins effect against mircroorganisms devoid of a cell wall?
no
name the natural penicillins
penicillin G (benzyl penicillin) penicillin v (phenoxymethyl penicillin) procaine penicillin (benzyl penicillin procaine) benzathine penicllin
all natural penicillins are unstable? true or false
true
penicillin G is used to treat
a. meningitis in children
b. nosocomial infections
c. nephrotoxcicity
meningitis in children
Name a drug effective against primary and secondary syphilis
penicllin
in gonorrhoea, penicillin resistant strains are treated with which 2 drugs?
ceftriaxone with septinomycin as a backup
why is penicllin G started initially and penicillin V continued when the clinical symptoms disappear?
such is done because the absorption of penicillin V is unpredictable
penicillin V is effective against anaerobes? true or false
true
name the antibacterial spectrum of penicllin g and penicillin v
G + cocci
G - cocci
G + bacilli
spirochetes
what is the common cause of penicillin G resistance?
mutations in one or more bacterial penicillin binding proteins
gonococcal opthalmia in neonates can be prevented by?
silver nitrate drops
what is the purpose of procaine in procaine penicillin? which route is it administered via?
procaine acts as an anesthetic by reducing pain at the site of injection.
given by IM route
when is benzathine penicillin used? what is its mechanism?
benzathine penicllin is used when prolonged low concentrations of benzyl penicillin are required.
benzylpenicillin dissociates and enters slowly into the bloodstream.
what are the indications of benzathine penicllin
rheumatic fever and early or latent syphilis, dosed every 2-4 weeks
antistaphylococcal penicillins are stable to penicillinase. True or false
name the antistaphylococcal penicillins
true
methicillin
cloxacillin
why is methicillin rarely used? when is it used?
rarely used because of its toxicity
used in MRSA
cloxacillin is often prepared in combination with ___________.
amipicillin
cloxacillin is unstable to acids but methicillin is stable. True or False?
false. methicillin is unstable and cloxacillin is stable.
name the aminopenicillins and their stability status to penicillinase
ampicillin - unstable
amoxacillin - unstable
amoxacillin + clavulanic acid (augmentin) - stable
aminopenicllins are unstable to acids. True or false
false. aminopenicllins are stable to acids
what is the role of clavulanic acid in augmentin?
its is a beta lactamase inhibitor that protects the drug from enzymatic hydrolysis
name a drug that cures listeria meningitis
ampicillin
list an example of a drug used to combat sinusitis
ampicillin or amoxacillin
name a drug used in the eradication of H.pylori
amoxacillin
name two drugs used in dental surgical infections. One of them specifically works against oragnisms with penicillinase activity. identify which one.
amoxacillin used for prophylaxis in dental surgery
amoxacillin and clavulanic acid for severe dental infections (with penicillinase activity)
name two drugs used in endocarditis infections
penicillin G and amoxacillin
name the main activity that tazobactam imparts along with piparcillin
stability against penicillinase producing micro organisms.
piparcillin is not effective against klebsiella. why?
due to constitutive penicillinase activity.
antipseudomonal penicillins are unstable against acids. true or false?
true.
piparcillin is active against. pseudomonas aeruginosa. true or false
true
name the antipseudomonal penicillins
piparcillin
piparcillin + tazobactam
name the penicillinase inhibitors. how do they work?
clavulanic acid
tazobactam
they are beta lactam structures with poor antibiotic activity but affinity to penicillinase enzyme so they block it and protect the drug.
penicillin V can be given orally. true or false
true
penicillins and aminoglycosides show synergism. why?
penicillins destroy the cell wall allowing aminoglycosides to enter and start inhibition of protein synthesis.
penicillins and aminoglycosides should not be placed in the same infusion. why?
penicillin is - charged
aminoglycosides are + charged
they form an inacitve complex in the same infusion
two reasons of natural resistance?
organism lacks cell wall
cell wall impermeable to penicillin
three reasons of acquired resistance?
altered permeability
altered PBP
beta lactamase
penicillin G penetrated the CSF when meninges are inflamed only. true or false
true
penicillin G is given
a. oral
b. IV and IM
c. oral and IV
d. oral and IM
b. IV and IM
penicillin G and penicillin V should be administered in the abscence of food. why? name other drugs with the same preference
delayed gastric emptying leads to prolonged contact with acidic environment
cloxacillin and augmentin
amoxacillin has complete absorption so it is not used in the treatment of?
shigella and salmonella enteritis
what is the primary route of excretion of penicillins
tubular secretion and glomerular filteration
with penicillins, Impaired renal function requires dose adjustment. normal one hour but with impairment
___ hr.
10 hours
what is penicillin combined with if prolonged release is desired? how does it work?
probenecid
inhibits penicillin secretion
piparcillin + tazobactam is teratogenic because it crosses the placental barrier. true or false.
false. not teratogenic
piparcillin + tazobactam crosses the BBB when meninges are not inflamed. true or false
false. only penetrates CSF when meninges are inflamed and as infection subsides BBB is re established.
adverse reactions of penicillins (6 points)
hypersensitivity diarrhoea nephrotoxicity neurotoxicity hematologic toxicities cation toxicity
