Chapter 10- Antimicrobial Drugs Flashcards
Chemotherapy
treatment with chemical substances
Drug
affects physiology
Antimicrobial drugs
chemotherapeutic agents used to treat infectious diseases
Penicillin
Used to treat bacterial infections
Bactericidal
They kill microorganisms directly
Bacteriostatic
They inhibit the growth of microorganisms
Semisynthetic
chemically altered antibiotics, partially man-made
Synthetic
Antibiotics that are manufactured in lab
Selective Toxicity
- Drug will only affect microorganisms without damaging human
- Mechanism of action will affect cell structure or metabolism but not both
5 ways an antimicrobial drug can kill/prevent microorganisms
- The inhibition of cell wall synthesis
- The inhibition of protein synthesis
- Disruption of the plasma membrane
- Inhibition of nucleic acid synthesis
- Inhibiting metabolic pathways
The inhibition of cell wall synthesis
and why are these not toxic to humans?
- Prevents the cross-linkage of NAM in the peptidoglycan layer (affects tetrapeptide bonds)
- Bacertial cell undergoes lysis due to movement of water
Humans don’t have cell walls
The inhibition of protein synthesis
- Targets the 70S ribosomes (either the 30S or 50S subunit)
- Targets translation
Disruption of the plasma membrane
- Some antifungal drugs combine with ergosterol to damage the cell membrane
- Effective in fungal infections
- Humans are susceptible, but not bacteria
Ergosterol
similar in composition to cholesterol which is found in gram negative bacteria
Inhibition of nucleic acid synthesis
- Blocks DNA replication or RNA transcription
- Affects both eukaryotic/prokaryotic cells
- Can damage the human host cell
Inhibiting metabolic pathways:
In order to produce DNA/RNA, bacteria need _____ _____. ____ disrupts DNA/RNA _______, but humans ______________
- Bacteria need folic acid
- PABA
- Humans do not use PABA and therefore have minimal toxicity to these medications
6th method- _____ ______, which..
Attachment antagonists- blocks viral attachment of receptor proteins
Which antibiotics are inhibitors of cell wall synthesis
Penicillin, Penicillin derivatives, and Cephalosproins
All penicillins have a _____ _____ structure containing a _____ _____ _____
All pencillins have a common core structure containing a beta-lactam ring
So, _____ _____ are..
Beta lactams are inhibitors of cell wall synthesis
Natural Penicillin exs and mech. of action
Penicillin G and Penicillin V
Inhibits cell wall synthesis
The original compound of all the penicillins is
Penicillin G
Natural Penicillin advantages
Inexpensive
Usually not toxic
Good against gram +
Natural Penicillin disadvantages
Narrow spectrum of activity
Susceptible to penicillinase (AKA beta lactamase)
Penicillin G is normally _____, and penicillin V can be ____ ____
Penicillin G is normally injected because if taken orally, penicillin G is destroyed by stomach acids
Penicillin V is stable in stomach acids and can be taken orally
Semisynthetic Penicillin- was developed by
by chemically adding a synthetic side chain to the common core structure of the natural penicillin
Semisynthetic Penicillin (3 points)
- More readily absorbed
- Less susceptible to deactivation by beta-lactamase
- Broader-spectrum of activity
Types of semisynthetic penicillins
- Oxacillin
- Amoxicillin
- Methicillin
Oxacillin
Semisynthetic penicillin that’s resistant to penicillinase (beta lactamase)
Amoxicillin
Semisynthetic penicillin that was developed to have a broader spectrum of activity
Effective against many gram-positive and gram-negative bacterias
Not resistant to penicillinase
Example of a hospital acquired disease
Pseudomonas aeruginosa
Methicillin
Used in description of antibiotic resistance (MRSA)
_______ differ from natural penicillins in that they are ____ to penicillinases and are _____ against more ___–_____ bacteria
Cephalosporins differ from natural penicillins in that they are resistant to penicillinases and are effective against more gram-negative bacteria
Polypeptide Antibiotics include ____ and _______
Bacitracin and Vancomycin