Lecture 15: Antibiotics Part 1 Flashcards
What color does a G+ bacteria stain?
Purple
Mnemonic:
(more Ps = more positive)
What is the main shape of G+ bacteria?
Cocci
What is the only coagulase positive Staphylococcus?
S. aureus
What are the two types of paired/chained cocci?
Streptococcus
Enterococcus
What is the more resistant Enterococcus?
E. faecium
What are the two shapes of G- bacteria?
Cocci
Bacilli
What 5 bacteria form the enterobacterales?
E. coli
Klebsiella spp.
Enterobacter spp.
Serratia spp.
Citrobacter spp.
AKA all lactose fermenters are enterobacterales.
What are the 3 main enterobacterales?
E. coli
Klebsiella spp.
Enterobacter spp.
What kind of bacteria is P. aeruginosa?
A non-lactose fermenter.
G- bacilli.
What are the anaerobic bacteria?
G+:
Peptostreptococcus
Clostridium
G-:
Bacteroides spp.
What are the 3 atypical bacteria?
Mycoplasma
Legionella
Chlamydophilia
Note:
Pneumonia is common from all 3 of these.
What do penicillins and cephalosporins do for their mechanism?
Inhibition of cell wall synthesis.
What does MRSA, VRE, ESBL, and CRE stand for?
MRSA: methicillin-resistant S. aureus
VRE: Vancomycin resistant enterococcus
ESBL: extended spectrum beta lactamase producing organism.
CRE: Carbapenem-resistant enterobacterales.
Note:
VRE and CRE are NOT THE SAME E.
What is the different between narrow and broad spectrum abx?
Broad means multiple strain coverage.
What is the difference between empiric and definitive therapy?
Empiric is not knowing what the specific organism is, but having a good idea.
Definitive is knowing what organism you’re going to treat.
What is MIC?
Lowest concentration of an abx needed to INHIBIT growth of a bacteria.
What does it mean when an abx is time-dependent?
The time spent above the MIC. AKA as long as you meet the MIC, it’s how long you stay above it, not the dosage itself.
Note:
Applies to many of the beta-lactamases, which are G- bacteria.
What does it mean when an abx is dose-dependent?
Concentration dependent, aka the higher the dose, the higher the efficacy.
What is meant by beta-lactamase bacteria?
A bacteria capable of producing an enzyme that can break apart beta-lactams.
What ABX make beta lactams?
Penicillins
Cephalosporins
Carbapenems
Monobactams
What ABX category is vancomycin?
Glycopeptide
What ABX category is daptomycin?
Cyclic glycopeptide
What ABX category ends in vancin?
Lipoglycopeptides
What are all cell wall agents able to do to bacteria?
Kill them.
All agents are bactericidal.
Describe the MOA of a beta-lactam.
Bind to penicillin-binding proteins in cell walls.
Interrupts cell wall synthesis, resulting in bacterial cell lysis and death.
What kind of toxicity can ensue from beta-lactams in renal dysfunction?
CNS toxicity.
Note:
Most ABX are renally dosed as a result.
What kind of disturbance can ensue from oral beta-lactam use?
GI disturbances.
What drug interacts with all the beta-lactams? What does it do?
Probenicid.
Increases serum concentration.
What is efficacy measured as?
Time above MIC (aka time-dependent)
What kind of agents usually use prolonged infusions?
Antipseudomonals.
What is the only natural pencillin?
The pencillins!
Penicillin VK, G, G sodium, G benzathine, G procaine/benzathine.
Why is benzathine added to pencillin?
Prolongs half-life.
What is a unique clinical use of penicillin?
Syphilis treatment
What is the reaction that occurs from penicillin use? What kind of reaction relationship is it?
Jarisch-Herxheimer reaction.
Time-related reaction.
What are the only two penicillins that do not require renal adjustments?
Nafcillin
Oxacillin
What is MSSA?
Methicillin susceptible staph A
Why is Oxacillin preferred over Nafcillin?
Nafcillin has a higher incidence of acute interstitial nephritis.
What class are nafcillin, oxacillin, and dicloxacillin in?
Penicillinase-resistant Penicllins
What are the two aminopenicillins?
Amoxicillin
Ampicillin
Note:
They start with A.
What specific bacteria are aminopenicillins used for?
Enterococcus spp.
They are the drug of choice.
Note:
If it is VRE, they are generally resistant to penicillins as well.
What is the only extended spectrum penicillin?
Piperacillin
No longer on market as a solo drug.
What is the bonus of having an ES penicillin over a regular one?
Additional G- coverage.
What was piperacillin originally intended for?
Antipseudomonal!
AKA it works against P. aeruginosa.