Exam 1: Antibiotics Flashcards
1st Generation Penicillins
Penicillin G (IV), Penicillin VK (PO)
structural analog of D-Ala D-Ala is ____
B-lactam drugs
Penicillin pharmacokinetics
inactivated by gastric acid
small Vd, short half life
wide distribution but poor CNS penetration
renal secretion
beta lactam mechanisms of resistance
1 - physical barrier 2 - mutant porin 3 - efflux pump 4 - beta-lactamases 5 - mutant peptidoglycan transpeptidase (PBP- 2a present in MRSA, resistant to essentially all B-lactams)
Penicillin adverse effects
low direct toxicity
kills GI bugs –>Cdiff
CNS tremors or convulsion
hypersensitivity
2nd Generation Beta Lactams
Nafcillin (IV), Dicloxacillin (PO QID), Methicillin.
Penicillinase resistant
Nafcillin pharmacokinetics
erratic oral absorption so give IV
biliary excretion
Nafcillin and Dicloxacillin are used for ____
gram + only
common for skin infections
MSSA
Amoxicillin and Ampicillin are used for
gram + and some gram -
but penicillinase sensitive
Amoxacillin kinetics
well absorbed, acid stable
can be taken with food (PO TID)
first line for syphilis
Penicillin
first line for GAS
Penicillin
tx for MSSA
Vancomycin, Nafcillin (IV) or Dicloxacillin (PO)
tx for otitis media
amoxicillin
IV/IM tx for pseudomonas
Pipericillin
tx for bite wounds
ampicillin/sulbactam or amoxicillin/clavulanate
tx for Lyme dz (bergdorferi)
ampicillin or amoxicillin
tx for H. flu
amp/sulbactam or amoxi/clavulanate
tx for MRSA
linezolid, tigecycline, daptomycin
glucosyltransferase (peptidoglycan synthetase) is blocked by ____
vancomycin
external phase of cell wall synthesis, step 1
peptidoglycan transpeptidase (penicillin binding protein) is blocked by _____
Beta lactase (external phase of cell wall synthesis, step 2)
4 classes of beta lactams
penicillins
cephalosporins
carbapenems
monobactams
which penicillins are penicillinase resistant?
nafcillin (IV)
dicloxacillin (PO)
Which penicillin is better absorbed orally? Pen G or Pen VK?
Pen VK
used PO QID
why would one give probenecid with penicillin?
it inhibits renal tubular secretion of the drug, keeping it in the system longer (longer t1/2)
which drugs have a post antibiotic effect?
penicillins
Nafcillin (IV) is excreted via _____
bile
PBP-2a
mutant peptidoglycan transpeptidase (penicillin binding protein)
makes it resistant to all beta lactams
MRSA has it
1st gen cephalosporins are___
Cefazolin (IV)
Cephalexin (PO)
Cefazolin and Cephalexin are resistant to_______ and used for _____ bacteria.
penicillinases
gram positive
cephalosporins are excreted via
kidney (secreted)
________ is often given prior to surgery to prevent wound infections.
Cefazolin (IV)
_______ is the drug of choice for gonorrhea, severe Lyme dz, and meningitis.
Ceftriaxone (IV)
_______ is useful for treatment of pseudomonas.
Ceftazidime (IV)
“makes pseudomonas turn on a dime”
3rd generation cephalosporins are resistant to _______ and have good penetration of ______.
ESBL (extended spectrum beta lactams)
CNS
the broadest spectrum beta lactic class is
carbapenems
Cilastin is given with Imipenem to inhibit ______ in the kidney, increasing it’s half life.
dehydropeptidase I, which rapidly hydrolyzes imipenem for excretion
Adverse effect of high dose imipenem is ______
seizures
esp. be careful with renal failure
Cilastin is not needed with _______ (carbapenem).
Meropenem
2nd line drug for pseudomonas (after aminoglycosides)
Aztreonam
Aztreonam is useful for treatment of __________.
gram negative aerobic rods
enterobacteriae
Which beta lactic has the least cross-allergenicity with penicillins or cephalosporins?
Monobactams (Aztreonam)
Which beta-lactam drug should be reserved for “last resort” use?
Carbapenems
Vancomycin is only useful for gram ______ bacteria.
positive
Vancomycin resistant bacteria have converted D-Ala to _________.
D-Lactate
Vancomycin should be reserved for treatment of _________ and _________.
MRSA
C. diff
True or False: Vancomycin is absorbed in the gut.
False.
Give orally to treat Cdiff to concentrate effect in the GI.
Adverse effects of Vancomycin (name 4)
Ototoxicity
Flushing (Red man syndrome)
Nephrotoxicity
Thrombophlebitis
List drugs that are nephrotoxic.
Vancomycin