Antibiotics II: Inhibitors of Cell Wall Synthesis Flashcards
Subclasses of beta-lactam antibiotics
Penicillins
Cephalosporins
Carbapenems
Monobactams
Beta-lactam _____ is essential for activity
Structure
Beta-lactam ring has a high affinity for bacterial ______
Penicillin binding proteins (PBPs)
Beta-lactams are bacteriostatic/Bactericidal and ____ dependent
Bactericidal; time dependent
Beta-lactams inhibit the ____ step of cell wall synthesis
Final (cross linking of NAM NAG polymers)
Inhibition of PBPs by beta-lactams is reversible/irreversible
Irreversible
PBP inhibition activates ____, causing disassembly of cell wall leading to cell lysis or apoptosis
Autolysins
What is the most common drug allergy?
Penicillins
What enzyme inactivates penicillins?
Beta-lactamase
Anti-staphylococcal cell-wall inhibitor
Nafcillin
Emergence of methicillin-resistance (MRSA) is due to ______
Altered PBPs with lower binding affinities
Aminopenicillin drug
Amoxicillin
How is coverage of amoxicillin different than that of penicillin?
Spectrum similar to penicillin but effective against some G- bacilli too
Common uses for amoxicillin
Sinusitis
Otis media
Lower respiratory infections
Extended-spectrum/anti-pseudomonal penicillin drug
Piperacillin-tazobactam (Zosyn)
Clavulanate function in amoxicillin-clavulanate (Augmentin)
Beta lactamase inhibitor; Protects amoxicillin from inactivation by beta-lactamases in G- bacteria
Penicillins have poor/good oral absorption
Poor (can cause diarrhea)
Penicillins have long/short half lives so must be given ____
Short; frequently (3-6x/day)
Penicillins are excreted by _____
Renal secretion
Adverse reactions of penicillins
Very safe class of antibiotics
Mild NVD
Amoxicillin can cause a maculopapular rash
True penicillin allergy is a Ig_ mediated hypersensitivity
IgE
True penicillin allergies cause a _____ rash
Urticarial
Cephalosporins are grouped by ____
Generations
Each Cephalosporin generations increases
Activity against G- and anaerobes
Resistance to inactivation by beta-lactamases
Penetration across BBB into CNS
First generation cephalosporin
Cefazolin
Second generation cephalosporin
Cefoxitin
Third generation cephalosporin
Ceftriaxone
Fourth generation cephalosporin
Cefepime
Fifth/advanced generation cephalosporin
Ceftaroline
Drug of choice for bacterial G- meningitis
Ceftriaxone
Only beta-lactam that is active against MRSA
Ceftaroline
Prototype carbapenem drug
Imipenem-cilistatin
Carbapenems are highly susceptible/resistant to inactivation by beta lactamases
Highly resistant
Why is imipenem combined with cilastatin?
To block renal inactivation
Uses for carbapenems
Multi-drug resistant infections
Anaerobic and mixed infections
Prototype monobactam drug
Aztreonam
Monobactams are only active against ____
G- aerobes
Monobactams are/are not cross-reactive with other beta-lactams
Are not cross reactive (can be given even if pt has severe penicillin allergy)
Aminoglycosides are ____toxic
Nephrotoxic