Summary

Urinary tract infection (UTI) is bacterial infection of the urinary tract, divided into lower UTI (cystitis - bladder) and upper UTI (pyelonephritis - kidney). It is one of the most common infections in clinical practice, affecting 50% of women at some point in their lives. Escherichia coli causes 70-90% of community-acquired UTIs. Management depends on classification as uncomplicated or complicated, patient factors, and local resistance patterns. [1,2]

Key Facts

• Incidence: 150 million cases globally per year. [3]
• Lifetime Risk (Women): 50-60%; 25% will have recurrence.
• Common Organism: E. coli (70-90% of uncomplicated UTI).
• Classification: Lower (cystitis) vs Upper (pyelonephritis); Uncomplicated vs Complicated.
• Diagnosis: Clinical symptoms + dipstick (nitrites/leucocytes) ± culture.
• Treatment: Short-course antibiotics for uncomplicated; longer courses for complicated/pyelonephritis.

Clinical Pearls

Nitrites = Gram-Negative Bacteria: Only organisms that reduce nitrate to nitrite (mainly Enterobacteriaceae) give positive nitrite. A negative nitrite does NOT exclude infection (Staph saprophyticus, Enterococcus don't produce nitrite).

Leucocyte Esterase Alone is Non-Specific: Positive leucocytes can occur with sterile pyuria (STI, TB, stones, interstitial nephritis). Send MSU if in doubt.

UTI in Men is Always Complicated: Men have longer urethras and prostatic antibacterial factors. Any UTI should prompt investigation for underlying cause (residual volume, prostate).

Asymptomatic Bacteriuria - When to Treat: ONLY treat in pregnancy and before urological procedures. Do NOT treat in elderly, catheterised, diabetics, or institutionalised patients (no benefit, drives resistance). [4]

General Assessment

• Temperature (fever suggests upper UTI/sepsis).
• Heart rate, blood pressure (sepsis assessment).
• Hydration status.

Abdominal Examination

• Suprapubic tenderness (cystitis).
• Loin tenderness, renal angle tenderness (pyelonephritis).
• Palpable bladder (retention).
• Abdominal mass (renal abscess).

Specific Tests

Costovertebral Angle (CVA) Tenderness

• Percussion over the flank at the angle of 12th rib and spine.
• Pain = suggests pyelonephritis.

Digital Rectal Examination (Men)

• Prostatic enlargement (BPH).
• Prostatic tenderness (prostatitis - avoid vigorous examination).

Pelvic Examination (If Indicated)

• Exclude vaginitis, STI.
• Particularly if dysuria without frequency.

Uncomplicated Cystitis

• Excellent prognosis.
• Symptoms resolve in 24-48 hours with treatment.
• Without treatment, 25-45% resolve spontaneously (but risk of progression).

Pyelonephritis

• Good prognosis if treated promptly.
• Mortality less than 1% in healthy adults.
• Higher risk with obstruction, diabetes, immunocompromise.

Recurrence Risk

• 25-30% of women have recurrence within 6 months.
• 3+ UTIs per year = recurrent UTI.

Long-Term Outcomes

• Uncomplicated UTI: No long-term sequelae.
• Recurrent pyelonephritis: Risk of renal scarring.
• Paediatric UTI: Investigate for VUR; risk of scarring.

Key Guidelines

Landmark Studies

1. IDSA Uncomplicated Cystitis Guidelines (2011) [7]

• Established trimethoprim-sulfamethoxazole (TMP-SMX) 3 days as benchmark.
• Nitrofurantoin 5 days equally effective.
• Fluoroquinolones reserved for resistance.
• Impact: Standardised treatment approach.
• PMID: 21292654.

2. Foxman et al. UTI Epidemiology (2000) [3]

• Characterised risk factors in young women.
• Sexual activity strongest modifiable risk factor in young women.
• PMID: 10809801.

3. Asymptomatic Bacteriuria Studies [4]

• Multiple RCTs show no benefit of treatment in elderly, diabetics, catheterised.
• Treatment only for pregnancy and pre-urological procedures.
• Impact: Reduced unnecessary antibiotic use.
• PMID: 16311099.

What is a UTI?

A urinary tract infection (UTI) is an infection caused by bacteria in any part of your urinary system - the kidneys, ureters, bladder, or urethra. Most UTIs affect the bladder (cystitis) and are easily treated with antibiotics.

Who Gets UTIs?

• Very common in women (1 in 2 will have one at some point).
• Less common in men, but can occur (especially with prostate problems).
• More common in pregnancy, diabetes, and with catheters.

What Are the Symptoms?

Bladder Infection (Cystitis)

• Burning or stinging when you urinate.
• Needing to urinate more often.
• Feeling like you need to go urgently.
• Pain in your lower tummy.
• Cloudy or smelly urine.
• Blood in urine.

Kidney Infection (Pyelonephritis)

• All of the above PLUS:
• High fever and chills.
• Pain in your side or back.
• Nausea and vomiting.
• Feeling very unwell.

How is it Diagnosed?

• Usually from your symptoms and a urine dipstick test.
• Sometimes a urine sample is sent to the lab.

How is it Treated?

• Antibiotics: Usually a short course (3 days for simple bladder infections).
• Drink plenty of fluids.
• Paracetamol: For pain and fever.
• Kidney infections: May need longer antibiotics or hospital treatment.

How Can I Prevent UTIs?

• Drink plenty of water.
• Don't hold on when you need to urinate.
• Wipe from front to back after using the toilet.
• Urinate after sex.
• Avoid perfumed products near the genital area.
• If you get frequent UTIs, talk to your doctor about prevention options.

When to Seek Urgent Help

• High fever or chills.
• Severe back or side pain.
• Vomiting and unable to keep fluids down.
• Blood in urine with fever.
• Symptoms not improving after 48 hours of antibiotics.
• Confused or very drowsy (especially elderly).