Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
30 Cards in this Set
- Front
- Back
|
What are the 4 classes of b-lactams?
|
Penicillin, cephalosporin, monobactam, carbapenem
|
|
|
What happens during Stage 1 of peptidoglycan synthesis?
|
results in N-acetylmuramic acid (NAM)-pentapeptide formation. the last two aa of penatpeptide are D-ala residues
|
|
|
How does D-cycloserine work?
|
competitively inhibits enzymes that make D-ala and add it to NAM-peptide chain during step 1
|
|
|
What organisms is D-cycloserine effective against?
|
TB resistant to 1st class drugs
|
|
|
What happens during Stage 2 of peptidoglycan synthesis?
|
NAM-pentapeptide is combined with NAG and some glycines are added to 3rd peptide. this disaccharide-peptide is added to growing chain and 55C lipid is released
|
|
|
How does vancomycin work?
|
Binds to D-ala-D-ala of pentapeptide and inhibits NAM-pentapeptide-NAG from adding to growing chain
|
|
|
How does Bacitracin work?
|
prevents dephosphorylation of 55C lipid which halts step 2
|
|
|
What is stage 3 of peptidoglycan synthesis?
|
crosslinking enzymes link the D-ala residue to the poly-glycine residue on opposing glycan chains?
|
|
|
How do b-lactam antibiotics work?
|
they mimic D-ala-D-ala and bind to bacterial enzymes to form a stable, inactive complex. these enzymes are PBPs
|
|
|
What factors affect efficacy of b-lactams?
|
affinity for PBPs, penetration into bacteria, presence/absence of resistance
|
|
|
What are the 4 mechanisms of B-lactam resistance?
|
b-lactamase (Gram- and S. aureus) via plasmid or chromosome, porin alteration, efflux pumps (Neisseria, Salmonella, Pseudomonoas, and mutated PBPs
|
|
|
How can we overcome b-lactamase producing organisms?
|
use b-lactamase resistant antibiotics or use with b-lactamase inhibitor like clavulonic acid or sulbactam (won't work against NDM plasmid)
|
|
|
How is MRSA different form Neisseria, H. flu, and S. pneumo in altering PBP?
|
MRSA makes new PBP acquired horizontally while others change affinity of original PBP
|
|
|
How does vancomycin resistance happen and what organism is notorious for this?
|
Gene products from resistance plasmid make "depsipeptide" where D-ala-D-lactate is present instead so vancomycin can't bind. Enterococcus faecium
|
|
|
What do Pen G and Pen V treat?
|
Gram+ cocci, Group A,B,C,G Strep and Enterococci, Gram+ bacilli, Neisseria, syphilis (penG oral, PenV IV)
|
|
|
What are the penicillinase-resistant penicillins?
|
Oxacillin and Nafcillin. oxacillin can be oral or IV and nafcillin in biliary excretion
|
|
|
What are Unasyn and Augmentin and what do they treat?
|
Ampicillin/sulbactam = Unasyn, amoxicillin/clavulonic acid = augmentin, they are penicillinase-sensitive and are used for penG/V stuff and GDS and H. Flu, e. coli, Shigella, Salmonella
|
|
|
What are carbenicillin and tacarcillin?
|
penicillinase suscpetible used for P. aeruginosa, E. coli, UTI, NOT Klebsiella (tacarcillin/clavulonic acid = Timenten)
|
|
|
What is peperacillin?
|
used for some Klebsiella, penicillinase susceptible. can be given w/ b-lactamase inhib
|
|
|
What is unique about monobactams?
|
can use in pts allergic to pen, use for Gram- rod
|
|
|
What is unique about carbapenems?
|
the broades spectrum there is, NOT for MRSA, used with Primaxin, a dihydropeptidase inhibitor that prevents hydrolyzation by renal tubule
|
|
|
What are cephalosporins?
|
similar to penicillin but resistant to penicillinases but suseptible to cephalosporinases
|
|
|
What is Keflex?
|
cephalexin, 1st gen. cephalo for orla use against Gram+ cocci except EC and MRSA
|
|
|
What is cefuroxime?
|
2nd gen cephalo, good for Gram- lower respiratory or otitis/sinusitis
|
|
|
What is ceftriaxone?
|
3rd gen cephalo, great for Gram-, cross BBB, good for E. coli, Kelbsiella
|
|
|
Can you give cephalos to pt w/ pen allergy?
|
NOOOOOOOO
|
|
|
What are some side effx of cephalos?
|
pain via IM admin, prothrombin deficiency, diarrhea, superinfection
|
|
|
What are side effects of vancomycin?
|
oto/nephrotoxic
|
|
|
What do you treat with vancomycin?
|
MRSA, resistant-strep pneumo, Staph, C. diff
|
|
|
What is aztreonam?
|
b-lactam good aginst Gram- rod
|
