CMOD Exam1 Flashcards
Name three synergistic drug combinations
- Penicillin + aminoglycosides
- Sulfanethoxazole + trimethoprim
- Amoxicillin + clavulanic acid
Four main mech of antimicrobials?
Inhibition of 1. Cell wall synth
- Protein synth
- Folic acid biosynthesis
- DNA/RNA synthesis
Which drug types are beta-lactams?
Penicillins, carbapenems, cephalosporins
What is the MOA for beta-lactams?
- Binding PBP ( penicillin-binding protein)
2. Destruction of the bacterial cell wall
How do beta-lactams destroy cell walls?
Inhibiting transpeptidase, which prevents the cross-linking of peptide glycol molecules in bacterial cell walls.
Which bacteria are beta-lactams most efficient against?
Gram positive bacteria, because they have a thick peptidoglycan layer.
Gram negatives are more resistant to beta-lactams bc ther LPS outer layer protects the thin, inner peptidoglycan layer.
Why are beta-lactam inhibitors added to some beta-lactam antibiotics?
To overcome resistance by beta-lactamases utilized by some bacteria.
Name two common beta-lactam/beta-lactam inhibitor combinations.
- Amoxicillin + clavulanic acid
2. Piperacillin + tazobactam
What are the prototypes of penicillins?
Penicillin G and penicillin V
Ampicillin: MOA
Beta-lactam but increased efficacy against gram-neg bacteria. binds PBPs and inhibits transpeptidase preventing cell wall formation.
Aminopenicillin; the added amino group makes the molecule more hydrophilic and able to cross the lipopolysaccharide layer more easily.
Aztreonam: MOA
Bactericidal
Monobactam; preferentially binds PBPs inhibiting cell wall synthesis.
Contains a sulfonic acid group.
Piperacillin: MOA
Broad spectrum penicillin; modifications in addition to an aminopenicillin. The extra nitrogen and carbon atoms increase the range of bacteria sensitive to it.
Usually admin in addit to beta-lactamase inhibitor (tazobactam)
Ceftriaxone:MOA
“Rocephin”
3rd gen beta-lactam; IV admin; used for STD treatment
Cephalexin: MOA
“Keflex”
Cephalosporin; Beta lactam; 1st gen; most common cephalosporin prescribed for outpatient use
Vancomycin: MOA
Glycopeptide that binds D-Ala-D-Ala and inhibits the transglycosylase involved in the peptidoglycan synthesis for cell wall.
Affective against Gram positive
Poorly absorbed in GI tract
Vancomycin: MOA+ASX
Glycopeptide that binds D-Ala-D-Ala and inhibits the transglycosylase involved in the peptidoglycan synthesis for cell wall.
Affective against Gram positive
Poorly absorbed in GI tract- must be admin via IV
What’s the structural difference between penicillins and cephalosporins?
Cephalosporins are more acid stable and made up of a 6 members ring attached to the lactam ring, rather than the thiazolidine ring in penicillins.
How do cephalosporins work?
Bactericidal and less susceptible to beta-lactamases. Same mechanism as beta-lactams; irreveribly bind PBPs, preventing them from binding the D-Ala-D-Ala terminus for cell wall synthesis.
Fosfomycin
inhibits one of the first steps in the synthesis of peptidoglycan. irreversibly binds enolpyruvyl transferase. Nucleotide precursors accumulate and cell death occurs.
Name the 7 classes of protein synthesis inhibitors
- aminoglycosides 2. macrolides 3. streptogramins 4. lincosamides 5. oxazolidinones 6. tetracyclines 7. mupirocin
Name an aminoglycoside and give MOA
Gentamicin- thought to be bactericidal bc MOA is irreversibly binding 30S ribosomal subunit and also creating fissures and pores in the outer cell membrane.
Whata are the ASX of aminoglycosides?
Nephrotoxicity. All aminoglycosides have poor GI absorption and are IV administered. However, they accumulate int eh proximal tubule of the kidney.
Aminoglycosides are particularly affective against….
gram-negative bacteria
Macrolides: MOA
bacteriostatic; bind 23S of 50S ribosomal subunit, inhibiting peptidyl-transferase. This blocks the addition of amino acids to the peptide chain.
