Causes of Cystitis in Men
Cystitis in men is almost always classified as complicated and typically results from underlying urological abnormalities, with bacterial infection most commonly caused by Escherichia coli and other enteric organisms, often associated with prostate disease, urinary obstruction, or instrumentation. 1
Primary Bacterial Pathogens
The microbial spectrum in male cystitis includes:
- E. coli remains the predominant pathogen, causing the majority of infections 2, 3
- Proteus species (Proteus mirabilis), particularly in men with urinary stones 1, 2
- Klebsiella species 1, 2
- Pseudomonas species 1
- Enterococcus species (Enterococcus faecalis) 1
- Serratia species 1
- Staphylococcus saprophyticus 2
The fecal-perineal-urethral route serves as the primary mechanism of infection, with enteric bacteria from rectal flora serving as the reservoir 4.
Underlying Anatomical and Functional Factors
Men require mandatory evaluation for underlying urological abnormalities because isolated cystitis without complicating factors is extremely rare. 1 The 2024 European Association of Urology guidelines emphasize that digital rectal examination should be performed to investigate the possibility of prostate diseases 1, as prostatitis cannot be excluded in most male UTI presentations 1.
Common Predisposing Conditions:
- Prostatic disease (benign prostatic hyperplasia, prostatitis) 1
- Urinary obstruction at any site in the urinary tract 1
- Incomplete bladder emptying 1
- Urinary stones (particularly with urease-producing bacteria like Proteus mirabilis) 1
- Foreign bodies including indwelling catheters 1
- Vesicoureteral reflux 1
- Recent instrumentation or urological procedures 1
- Urethral or bladder diverticula 1
Healthcare-Associated and Resistance Factors
- Catheter-associated infections represent a major cause, with bacteriuria incidence of 3-8% per day of catheterization 1
- Multidrug-resistant organisms and ESBL-producing bacteria are increasingly common in complicated UTIs 1
- Healthcare-associated infections carry higher risk of resistant pathogens 1
- Prolonged catheterization duration is the most important risk factor for catheter-associated UTI development 1
Age-Specific Considerations
Younger Men (<35 years):
- Chlamydia trachomatis and Neisseria gonorrhoeae cause urethritis-associated epididymitis that may present with lower urinary tract symptoms 1, 5
- Sexual activity and sexually transmitted pathogens should be considered 5
Older Men (>35 years):
- Enteric organisms predominate 5
- Prostatic enlargement and incomplete emptying become more significant 1
Important Clinical Pitfall
The key distinction is that "uncomplicated cystitis" by definition is limited to non-pregnant women 1. Any UTI in males is automatically classified as complicated, requiring: