Hi, M Running A Lab As A Biochemist,,, I Have

Hi, m running a lab as a biochemist,,, I have a patient with a complaint of UTI, as they came from UAE,,, nd feeling that she and her son both are infected with UTI. She has 2-3 pus cells with pH 7.0,, but no growth is observed in her urine culture... What must be the reason then ??? and is it compulsory to have growth with 3-4 pus cells.