Patients who have had a kidney transplant within the previous 6 months Young children with gross vesicoureteral reflux (VUR) Before certain invasive genitourinary procedures that can cause mucosal bleeding (eg, transurethral resection of the prostate) Certain patients (eg, postmenopausal women; patients with controlled diabetes; patients with ongoing use of urinary tract foreign objects such as stents, nephrostomy tubes, and indwelling catheters) often have persistent asymptomatic bacteriuria and sometimes pyuria.