Pus cells 10 to 14 in urine but culture showed no growth. ..Why?

Inflammation. Assuming pus cells are white blood cells (wbc's) in the urine (pyuria) , it is also seen in other situations such as irritation (eg. Urinary catheter) or excess wbc's (eg.Leukemias.). For uti's, clinical symptoms need to be prsent such as pain on urination. Note that you can still have a UTI without a positive cultre since not all bacteria can grow in the micro lab (eg. Chlamydia, mycoplasma).
Pus cells. I always tell my pts that every test or a test result is a piece of puzzle. On its own it doesn't mean a lot ... "pus " cells can be simply representing some inflammation . Since cultures r negative one can assume that there is no bacterial infection in urine .. Hope it helps!