UTIs affect 6 in 10 women over their lifetime — costing the US $3.5 billion annually — and 26 percent recur within 6 months. This complete guide covers cystitis vs pyelonephritis symptom differences, why E. coli causes 80 to 85 percent of UTIs, the antibiotic resistance table (ampicillin 40 to 50 percent resistant vs nitrofurantoin just 1 to 2 percent), first-line treatments, and the best evidence-based prevention strategies including post-coital urination, vaginal oestrogen,