Urinary tract infection (lower) - men
Exam Tips
- In UK exams, male UTI is usually treated as complicated: send MSU/CSU for culture before antibiotics and treat for 7 days, not 3 days.
- Do not diagnose solely from dipstick in men; negative dipstick does not safely exclude infection.
- If fever, flank pain, rigors, hypotension, or severe malaise are present, think pyelonephritis/sepsis rather than isolated lower UTI.
- In older adults, new dysuria alone or at least two new urinary/system changes increases likelihood of UTI; isolated delirium or fever should trigger a broader search for causes.
- Nitrofurantoin does not adequately treat prostatitis or upper UTI; tissue penetration is a common viva pitfall.
- For visual memory, revise a diagram of ascending infection, bladder outlet obstruction, and catheter biofilm (core urology/microbiology chapter figure).
Definition
Lower urinary tract infection in men is a symptomatic bacterial infection of the bladder (clinical cystitis) without evidence of prostatitis, epididymo-orchitis, urethritis, or upper tract infection. In UK practice, any male UTI is treated as a potentially complicated infection because structural, functional, or prostatic factors are more common than in women and increase the risk of treatment failure or recurrence.
Pathophysiology
Most infections are ascending: enteric organisms colonise the periurethral area, enter the urethra, then multiply in bladder urine when host clearance is impaired. Male sex usually confers protection (longer urethra, antibacterial prostatic secretions), so infection often implies a facilitating factor such as bladder outlet obstruction (for example BPH), urinary stasis, instrumentation, stones, or catheter biofilm. Escherichia coli remains the commonest pathogen, but in men there is a higher proportion of non-E. coli organisms (for example Klebsiella, Proteus, Enterococcus, Pseudomonas in catheter/structural disease), with occasional haematogenous seeding (for example Staphylococcus aureus). For visual revision, see textbook figures showing ascending infection pathways and catheter biofilm formation.
Risk Factors
- Age over 50 years
- Benign prostatic hyperplasia or other outflow obstruction (stones, urethral stricture)
- Indwelling urinary catheter or intermittent catheterization
- Recent urinary tract instrumentation or urological surgery
- Previous UTI (risk rises with each episode)
- Diabetes mellitus
- Immunosuppression
- Recent hospitalisation or long-term care residence
- Uncircumcised status
- Anal intercourse and other sexual exposure risks
Clinical Features
Symptoms
- Dysuria
- Urinary frequency
- Urgency
- Nocturia
- Suprapubic pain/discomfort
- Visible haematuria
- In older/frail men: atypical presentation such as new confusion, functional decline, or new incontinence
Signs
- Suprapubic tenderness
- Pyrexia may occur but isolated fever is non-specific in older adults
- Visible haematuria
- Systemic instability (tachycardia, hypotension, rigors) suggests sepsis/upper tract disease rather than simple lower UTI
Investigations
Management
Lifestyle Modifications
- Encourage adequate oral hydration and regular voiding
- Provide safety-net advice: seek urgent care for fever, flank pain, vomiting, confusion, or sepsis features
- Optimise catheter care; replace long-term catheter if clinically indicated and send fresh CSU
- Address modifiable contributors (constipation, poor fluid intake, glycaemic control)
Pharmacological Treatment
First-line oral antibiotics for lower UTI in men (empiric, then culture-directed)
- Nitrofurantoin modified-release 100 mg twice daily for 7 days
- Trimethoprim 200 mg twice daily for 7 days (use if low resistance risk or culture susceptible)
Obtain urine culture before treatment where possible. Nitrofurantoin is unsuitable if eGFR is significantly reduced (generally avoid if eGFR <45 mL/min/1.73 m2; short-course cautious use at 30-44 only if benefits outweigh risks). Not for suspected prostatitis or pyelonephritis due to poor tissue penetration.
Alternative oral options when first-line unsuitable (guided by sensitivities/local policy)
- Pivmecillinam 400 mg stat then 200 mg three times daily to complete 7 days
- Cefalexin 500 mg two or three times daily for 7 days
Use culture results and local antimicrobial guidance to refine therapy. Check beta-lactam allergy before cefalexin; monitor for C. difficile risk with broad-spectrum agents.
Supportive pharmacology
- Paracetamol 1 g up to four times daily (max 4 g/day)
Use for pain/fever if no contraindication; avoid masking deterioration and reassess if symptoms persist beyond 48 hours.
Surgical / Interventional
- No routine surgery for simple lower UTI
- Urgent urology input for obstructive uropathy, recurrent infections with structural cause, abscess, or persistent retention
- Procedural management may include catheter change, relief of obstruction, or stone intervention when indicated
Complications
- Acute pyelonephritis
- Bacteraemia and sepsis (higher risk with instrumentation/catheters)
- Acute bacterial prostatitis or prostatic bacterial reservoir causing relapse
- Renal impairment, especially with obstruction or recurrent infection
- Struvite stone formation, particularly with Proteus species
Prognosis
With prompt culture-guided treatment, most men improve clinically within 48-72 hours and recover fully. Prognosis is less favourable when there is delayed treatment, resistant organisms, catheter dependence, urinary obstruction, or significant comorbidity, and these groups have higher recurrence risk and may need urological evaluation.
Sources & References
💊BNF Drug References(3)
- Cefalexin[management.pharmacological]
- Methenamine hippurate[management.pharmacological]
- Trimethoprim[management.pharmacological]
✅NICE Guidelines(1)
- Urinary tract infection (lower) - men[overview]
📖Textbook References(1)
- [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 1334, 1335)[context]