Final answer:
Bacteria are the most common cause of UTIs, notably E. coli from fecal contamination, with women being at higher risk due to anatomical differences. Bladder infections are the most common type of UTI, and antibiotics are typically used for treatment.
Step-by-step explanation:
The most common type or cause of urinary tract infections (UTIs) is bacteria. Specifically, Escherichia coli (E. coli) bacteria, which are normally present in the digestive tract, are the primary culprit. They cause infections when they are introduced to the urinary tract, typically from fecal matter due to the anatomical proximity of the anus to the urethra, especially in females. This leads to common types of UTIs such as bladder infections (cystitis) and infections of the urethra (urethritis). UTIs are much more prevalent in women than in men, with risk factors including sexual intercourse, use of diaphragms or spermicides, and anatomy differences. UTIs in women are often treated with antibiotics, like ciprofloxacin, to clear the infection.