How to investigate a Urinary Tract Infection (UTI) with bacteremia in a male?

Investigation of UTI with Bacteremia in Males

In males with UTI and bacteremia, a thorough urological evaluation is mandatory, including urine culture, blood cultures, and imaging to identify underlying anatomical or functional abnormalities, followed by appropriate targeted antimicrobial therapy for 7-14 days. 1

Initial Assessment and Diagnosis

Laboratory Investigations:

• Urine culture and susceptibility testing: Essential before starting antibiotics to guide targeted therapy 1
• Blood cultures: At least two sets to identify the causative organism in bacteremia
• Complete blood count: To assess inflammatory response
• Renal function tests: To evaluate kidney function and guide antibiotic dosing
• Inflammatory markers: CRP, procalcitonin to assess severity

Imaging Studies:

• Ultrasound of kidneys and bladder: First-line imaging to identify obstruction, stones, or anatomical abnormalities
• CT urography: For detailed evaluation if ultrasound is inconclusive or if complications are suspected
• Post-void residual measurement: To assess for incomplete bladder emptying

Identifying Complicating Factors

All UTIs in males are considered complicated 1, 2. Additional complicating factors to identify include:

• Urinary tract obstruction
• Foreign bodies (catheters, stents)
• Incomplete voiding
• Vesicoureteral reflux
• Recent history of instrumentation
• Diabetes mellitus
• Immunosuppression
• Healthcare-associated infections
• ESBL-producing or multidrug-resistant organisms

Antimicrobial Management

Initial Empiric Therapy:

For UTI with bacteremia (severe infection), the European Association of Urology strongly recommends 1:

• Combination therapy:

  • Amoxicillin plus an aminoglycoside, OR
  • A second-generation cephalosporin plus an aminoglycoside, OR
  • An intravenous third-generation cephalosporin

• Fluoroquinolones (e.g., ciprofloxacin) should only be used if:

  • Local resistance rate is <10%
  • Patient does not require hospitalization
  • Patient has anaphylaxis to β-lactam antimicrobials
  • Patient has not used fluoroquinolones in the last 6 months

Duration of Therapy:

• Standard duration for males with UTI and bacteremia: 14 days (when prostatitis cannot be excluded) 1, 2
• A shorter course (7 days) may be considered when 1:
  • Patient is hemodynamically stable
  • Patient has been afebrile for at least 48 hours
  • There are relative contraindications to prolonged antibiotic use

Recent evidence suggests that 7-day therapy may be as effective as 14-day therapy for afebrile men with UTI when using ciprofloxacin or trimethoprim/sulfamethoxazole 3.

Follow-up Investigations

Short-term Follow-up:

• Clinical reassessment within 48-72 hours to evaluate response to therapy
• Adjust antibiotics based on culture and susceptibility results

Long-term Follow-up:

• Urological evaluation: To identify underlying structural or functional abnormalities
• Cystoscopy: To evaluate for bladder pathology, especially in men >50 years
• Prostate assessment: Digital rectal examination and consideration of PSA testing if appropriate
• Uroflowmetry: To assess for bladder outlet obstruction

Special Considerations

Prostate Involvement:

• Prostatitis should be considered in all males with UTI 2
• May require extended treatment duration (14 days) 1

Catheter-Associated UTI:

• If present, remove or replace the catheter when possible 1
• Catheter-associated UTIs are the leading cause of secondary healthcare-associated bacteremia 1
• Mortality associated with catheter-associated bacteremia is approximately 10% 1

Multidrug-Resistant Organisms:

• For ESBL-producing organisms, consider carbapenems, ceftazidime/avibactam, or meropenem/vaborbactam 2
• Adjust therapy based on susceptibility results

Common Pitfalls to Avoid

1. Inadequate duration of therapy: Treating for too short a period, especially when prostatitis cannot be excluded
2. Failure to identify underlying anatomical abnormalities: Always investigate for structural causes
3. Inappropriate empiric antibiotic selection: Consider local resistance patterns
4. Neglecting to adjust therapy based on culture results: Always tailor therapy once susceptibility data is available
5. Missing prostate involvement: Consider prostatitis in all male UTIs

By following this structured approach to investigating and managing UTI with bacteremia in males, clinicians can ensure appropriate diagnosis, treatment, and follow-up to reduce morbidity and mortality associated with these infections.