What is the typical cause and treatment of urinary tract infections (UTIs) in adult males?

Urinary Tract Infections in Men: Typical Causes and Treatment

Primary Causative Organism

UTIs in men are usually caused by Escherichia coli, which accounts for approximately 50% of cases, though the microbial spectrum is broader than in women and includes Proteus species, Klebsiella species, Pseudomonas species, and Enterococcus species. 1, 2, 3

• The remaining 50% of male UTIs are caused by other gram-negative enteric organisms and gram-positive species, making male UTIs more diverse in their microbiology compared to female UTIs 4
• Antimicrobial resistance is more common in male UTIs, with documented resistance rates of 53% for amoxicillin, 34% for trimethoprim-sulfamethoxazole, and 22% for ciprofloxacin in some populations 5

Classification as Complicated Infections

All UTIs in men should be considered complicated infections requiring longer treatment duration (14 days) compared to uncomplicated UTIs in women. 1, 6, 7

• This classification is based on anatomical and physiological factors unique to the male genitourinary tract 1
• Most men with UTI have an underlying functional or anatomic abnormality of the genitourinary tract, with prostatic hypertrophy and genitourinary instrumentation being major predisposing factors 4
• Prostatitis cannot be excluded in most initial presentations, necessitating the extended treatment duration 1, 6

First-Line Antibiotic Treatment

Trimethoprim-sulfamethoxazole (TMP-SMX) 160/800 mg twice daily for 14 days is the recommended first-line treatment for men with UTIs when fluoroquinolones should be avoided. 1, 6

Alternative First-Line Options:

• Ciprofloxacin 500-750 mg twice daily for 14 days may be used only when local fluoroquinolone resistance is <10% AND the patient has not used fluoroquinolones in the past 6 months 6, 7, 8
• Levofloxacin 750 mg once daily is an alternative fluoroquinolone option with similar efficacy 6
• Cefpodoxime 200 mg twice daily for 10 days or ceftibuten 400 mg once daily for 10 days are effective oral cephalosporin alternatives 1, 6

Critical Treatment Duration Evidence

A 7-day course of ciprofloxacin is inferior to 14-day treatment in men, achieving only 86% cure rate versus 98% with 14 days. 7

• A shorter 7-day course may be considered ONLY if the patient becomes afebrile within 48 hours and shows clear clinical improvement 1, 6, 7
• Inadequate treatment duration leads to persistent or recurrent infection, particularly when prostate involvement is present 1, 6

Essential Diagnostic Steps

Obtain urine culture and susceptibility testing before initiating antibiotics to guide therapy adjustments. 6, 7

• Dipstick tests are unreliable in men, with sensitivities of only 54% for leukocytes and 38% for nitrite 5
• Digital rectal examination should be performed to evaluate for prostate involvement 1
• Assess for anatomical or functional abnormalities, as these are common in male UTIs 6, 7

Treatment for Severe Presentations

For men with systemic symptoms or severe illness, initiate intravenous therapy with a third-generation cephalosporin as monotherapy, or amoxicillin/second-generation cephalosporin plus aminoglycoside. 6

• For multidrug-resistant organisms, consider ceftazidime-avibactam 2.5 g three times daily, meropenem-vaborbactam 2 g three times daily, or cefiderocol 2 g three times daily 1, 6

Critical Pitfalls to Avoid

Do not use fluoroquinolones if local resistance rates exceed 10%, the patient used them in the past 6 months, or they were recently hospitalized in a urology department. 6, 7

• Fluoroquinolones should NOT be used as first-line agents for uncomplicated UTIs due to FDA warnings about disabling and serious adverse effects 1
• Do not treat asymptomatic bacteriuria in men, as this increases the risk of symptomatic infection and bacterial resistance 1, 6
• Avoid empiric treatment without urine culture in men—40% of symptomatic men may have sterile urine 5
• Beta-lactams including cephalexin are classified as alternative agents with inferior efficacy compared to first-line options 1
• Amoxicillin-clavulanate has high persistent resistance rates (54.5%) in E. coli UTI cohorts, limiting its utility as first-line empirical therapy 1