Urinary tract infections: These occur when bacteria enter your body through the urethra and multiply in your bladder. Symptoms can include a persistent urge to urinate, pain and burning with urination, and extremely strong-smelling urine.
For some people, especially older adults, the only sign of illness might be microscopic blood in the urine.
Kidney infections (pyelonephritis): These can occur when bacteria enter your kidneys from your bloodstream or move from your ureters to your kidney(s). Signs and symptoms are often similar to bladder infections, though kidney infections are more likely to cause a fever and flank pain.