What are the odds of developing a fungal Urinary Tract Infection (UTI)?

Fungal Urinary Tract Infections: Incidence and Risk Factors

Fungal urinary tract infections (UTIs) are rare in community settings, occurring in only 3-5% of the general population, but are much more common in hospitalized patients where they can account for 10-30% of positive urine cultures. 1

Epidemiology and Risk Factors

Fungal UTIs are predominantly caused by Candida species, with Candida albicans being the most commonly isolated organism. The likelihood of developing a fungal UTI is strongly associated with specific risk factors:

High-Risk Populations:

• Hospitalized patients (10-30% of positive hospital urine cultures) 1
• Catheterized patients (indwelling urinary catheters significantly increase risk) 2, 3
• Immunocompromised individuals 3
• Patients with diabetes mellitus 3
• Patients on broad-spectrum antibiotics (disrupts normal flora) 1
• Elderly patients 3
• Patients with structural urinary tract abnormalities 3
• Patients on SGLT2 inhibitors (may increase risk of fungal UTIs) 4

Additional Risk Factors:

• Chronic renal failure 3
• Hemodialysis 3
• Renal transplantation 3
• Use of corticosteroids or immunosuppressive medications 1, 3
• Recent urologic procedures or instrumentation 2
• Nephrostomy tubes 3

Diagnosis

Fungal UTIs can present as:

• Asymptomatic funguria (most common) 1
• Symptomatic cystitis 1
• Pyelonephritis 1
• Severe sepsis with fungemia (rare) 1

Diagnostic Criteria:

• Fungal concentration >10³/mm³ in urine is typically considered significant 1
• Presence of leukocyturia (though no specific cutoff has been established) 1
• Visualization of yeast cells and pseudohyphae in urine sediment 5
• Culture with ≥50,000 CFU/mL of a fungal pathogen 2

Management Approach

When to Treat:

• Treatment is recommended only when funguria is symptomatic or when host factors increase the risk of fungemia 1
• Asymptomatic funguria should generally not be treated unless the patient is at high risk or prior to urologic procedures 2

Treatment Options:

• Fluconazole is the primary treatment option due to high urinary concentrations 1
• Amphotericin B deoxycholate is an alternative option 1
• Other antifungal agents have extremely low concentrations in urine and are generally not recommended 1

Prevention Strategies:

• Remove urinary catheters as soon as possible 2, 1
• Limit unnecessary antibiotic use 1
• Optimize diabetes management 1
• Avoid prophylactic antimicrobials at the time of catheter placement, removal, or replacement 2

Special Considerations

Catheter-Associated Fungal UTIs:

• Catheter removal or replacement is a crucial part of management 2
• Do not screen for or treat catheter-associated asymptomatic funguria 2
• Avoid routine periodic catheter changes to prevent funguria 2

Complicated Fungal UTIs:

• Consider upper tract imaging for patients with persistent symptoms 2
• Fungal balls may require both antifungal therapy and surgical intervention 4
• Prompt replacement of nephrostomy tubes within 4 days of infection diagnosis reduces recurrence risk 2

Conclusion

While fungal UTIs are uncommon in the general population, they represent a significant concern in hospitalized and immunocompromised patients. Recognition of risk factors, appropriate diagnostic criteria, and targeted treatment approaches are essential for effective management. The primary focus should be on treating symptomatic infections and addressing modifiable risk factors to prevent recurrence.