Antibiotics Flashcards
which penicillins are penicillinase sensitive (3)
penicillin G and V
ampicillin
amoxicillin
which penicillins are penicillinase resistant (3)
oxacillin
naficillin
dicloxacillin
mechanism penicillin
blocks cross-linking of peptidoglycan by binding penicillin-binding proteins (transpeptidases)
clinical use penicillin (3)
- gram positive (S. pneumo, S. pyogenes, Actinomyces)
- N. meningitidis
- Syphillis
is penicillin bactericidal or bacteriostatic?
bactericidal
side effects penicillin (2)
- hypersensitivity
2. hemolytic anemia
mechanism of resistance to penicillin
penicillinase (beta-lactamase) cleaves beta-lactam ring
ampicillin / amoxicillin mechanism
blocks cross-linking of peptidoglycan by binding penicillin-binding proteins (transpeptidases)
what do you combine ampicillin / amoxicillin with?
clavulanic acid (protect against beta-lactamase)
which has greater oral bioavailability, amoxicillin or ampicillin?
amoxicillin
which has wider spectrum, penicillin or ampicillin/amoxicillin?
ampicillin/amoxicillin
clinical use ampicillin / amoxicillin
H. influenzae E. coli Listeria Proteus Salmonella Shigella Enterococci (HELPSS kill enterococci)
side effects ampicillin / amoxicillin (2)
- hypersensitivity
2. pseudomembranous colitis
mechanism of resistance to ampicillin / amoxicillin
penicillinase (beta-lactamase) cleaves beta-lactam ring
what are three penicillinase-resistant penicillins?
- oxacillin
- nafcillin
- dicloxacillin
mechanism of penicillinase-resitstant penicillins
blocks cross-linking of peptidoglycan by binding penicillin-binding proteins (transpeptidases)
which has a wider spectrum, penicillin or penicillinase-resistant penicillins?
penicillin
why are penicillinase-resistant penicillins resistant to penicillinase?
bulky R group blocks beta-lactamase access to ring
clinical use penicillinase-resistant penicillins
S. aureus (except MRSA)
how is MRSA resistant to penicillinase-resistant penicillins?
altered penicillin-binding protein target site
side effects penicillinase-resistant penicillins
- hypersensitivity
2. interstitial nephritis
what two drugs are antipseudomonals?
- ticarcillin
2. piperacillin
mechanism antipseudomonals
blocks cross-linking of peptidoglycan by binding penicillin-binding proteins (transpeptidases)
which has a wider spectrum, penicillin or antipseudomonals?
antipseudomonals
clinical use antipseudomonals (2)
- Pseudomonas
2. gram-negative rods
what do you give antipseudomonals with?
beta-lactamase inhibitors (antipseudomonals are susceptible to penicillinase)
side effect antipseudomonals
hypersensitivity
what are three beta-lactamase inhibitors?
- clavulanic acid
- sulbactam
- tazobactam
(CAST)
what do beta-lactamase inhibitors do
protect penicillin antibiotics from destruction by beta-lactamase (penicillinase)
cephalosporin mechanism
beta-lactam drugs –> inhibit cell wall synthesis
less susceptible to penicillinases
are cephalosporins bacteriostatic or bactericidal?
bactericidal
organisms not covered by cephalosporins
Listeria Atypicals (chlamydia, mycoplasma) MRSA Enterococci (LAME)
what cephalosporin covers MRSA?
ceftaroline
what are two 1st generation cephalosporins?
- cefazolin
2. cephalexin
what are three 2nd generation cephalosporins?
- cefoxitin
- cefaclor
- cefuroxime
what are three 3rd generation cephalosporins?
- ceftriaxone
- cefotaxime
- ceftazidime
what is one 4th generation cephalosporin?
cefepime
what is one 5th generation cephalosporin?
ceftaroline
clinical use 1st generation cephalosporins (5)
- gram positive cocci
- Proteus
- E. coli
- Klebsiella
- prior to surgery to prevent S. aureus wound infections
PEcK
clinical use 2nd generation cephalosporins (7)
- H. influenzae
- Enterobacter
- Neisseria
- Proteus
- E. coli
- Klebsiella
- Serratia
clinical use 3rd generation cephalosporins
serious gram-negative infections (resistant to other things
clinical use ceftriaxone (2)
- meningitis
2. gonorrhea
clinical use ceftazidime
Pseudomonas
clinical use 4th generation cephalosporins
- greater activity against Pseudomonas
2. greater activity against gram positive
clinical use 5th generation cephalosporins
broad coverage, including MRSA
does NOT cover Pseudomonas
side effects cephalosporins
- hypersensitivity
- vitamin K deficiency
- increases nephrotoxicity of aminoglycosides
(low cross-reactivity with penicillins
mechanism aztreonam
prevents peptidoglycan cross-linking by binding penicillin-binding protein 3
–> resistant to beta-lactamases
does aztreonam have any cross-allergenicity with penicillins?
NO!!!
what other antibiotic is aztreonam synergistic with?
aminoglycosides
what two groups of people is it useful to use aztreonam for?
- penicillin allergies
2. renal insufficiency who can’t use aminoglycosides
is aztreonam susceptible to beta-lactamases?
NO!!
clinical use aztreonam
ONLY gram negative rods
side effect aztreonam
GI upset
what are four carbapenems?
- imipenem
- meropenem
- ertapenem
- doripenem
mechanism imipenem
broad-spectrum, beta-lactamase resistant carbapenem
what do you administer imipenem with?
cilastatin (inhibits renal dehydropeptidase I to decrease inactivation of drug in renal tubules)
what is cilastatin?
inhibits renal dehydropeptidase I to decrease inactivation of imipenem in renal tubules
clinical use carbapenems (3)
- gram-positive cocci
- gram-negative rods
- anaerobes
ONLY use in life-threatening infections b/c of side effects
which carbapenem has a decreased risk of seizures
meropenem
side effects carbapenems (3)
- GI distress
- rash
- CNS toxicity (seizures)
vancomycin mechanism
inhibits cell wall peptidoglycan formation by binding D-ala D-ala
is vancomycin bacteriostatic or bactericidal?
bactericidal
clinical use vancomycin
gram-positive ONLY
use for multidrug-resistant organisms (i.e. MRSA, enterococci, and C. difficile)
how do you administer vancomycin to treat pseudomembranous colitis?
oral
side effects vancomycin (4)
- Nephrotoxicity
- Ototoxicity
- Thrombophlebitis
NOT - red man syndrome
what drug causes red man syndrome
vancomycin
how do you prevent red man syndrome
pretreatment with antihistamines
slow infusion rate
mechanism of resistance to vancomycin
modification of D-ala D-ala to D-ala D-lac in cell wall precursors
what protein synthesis inhibitors act on the 30S subunit?
Aminoglycosides
Tetracyclines
are aminoglycosides bacteriostatic or bactericidal?
bactericidal
are tetracyclines bacteriostatic or bactericidal?
bacteriostatic
what protein synthesis inhibitors act on the 50S subunit?
Chloramphenicol
Clindamycin
Erythromycin (macrolides)
Linezolid