Why Men Get Urinary Tract Infections
Men develop UTIs primarily due to anatomical and functional abnormalities of the urinary tract, with prostatic hypertrophy and associated obstructive uropathy being the dominant causes in older men, while younger men typically develop UTIs from sexually transmitted pathogens or underlying structural abnormalities. 1
Age-Related Mechanisms
Young Men (<35 years)
- UTIs are rare in healthy young men without underlying abnormalities 1
- When they occur, the primary causes include:
- Sexually transmitted organisms (Chlamydia trachomatis, Neisseria gonorrhoeae) causing urethritis that can ascend 1
- Sexual activity-related infections, particularly in men who are the insertive partner during anal intercourse (enteric organisms like E. coli) 1
- Underlying structural abnormalities such as urethral strictures, congenital anomalies, or voiding dysfunction 1, 2
Older Men (>60 years)
- The prevalence increases substantially after age 60 due to prostatic disease 1
- Benign prostatic hyperplasia (BPH) causes obstructive uropathy and voiding dysfunction, creating stasis and incomplete bladder emptying 1
- 6-15% of men aged 75+ living in the community have bacteriuria, compared to essentially 0% in young healthy men 1
- Prostatic hypertrophy is the predominant mechanism for the age-related increase in male UTI prevalence 1
Specific Causative Factors
Anatomical and Functional Abnormalities
The following conditions predispose men to UTIs by creating favorable environments for bacterial colonization 1:
- Urinary tract obstruction at any level (most commonly from BPH) 1
- Incomplete bladder voiding leading to urinary stasis 1, 3
- Bladder or urethral diverticula 1
- Urethral strictures 1
- Vesicoureteral reflux 1
Instrumentation and Foreign Bodies
- Indwelling urinary catheters carry a 3-8% daily risk of bacteriuria 1
- Long-term catheterization results in virtually 100% bacteriuria rates 1
- Recent urinary tract instrumentation or surgery significantly increases infection risk 1
Prostate-Specific Factors
- Chronic bacterial prostatitis serves as a persistent bacterial reservoir, causing recurrent UTIs 2
- Prostatic inflammation can take 6-8 weeks to resolve, creating prolonged susceptibility 4
- Bacteriuria is common in symptomatic BPH, with studies showing 44.7% of men with BPH having positive urine cultures 3
Medical Comorbidities
- Diabetes mellitus increases UTI risk, though the effect is less pronounced in men than women 1
- Immunosuppression from any cause 1
- Neurologic conditions affecting bladder function (spinal cord injury patients have 23-89% bacteriuria rates) 1
Microbiology
The bacterial spectrum in men differs from uncomplicated UTIs in women 1:
- E. coli remains most common (47.6% in BPH patients), but accounts for a smaller proportion than in women 1, 3
- Other organisms are more prevalent: Proteus spp., Klebsiella spp., Pseudomonas spp., Enterococcus spp., and coagulase-negative staphylococci 1, 3
- Antimicrobial resistance is more common in male UTIs due to the complicated nature and frequent antibiotic exposure 1, 3
Clinical Implications
Why UTIs in Men Are Considered "Complicated"
By definition, UTIs in males are generally considered complicated infections because 1, 5:
- An underlying anatomical or functional abnormality usually exists 2
- Prostatitis cannot be excluded in most cases, requiring longer treatment (14 days vs. 3-7 days) 1, 4
- Higher rates of antimicrobial resistance necessitate urine culture and susceptibility testing 1, 5
Key Pitfalls to Avoid
- Never assume a male UTI is uncomplicated without thorough evaluation for underlying causes 2, 5
- Always obtain urine culture before treatment in men, as empiric therapy may fail due to resistance patterns 1, 5
- Consider prostatitis in all men with UTI symptoms, as this requires prolonged antibiotic therapy (4-12 weeks for chronic bacterial prostatitis) 4, 2
- Evaluate for BPH in men >60 years with recurrent UTIs, as surgical management may be needed for definitive treatment 1