CH5-S1 Flashcards
Chemotherapy:
the use of drugs to treat a disease
Antibiotic:
Produced by a microbe inhibits other microbes
_______:
synthetic chemicals
Chemotherapeutic agent
Today distinction blurred -> many newer “antibiotic” are biological products that are ____________.
chemically modified or chemically synthesize
Features of antimicrobial drug:
Selective toxicity, therapeutic index may be high (less toxic), bacteriostatic , bactericidal, narrow or broad activity spectrum
Selective toxicity of antimicrobial drug:
Drug kills pathogens without damaging the host
Therapeutic index is ___________
the ratio between toxic dose and therapeutic dose
( TI = TD50 / ED50)
Bacteriostatic meaning:
Inhibits bacteria from reproducing, but does not kill them
Bactericidal meaning:
Actively kill bacteria
Features of antimicrobial drugs:
Activity spectrum:
Narrow spectrum:
Active against one or very few types
Features of antimicrobial drugs:
Activity spectrum:
Broad spectrum:
Active against several types of microorganisms
Antibiotic sensitivity testing by:
Tube dilution tests and Disc-diffusion test (Kirby-Bauer technique)
Disc-diffusion test (Kirby-Bauer technique)
The larger the zone, the _____ sensitive the microbe to the antibiotic
larger
Disc-diffusion test (Kirby-Bauer technique):
Surface of an agar plate is spread with bacteria
Small discs containing a prepared amount of antibiotic are placed on the plate
Zone of inhibition surrounding the discs is measured and compared with a standard for each drug
The results of the Kirby Bauer disk diffusion susceptibility test are reported only as susceptible, intermediate or resistant. ______ are not reported to physicians.
Zone sizes
________:
Initial antibiotic regimen
Use broad-spectrum antimicrobial agents to cover multiple possible pathogens commonly associated with the specific clinical syndrome
Empiric therapy
________:
After identification of the etiologic pathogen and/or antimicrobial susceptibility data are available
Narrow the antibiotic spectrum
Definitive therapy
Important considerations when prescribing antimicrobial therapy:
Accurate diagnosis of infection, understanding the difference between empiric and definitive therapy, interpretation of antimicrobial susceptibility testing results, understanding drug characteristics, health status of the patient
Tube dilution tests:
Minimal inhibitory concentration (MIC):
lowest concentration of drug that ___________.
visible growth of bacteria
Tube dilution tests:
Minimal bactericidal concentration (MBC):
inhibits at least 99.9% of the bacterial colonies
