Inhibitors Of Cell Wall Synthesis Flashcards
Beta-Lactam structure
Essential for activity
structural analog of D-Ala-D-ALA residue of NAM/NAG
Beta-lactam ring has high affinity for
Bacterial PBPs
Beta-lactam mechanism of action
T>MIC
Irreversible inhibition of PBPs=autolysin activation
Penicillin resistance due to
decreased permeability
Mutation in PBPs (G+ strains)
Enzymatic inactivation (beta-lactamase, ex.ESBL)
Penicillin G and V are active against
G+ cocci/bacilli
Anaerobes
NOT G- cocci, beta-lactamase producing strains
Penicillin G is given
IV or IM
Penicillin V is given
Orally
Nafcillin is active against
PCN G-resistant methicillin susceptible staph (MSSA) and streptococci
Methicillin is not used because
It causes acute interstitial nephritis
MRSA has emerged due to
Altered PBPs
PBP2/mecA is resistant to all beta-lactams except
Ceftaroline
Amoxacillin is active against G- bacilli due to
Charged amino group that enables transfer though outer membrane porins
Piperacillin-tazobactam has better activity against G- strains (notably P. Auriginosa) due to
Modified amino-PCN R group
Clavulate and tazobactam role
Protect antibiotics from inactivation by beta-lactamases in G- bacteria
Beta lactamase have _ half lives
Short
Penicillin G benzathine is given_
IM weekly
_ prolongs penicillin duration by extending half life
Probenecid
Adverse reactions of penicillins include
Nausea/diarrhea
Maculopapular rashes (amino penicillins-amoxacillin, esp in people with EBV)
Allergy- urticarial rash