OVERVIEW

What is a urinary tract infection?

A urinary tract infection (UTI) refers to an inflammatory reaction in the urinary system caused by pathogenic bacteria such as bacteria entering the urinary tract. Common symptoms include frequent urination, urgency, painful urination, chills, fever, lower back pain, bacteriuria, and pyuria. Treatment primarily involves antibacterial medications, supplemented by symptomatic relief and lifestyle adjustments.

In general, most patients can achieve a cure with proper treatment. However, if left untreated or improperly managed, recurrent or progressive infections may lead to permanent kidney damage, sepsis, or other severe complications, which can even be life-threatening.

Preventive measures include drinking plenty of water, maintaining a light diet, washing the perineal area regularly with warm water, and urinating promptly after sexual intercourse.

How common are urinary tract infections?

UTIs are one of the most common infectious diseases, affecting 130 to 175 million people globally each year, making them the second most prevalent infection after respiratory infections^[1].

In China, the incidence rate is approximately 2% (meaning about 2 out of 100 people have a UTI). The male-to-female incidence ratio is about 1:8, with women being more susceptible—about 60% of women will experience at least one UTI in their lifetime^[2].

What are the types of urinary tract infections?

1. By infection site^[1]:

   • Upper UTI: Infections occurring in the ureters or above, such as acute pyelonephritis.
   • Lower UTI: Infections in the bladder and urethra, such as acute uncomplicated cystitis.

2. By urinary tract condition at the time of infection:

   • Uncomplicated UTI: No underlying urinary abnormalities, including simple lower or upper UTIs.
   • Complicated UTI: Associated with functional/structural urinary abnormalities or immunodeficiency, such as hospital-acquired UTIs or catheter-associated UTIs.
   • Recurrent UTI: Further classified as reinfection or bacterial persistence^[1].

3. Reinfection: A new infection caused by external bacteria re-entering the urinary tract.

4. Bacterial persistence: Recurrent infection from the same bacteria remaining in the urinary tract (e.g., due to stones or prostate issues).

   • Asymptomatic bacteriuria: No UTI symptoms, but urine tests show elevated bacterial counts.
   • Urethral syndrome: May relate to congenital anatomical abnormalities of the urethral meatus, shortening the distance to the vaginal opening, leading to backflow of vaginal secretions or urethral irritation during intercourse.

Which department should I visit for a UTI?

Adults should consult urology or nephrology, while children should visit pediatrics.

SYMPTOMS

What are the common symptoms of urinary tract infections?

Common symptoms of urinary tract infections include frequent urination, urgency, painful urination, hematuria, back pain, suprapubic tenderness, fever, etc. Different types of UTIs present differently:

• Cystitis: Typically without fever or back pain, mainly manifesting as frequent urination, urgency, dysuria, difficulty urinating, and lower abdominal discomfort. Some patients may experience urinary retention or post-void dribbling of blood.
• Acute pyelonephritis: More common in young and middle-aged women, often with sudden onset of systemic infection symptoms such as fever, chills, headache, and body aches. May be accompanied by urinary irritation (e.g., frequent urination, urgency, dysuria) or lower back pain.
• Chronic pyelonephritis: Often presents as persistent lower back soreness, intermittent urinary frequency, discomfort during urination, low-grade fever, and increased nocturia. Prone to recurrent episodes.

What serious complications can urinary tract infections cause?

• Urosepsis: Pathogens from UTIs multiply and spread through the bloodstream, causing urosepsis. Symptoms include high fever, chills, rapid breathing, tachycardia, and hypotension.
• Septic shock: Severe infection may lead to septic shock, characterized by hypotension, confusion, and cold/clammy skin.
• Kidney failure: Bacterial UTIs can damage kidneys, leading to renal failure. Symptoms include oliguria (<400 mL/day), anuria (<100 mL/day), proteinuria, or cylindruria.
• Infertility: UTIs spreading to the reproductive system may cause fertility issues.

CAUSES

What are the causes of urinary tract infections?

• Bacterial infection: The vast majority of UTIs are caused by bacteria invading the urinary system^[3], with Escherichia coli being the most common pathogen. Other bacteria such as Proteus, Enterobacter aerogenes, Klebsiella pneumoniae, Pseudomonas aeruginosa, Candida albicans, and Staphylococcus aureus can also cause UTIs.
• Iatrogenic factors: Long-term indwelling catheters (retained in the bladder after catheterization) or improper disinfection may allow bacteria on the catheter to enter the urethra, leading to UTIs^[3].
• Medication factors: Long-term use of glucocorticoids or immunosuppressive drugs can weaken the immune system, increasing the risk of UTIs^[3].
• Disease factors: Conditions such as neurogenic bladder, stones, congenital malformations, or urethral fistulas may obstruct urine flow, contributing to UTIs^[3].

Who is at higher risk for urinary tract infections?

Since the female urethra is significantly shorter than the male urethra, UTIs are more common in women, especially those who are sexually active or postmenopausal. Additionally, the following groups are more susceptible to UTIs^[3]:

• Individuals with long-term indwelling catheters, cystostomy tubes, or ureteral stents: Prolonged catheter use or improper disinfection increases infection risk.
• Those who frequently hold in urine: Retaining urine for extended periods allows bacterial growth in the bladder, raising UTI risk.
• People with obstructive urinary diseases: Conditions like bladder outlet obstruction, urethral strictures, stones, or tumors can impair urine flow, leading to recurrent UTIs.
• Individuals with vesicoureteral reflux: Bacteria can multiply more easily in the urinary tract, increasing infection susceptibility.
• Post-urinary diversion surgery patients: Poor urine drainage and retention raise UTI risk.
• Those undergoing chemotherapy or radiotherapy: Damage to the urothelium makes bacterial invasion more likely.
• People with chronic conditions: Kidney dysfunction, transplanted kidneys, diabetes, or immunodeficiency weaken immunity, making recurrent infections more common.
• Men over 60: Enlarged prostates increase UTI susceptibility.
• Individuals with poor hygiene: Inadequate perineal cleaning allows bacteria from the vagina or anus to enter the urethra.
• Elderly women: Short urethras, high bacterial presence in the perineal area, and weakened immunity make them more prone to ascending UTIs.

Are urinary tract infections contagious?

Generally, UTIs are rarely transmitted between people. However, certain specific infections, such as gonococcal urethritis and non-gonococcal urethritis, can spread through sexual contact.

Are urinary tract infections hereditary?

Since UTIs are caused by pathogenic bacteria invading the urinary system, they are not inherited. However, genetic predispositions may increase susceptibility. For example, studies suggest that the SP-A1 19Ala allele and SP-A2 223Gln allele are risk factors for recurrent UTIs^[4].

DIAGNOSIS

How do doctors diagnose urinary tract infections?

Doctors typically diagnose UTIs based on clinical symptoms, physical examinations, and auxiliary tests such as urinalysis, blood tests, urine culture, and urinary tract ultrasound.

What tests are needed to diagnose a urinary tract infection?

• Detailed physical examination: Helps preliminarily identify the infection site, such as suprapubic tenderness or costovertebral angle tenderness.
• Urinalysis and blood tests: Provide initial assessment of whether a UTI is present.
• Urine culture: Identifies the specific bacteria causing the infection and guides antibiotic treatment based on sensitivity results.
• Imaging tests: Including urinary ultrasound, CT, or MRI to detect obstructions, hydronephrosis, stones, or other abnormalities, guiding further treatment.

What precautions should UTI patients take for urinalysis, urine culture, and urinary ultrasound?

• Urinalysis: Collect a clean midstream urine sample.
• Urine culture: Ideally collect a clean midstream urine sample before starting treatment.
• Urinary ultrasound: Patients should retain urine beforehand to ensure a full bladder.

What conditions are easily confused with UTIs, and how to differentiate them?

Benign prostatic hyperplasia (BPH): Both conditions may cause lower urinary tract symptoms like frequent or urgent urination. However, UTIs often involve bacteriuria or pyuria, while BPH lacks bacterial infection. A digital rectal exam may reveal an enlarged prostate. Urinalysis, urine culture, and ultrasound can help distinguish them. Patients with such symptoms should seek medical evaluation for accurate diagnosis.

Vaginitis: Caused by bacterial infection of the vagina, it may share urinary symptoms like dysuria and urgency. Key differences include vaginal irritation and foul-smelling discharge. Symptoms can help differentiate the two.

TREATMENT

What are the treatment methods for urinary tract infections?

The treatment of urinary tract infections primarily involves antibacterial medications, supplemented with symptomatic treatment and lifestyle adjustments.

If the patient has removable high-risk factors for infection, treatment should also include addressing these factors, such as removing stones or catheters.

Medication^[5]:

• Ciprofloxacin: Suitable for patients with bacterial urinary tract infections, it has antibacterial effects but may cause adverse reactions such as abdominal discomfort, diarrhea, nausea, and vomiting.
• Levofloxacin: Has antibacterial effects and is suitable for urinary tract infections. It may cause adverse reactions such as abdominal pain, dizziness, and headache. It is contraindicated for pregnant and breastfeeding women.
• Nitrofurantoin: Has antibacterial effects and is suitable for urinary tract infections. It may cause adverse reactions such as nausea, vomiting, poor appetite, and diarrhea.
• Compound sulfamethoxazole: Suitable for bacterial urinary tract infections. It may cause adverse reactions such as joint and muscle pain and fever. It is contraindicated for pregnant and breastfeeding women.
• Fosfomycin: Suitable for urinary tract infections. It may cause adverse reactions such as nausea, poor appetite, upper abdominal discomfort, loose stools, or mild diarrhea. It is contraindicated for pregnant and breastfeeding women.

Pregnant patients should avoid medications toxic to the fetus and mother, such as tetracyclines (chlortetracycline, oxytetracycline, etc.) and aminoglycosides (gentamicin, amikacin, etc.). It is recommended to use low-toxicity drugs with no significant impact on the fetus or mother and no teratogenic effects (e.g., amoxicillin, cefradine, etc.). Specific medications should be taken as prescribed by a doctor.

Surgical Treatment:

• Extracorporeal shock wave lithotripsy: Suitable for urinary tract infections caused by urinary or bladder stones. Advantages include accuracy, safety, shorter hospital stays, and faster recovery compared to traditional surgery. However, its application is limited, and it is ineffective for stones >1 cm in diameter. Contraindicated for pregnant women, menstruating women, hypertensive patients, and those with cardiac pacemakers.
• Catheter management: For urinary tract infections caused by long-term indwelling catheters, the catheter should be removed if no longer necessary. If continued drainage is required, a new catheter or alternative methods may be used, depending on the patient's condition and compliance^[1].
• Urethral dilation: Suitable for patients with urethral syndrome. This procedure can relieve spasms of the external urethral sphincter, reduce urethral resistance, and eliminate bladder neck obstruction, thereby improving bladder irritation and dysuria symptoms. However, as an invasive procedure, it may damage the urethral mucosa, and repeated operations may lead to scarring and stenosis.

General Treatment:
Patients with discomfort should rest, drink plenty of water, and urinate frequently to flush the urinary tract and promote recovery.

How long does urinary tract infection treatment take?

The treatment period for urinary tract infections is generally 3–14 days, but the duration may vary depending on the severity of the condition, individual constitution, and treatment plan^[1].

• Non-pregnant women with acute uncomplicated cystitis: Single-dose or 3-day therapy.
• Non-pregnant women with acute uncomplicated pyelonephritis: Mild cases are recommended to take oral antibiotics for 14 days. If ineffective after 48–72 hours, sensitive antibiotics should be selected based on drug sensitivity tests. If bacteria persist after 14 days, the treatment should be adjusted and extended to 6 weeks. Severe cases may require intravenous medication, switching to oral medication after symptom relief.
• Men with uncomplicated urinary tract infections: Generally recommended for 7 days.
• Complicated urinary tract infections: Sensitive antibiotics should be selected based on drug sensitivity tests, generally recommended for 7–14 days, and may be extended to 21 days if necessary.

Is follow-up necessary for urinary tract infections?

Follow-up is usually necessary for urinary tract infections. Some patients with non-removable risk factors, such as permanent catheters or neurogenic bladder, often experience recurrent infections and require regular follow-up.

How is follow-up for urinary tract infections conducted?

Follow-up includes urine tests, blood tests, urine cultures, and urinary tract ultrasounds. Tests are generally required before and after stopping medication.

Can urinary tract infections be cured?

Yes. Most patients can be cured with timely and standardized treatment^[5].

Can urinary tract infections recur?

Yes. For patients with persistent, non-removable risk factors, urinary tract infections are prone to recurrence^[5].

DIET & LIFESTYLE

What should patients with urinary tract infections pay attention to in their diet and daily life?

• Drink plenty of water and urinate frequently;
• Consume fruits and vegetables rich in vitamin C to boost immunity;
• Maintain personal hygiene by bathing regularly and changing underwear frequently;
• Patients requiring long-term or intermittent catheterization must strictly follow aseptic techniques (after opening the catheterization kit, wear sterile gloves first, then place a fenestrated drape, clean and disinfect the perineum from top to bottom and inside out, and perform catheterization in a sterile environment) to avoid contamination and bacterial invasion leading to UTIs;
• Take antibiotics strictly as prescribed in terms of dosage, timing, and course duration—do not stop medication without authorization;
• Adhere to regular follow-up examinations.

Can urinary tract infections affect fertility?

If a UTI spreads to male reproductive organs, it may cause conditions like prostatitis or orchitis, potentially affecting fertility.

PREVENTION

Can Urinary Tract Infections Be Prevented? How to Prevent UTIs?

Yes, UTIs can be prevented through the following measures:

• Drink plenty of water and urinate frequently;
• Maintain personal hygiene by bathing regularly, changing underwear often, and wiping from front to back after bowel movements for women;
• Wash the perineal area with warm water frequently to keep it clean, and urinate promptly after sexual intercourse;
• For patients with recurrent UTIs, oral antibiotics such as nitrofurantoin or fosfomycin trometamol can be taken to prevent recurrence;
• Postmenopausal women may use vaginal estrogen under the guidance of a gynecologist;
• Actively address high-risk factors for infection, such as controlling blood sugar and removing urinary stones.