Antimicrobial susceptibility testing
Definition: In vitro study of bacterial susceptibility to antibiotics.
Types
1-Disc diffusion tests
Limitation of disc diffusion tests:-
-Not applied to slowly –growing, Fastidious organisms or anaerobes .
-Mycobacterial and fungus susceptibility testing requires specific techniques
- The reported sensitivity tests results not applied to clinical sites infections, e.g –salmonella Typhi to aminoglycosids.
-Not related to the achieved serum levels or body fluid levels of antibiotics.
-Bacteriostatic measures only.
-Can’t be applied to certain antibiotics such as polymyxines.
2,Dilution susceptibility testes:-
(micro) minimal inhibitory and minimal bactericidal activity methods.
Methods
-Broth dilution tests
-Agar dlution method.
Application:-
-Serious infection where endpoint concentration is ended
-Disc diffusion yield inter mediate susceptibility
-Life threatening infection due to organisms with unpredictable susceptibility pattern.
-Fastidious or slowly growing organisms.
-Failure of antibiotic therapy
-Serious infections caused by organisms susceptible only to toxic agents
Limitation
-Difficult
It needs the knowledge about the achievable level in serum or body filmed
3- Automated method
4-Antimicrobial concentration gradient methods
-A serial antibiotic dilations are incorporated into the agar.
-E test
http://www.amazon.com/Lectures-applied-clinical-microbiology-ebook/dp/B004Y0XF54
Definition: In vitro study of bacterial susceptibility to antibiotics.
Types
1-Disc diffusion tests
Limitation of disc diffusion tests:-
-Not applied to slowly –growing, Fastidious organisms or anaerobes .
-Mycobacterial and fungus susceptibility testing requires specific techniques
- The reported sensitivity tests results not applied to clinical sites infections, e.g –salmonella Typhi to aminoglycosids.
-Not related to the achieved serum levels or body fluid levels of antibiotics.
-Bacteriostatic measures only.
-Can’t be applied to certain antibiotics such as polymyxines.
2,Dilution susceptibility testes:-
(micro) minimal inhibitory and minimal bactericidal activity methods.
Methods
-Broth dilution tests
-Agar dlution method.
Application:-
-Serious infection where endpoint concentration is ended
-Disc diffusion yield inter mediate susceptibility
-Life threatening infection due to organisms with unpredictable susceptibility pattern.
-Fastidious or slowly growing organisms.
-Failure of antibiotic therapy
-Serious infections caused by organisms susceptible only to toxic agents
Limitation
-Difficult
It needs the knowledge about the achievable level in serum or body filmed
3- Automated method
4-Antimicrobial concentration gradient methods
-A serial antibiotic dilations are incorporated into the agar.
-E test
http://www.amazon.com/Lectures-applied-clinical-microbiology-ebook/dp/B004Y0XF54
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