I Frequently Get Urinary Tract Infections And This Past Week

I frequently get urinary tract infections and this past week have taken FLAGY for my infection. The doctor gave me SIEMENS test strips to take home with me since I get them so frequently and I checked my urine after a full course of antibiotics and the strip is still coming up positive. Is that normal? Should I try the test strips again in a couple of days? or should it say negative by now. My last pill was finished yesterday. Please advise. Thank you.