urinary infections

The urinary tract is almost always invaded from the exterior via the urethra. The regular flushing of the urinary tract with urine serves as a defense against invading microorganisms.

Urine in the bladder is normally sterile, and successful pathogens (e.g., gonococci, E. coli) adhere to the urinary epithelium.

Anatomy is an important factor for infection. Women have more than 10 times as many urinary tract infections (UTIs) as men, because the distance between the urinary bladder and skin (i.e., the length of the urethra) is 5 cm, in contrast to 20 cm in men.

Obstruction of urinary flow and/or reflux can compromise normal defenses and increase susceptibility to UTIs.

UTIs can spread retrogradely from the bladder to the kidney and cause acute and chronic pyelonephritis, which is the major preventable cause of renal failure.