IA. General microbiology | 12. Antibiotic sensitivity tests in laboratory. Chemoprophylaxis. Antibacterial therapy. Flashcards
I. Definitions
1. What is antibiotic?
natural agent synthesized by a bacterial or fungal strain that can inhibit or kill other microorganisms
I. Definitions
2. What is synthetic antibiotics?
a naturally synthetized agent which is modified chemically in order to have antimicrobial + pharmacokinetic properties advantages
I. Definitions
3. What is a Chemotherapeutic agent?
an antimicrobial agent synthesized chemically
I. Definitions
4A. What is a Bacteriostatic effect?
The antimicrobial agent (AA) can only inhibit the growth of the microorganisms but is unable to kill them within a short period of time and rely on host defense mechanisms for final eradication of the infection
- This is determined in vitro by testing standardized concentrations of organisms against a series of antimicrobial dilutions
- MIC (minimum inhibitory concentration): lowest concentration that inhibits the growth of the organisms after overnight incubation
I. Definitions
4B. How is Bacteriostatic effect determined?
This is determined in vitro by testing standardized concentrations of organisms against a series of antimicrobial dilutions
I. Definitions
4C. What is MIC(minimum inhibitory concentration)? (Bacteriostatic effect)
lowest concentration that inhibits the growth of the organisms after overnight incubation
I. Definitions
5A. What is Bactericidal effect?
The antimicrobial agent (AA) can kill growing microorganisms within a short period of time
- This is determined in vitro by exposing a standardized concentration of organisms to a series of antimicrobial dilutions
- MBC(minimum bactericidal concentration): lowest concentration that kills 99.9% of the population
I. Definitions
5B. How is Bactericidal effect determined?
The antimicrobial agent (AA) can kill growing microorganisms within a short period of time
- This is determined in vitro by exposing a standardized concentration of organisms to a series of antimicrobial dilutions
I. Definitions
5C. What is MBC (minimum bactericidal concentration)? (Bactericidal effect)
MBC (minimum bactericidal concentration): lowest concentration that kills 99.9% of the population
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6. What is Selective toxicity?
- The antibiotic has an effect only on the bacteria, but not on the human host.
- The target of the antibiotic (cell wall, ribosome) only present in the bacteria but not in the human host→ only toxic for microbe
I. Definitions
7A. What is Chemotherapeutic Index (Ehrlich)?
- Def.: The highest concentration of the antimicrobial agent that can be tolerated by the host organism divided by the lowest concentration of the antimicrobial agents that inhibit or kill the microorganism
- Chemotherapeutic Index (CI) = Dosis tolerata maxima (DTM)/Dosis curativa maxima (DC
+) When the drug is safer (e.g. B-lactams)
+) When the l → the drug is more toxic (e.g. glycopeptide, aminoglycoside)
I. Definitions
7B. What are the features of calculating with Chemotherapeutic Index (Ehrlich)?
Chemotherapeutic Index (CI) = Dosis tolerata maxima (DTM)/Dosis curativa maxima (DCM)
- When the drug is safer (e.g. B-lactams)
- When the l → the drug is more toxic (e.g. glycopeptide, aminoglycoside)
I. Definitions
8A. What is Antibiotic susceptibility testing?
An Antibiogram is the result of an antibiotic sensitivity test; it’s an in vitro sensitivity, but the correlation of in vitro to in vivo sensitivity is often high enough for the test to be clinically useful
II. Antibiotic susceptibility testing
1. What are the methods of Antibiotic susceptibility testing?
II. Antibiotic susceptibility testing - Dilution methods
2. What are the 4 dilution method that we can use for Antibiotic susceptibility testing?
- Broth dilution methods (tube and microdilution)
- Tube dilution method
- Microdilution method
- Agar dilution method