Escherichia coli, a type of bacteria commonly found in the gastrointestinal tract, easily travels the short distance from the anus to the urethra, particularly in women, according to Mayo Clinic. E. coli then typically travels to the bladder and multiplies, causing a urinary tract infection.
The female anatomy makes women more vulnerable to UTIs, explains Mayo Clinic, because the urethral opening lies near both the anus and vagina and the urethra, or tube leading to the bladder, is short. Sexual intercourse allows the bacteria that cause UTIs to get access to the urethra. The most common UTIs are an infection of the urethra, called urethritis, or a bladder infection, called cystitis.
People who have diabetes or women who are pregnant are more likely to develop UTIs, according to Mayo Clinic. If a lower UTI is left untreated, the infection can travel up the ureter to the kidneys, causing a kidney infection that can result in permanent kidney damage.
Symptoms of a UTI include a burning sensation when urinating, an urgent need to urinate but little urine coming out, low belly pain, or urine that is cloudy, pink, red or foul-smelling, according to WebMD. Medical diagnosis and treatment, typically with an antibiotic, are required to clear up a UTI.