2: Abx Flashcards
Endogenous Abx
In the body; ex nasal mucus and tears contain lysozyme
Bacteriostatic vs bactericidal
Bacteriostatic: prevents further growth/multiplication
Bactericidal: kills bacteria
Five bacterial processes targeted by Abx
- Cell wall synthesis
- Protein synthesis
- DNA/RNA synthesis
- Folate synthesis
- Membrane integrity
Beta-lactamase
Enzymes in some bacteria that confer Abx resistance
Penicillinase
A sub-type of beta-lactamase in bacteria that are sensitive to oxacillin, which is resistant to degradation by penicillinase
B-lactamase inhibitors
Used in combo with B-lactam Abx to extend spectrum of Abx activity
Examples of B-lactamase inhibitors
Clavulanic acid, sulbactam, tazobactam
When is risk of cross-reactivity acceptable in a pt with PCN allergy when giving cefaclor
If the pt has mild allergic rxn - if anaphylaxis, cannot use cefaclor
What enzyme is produced by MRSA/ORSA
Penicillinase
MRSA vs MSSA vs ORSA
MRSA: methicillin resistant s. Aureus
MSSA: methicillin susceptible
ORSA: oxacillin resistant
Two of the most rapidly growing multi-drug resistant strains of bacteria
VRSA and VRE
Four Abx to never use with pregnant women (Class D)
- Doxycycline
- Aminoglycosides
- Tetracyclines
- Tigecycline
Should most infections be treated with single Abx or combination
Single
Two negatives to combining Abx
Increase toxicity + can result in antagonism
Three major mechanisms of Abx synergism
- Blocking sequential steps of metabolic sequence
- Inhibiting enzymatic activation
- Enhancing antimicrobial agent uptake
