Protein Synthesis Inhibitors II

Question 1

Inhibitors of protein synthesis (Besides TCM)

Answer 1

Aminoglycosides
Clindamycin
Streptogramins
Linezolid

Question 2

Used in combination with a beta-lactam antibiotic in serious infection with Gram-negative bacteria, and this combination kills gram positive bacteria.

These antibiotics can also be used in combination with Vancomycin, or a beta lactam antibiotic for gram-positive endocarditis, and to treat TB.

Answer 2

Aminoglycosides

Question 3

Aminoglycosides are bacteriostatic or cidal?

Answer 3

Bacteriocidal

Question 4

Aminoglycoside solubility

Answer 4

Water soluble

Question 5

Route of administration for aminoglycoside.

Answer 5

Parenteral (not orally)

Question 6

These bactericidal protein synthesis inhibitors can be used to treat endocarditis.

Answer 6

Aminoglycosides

Question 7

When aminoglycosides are combined with beta-lactam antibiotics, they extend coverage to include what type of pathogens?

Answer 7

Gram-positive

Question 8

How do aminoglycosides enter the bacterial cell?

Answer 8

Passive diffusion into the cell through the porin channels.

• This is an oxygen-dependent process.
• This process is inhibited by anaerobic conditions.

Question 9

Enhances the transport of Aminoglycosides into the bacteria via porin channels.

Answer 9

Penicillin

Vancomycin

Question 10

Aminoglycosides MOA

Answer 10

1) Block the formation of the initiation complex.
2) Cause misreading of mRNA (the wrong amino acids are brought over).
3) Break up polysomes into non-functional monosomes.

Question 11

Three ways bacteria are resistant to Aminoglycosides

Answer 11

1) Bacteria make transferase enzymes that inactivate the aminoglycoside.
2) Aminoglycoside can’t enter the bacterial cell.
3) Mutation of the receptor protein on the 30s ribosomal subunit.

Question 12

Bacteria make transferase enzymes that inactivate aminoglycosides by:

Answer 12

APA

Acetylation
Phosphorylation
Adenylylation

Question 13

Aminoglycosides are SYNERGISTIC with which substances?

Answer 13

Beta-lactam antibiotics

Question 14

Administration of aminoglycosides with beta-lactam antibiotics.

Answer 14

When administered in direct contact with each other, they INACTIVATE each other.

So they need to be administered within separate lines so that they first encounter each other in the blood where they’re diluted.

Question 15

Which drug is this?

GI absorption is poor, so it has to be administered intramuscularly.

Not usually absorbed after topical administration.

Penetration into cells and CSF is poor.

Answer 15

Aminoglycosides.

Question 16

This organ eliminates aminoglycosides.

Answer 16

Kidney (like tetracyclines! Exception = Mino and Doxycycline).

Question 17

Half-life of aminoglycosides in the serum compared to its half-life when the kidneys aren’t working.

Answer 17

2-3 hrs –> 24-48 hours

Question 18

Do aminoglycosides enter cells readily?

Answer 18

No, because they’re highly polar and cell membranes have hydrophoic components.

Question 19

Role of aminoglycosides in the presence of inflammation.

Answer 19

CSF levels reach 30% of that in plasma during inflammation.

In neonatal meningitis, amounts may be higher.

Question 20

Is the 8 or 24 hr dosing regimen best for aminoglycosides?

Answer 20

24 hr bc there’s less toxicity.

Question 21

These two bacterial protein synthesis inhibitors bind to the same spot on the 50s ribosome.

Answer 21

Erythromycin and Clindomycin

Question 22

Clindamycin bacteriostatic or cidal?

Answer 22

STATIC

Question 23

These protein synthesis inhibitors are now recommended for prophylaxis of endocarditis in patients with valvular heart disease who are to undergo dental procedures and are allergic to penicillin.

Answer 23

Clindamycin

Question 24

If you’re resistant to Clindamycin, then you have cross-resistance to what other antibiotic?

Answer 24

Macrolides

Question 25

These species are resistant to Clindamycin bc they have poor permeability of the outer membrane to Clindamycin.

Answer 25

Gram-negative aerobic species