Antibiotics I Flashcards
What does bacteriostatic mean?
Stops growth or replication of microorganism
What does bactericidal mean?
KILL (the microorganism)
Drop the MIC aka drop the ___________
Minimal inhibitory concentration (the smallest amount needed to have its effect)
What is the Post-antibiotic effect (PAE)?
The PAE is when the antibiotic has bactericidal activity after its concentration falls below the MIC. This can occur if the antibiotic accumulates in the tissue or the bacteria itself.
When can a superinfection occur?
When you are undergoing antimicrobial therapy that is getting rid of your normal happy oral/gut flora, you can get a super duper infection. Wahh.
When we talk about pharmacokinetics we talk about the LADME process. Wtf is the LADME process?
LADME=
- Liberation: release of drug from dosage form
- Absorption: drug goes from site of admin to blood
- Distribution: drug goes to tissues
- Metabolism: drug is transformed into easily eliminated products
- Excretion: get rid of the drug or metabolite
What is the one-compartment model?
Drugs rapidly equilibrate with the tissue and there is linear elimination over time.
What is the two-compartment model?
Drugs slowly equilibrate with the tissue. There is a distribution phase where the drug moves between central compartment and tissue compartment and elimination phase where you guessed it, elimination happens.
What is the relationship between the % of antibiotic bound to protein and its antimicrobial activity?
Inverse. More protein bounded drug, less bacteria fighting power
What are some of the predictors of efficacy of antibiotics? (factors that define certain antibiotics)
- Concentration dependent killing: more drug=more killing
- Time-dependent killing: want to max the amount of above MIC exposure.
- Area under the curve concentration/time curve: PAE, so basically the drug is still doing its job when it is in the tissue and you don’t need to focus on keeping concentrations above MIC.
What are some examples of Concentration dependent antibiotics with some PAE
- Aminoglycosides
- Daptomycin
- Quinolones
- Ketolides
My AMIGO likes QUINOA with a DAP of HIGH CONCENTRATION KETONES.
What are some examples of Time dependent antibiotics with minimal PAE
- Beta-lactams (penicillins, carbapenems, cephalosporins)
2. Vancomycin (some)
What are some examples of Time dependent killing and moderate to long PAE
- Chloramphenicol
- Clindamycin
- Tetracycline
- Oxazolidines
- Streptogramins
- Glycopeptides
- Macrolides
- Sulfonamides
GMC COSTS a lot of PAE and time
When we compare mammalian cells to the bacterial cells, there are two differences we should keep in mind. Out of all the differences that exist, guess the two I’m thinking of.
- We have no cell wall
2. We don’t use D amino acids ever
Whats the difference between gram positive and gram negative?
Gram positive: cell wall made of peptidoglycan
Gram negative: periplasmic cell wall made of peptidoglycan with another cell membrane with lipopolysaccaride (LPS) sticking out of it.
What kind of antibiotics work on inhibiting the cell wall biosynthesis?
Beta lactams, which includes:
- Penicillins
- Cephalosporins
- Monolactams
- Carbapenems
Glycopeptides (Vancomycin, Teicoplanin)
How to beta lactams do their job in inhibiting cell wall biosynthesis?
They inhibit the enzyme transpeptidase. This enzyme is usually used to make peptidoglycan polymer crosslinks between D-Ala-D-Ala subunit and glycine. The shared 4 sided beta-lactam ring structure allows the antibiotic to bind to the enzyme and keep it from doing its real job.
What is the significance of penicillin binding protein (PBPs)?
These are all the proteins that penicillins will bind to (apparently its not just the transpeptidase we just learned about). In order for the beta-lactam to be effective it must inhibits many other PBPs
What are the 4 types of penicillin?
- G: naturally occurring, acid labile and V: synthetic, acid stable. Both cover Gram +
- Penicillinase-resistant
- Extended range: covers gram - as well
- Antipsuedomonal
Penicillins have 2 named rings in their structure
- B-lactam ring (4 sides)
2. Thiazolidine ring (5 sides)
What can you do to absorb the penicillin slower?
Inject with procaine or benzathine.
Where does penicillinase (the enzyme produced by bacteria to destroy our antibiotics) usually strike the antibiotic?
Right in the beta-lactam ring (specially between the nitrogen and the carbonyl in case you were curious). What a jerk.