Rational Use Of Antibiotics And Development Of Resistance Flashcards
What is an MIC?
Minimum inhibitory concentration- the lowest concentration of an antibacterial drug that stops multiplication of a bacterial isolate
What are 4 Examples of Drug inactivating enzymes ?
-Beta Lactamases
-Aminoglycoside modifying enzymes
-Mactolide- lincosamode- streptogramin modifying enzymes
-Chloramphenicol amino transferase
What do drug inactivating enzymes do ?
Inactive enzymes that inactivate the drug before or after it enters the microbial cell
What are some of the drug inactivating enzymes ?
Beta Lactamases
-classic beta lactamase
- extended spectrum beta lactamases (EPBL)
-Broad spectrum beta lactamases (BSBL)
- Carbapenases
Aminoglycoside modifying enzymes
- gentamicin group inactivating enzymes
-amikacin group inactivating enzymes
-miscellaneous enzymes
MLSB group
Chloramphenicol amino transferase
Which drugs inhibit classic beta lactamases? (Also know what they are)
Inhibited by beta lactamase inhibitors
-clavulanic acid
-tazobactam
-sulbactam
Where do beta lactamases act?
Plasmids and chromosomes
Where do ESBL act?
On plasmids
What do beta lactamases inhibit ?
Penicillin and cephalosporins
Why is ESBL a good prophylactic agent?
There’s no activation of cephamycins (cefoxitin)
Which beta lactamase is often used in surgical prophylaxis?
ESBL
Which drugs inactivate ESBL?
Partially inactivated by b lactamase inhibitors
- Tazobactam»_space; clavulanic acid
Where do BSBL act?
Chromosomes (sometimes plasmids)
Which drugs does BSBL inhibit?
All beta lactams except carbapenems
Where do carbapenamases act?
On chromosome, plasmids and transposons
What do carbapenemases inhibit?
Carbapenems and penems
What do chloramphenicol amino transferase mostly affect?
H influenza and anaerobes
What does MLSB group mostly affect?
S aureus
S pneumoniae
S pyogenes
What is cell envelop modification and active drug removal ?
- When the envelope becomes less penetrable to the drug
- when the drug is actively expelled from microbial after entry
Why are cell envelop modification and active drug removal pumps referred to combined?
They have low resistance as single mechanisms but high resistance combined
What is target modification ?
When the target site binds with less strength to the drugs
What drugs does target modification affect?
All drugs especially B-lactams and Quinolones
why don’t we want organisms spending too much time on the mutant selection window?
It gives more time for mutants to multiply and so an increase of resistant sub population
Also increases chance of next mutation to occur
What drugs are time dependent?
Cell wall synthesis inhibitors (B-lactams and glycopeptides)
What drugs are concentration dependent ?
Most protein synthesis inhibitors (aminoglycosides, Quinolones )
