A 4 yrs old girl took tab Nitrofurantoin for one month for UTI. Few days after stopping Nitrofurantoin she again developed burning in micturition. Her urine show 3-4 wbc per hpf. Culture shows 10000 colonies per ml.

Sensitivity to Nitrofurantoin. Culture of urine show extended-spectrum beta-lactamase positive. USG abdomen. How long Nitrofurantoin should be given?