cephamycins and carbapenems abx Flashcards
what is characteristic of cephamycins?
7a methoxyl group (often classified as second gen cephalosporins) this group increases stability against b-lactamases
name and pearls?
parenteral only, cephamycin, broad spectrum, can cause hypothrombinemia and disulfiram reaction to alcohol; stable against b-lactamases
carbapenems class info
carbon analogs of penicillins, increased reactivity due to higher ring strain, inhibits b lactamases
imipenem info
co-administer with cilastatin for broad spectrum activity. last line magic bullet, parenteral administration
how to recognize a monobactam
lone b-lactam ring; sulfamic acid group, gram - spectrum,
which monobactam has cross-allergenicity with penicillins and cephalosporins?
ceftazadime due to oxime ether
what is a glycopeptide antibiotic?
vancomycin
MOA for vanc?
inhibits gram + cell wall biosynthesis by binding to D-ala-D-ala before cross linking occurs
vanc spectrum of activity
gram + only (any with MIC 4ug/mL)
mechanism of resistance to vanc
change in peptidoglycan precursor to D-Ala-D-lactate
vanc pk
not absorbed orally; iv admin with t1/2 of 4-11 hours; eliminated renally
use of vanc
C diff and MRSA
vanc sensitivityy
skin rash related to rate of infusion; stop and give antihistamine
vanc AE
ototoxicity, nephrotoxicity
drug name?
vancomycin
what are the lipoglycopeptide antibiotics?
oritavancin, telavancin, dalbavancin,
name and pearls?
oritavancin; inhibits transpeptidation and transglycolation (disrupts membrane of gram + bacteria) may be used in single dose regimen
lipoglycopeptide spectrum of activity
gram positive bacteria (including MRSA)
name and pearls?
telavancin; binds to d-ala-d-ala terminus; used for MRSA and other gram +
name and pearls?
second gen lipoglycopeptide; binds to d-ala-d-ala; active against MRSA and MRSE; t1/2 is 204 hours; may be used in a single dose regimens
strepogramin susceptibility
gram + enterococcus faecium (not faecalis), MRSA
synercid individual drugs and MOA
quinupristin (binds in the ribosomal tunnel to 23SrRNA), dalfopristin (interferes with peptidyl transferase). each bacteriostatic alone; bacteriocidal when combined
quinupristin resistance
adenine methylation of A2058 in 23S rRNA prevents from binding (makes synercid bacteriostatic at normal dose), resistance may also be due to efflux and metabolism, extend dosing to TID
some streptogramins in animal feeds
causes resistance (ex: virginiamycin)
drug interactions with streptogramins
CYP 3A4
oxazolidinones MOA
inhibit protein synthesis through the 50s ribosomal subunit (23S rRNA)
what drug is an oxazolidinone?
linezolid
Linezolid therapeutic use
vanc resistant enterococcus faecium, HAP from MRSA last line only
how does linezolid resistance occur?
G to U substitution that results in reduced affinity of linezolid to the 50s subunit
linezolid AE
tongue discoloration, thrush, thrombocytopenia, GI bleeding, anemia, myelosuppression, neuropathy
how is linezolid metabolized?
morpholine ring
linezolid bioavailability
100% orally bioavailability or can be given parenterally
what enzyme does linezolid inhibit (think drug interactions)
monoamine oxidase Inhibitor (MAO-I) avoid foods rich in tyramine and other BP raising meds (sudafed)
tedizolid
more potent than linezolid; is a prodrug, oral or IV admin
