尿路感染（UTI）每年影响全球超过1.5亿人，是临床实践中最常见的细菌感染之一。从其他方面健康女性的非复杂性下尿路感染（膀胱炎）到严重的上尿路感染（肾盂肾炎）以及需要住院治疗的导管相关UTI，病情轻重不一。本指南涵盖UTI的临床谱——包括病因、诊断、抗菌药物治疗方案及预防，并结合基于EAU和IDSA指南的循证临床见解。
What is a Urinary Tract Infection?
A urinary tract infection (UTI) is an infection that affects any part of the urinary system — including the kidneys, ureters, bladder, and urethra. Most infections involve the lower urinary tract, primarily the bladder and the urethra.
UTIs are among the most common bacterial infections in the world. While they can affect anyone, women are significantly more susceptible due to their shorter urethra, which allows bacteria to reach the bladder more easily.
When to see a doctor
If you experience burning urination, pelvic pain, cloudy urine, or a persistent urge to urinate, consult a healthcare professional. Untreated UTIs can spread to the kidneys.
Urinary tract infections represent a spectrum of conditions ranging from uncomplicated cystitis in healthy premenopausal women to complex urosepsis in catheterized, immunocompromised, or structurally abnormal patients. Classification is critical for guiding empirical therapy.
| Classification | Definition | Key Considerations |
|---|---|---|
| Uncomplicated UTI | Lower UTI in non-pregnant women without structural/functional abnormalities | Short-course antibiotics; no imaging required |
| Complicated UTI | Any UTI associated with functional/structural urinary tract abnormality, or in special populations (men, pregnant women, immunocompromised, catheterized patients) | Urine culture mandatory; longer treatment course |
| Recurrent UTI | ≥3 episodes per year or ≥2 episodes in 6 months | Investigate underlying cause; consider prophylaxis |
| Catheter-associated UTI (CAUTI) | UTI in patients with urinary catheter in place for >2 days | Remove catheter if possible; distinct antibiogram |
| Asymptomatic Bacteriuria | ≥10⁵ CFU/mL on 2 consecutive specimens without symptoms | Treatment only in pregnancy and pre-urological procedures |
Anatomy of the Urinary Tract
Kidneys
Filter blood, produce urine. Kidney infections (pyelonephritis) are serious and require prompt treatment.
Ureters
Tubes carrying urine from kidneys to bladder. Can be affected by stones or strictures.
Bladder
Stores urine. Cystitis (bladder infection) is the most common UTI form.
Urethra
Carries urine outside the body. Urethritis often presents with discharge and burning.
Clinical Note — Ascending Infection Pathway
The most common route of infection is ascending, with periurethral colonization by uropathogens (predominantly E. coli expressing type 1 and P fimbriae) followed by bladder invasion. Vesico-ureteral reflux (VUR), bladder outlet obstruction, ureteral stenting, and nephrostomy access all create conditions that promote retrograde ascent into the upper urinary tract. The female urethra (3–4 cm) versus the male (20 cm) accounts for the marked sex disparity in uncomplicated UTI incidence.
Causes & Risk Factors
UTIs are most commonly caused by bacteria from the gut, particularly Escherichia coli (E. coli), which accounts for around 80–85% of cases. These bacteria can enter the urinary tract and multiply rapidly.
| Pathogen | Frequency | Key Notes |
|---|---|---|
| Escherichia coli | 80–85% | Virulence factors: fimbriae, hemolysin, cytotoxic necrotizing factor |
| Staphylococcus saprophyticus | 5–15% (young women) | Novobiocin-resistant; seasonal peaks in summer/autumn |
| Klebsiella pneumoniae | 5–8% | Emerging ESBL producers; nosocomial setting |
| Proteus mirabilis | 2–5% | Urease-producer; associated with struvite stones |
| Pseudomonas aeruginosa | <3% | Predominantly nosocomial/catheter-associated; high resistance rates |
| Enterococcus faecalis | <5% | Post-urological procedure; consider VRE in hospital settings |
Risk Factors
Signs & Symptoms
Lower UTI (Cystitis / Urethritis)
- Burning or painful urination (dysuria)
- Frequent, urgent need to urinate
- Passing only small amounts of urine
- Cloudy, dark, or strong-smelling urine
- Blood in urine (haematuria)
- Pelvic pressure or discomfort
Upper UTI (Pyelonephritis) ⚠️
- Fever and chills
- Flank, back, or side pain
- Nausea and vomiting
- High temperature (>38°C / 100.4°F)
- Costovertebral angle tenderness
- Requires immediate medical care
Clinical Pearl — Atypical Presentations
Elderly patients (especially those with dementia or delirium) and immunocompromised individuals frequently lack classic dysuria/frequency, presenting instead with unexplained delirium, falls, or haemodynamic instability. Catheterized patients may be asymptomatic or present only with suprapubic discomfort. Overdiagnosis of UTI in the elderly (attributing delirium to UTI without meeting formal NHSN/IDSA criteria) is a recognised quality metric and contributes to unnecessary antibiotic exposure.
Diagnosis
Your doctor will likely ask about your symptoms and request a urine sample. A dipstick test can detect signs of infection quickly, while a urine culture identifies the specific bacteria involved and guides antibiotic selection.
Symptom Assessment
Medical history & physical exam
Urinalysis
Dipstick + microscopy
Urine Culture
Identifies organism & sensitivity
Urinalysis Interpretation
- Leukocyte esterase: Sensitivity 75–96%; specificity 94–98%. Positive suggests pyuria (>5 WBC/hpf)
- Nitrites: Specificity ~95%; sensitivity ~50%. Only gram-negative Enterobacteriaceae reduce nitrates
- Combined LE + nitrite: Best discriminator in uncomplicated cystitis; negative dipstick has high NPV to exclude UTI
- Microscopy: Pyuria threshold: ≥10 WBC/mm³ on uncentrifuged specimen; bacteriuria: ≥10²–10⁵ CFU/mL depending on context
Imaging Indications
- Ultrasound: First-line for suspected obstruction, abscess, or paediatric UTI
- CT urogram: Diagnostic standard for pyelonephritis complications (abscess, emphysematous pyelonephritis), nephrolithiasis
- VCUG/MAG3: Evaluate vesico-ureteral reflux in paediatric recurrent UTI
- Cystoscopy: Recurrent haematuria, suspected bladder lesion, or structural abnormality
UTI治疗：抗菌药物、补液与复发性UTI管理
Most UTIs are effectively treated with a short course of oral antibiotics. It's important to complete the full course even if symptoms improve early. Your doctor will choose the antibiotic based on the bacteria identified and local resistance patterns.
Important: Never self-medicate
Using the wrong antibiotic or stopping treatment early contributes to antibiotic resistance and may not cure the infection. Always follow your doctor's prescription.
| UTI Type | First-Line (EAU/IDSA) | Duration | Notes |
|---|---|---|---|
| Uncomplicated Cystitis | Nitrofurantoin, Fosfomycin, Pivmecillinam | 3–5 days | Avoid fluoroquinolones as first-line; preserve for complicated UTI |
| Uncomplicated Pyelonephritis (mild) | Ciprofloxacin (if local resistance <10%) or TMP-SMX guided by cultures | 7–14 days | Culture before starting; adjust to sensitivity results |
| Complicated UTI / Hospitalised Pyelonephritis | IV ceftriaxone or piperacillin-tazobactam (initial empirical) | 10–14 days (step-down oral when appropriate) | Blood cultures; urology consult if obstruction suspected |
| CAUTI | Per local antibiogram; remove/replace catheter | 7 days (14 days if slow response) | Do not treat asymptomatic bacteriuria in catheterized patients |
| Recurrent UTI (prophylaxis) | Nitrofurantoin 50mg nocte or post-coital, D-mannose, intravaginal oestrogens (post-menopausal) | 3–6 months | Exclude anatomical cause first; review after 6 months |
💧 Hydration
Drinking plenty of water helps flush bacteria from the urinary tract. Aim for 1.5–2 litres daily, more during hot weather or fever.
🌿 Symptom Relief
Paracetamol or ibuprofen may help with discomfort. Some patients find urinary alkalinising agents (e.g. potassium citrate) soothing, though evidence is limited.
Prevention
Stay well hydrated
Adequate fluid intake dilutes urine and encourages frequent voiding, reducing bacterial colonisation time in the bladder.
Wipe front to back
This prevents transfer of gut bacteria from the anal area to the urethra — a simple but highly effective hygiene practice.
Urinate after sexual intercourse
Voiding after sex helps flush bacteria that may have been introduced into the urethra during sexual activity.
Avoid irritating products
Perfumed soaps, douches, and deodorant sprays near the genital area can disrupt natural flora and increase infection risk.
Cranberry products & D-Mannose
Some evidence supports the use of cranberry extract (PACs) and D-Mannose supplements in reducing recurrent UTIs by inhibiting bacterial adhesion to the urothelium.
Manage underlying conditions
Good glycaemic control in diabetes, prompt treatment of urinary obstruction, and minimising unnecessary catheterisation all reduce UTI risk significantly.
Clinical Insights & Current Guidelines
EAU 2024 Urological Infections Guidelines — Key Updates
- • Fluoroquinolones are no longer recommended as empirical first-line therapy for uncomplicated cystitis due to ecological collateral damage and resistance pressure.
- • Fosfomycin trometamol (3g single dose) remains a preferred option for uncomplicated cystitis with favourable resistance profile.
- • Post-procedural antibiotic prophylaxis (e.g. ureterorenoscopy, PCNL) is recommended only when pre-operative urine culture is positive or contamination risk is high.
- • Catheter-associated bacteriuria: treat only if symptomatic, pregnant, or prior to urological instrumentation.
Antimicrobial Stewardship Considerations
- • Reserve carbapenems for documented ESBL/carbapenem-susceptible organisms; meropenem for KPC/NDM-producing Enterobacteriaceae only if no alternative.
- • Urine cultures from catheterised patients frequently represent colonisation — clinical context is paramount.
- • Repeated quinolone exposure promotes fluoroquinolone-resistant E. coli and MRSA — consider resistance monitoring in high-risk populations.
Urological Device Considerations
Ureteral access sheaths (UAS), nephrostomy drainage catheters, and JJ stents all represent foreign body surfaces that predispose to biofilm formation. Continuous suction sheaths (e.g. Manawa FANS series) reduce intra-renal pressure build-up during ureteroscopy, potentially lowering pyelovenous backflow and infectious complications. Appropriate antibiotic prophylaxis before endourological procedures and timely removal of drainage devices remain the cornerstones of post-procedural UTI prevention.
常见问题：尿路感染
UTI的主要症状有哪些？
下尿路感染（膀胱炎）最常见的症状包括排尿时灼热或疼痛（排尿困难）、频繁急迫的排尿感、尿液浑浊或气味强烈，以及盆腔压迫感。上尿路感染（肾盂肾炎）会出现额外症状：体温超过38°C的发热、寒战、腰部疼痛、恶心和呕吐。肾盂肾炎需要立即就医。
尿路感染如何治疗？
大多数非复杂性UTI采用3〜5天的口服抗菌药物疗程治疗。现行EAU指南推荐呋喃妥因、磷霉素或匹美西林作为一线选择。由于耐药性问题，氟喹诺酮类药物应避免作为一线用药。复杂性或上尿路感染可能需要7〜14天的治疗，严重肾盂肾炎可能需要静脉抗菌药物和住院治疗。
复发性UTI的病因是什么？
复发性UTI（每年3次或以上）因解剖因素在女性中最为常见。常见原因包括性行为、绝经、膀胱排空不完全、肾结石、输尿管狭窄和长期留置导尿管。治疗包括针对基础病因的处理、低剂量预防性抗菌药物、D-甘露糖补充，或绝经后女性的阴道内雌激素治疗。
膀胱炎和肾盂肾炎的区别是什么？
膀胱炎是膀胱（下尿路）感染，表现为排尿困难、尿急和尿频，无发热。肾盂肾炎是肾脏感染（上尿路），更为严重——表现为发热、腰痛、恶心和全身症状。肾盂肾炎需要及时抗菌药物治疗，尤其是孕妇、老年人或免疫功能低下患者可能需要住院治疗。
如何预防UTI？
主要UTI预防策略包括保持充足水分摄入（每天1.5〜2升水）、性行为后排尿、如厕后从前向后擦拭、避免在生殖器区域使用芳香产品，以及管理糖尿病或尿路梗阻等基础疾病。蔓越莓提取物（PACs）和D-甘露糖补充剂通过抑制细菌对尿路上皮的粘附，有减少复发的证据。