Infection is not a NANDA approved nursing diagnosis. However, if your patient is symptomatic there is another diagnosis related to the urinary system that would better suit your care plan and allow you to address the infection as well.
As someone else said, infection isn't NANDA approved. You can use risk for infection, but it shouldn't relate to the UTI. Think about what else leads to a risk for infection in hospitalized patients. Think about IV lines, Foley catheters, invasive procedures, IM and subcutaneous injections, surgical procedures, etc. If you use risk for infection in that manner, then it can apply.
You should choose another, more appropriate, diagnosis/set of diagnoses to address the UTI.