If this were to occur in stranded DNA, supercoiling or tension would be created within the helix. The quinolone and FQ antibiotics inhibit the action of DNA gyrase. The FQ may also cause arthropathy in children, characterised by joint swelling and pain. They may also have teratogenic effects of a similar nature and are therefore contraindicated during pregnancy. Decreases DNA function, inhibiting bacterial protein synthesis and replication.
Resistance is rare.
A urinary antiseptic, by the metabolites formaldehyde and ammonia. May cause crystalluria and stone formation. Many bacteria are unable to take up exogenous folic acid. Mammalian cells do not synthesis folate, consequently the sulphonamides have no effect in humans. Trimethoprim shows selectivity for bacterial DHF reductase at low doses, although some inhibition may occur at high doses.