DNA gyrase inhibitors and DNA strand breakers Flashcards
DNA gyrase is a topoisomerase. True or false?
True
What is the role of DNA gyrase?
It is an enzyme that introduces negative (left-handed) superhelical turns into duplex bacterial DNA, using energy of ATP
Why is supercoiling needed?
So DNA can fit into bacterial cell
Length of DNA helix 1300micrometers
Length of bacterial cell 1 micrometer
DNA uncoils before replication and transcription. True or false?
True
Why is DNA gyrase a good anti-bacterial target?
Mammals don’t supercoil DNA
How do quinolones work?
Block the alpha subunit of DNA gyrase and prevent supercoiling of bacterial DNA. They interfere with DNA breakage and re-joining
Quinolones are narrow-spectrum antibiotics. True or false?
False - broad spectrum
Quinolones are effective against gram negative bacteria which are resistant to penicillins. True or false?
True
Nalidixic acid is a quinolone that is active against gram negative bacteria only. True or false?
False - gram positive and negative
Nalidixic acid is used for treatment of uncomplicated UTI. True or false?
True
What are the indications for ciprofloxacin?
respiratory infections (not pneumococcal pneumonia)
UTI
gonorrhoea
prophylaxis of meningococcal minigitis
Anthrax - prophylaxis and post-exposure prophylaxis
Ciprofloxacin is metabolised by CYP450 1A2. Why is this a problem?
Can lead to overdose of caffeine, warfarin and other drugs
Absorption of which drug is reduced when magnesium or aluminium antacids are taken?
Ciprofloxacin
Severe CNS disturbance can take place when ciprofloxacin is co-administered with which group of drugs?
NSAIDs
Ciprofloxacin is contraindicated in pregnancy. True or false?
True
Third generation quinolones are indicated in pneumonia and UTIs. True or false?
True
Give the name of a third generation quinolone?
Levofloxacin
What are the names of three second generation quinolones?
Ciprofloxacin
Norfloxacin
Ofloxacin
What are nitrofurans used to treat and what is an example of one?
Gram positive and negative UTIs
Nitrofurantoin
What are nitroimidazoles used to treat?
Anaerobic bacterial infections and protozoal infections
The normal microflora of the intestine has roughly 500 species of bacteria. True or false?
True
Elderly are especially susceptible to C.diff. True or false?
True
Treating a patient who has C.diff with a broad spectrum antibiotic leads to elimination of most of the normal microflora of the intestine and promotes overgrowth of C.diff. True or false?
True
How is C.diff treated?
Discontinue the inducing antibiotic, to allow reconstitution of the microflora
Rehydration
Oral metronidazole is first line treatment
Oral metronidazole is first line treatment for C.diff. What is given as second line treatment?
Oral vancomycin
How is C.diff transmitted?
Person-person
Hospital environment
Healthcare staff
Spores are resistant to alcohol handwash. True or false?
True
What is a new drug that has proven to be successful against C.diff?
Fidaxomicin
