Bacteria Causing Hemorrhagic Urinary Tract Infections
Escherichia coli (E. coli) is the most common bacterial cause of hemorrhagic urinary tract infections, responsible for 80-85% of cases, particularly in uncomplicated UTIs. 1, 2
Common Bacterial Pathogens
The microbial spectrum causing hemorrhagic UTIs includes:
Primary Pathogens
- Escherichia coli: Most prevalent uropathogen (80-85% of uncomplicated UTIs, 21-54% of hospital-acquired UTIs) 3, 1, 2
- Proteus species: Associated with urinary stones and can cause hemorrhagic cystitis 3
- Klebsiella species: More common in complicated UTIs and can cause significant hematuria 3, 2
- Pseudomonas species: Frequently seen in catheter-associated and complicated UTIs 3
- Serratia species: Can cause hemorrhagic UTIs, especially in healthcare settings 3
- Enterococcus species: Common in complicated UTIs with potential for hemorrhagic presentation 3
Secondary Pathogens
- Staphylococcus saprophyticus: Causes 5-10% of uncomplicated UTIs, particularly in young women 2
- Streptococcus agalactiae (Group B Streptococcus): Can cause hemorrhagic UTIs, especially in pregnant women and diabetics 2
Pathogen Distribution Based on UTI Type
Uncomplicated UTIs
- E. coli predominates (80-85%)
- S. saprophyticus, Proteus mirabilis, and Klebsiella species account for most remaining cases 1, 2
Complicated UTIs
- More diverse bacterial spectrum
- E. coli remains common but at lower rates (21-54%)
- Higher prevalence of Proteus, Klebsiella, Pseudomonas, Serratia, and Enterococcus 3
- More likely to present with hematuria/hemorrhagic symptoms due to underlying structural abnormalities 3
Catheter-Associated UTIs
- Broader microbial spectrum with increased risk of hemorrhagic presentation
- E. coli remains common but with increased presence of Pseudomonas, Klebsiella, and Enterococcus 3
- Incidence of bacteriuria with indwelling catheterization is 3-8% per day 3
Risk Factors for Hemorrhagic UTIs
Factors that increase the likelihood of hemorrhagic presentation include:
- Obstruction at any site in the urinary tract
- Foreign bodies (catheters, stents)
- Vesicoureteral reflux
- Recent instrumentation
- Extended-spectrum β-lactamase (ESBL) producing organisms
- Multidrug-resistant organisms
- Diabetes mellitus
- Immunosuppression
- Healthcare-associated infections 3
Clinical Implications
- Hemorrhagic UTIs often indicate complicated infections requiring more aggressive management
- Urine culture with susceptibility testing is essential before initiating therapy 4
- Empiric antibiotic selection should cover the most likely pathogens based on local resistance patterns
- For complicated hemorrhagic UTIs, combination therapy may be necessary:
- Amoxicillin plus an aminoglycoside
- Second-generation cephalosporin plus an aminoglycoside
- Intravenous third-generation cephalosporin 3
Common Pitfalls and Caveats
- Misdiagnosis: Not all hematuria indicates infection; consider urological malignancies, stones, or glomerular disease
- Inadequate cultures: Obtain cultures before antibiotics to identify the causative organism
- Resistance concerns: Local resistance patterns significantly impact treatment success; E. coli resistance to fluoroquinolones is increasing globally 5
- Overlooking complicated UTI: Hemorrhagic presentation often indicates a complicated UTI requiring more extensive evaluation
- Catheter management: For catheter-associated hemorrhagic UTIs, catheter removal or replacement before starting antibiotics improves outcomes 3
Remember that while E. coli remains the predominant pathogen in hemorrhagic UTIs, the presence of blood in urine often suggests a complicated infection with potential involvement of a broader spectrum of pathogens, requiring more comprehensive evaluation and targeted antimicrobial therapy.