Lecture 3: Antibiotics Part 2 Flashcards
What two amino acids connect bacterial cell walls together?
D-Ala to D-Ala
What drug class does vanco fall under?
Glycopeptide
What is the MOA of vanco and is it bactericidal or bacteriostatic?
Inhibits bacterial cell wall synthesis by binding to the D-ala D-ala chain and preventing the formation of peptidoglycan.
Results in a weakened cell wall and inability to replicate further.
It is a bactericidal drug.
How does VRE resist vanco?
Alters the binding site to D-ala-D-Lac.
What is the main hole in vanco coverage?
G-. Does not cover G-!
What are the main things vanco is good for?
MRSA!!!!!!! (IV)
C. Diff (oral)
Minor:
Listeria
Corynebacterium
Strep
Staph Pneumo
S. entercoccus
Is MRSA a G+ cocci or bacili?
G+ Cocci
Is C. Diff a G+ cocci or bacilli?
G+ Bacilli
What are the indications for vanco?
MRSA - IT IS THE INPATIENT DRUG OF CHOICE
C. diff - only for severe for refractory C. diff colitis.
How is vanco metabolized/excreted?
NO liver metabolism
Renal Excretion
Therefore adjust for renal impairment!
What pregnancy category is vanco?
Oral is B
IV is C
If someone has impaired renal function, how is dosing adjusted?
Less frequent dosing intervals.
What two things about a person determine their general vanco dosing?
CrCl
Total Body weight
How is vanco monitoring done?
Severe MRSA and other severe infections use AUC calculations.
All other normal infections are trough level.
When is a loading dose indicated for vanco?
Severe infections.
Why does vanco need monitoring?
It has a narrow therapeutic window.
When do I measure a trough level for vanco?
30 mins prior to next infusion AFTER SS is reached.
How many doses of vanco does it typically take to reach SS?
4 doses.
When do I get peak levels of vanco?
1-2 hours post dose.
What is the main adverse effect of vanco that is not life-threatening?
Hyperemia/red-man syndrome.
What is hyperemia caused by and how do I treat it?
It is pruritis with erythematous rash of the face, neck, and upper torso.
Caused by rapid infusions or high doses.
Treated by slowing the infusion and/or pretreating with an antihistamine.
What is a deadly adverse effect of vanco and what demographics are most susceptible?
Nephro and ototoxicity with high daily doses.
Occurs most frequently in renally impaired or elderly pts.
Occurs even more frequently when used with an aminoglycoside.
Requires monitoring of BUN/Cr and s/s of auditory dysfunction.
What are some alternatives to vanco?
For MRSA:
Telavancin, Dalbavancin, and Oritavancin are similar.
Daptomycin work EXCEPT if MRSA is in the lungs. (ALSO GOOD FOR VRE)
Linezolid: oral (uncommon)
Note:
All of these work vs VRE also except tela and dalba.
What are the 4 main aminoglycosides?
Gentamicin
Tobramycin
Amikacin
Streptomycin
Note:
micin
mycin
cin
Where do aminoglycosides work on the bacteria?
30S subunit, leading to inhibition of 50S subunit as well.
Are aminoglycosides bactericidal or bacteriostatic?
Bactericidal
What is the MOA of an aminoglycoside?
Binds to the 30S subunit, inhibiting protein synthesis.
What are the 4 ways a bacteria can build resistance to an aminoglycoside?
- Chromosomal mutation (AKA can’t bind to ribosome)
- Enzymatic destruction
- Lack of permeability through the cell wall.
- Efflux pumps
What are the primary indications for an aminoglycoside?
Gram -
MYCOBACTERIUM TUBERCULOSIS (TB!!!)
Note:
AmiNOGlycosides = no G+
What is one of the most common combinations an aminoglycoside is used with?
Ampicillin + gentamicin.
What are the BBW for an aminoglycoside?
Ototoxicity
Nephrotoxicity
Neuromuscular paralysis
Is an aminoglycoside OK to give in pregnancy?
No. Category D.
What is aminoglycoside dosing dependent on?
Weight and renal function
Note:
Pretty much the same as vanco.
How are aminoglycosides monitored?
Serum drug levels, aka peak and trough.
It has a narrow therapeutic window and therefore a high risk of toxicity, just like vanco.
Monitor BUN/Cr and audiometry.
What are the tetracyclines?
Tetracycline
Doxycycline
Minocycline
What is the MOA of a tetracycline?
Binds to 30S subunit.
Blocks tRNA.
Is tetracycline bacteriostatic or bactericidal?
Bacteriostatic
How do bacteria build resistance to tetracycline?
- Efflux pumps
- Enzymatic deactivation.
Note:
Resistance is increasing! Concerning because doxy is used a lot as first-line for many things.
What is the coverage of the tetracyclines?
G+ and G-
MRSA!!!
ATYPICALS (mycoplasma, rickettsiae, chlamydiae, spirochetes)
What 5 diseases/infections is Doxy first-line for?
Chylamydial infections
Rocky mountain spotted fever (Rickettsiae)
M. Pneumonia (Walking pneumonia)
Lyme disease (Spirochetes)
Cholera (Vibrio)
What are the 4 first-line treatment indications for doxy? (Diseases)
Lyme disease
Rocky mountain spotted fever
Cholera
Acne
Note:
Additional include Chylamydia, PID, and empiric therapy for CAPs.
What is a tetracycline CI in?
ABSOLUTE CI < 8 y/o due to tooth discoloration.
ABSOLUTE CI in pregnancy.
Relative CI < 13 y/o
What is the PK of tetracyclines?
Liver metabolism
Urine and Bile excretion.
What can you not take with tetracyclines?
Counseling:
No antacids (TUMS)
No dairy
What infections can be CAUSED by tetracycline?
Candida infections
C. Diff