A 32-year-old woman has flank pain and fever. She has a history of type I diabetes mellitus. Temperature is 102 F. Leukocyte count is 23,000/μL with 80% neutrophils. Urine culture is positive for E. coli. IV antibiotics are administered. Ten days later, she remains febrile. Which of the following is the most likely cause?
Development of antibiotic resistance
Drug reaction
Membranous glomerulonephritis
Natural course of E. coli pyelonephritis in diabetic patient
Perinephric abscess
