S9.2 Antibacterials

Question 1

What are antibacterials/ antimicrobials?

Answer 1

Chemical substances that kills or inhibits the growth of bacteria at a discrete target site.

Question 2

Name some antibiotics which inhibit DNA synthesis

Answer 2

Quinolones e.g. ciprofloxacin

Folic acid antagonists e.g. trimethoprim

Question 3

Name some antibiotics which affect protein synthesis

Answer 3

Aminoglycosides e.g. gentamicin
Macrolides e.g. erythromicin, clarythromycin
Tetracyclines e.g. Doxycycline

Question 4

Name some antibiotics which effect cell wall synthesis?

Answer 4

Beta-lactams e.g. penicillins, cephalosporins, carbapenems

Glycopeptides e.g. vancomycin

Question 5

What is empirical treatment?

Answer 5

The initial therapy given based on the best educated guess, before commencing revised treatment following culture

Question 6

Give some antibiotic ADRs?

Answer 6

Toxicities, Allergic reactions, idiosyncratic reactions

Question 7

How can we measure antibiotic activity?

Answer 7

Disk sensitivity testing

E-test for MIC (minimum conc of antibiotic required to inhibit growth of bacterium)

Question 8

What are the DDIs for clarithromycin?

Answer 8

Clarithromycin inhibits CYP2D6 potentially increasing plasma concentration of co-prescribed drugs such as statins or carbamazepine

Question 9

What are the DDIs for doxycycline?

Answer 9

Increased bleeding risk when taken with warfarin.

Increased hepatotoxicity when when taken with statins

Question 10

Describe resistance via chromosomal gene mutation

Answer 10

Resistance develops as a result of gene mutations within the bacterial itself.

Question 11

Describe resistance via Horizontal gene transfer

Answer 11

Resistance is acquired from another bacterium passing on the information by either; transformation, conjugation or transduction.