How likely is someone to have a bladder infection with no symptoms?

Colonization: Some people have bacteria in their urine that does not cause symptoms, but is difficult to eradicate. In this case, one can differentiate between a real infection, in which the person has symptoms (pain, burning with urination, fever, even sepsis) or is merely colonized with minimally virulent bacteria. The latter may be best-served by surveillance rather than aggressive antibiotic treatment.