Quinolones

Question 1

Name some common quinolone antibiotics?

Answer 1

Ciprafloxacin
Levofloaxacin
Moxifloxacin
- FLOAXCINs

Question 2

What part of the bacteria do quinolones traget?

Answer 2

DNA synthesis

Question 3

How do quinolones work?

Answer 3

Quinolones inhibit the enzymes responsible for remodelling of DNA during replication - DNA gyrase and topoisomerase
this inhibition of DNA synthesis is BACTERIOCIDAL

Question 4

Are quinolones bactericidal or bacteriostatic?

Answer 4

Bactericidal

Question 5

What spectrum do quinolones have?

Answer 5

Particularly good at targeting Gram - bacteria (making them good for UTIs and GI infections)
Later generations have an increases target for gram + making them useful for LRTIs

Question 6

How do bacteria develop resistance against quinolones ?

Answer 6

• Decreased permeability
• Efflux system
• Target enzymes
• Horizontal transmission via plasmids accelerates resistance

Question 7

What are the common uses for quinolones?

Answer 7

• *Often left for second/third lines choice due to rapid resistance and C.dff
  1. UTI - including pyelonephritis
  2. Severe GI infections (shigella and campylobacter- TRAVERS DIARRHOEA)
  3. Pseudomonas Auriginosa - Ciprafloxacin is the only oral abx against this

Question 8

What are the contraindications for using quinolones?

Answer 8

Epileptics/at risk of seizures (lowers seizure threshold)
Children (are growing so at risk of arthropathy)
Cardiac disease (QT prolonged and risk of arrhythmias)
Electrolyte disturbance (QT prologued and risk of arrhythmias)

Question 9

What are the common interactions with quinolones?

Answer 9

Calcium, antacids and ions (divalent cations so reduce absorption)
CYP450 inhibitors (interferes with drugs metabolised by CYP450 especially theophylline)
NSAIDS (increases risk of seizures)
Prednisolone (increases risk of tendon rupture)
Drugs that prolong the QT interval
- amiodrarone
- antipsycotics
- Quinine
- Macrolide
- SSRIS

Question 10

What drug metabolised by CYP450 do quinolones commonly interact with?

Answer 10

THEOPHYLLINE

Question 11

What are the side effects of quinolones?

Answer 11

• GI UPSET
• Hypersensitivity
• Neurological effects (seizures and hallucinations)
• Inflammation and tendon rupture
• Prolong QT interval (increases risk of arrhythmia’s)
• C. Diff

Question 12

Why are quinolones vernally reserved for second and third line treatment?

Answer 12

Rapid resistance

C.DIFF

Question 13

How are quinolines excreted?

Answer 13

Kidney

Question 14

What forms do quinolones come in?

Answer 14

Oral and IV

Question 15

What other antibiotic increases the QT intveral?

Answer 15

Macrolides