Antibiotics

Question 1

Antibiotics that inhibit cell wall synthesis

Answer 1

Beta-lactam ring:

• • Penicillin
• • Carbapenems (meropenem)
• • Cephalosporins

Without beta-lactam ring:

• • Vancomycin
• • Teicoplanin

Question 2

Folic acid chain in full

Answer 2

PABA (para-aminobenzoic acid) –> DHFA (dihydrofolic acid) –> THFA (tetrahydrafolic acid) –> Folic acid

Question 3

Antibiotics that inhibit folic acid metabolism:

Answer 3

Sulfamethoxazole – Blocks conversion of PABA –> DHFA

Trimethoprim – Blocks conversion of DHFA –> THFA

Co-trimoxazole – Combination of Sulfamethoxazole and Trimethoprim

Question 4

Metronidazole mechanism of action

Answer 4

Inhibits nucleic acid synthesis

Question 5

Drugs that inhibit nucleic acid synthesis

Answer 5

Metronidazole

Question 6

What organisms does metronidazole act on?

Answer 6

Anaerobic cells

Only reduced into its active form in anaerobic cells - active form inhibits nucleic acid synthesis

Question 7

Antibiotics that inhibit protein synthesis by targeting the ribosome

Answer 7

Macrolides - (erythromycin, clarithromycin and azithromycin)

Clindamycin

Tetracyclines (such as doxycycline)

Gentamicin

Chloramphenicol

Question 8

What other drugs is a patient likely to be allergic to if they have a penicillin allergy?

Answer 8

10% of ptx with penicillin allergy will have reaction to cephalosporins and carbapenems

In reality this is closer to 1% as only 10% of patients that report allergy have a true allergy