antibiotics Flashcards
Which drugs block cell wall synthesis by inhibition of peptidoglycan cross-linking
Penicillin, methicillin, ampicillin, piperacillin, cephalosporins, aztreonam, imipenem
which drugs block peptidoglycan synthesis
Bacitracin, vancomycin
which drugs block nucleotide synthesis by inhibiting folic acid synthesis (involved in methylation)
Sulfonamides, Trimethoprim
which drugs block DNA topoisomerase
Fluoroquinolones
which drugs block mRNA synthesis
Rifampin
which drug damages DNA
Metronidazole
Which drugs block protein synthesis at 50S ribosomal subunit
Chloramphenicol, macrolides, clindamycin, streptogramins (quinupristin, dalfopristin), linezolid
Which drugs block protein synthesis at 30S ribosomal subunit
Aminoglycosides, Tetracyclines
Name types of penicillins
Penicillin G (IV and IM & Penicillin V (oral)
Mechanism of penicillin
- binds penicillin-binding protein (pbp; transpeptidases– block transpeptidases cross-linking of peptidoglycan– active autolytic enzymes
Clinical use of penicillin
- mostly for gram(+) organisms (S. pneumo, S. pyogenes, Actinomyces)– N. meningitidis, T.pallidum, Syphilis
What are penicillins bactericidal for
- gram (+) cocci- gram (+) rods- gram (-) cocci- spirochetes
Penicillin toxicity
NAME?
Penicillin resistance caused by
beta lactamases cleave beta lactam ring
Name the narrow spectrum penicillins
Oxacillin, nafcillin, dicloxacillin
Mechanism of narrow spectrum penicillins
oxacillin, nafcillin, dicloxacillin- same as penicillin (binds PBP, block transpeptidases cross-linking peptidoglycans)
Narrow spectrum penicillins – characteristics
oxacillin, nafcillin, dicloxacillin- penicillinase resistant because bulky R group which blocks access of beta lactamase to beta lactam ring
clinical use of Narrow spectrum penicillins
oxacillin, nafcillin, dicloxacillin- S. aureus (except MRSA)
Why is MRSA resistant to narrow specrum penicillins?
oxacillin, nafcillin, dicloxacillin- because of altered PBP
Toxicity caused by narrow spectrum penicillins
oxacillin, nafcillin, dicloxacillin - - hypersensitivity reactions- - interstitial nephritis
What is the use of nafcillin
naf for staph
Name wide spectrum penicillins
ampicillin, amoxicillin (aminopenicillins)
Mechanism of wide spectrum penicillins
ampicillin, amoxicillin - same as penicillin- binds PBP, block transpeptidases cross-linking peptidoglycans
Difference between narrow and wide spectrum penicillins
ampicillin, amoxicillin vs nafcillin, oxacillin, dicloxacillin - wide spectrum are penicillinase sensitive whereas narrow spectrum are penicillinase resistant
What are wide spectrum penicillins commonly combined with and why
ampicillin, amoxicillin -clavulanic acid to protect against beta lactamase
What is the difference between amoxicillin and ampicillin
amoxicillin has more oral bioavailability than ampicillin
what are the uses for wide spectrum penicillins
Haemophilus influenzae;E. coli;Listeria monocytogenes; Proteus mirabilis; Salmonella; Shigella; enterococci; “ampicillin/amoxicillin HELPSS kill enterococci”
toxicity caused by wide spectrum penicillins
hypersensitivity, ampicillin rash, pseudomembranous colitis
resistance to wide spectrum penicillins caused by
beta lactamases cleave beta lactam ring
Name extended spectrum penicillins
ticarcillin, piperacillin
what is the mechanism of extended spectrum penicillins
Ticarcillin, piperacillin - same as penicillin (bind PBP, block transpeptidases cross-linking peptidoglycan)
use of extended spectrum penicillins
ticarcillin, piperacillin - antipseudomonal (Pseudomonas spp.) - gram (-) rods
limitations of extended spectrum penicillins
susceptible to penicillinase, so use with clavulanic acid
toxicity to extended spectrum penicillins
hypersensitivity
name beta lactamase inhibitors
NAME?
use of beta lactamase inhibitors
often used with penicillins to protect the antibiotic from destruction by beta lactamase (penicillinase)
Cephalosporins – mechanism
beta lactam drug that inhibits cell wall synthesis but are less susceptible to penicillinases
are cephalosporins bactericidal or bacteristatic
NAME?
name first generation cephalosporins
cefazolin, cephalexin
1st gen cephalosporins – use
cefazolin, cephalexin - gram (+) cocci - Proteus mirabilis - E. coli - Klebsiella pneumoniae - “PEcK”
common use of cefazolin
used prior to surgery to prevent S. aureus infection
2nd gen cephalosporins – names
cefoxitin, cefaclor, cefuroxime
2nd gen cephalosporins – use
cefoxitin, cefaclor, cefuroxime- gram (+) cocci- Haemophilus influenzae- Enterobacter aerogenes- Neisseria spp.- Proteus mirabilis- E. coli- Klebsiella pneumoniae- Serratia- “HEN PEcKS”
3rd gen cephalosporins – names
ceftriaxone, cefotaxime, ceftazidime
3rd gen cephalosporins – use
ceftriaxone, cefotaxime, ceftazidime - serious gram (-) infections resistant to other beta lactams
Use of ceftriaxone
meningitis and gonorrhea
use of ceftazidime
pseudomonas
4th gen cephalosporins – name
cefepime
4th gen cephalosporins – use
increased activity vs Pseudomonas and gram (+) organism
Name organisms typically not covered by cephalosporins + exception
LAME - Listeria - Atypicals (chlamydia, mycoplasma) - MRSA - Enterococci ; Exception: Ceftaroline covers MRSA
What is ceftaroline
the first “5th generation” cephalosporin
ceftaroline – use
broader Gram-positive spectrum of activity than all other cephalosporins