Urinary tract infections (UTIs), also known as urinary tract infections, are very common. Especially in the elderly population, urinary tract infections are an important problem in both men and women. Urinary tract infections are a common primary focus of Gram-negative bacillary bacteremia, and the most common primary focus of bacteremia in elderly patients is a urinary tract infection. Therefore, the prevention and treatment of UTI in the elderly is important. Elderly patients have a significantly increased chance of developing infections and often complex UTIs due to the following factors. First, urological factors. In elderly men with lower urinary tract infections, most of them can find obstructive lesions in the lower urinary tract after careful examination, such as prostatic hyperplasia, bladder neck sclerosis, and neurogenic bladder dysfunction. Urinary tract infections with comorbidities are often more complex in terms of pathogenic bacteria and prone to drug-resistant strains. Combined infections are difficult to cure if the primary disease is not resolved. The use of a catheter can weaken the host’s defense mechanisms, making it susceptible to urinary tract infections. Catheters can cause mechanical damage to the urinary tract epithelium and promote the colonization of pathogenic bacteria. The mucosal defense barrier is damaged, mucin secretion is reduced, and bacterial adhesion is decreased; the mechanical blocking effect of the internal and external urethral sphincter is lost, and bacteria invade freely from the urethral orifice; the dilution effect of urine flushing is weakened, and bacteria then colonize. The bacterial mycelium forms a film on the catheter that has been left in place for a long time, making it impossible for antibiotics to enter. Chronic infections of the genital system and adjacent infections such as intestinal infections in elderly men pose a threat to the urinary tract as potential foci of infection in the body. Epididymitis is often the first clue to a urinary tract infection with obstruction. A causative factor specific to the vulnerability of elderly female patients to infection is abnormal urinary function. The most common is dysfunction of the detrusor muscle and, in a few cases, bladder outlet obstruction, either structural or functional. Women with bladder outlet obstruction generally do not present with typical obstructive symptoms, but rather complain of urinary frequency, urgency, urge incontinence, or recurrent urinary tract infections. Urinary tract infections are often the most common clinical symptom of abnormal urinary function. Second, internal factors. After getting older, they are prone to diseases causing general immune deficiency such as diabetes, chronic wasting disease, uremia, receiving immunosuppressant or corticosteroid treatment, which are prone to combined urinary tract infections, and their pathogenic bacteria are often complex and prone to drug-resistant strains. Third, gynecological factors. Older women have recurrent urinary tract infections that are not easily cured and are associated with a decrease in estrogen. The normal urinary tract mucosa is covered with a layer of mucin, which prevents bacteria from adhering and then invading the urinary tract mucosa. Estrogen promotes the secretion of mucin in the urinary tract. In old age, as estrogen decreases, the anti-bacterial adhesion effect decreases and bacteria can adhere to the urinary tract epithelium, thus making it easy for infection to occur. In addition, prolapse of the uterus or vagina (which can be found in squatting position) squeezes the urethra and leads to poor drainage, which also leads to urinary tract infections.