A 50 yr old women with reccurent uti in last 1 yr( 4 episodes). Patient had taken antibiotic course according to c/s report. On 3 rd episode she took extended antibiotic course for 30 days. Everytime   her c/s shows e.coli.

Her usg abd is normal including post voidal bladder volume. She had menopause  at the age of 45. Please suggest appropriate management.