Hello! Thank you for the query. E.Coli bacteria is a regular one present in the intestines. If it appears in the urine this simply means that you have urinary tract infection. There might be few reason for that. If you are a female, wiping in wrong direction (from anus to vaigina) can cause such infection. As you are overweight, most likely you do have also diabetes which is also very often factor of such infection. In same cases, especially after couples of surgeries, fistula between the urinary bladder and large intestine is also possible. I suggest you to check your glucose level and have it controlled well, wipe in correct direction, drink more mineral water and use cranberry supplements or juice. You should also get prescription for antibiotic which covers this infection (antibiogram should be attached to your result). If this infection will appear again, further diagnostics should be ordered (abdominal ultrasound, colonoscopy). Hope this will help. Regards.