Antibacterial Drugs Flashcards
Name the key benefit and downside of antibiotics
+ allow for more invasive procedures
- bacteria can become resistant after time
What is the difference between gram-positive and gram-negative bacteria?
Gram-negative:
- lipid outer layer, 2 periplasms, small peptidoglycan layer
gram-positive
- thicc peptidoglycan layer, periplasm, membrane
Name comes from biological assay, peptidoglycan gives a stronger result therefore thicker peptidoglycan wall -> gram pos
What is the difference between bacteriostatic and bactericidal drugs?
static:
requires immunocompetent host
non-life threatening
for uncomplicated infections
cidal:
deep-seated infection
life-threatening
Define MIC and MBC and how they are calculated?
Minimal inhibitory concentration and minimal bactericidal concentration
Calculated with Dilution test:
-serial dilution of antimicrobial drug
- incubate on plate
- last conc to not have any growth = MBC
- last conc to not show visible growth = MIC
What is a broad spectrum antibiotic (as opposed to a narrow spectrum antibiotic)
Treats many types of bacteria, not specific
What are the 3 types of antimicrobial therapy?
- Definitive Drug therapy: antibiotics prescribed based on Organism identity and susceptibility
- Empiric therapy: “this other person had the same thing and reacted well to this”
- prophylactic therapy: use of antimicrobial agent to prevent infection
How do Penicillin and Aminoglycoside synergize when given as an antibiotic treatment?
Aminoglycoside is a protein synthesis inhibitor, but it can’t reach the ribosomes because of the cell wall
Penicillin inhibits the cell wall but doesn’t do anything else
What are the 5 major mechanisms of bacterial resistance?
Decreased entry enhanced efflux Bypass pathway Altered target site Enzymatic Degradation
True/False? We only have a few antibiotic drugs because we don’t need that many
False, bacteria become resistant and don’t respond to them anymore
True/False? A resistant bacterium can transmit antibacterial resistance to another bacterium
True
Which of the gram types of bacteria is easier to treat and why?
Gram-positive, because its cell membrane is much simpler and doesn’t contain many enzymes that could interfere with antibiotics
How is the periplasm of bacterial cell walls formed?
3 thick steps
1) peptidoglycan units (made up of MurNAc and GlcNAc, which each have L-Lysine and D-alanine residues) are phosphorylated by Bactoprenol IN CYTOPLASM
2) Bactoprenol flips the peptidoglycan unit into the periplasm and pops off (to repeat the process)
3) Penicillin-Binding protein (PBP) polymerizes the peptidoglycan units and crosslinks their L-lys and D-ala residues together
What do all beta lactams have in common?
square carbonyl-N ring
What is a beta-lactamase and what is its problem?
They open the beta-lactam ring making them ineffective
What is NDM-1?
Gene that confers resistance to all beta-lactam antibiotics in Canada
