Quinolones and DNA strand breakers Flashcards
What does DNA gyrase do?
supercoils bacterial DNA by a process of cutting and rejoining using ATP, so that the DNA can fit into the cell
How do quinolones work?
they bind to A subunit of DNA gyrate, preventing the supercoiling of DNA
What is a first gen quinolone and what is it used for?
Nalidixic acid - UTIs
What is a second gen quinolone and what is it used for?
fluoroquinolones such as ciprofloxacin and ofloxacin
- used for RTIs and prophylaxis of meningococcal meningitis and treatment of Anthrax
when can ciprofolxacin not be used?
- in children due to side effects
- with antacids as absorption is reduced
- with NSAIDS as it causes CNS disturbances
- in pregnancy
What is a third gen quinolone and what is it used for?
levofloxacin
- pneumonia and UTIs
give examples of DNA strand breakers:
nitrofurans (e.g. nitrofurantoin, nitroimadazoles such as metronidazole)
How do nitrofurans work?
they become radicals in anaerobic conditions and these radical anions extract a H from DNA causing cleavage of the sugar-phosphate backbone
what are nitrofurans used to treat?
UTIs (anaerobic bacterial infections only)
by taking a broad spectrum antibiotic, what bacterial infection are you likely to get?
clostridium difficile (as you use a broad spectrum antibiotic, it eliminates a lot of the normal microflora)
what are symptoms of C.difficile?
diarrhoea, abdominal pain and tenderness, fever, nausea
how do you treat this c.difficile?
- stop the antibiotic that caused it
- rehydration
- metronidazole (1st line)
- oral vancomycin
