Antimicrobials - Drugs Affecting Nucleic Acid Synthesis

Question 1

2nd Generation Fluoroquinolones

Answer 1

Ciprofloxacin

Question 2

1st Generation Fluoroquinolones

Answer 2

Nalidixic Acid

Question 3

4th Generation Fluoroquinolones

Answer 3

Gemifloxacin and Moxafloxicin

Question 4

3rd Generation Fluoroquinolones

Answer 4

Levofloxacin

Question 5

MOA of Fluoroquinolones

Answer 5

Enter bacteria through porins and irreversibly interfere with Topoisomerase II (gyrase) and Topoisomerase IV to inhibit DNA replication

Question 6

Indications for 2nd Generation Fluoroquinolones

Answer 6

Traveler’s diarrhea, P.aeruginosa in CF patients

Question 7

Indications for 4th Generation Fluoroquinolones

Answer 7

Monotherapy for CAP

Question 8

Indications for 1st Generation Fluoroquinolones

Answer 8

Uncomplicated UTIs

Question 9

Indications for 3rd Generation Fluoroquinolones

Answer 9

CAP, Prostatitis (E.coli)

Question 10

What can adversely affect Fluoroquinolone absorption?

Answer 10

Divalent cations, milk, antacids

Question 11

AE of Fluoroquinolones

Answer 11

“Lones hurt bones” - Connective Tissue problems i.e. tendon rupture; QT prolongation with 3rd and 4th generation

Question 12

Contraindications of Fluoroquinolones

Answer 12

Pregnancy, nursing mothers, age <18

Question 13

Resistance to Fluoroquinolones

Answer 13

Mutations in Topoisomerase II or IV, efflux pumps

Question 14

What are the Sulfonamides?

Answer 14

Sulfasalazine, Sulfamethoxazole, Sulfadiazine; structural analogs of PABA

Question 15

Indications of Sulfasalazine

Answer 15

Inflammatory bowel disease

Question 16

MOA of Sulfonamides

Answer 16

Competitive inhibition of Dihydropteroate synthase (bacterial enzyme) –> decrease in folic acid synthesis

Question 17

Contraindications of Sulfonamides

Answer 17

Patients with G6PD deficiency, Newborns and infants due to Kernicterus

Question 18

AE of Sulfonamides

Answer 18

Hypersensitivity crystalluria due to nephrotoxicity

Question 19

Which drugs may increase plasma levels of Sulfonamides?

Answer 19

Warfarin, Phenytoin, and Methotrexate

Question 20

MOA: inhibits DHF Reductase, decreasing pyrimidine and purine synthesis

Answer 20

Trimethoprim (structural analog of Folate)

Question 21

Indications of Trimethoprim

Answer 21

Bacterial prostatitis, Bacterial Vaginitis, UTIs; reaches high concentration in prostate and vaginal fluid

Question 22

Contraindications of Trimethoprim

Answer 22

Category X

Question 23

AE of Trimethoprim

Answer 23

Megaloblastic Anemia, Leucopenia

“TMP treats marrow poorly”

Question 24

Contraindications of Cotrimoxazole

Answer 24

1st trimester of pregnancy

Question 25

DOC for PCP

Answer 25

Cotrimoxazole

Question 26

DOC for Nocardiosis

Answer 26

Cotrimoxazole

Question 27

DOC for Uncomplicated UTIs

Answer 27

Cotrimoxazole

Question 28

Alternative drug for Toxoplasmosis

Answer 28

Cotrimoxazole

Question 29

DOC for C.difficile

Answer 29

Metronidazole

Question 30

AE of Cotrimoxazole

Answer 30

Stevens-Johnson Syndrome, Hemolytic Anemia, increased AE incidence in AIDS patients

Question 31

AE of Metronidazole

Answer 31

Disulfiram-like rxn, dark urine

Question 32

Contraindications of Metronidazole

Answer 32

Category X in 1st trimester

Question 33

MOA of Metronidazole

Answer 33

Reductive bioactivation of its nitro group by Ferredoxin –> cytotoxic products that interfere with nucleic acid synthesis

Question 34

Urinary Antiseptic used for treatment and prophylaxis of lower UTIs

Answer 34

Nitrofurantoin

Question 35

Contraindications of Nitrofurantoin

Answer 35

Infants, full-term pregnancy, renal insufficiency, G6PD deficiency

Question 36

MOA of Nitrofurantoin

Answer 36

Reduction by bacteria –> reactive intermediates that damage bacterial DNA but no systemic effects