Intro to Antibiotics Flashcards
3 general ways to use antibiotics
Empiric
Definitive
Prophylaxis
Source control
When all the infection that can be removed is removed
By drainage or surgically
Antibiogram
A summary of all the bacterial isolates over a given period of time and what % of them are susceptible to which antibiotics
Every hospital has one
4 routes of delivery
PO (by mouth)
IV
IM
PR (by rectum)
3 times we should use IV antibiotics
When patients cannot take oral antibiotics
When there is no oral option
When rapid peak serum antibiotic levels are critical
6 reasons why patients fail antibiotic therapy
Wrong bug Wrong drug Drug is not getting to bug Wrong diagnosis Inadequate source control Too much/too little immune system
Bacteriostatic
Drugs slow or stop replication so immune system can eliminate bacteria
Bactericidal
Drugs can kill bacteria directly
Synergy (and classic example)
2 drugs together have higher bactericidal activity than either alone
Ex: Beta lactam and aminoglycoside
Minimal inhibitory concentration
Minimal concentration of the antibiotic needed to inhibit the growth in vitro
Time-dependent antibiotic
Activity depends on the duration of time the concentration is over the MIC
Higher dose will not enhance activity
Need to be frequently dosed
Concentration-dependent antibiotic
Activity depends on the absolute concentration greater than MIC
A higher dose = higher activity
3 general targets of antibiotics
Cell wall synthesis
Nucleic acid synthesis
Protein synthesis
Where do 1. Beta Lactams 2. Tetracyclines 3. Macrolides 4. Quinolones target?
- cell wall
- 30S ribosomal subunit
- 50S ribosomal subunit
- DNA gyrase
4 general types of beta lactams
Penicillins
Cephalosporins
Carbapenems
Monobactams
General info about beta lactams
Most common antibiotics
Core beta lactam ring with unique side chain
Time-dependent killing (so need to be frequently doses)
Bactericidal
Safe in pregnancy and for children
What is the major mechanism of resistance in gram positive organisms?
Alteration of PBP