How To Cure Frequent Urination After Undergoing TURP Surgery?

My father has gone through TURP surgery 3 weks ago age is 75yrs. But still now he has problem of frequent urination . In sleep he has always wetting bed.after turp he has urine infection now it is mostly checked by miksan 500mg injection twice daily for 5 days and now cifran od 1gm for 10days(oral) suggest suitable remedies and cause of it.how much time will take to slove the problem