Quinolones

Question 1

list 4 quinolones

Answer 1

1) Ciprofloxacin
2) Levofloxacin
3) Moxifloxacin
4) Ofloxacin

Question 2

Quinolones are generally reserved as second or third-line treatment due to rapid emergence of resistance and an association C.diff. What are they commonly indicated for?

Answer 2

1) Urinary tract infection (UTI) mostly G-negative
2) Severe gastroenteritis (e.g. due to Shigella, Campylobacter)
3) Lower respiratory tract infection (LRTI) (Gram-positive and Gram-negative organisms; therefore moxifloxacin or levofloxacin preferred)
4) Anthrax, Gonorrhoea, samonella

Question 3

outline the spectrum of activity of quinolones

Answer 3

1) broad spectrum of activity, particularly against Gram-negative bacteria.
2) Ciprofloxacin - significant activity against Pseudomonas aeruginosa.
3) moxifloxacin and levofloxacin, have enhanced activity against Gram-positive organisms

Question 4

outline the MoA of quinolones

Answer 4

Quinolones kill bacteria by inhibiting DNA synthesis (bactericidal). Bacteria rapidly develop resistance to quinolones.

Question 5

list the important adverse side effects caused by quinolones

Answer 5

1) Neurological effects- lowering of the seizure threshold and hallucinations, and inflammation and rupture of muscle tendons.
2) Quinolones (particularly moxifloxacin) cause hepatotoxicity and prolong the QT interval therefore increasing the risk of arrhythmias.
3) Quinolones and cephalosporins are the broad-spectrum antibiotics most commonly associated with C. difficile colitis

Question 6

Who should quinolones be used in caution with?

Answer 6

1) Joint disorders
2) Epilepsy
3) G6PD deficiency
4) Children or adolescents - arthropathy
5) Pregnancy
6) Over 60 - more prone to tendon damage

Question 7

list some of the important interactions with regards to quinolones

Answer 7

1) calcium, antacids- reduce absorption and efficacy of quinolones.
2) Ciprofloxacin inhibits certain CYP P450 enzymes, increasing risk of toxicity with some drugs, notably theophylline
3) Co-prescription of NSAIDs increases the risk of seizures, and of prednisolone increases the risk of tendon rupture
4) Caution if taking other drugs that prolong the QT interval or cause arrhythmias, such as amiodarone, antipsychotics, quinine, macrolide antibiotics and SSRIs.

Question 8

what patient and carer advice should be given to those taking quinolones?

Answer 8

1) Avoid excessive exposure to sunlight
2) do not take indigestion remedies, or medicines containing iron or zinc, 2 hours before or after you take this medicine

Question 9

why might ciprofloxacin be a good drug to take travelling?

Answer 9

Ciprofloxacin has good antibacterial activity against organisms causing severe traveller’s diarrhoea, including Shigella, Salmonella and Campylobacter.

Question 10

which bacteria should quinolones be avoided in?

Answer 10

Many Staphylococci are resistant to quinolones and their use should be avoided in MRSA infections.