Urine is usually sterile, which means it does not have any bacteria, viruses or fungi. A UTI can occur when a microorganism enters the urinary system through the urethra. Most infections are caused by Escherichia coli (E. coli), which is a digestive tract bacterium that lives in the colon, and spreads to the urethra from the anus. Other microorganisms including Chlamydia and Mycoplasma can cause UTIs in men and women, but these UTIs are usually restricted to the urethra and the reproductive system. Since these microorganisms are sexually transmitted, both partners require treatment if infections occur.
Some people have higher risks of developing UTIs.
- Other causes that increase the risk of UTIs include structural abnormalities of the urinary system, urinary stones and bladder obstruction.
- People with diabetes are also more prone to UTIs because of the excess sugar in the urine. Men with an enlarged prostate have a high risk of developing UTIs because they are usually unable to empty their bladder completely.
- UTIs can also occur in babies born with abnormality in the urinary system.
- Women are more vulnerable than men to UTIs (1 woman in 5 develops UTI during her lifetime) because they have a shorter urethra, therefore bacteria do not have a long distance to travel before they reach the bladder. Women’s risk usually increases when they become sexually active, and also after menopause due to the dry state of the urethra and vagina.