Rational Use Of Antibiotics And Development Of Resistance

Question 1

What is an MIC?

Answer 1

Minimum inhibitory concentration- the lowest concentration of an antibacterial drug that stops multiplication of a bacterial isolate

Question 2

What are 4 Examples of Drug inactivating enzymes ?

Answer 2

-Beta Lactamases
-Aminoglycoside modifying enzymes
-Mactolide- lincosamode- streptogramin modifying enzymes
-Chloramphenicol amino transferase

Question 3

What do drug inactivating enzymes do ?

Answer 3

Inactive enzymes that inactivate the drug before or after it enters the microbial cell

Question 4

What are some of the drug inactivating enzymes ?

Answer 4

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

Question 5

Which drugs inhibit classic beta lactamases? (Also know what they are)

Answer 5

Inhibited by beta lactamase inhibitors
-clavulanic acid
-tazobactam
-sulbactam

Question 6

Where do beta lactamases act?

Answer 6

Plasmids and chromosomes

Question 7

Where do ESBL act?

Answer 7

On plasmids

Question 8

What do beta lactamases inhibit ?

Answer 8

Penicillin and cephalosporins

Question 9

Why is ESBL a good prophylactic agent?

Answer 9

There’s no activation of cephamycins (cefoxitin)

Question 10

Which beta lactamase is often used in surgical prophylaxis?

Answer 10

ESBL

Question 11

Which drugs inactivate ESBL?

Answer 11

Partially inactivated by b lactamase inhibitors
- Tazobactam&raquo_space; clavulanic acid

Question 12

Where do BSBL act?

Answer 12

Chromosomes (sometimes plasmids)

Question 13

Which drugs does BSBL inhibit?

Answer 13

All beta lactams except carbapenems

Question 14

Where do carbapenamases act?

Answer 14

On chromosome, plasmids and transposons

Question 15

What do carbapenemases inhibit?

Answer 15

Carbapenems and penems

Question 16

What do chloramphenicol amino transferase mostly affect?

Answer 16

H influenza and anaerobes

Question 17

What does MLSB group mostly affect?

Answer 17

S aureus
S pneumoniae
S pyogenes

Question 18

What is cell envelop modification and active drug removal ?

Answer 18

• When the envelope becomes less penetrable to the drug
• when the drug is actively expelled from microbial after entry

Question 19

Why are cell envelop modification and active drug removal pumps referred to combined?

Answer 19

They have low resistance as single mechanisms but high resistance combined

Question 20

What is target modification ?

Answer 20

When the target site binds with less strength to the drugs

Question 21

What drugs does target modification affect?

Answer 21

All drugs especially B-lactams and Quinolones

Question 22

why don’t we want organisms spending too much time on the mutant selection window?

Answer 22

It gives more time for mutants to multiply and so an increase of resistant sub population

Also increases chance of next mutation to occur

Question 23

What drugs are time dependent?

Answer 23

Cell wall synthesis inhibitors (B-lactams and glycopeptides)

Question 24

What drugs are concentration dependent ?

Answer 24

Most protein synthesis inhibitors (aminoglycosides, Quinolones )