Nucleic acid synthesis inhibs-Antimicrobials

Question 1

What two bacterial enzymes are necessary in order to separate bacterial DNA, prevent supercoiling and separate daughter chromosomes?

Answer 1

• Topoisomerase II (DNA gyrase)

- Topoisomerase IV

Question 2

Which class of antimicrobials is bactericidal, broad-spectrum, active agains Gram (+/-) and works by blocking DNA gyrase (Topo II) and Topo IV?

Answer 2

Quinolones/Fluoroquinolones

*DNA gyrase in G(-) and Topo IV in G(+)

Question 3

Ciprofloxacin, and ofloxacin have extended Gram (-) coverage and are examples of what generation of Fluoroquinolones?

Answer 3

2nd generation

Question 4

Which antimicrobial is the most potent of the fluoroquinolone for systemic G (-), is used for Gonorrhea, UTI, is the drug of choice for Anthrax and is best in this class for Pseudomonas?

Answer 4

Ciprofloxacin

Question 5

Levofloxacin is an example of which generation of fluoroquinolone that is used for G (+/-) and used with S pneumonias/respiratory infections, complicated UTIs and is an alternative for anthrax?

Answer 5

3rd generation

Question 6

Moxifloxacin is an example of which generation of fluoroquinolone that has enhanced G(+) and anaerobic activity and is the best respiratory fluoroquinolone?

Answer 6

4th generation

*has poor P. aeruginosa activity

Question 7

What is the drug of choice for the G(+) bacilli, Bacillus anthracis?

Answer 7

Ciprofloxacin

*also very effective agains acute diarrheal pathogens

Question 8

What are two effective treatments for UTIs caused by Gram (-) rods?

Answer 8

Ciprofloxacin and Levofloxacin

Question 9

What is an effective treatment agains infections that are unresponsive to B-lactam drugs?

Answer 9

Levofloxacin

Question 10

Though once daily dosing of fluoroquinolone are used because of long half-lives, what should not be taken with these drugs?

Answer 10

Antacids, foods or dietary supplements with divalent cations

Question 11

Which fluoroquinolone is the only one to reach the CSF in clinically active levels?

Answer 11

Oxfloxacin

*most result in higher levels in the lungs than in the serum

Question 12

What are the 5 most common side effects of Fluoroquinolones?

Answer 12

1-C difficile colitis (mainly with ciprofloxacin)
2-CNS issues like headaches (should not use with NSAIDS and should be monitored closely in epileptics)
3-Nephrotoxicity (drink lots of water to avoid)
4-Prolonged QT (especially moxifloxacin)
5-CT problems (don’t use in pregnant, children, or those with myasthenia gravis, can cause tendinitis)

Question 13

What are 3 non-quinolone drugs that disrupt nucleic acid synthesis?

Answer 13

1-Metronidazole
2-Rifampin
3-Nitrofurantoin

Question 14

Which non-quinolone inhibits DNA replication, is used to treat tetanus, and tetanus and should not be used with alcohol or 1st trimester of pregnancy?

Answer 14

Metronidazole (Flagyl)

*has an antabuse reaction with alcohol to cause instant hangover by blocking aldehyde dehydrognase, building up acetaldehyde

Question 15

Which non-quinolone inhibits DNA-dependent bacterial RNA polymarse, is broad spectrum (G(+/-) and mycobacteria), used for TB and leprosy, turns watery secretions orange-red and is a CYP 450 inducer?

Answer 15

Rifampin (Rifamycins)

*increases metabolism of drugs so may need to increase dose of other drugs

Question 16

Which non-quinolone has highly-reactive intermediates that attack bacterial ribosomal proteins, is used for uncomplicated UTIs and should not be used in those with decreased renal function or in the last 4 weeks of pregnancy due to hemolytic anemia?

Answer 16

Nitrofurantoin (Macrobid)

Question 17

What is unique about Nitrofurantoins pharmacokinetics?

Answer 17

it is bactericidal and reaches therapeutic levels quickly in the bladder.