What organism commonly causes hematuria in Urinary Tract Infections (UTIs)?

Organisms Causing Hematuria in Urinary Tract Infections

Escherichia coli (E. coli) is the most common organism causing hematuria in urinary tract infections, followed by Proteus species, Klebsiella species, Pseudomonas species, Serratia species, and Enterococcus species. 1

Primary Causative Organisms

The European Association of Urology guidelines (2024) identify several key organisms associated with UTIs that can cause hematuria:

1. Escherichia coli (E. coli) - Most common organism (accounts for approximately 75% of recurrent UTIs) 1
2. Proteus species - Known for producing urease enzyme that can lead to stone formation and subsequent hematuria
3. Klebsiella species - Common in complicated UTIs
4. Pseudomonas species - Often seen in healthcare-associated infections
5. Serratia species - Less common but can cause complicated UTIs
6. Enterococcus species - More common in patients with urological abnormalities

Mechanisms of Hematuria in UTIs

Hematuria in UTIs occurs through several mechanisms:

• Direct mucosal damage - Bacterial invasion of the urinary epithelium causing inflammation and bleeding
• Toxin production - Bacterial toxins damaging blood vessels in the urinary tract
• Inflammatory response - Host immune response causing collateral damage to blood vessels
• Stone formation - Particularly with urease-producing organisms like Proteus species

Clinical Presentation

Hematuria may present as:

• Gross hematuria - Visible blood in urine (has a high association with malignancy of up to 30-40%) 1
• Microscopic hematuria - Detected on urinalysis (3 or more RBCs per high power field)

When hematuria is accompanied by other UTI symptoms such as:

• Dysuria
• Urinary frequency
• Urinary urgency
• Suprapubic pain
• Fever (in upper UTIs)

Risk Factors for UTI with Hematuria

Several factors increase the risk of developing UTIs with hematuria:

• Catheter-associated UTIs - Signs include new onset of fever, altered mental status, and acute hematuria 1
• Complicated UTIs - Due to structural or functional abnormalities of the urinary tract 1
• Healthcare-associated infections - Often involving resistant organisms 1
• Recent instrumentation of the urinary tract 1
• Immunosuppression - Altered host defense mechanisms 1

Diagnostic Approach

When hematuria is present in a suspected UTI:

1. Urine culture and sensitivity testing should be performed before starting antibiotics 1, 2
2. Imaging may be indicated for complicated UTIs or persistent hematuria after treatment
3. Cystoscopy may be needed for persistent hematuria, especially in patients over 35 years 1

Treatment Considerations

For UTIs with hematuria, treatment should target the most likely causative organisms:

• First-line options include nitrofurantoin, trimethoprim-sulfamethoxazole (if local resistance <20%), or fosfomycin 2, 3

• For complicated UTIs with hematuria, consider broader coverage with:

  • Amoxicillin plus an aminoglycoside
  • Second-generation cephalosporin plus an aminoglycoside
  • Intravenous third-generation cephalosporin 1

• Fluoroquinolones (e.g., ciprofloxacin) should only be used if local resistance rates are <10% 1, 4

Special Considerations

• Persistent hematuria after treatment warrants further investigation to rule out underlying urological conditions
• Gross hematuria requires a more thorough evaluation due to higher association with malignancy 1
• Cell wall deficient bacteria have been reported as a cause of idiopathic hematuria and may require special culture techniques 5

Treatment Duration

• Uncomplicated UTI: 3-5 days of treatment 2
• Complicated UTI: 7-14 days of treatment 1, 2
• Male UTIs: Longer treatment (14 days) when prostatitis cannot be excluded 1

Remember that hematuria can be a sign of more serious conditions beyond UTI, so persistent hematuria after appropriate antibiotic treatment warrants further investigation.