Had recent laprascopic ovarian cystectomy, got infections and taking 3 antibiotics nitrofurantoin.metronizadole and flucoxicillin, is it safe to do so?

Fine: Assuming your treating dr. Knows what infection they are treating you for and or trying to prevent further infections, that is safe. Make sure you follow-up with the treating dr. To assure continuity of care and that you are followed appropriately through your post operative course. Best wishes to you.

Yes: None of these drugs are known to negatively interact with one another.