A 32-year-old otherwise healthy woman presents with 2 days of dysuria, urinary frequency and suprapubic discomfort. She is afebrile with normal vital signs and no flank pain. Urinalysis is positive for nitrites and leucocytes. According to Australian primary care guidance, which oral antibiotic is an appropriate first-line choice for uncomplicated acute cystitis in a non-pregnant woman, assuming local resistance patterns are acceptable?