A 32-year-old woman from Delhi presents with a 14-day history of fever, headache, and abdominal pain. She reports no diarrhea but has been constipated for the past week. On examination, she has a temperature of 39.2°C, hepatomegaly, and a faint maculopapular rash on the trunk. Widal test shows O antigen titer of 1:160 and H antigen titer of 1:320. Blood culture is negative. Urine culture grows the same organism as isolated from blood culture on day 5 of illness. What is the most likely diagnosis and what is the significance of the urine culture finding?