Antibiotics Flashcards
penicillin mechanism
1) bind PBP (transpeptidase)
2) block transpeptidase cross-linking peptidoglycan
3) active autolytic enzymes
penicllin spectrum
gram positive (s. pneumo. s. pyogenes, actinoymyces), n. meningitidis, T. pallidum.
penicillin toxicity:
hypersensitivity + hemolytic anemia
ampicillin / amoxicillin spectrum of use
extended-spectrum penicillin: H. influenzae, E. coli, Listeria mono, Proteus mirabilis, Salmonella, Shigella (HELPSS)
ampi/amoxicillin toxicity
hypersensitivity, rash, pseudomembranous colitis
penicillinase-resistant penicillins = oxacillin, nafcillin
bulky R group blocks access of beta-lactamase to b-lactam ring.
used for s. aureus
nafcillin toxicity
interstitial nephritis
ticarcillin / piperacillin = antipseudomonals
use WITH b-lactamase inhibitors.
be careful of hypersensitivity
cephalosporins general mechanism
inhibit cell wall synthesis –> bactericidal
less susceptible to penicillinase.
cephalo organisms by generation
1) PEK = proteus, Ecoli, Klebsiella
2) HEN PEKS = H. influ, Enterobacter, Neisseria, Protus, Ecoli, Klebsiella, Serratia
3) serious gram-negative infections (resistant to b-lactams):
Ceftriaxone = meningitis / gonorrhea Ceftazidime = pseudomonas
4) Cefepime = incr. activity against pseudomonas + gram-positive
5) ceftaroline = broad spectrum gram-pos & gram-neg –> MRSA! (no pseudomonas)
cephalo sfx
1) vit. K deficiency.
2) INCREASED nephrotoxicity of aminoglycosides
aztreonam mechanism
prevents peptidoglycan cross-linking by binding to PBP 3. synergistic w/ aminoglycosides
aztreonam spectrum
gram-neg rods: NOT useful for gram+ or anaerobes. useful for those who have penicillin allergies / renal insufficiency w/o aminoglycoside tolerance
carbapenems mechanism
broad-spectrum. administer w/ cilastin (inhibi renal dehydropeptidase I) to dec. drug inactivation in renal tubules
carbapenem spectrum
gram-+ cocci, gram- rods, anaerbos. wide spectrum. reserved for life-threatening infections / last resort.
special carbapenems
meropnem has dec. risk of seizures –> stable against dehydropeptiase I
carbapenem toxicity
seizures / rash
vancomycin mechanism
binds D-ala-D-ala part of cell wall precursor. bactericidal that inhibits cell wall peptidoglycan
vanco clinical use
gram+ (MRSA, c. difficile)
vanco toxicity
NOT: nephrotoxicity, Ototoxicity, Thrombophelbitis.
diffuse flushing = red man syndrome (infuse slowly & w/ antihistamines)
aminoglycosides mechanism
inhibition formation of initiation complex –> misreading of mRNA. block translocation.
requires O2 for UPTAKE –> ineffective against ANAEROBES
clinical use of aminoglycosides
gram-negative rod infections. synergistic w/ b-lactam. neomycin for bowel surgery
aminoglycosides toxicity
1) nephrotoxicity (when combined w/ cephalosporin)
2) neuromuscular blockade
3) ototoxicity
4) teratogen
tetracycline mechanism
bacteriostatic: bind to 30S –> prevent aminoacyl-tRNA attachment.