What is the difference between a Urinary Tract Infection (UTI) and a Sexually Transmitted Infection (STI) in adult males?

Difference Between UTI and STI in Adult Males

Urinary tract infections (UTIs) and sexually transmitted infections (STIs) are fundamentally different conditions in adult males: UTIs involve bladder or kidney infections caused by enteric bacteria like E. coli and are NOT sexually transmitted, while STIs cause urethritis through sexually transmitted pathogens like Chlamydia trachomatis and Neisseria gonorrhoeae and require partner notification and treatment. 1, 2

Key Distinguishing Features

Anatomic Location and Pathophysiology

• UTIs affect the bladder (cystitis), kidneys (pyelonephritis), or prostate in males, caused predominantly by E. coli and other enteric Gram-negative bacteria that ascend from the gastrointestinal tract 1, 3
• STIs cause urethritis (inflammation of the urethra itself) through sexually transmitted organisms including C. trachomatis, N. gonorrhoeae, Mycoplasma genitalium, Ureaplasma urealyticum, and Trichomonas vaginalis 1
• Bladder infections do NOT spread person-to-person like gonorrhea or chlamydia 2

Clinical Presentation

UTI symptoms in males:

• Dysuria with bladder or suprapubic discomfort 1
• Urinary frequency and urgency 1
• Fever, flank pain, and systemic symptoms if pyelonephritis or complicated UTI 1
• Rare in young men without anatomic abnormalities or instrumentation 3, 4

STI/Urethritis symptoms:

• Mucopurulent or purulent urethral discharge 1
• Dysuria with urethral pruritis (itching) 1
• Many infections are completely asymptomatic 1
• Symptoms often milder than gonorrhea when caused by chlamydia 1

Diagnostic Approach

For suspected UTI:

• Urine culture is the gold standard, with ≥10,000 CFU/mL considered positive in symptomatic males 1, 3
• Urinalysis showing pyuria and bacteriuria supports diagnosis 1
• Consider anatomic abnormalities or recent instrumentation in young men 3, 4

For suspected urethritis/STI:

• Gram stain of urethral discharge showing ≥5 polymorphonuclear leukocytes per oil immersion field confirms urethritis 1
• Gram-negative intracellular diplococci on Gram stain is diagnostic for gonorrhea in symptomatic men (>99% specificity) 1
• Nucleic acid amplification tests (NAATs) on first-void urine or urethral swabs detect N. gonorrhoeae and C. trachomatis with superior sensitivity 1
• If Gram stain shows no intracellular diplococci, diagnose as nongonococcal urethritis (NGU) 1

Critical Diagnostic Pitfall

• Pyuria and abnormal urinalysis occur with BOTH UTIs and STIs, making urinalysis alone unreliable for distinguishing between them 5, 6, 7
• A study found that 92% of women with genitourinary symptoms had abnormal urinalysis findings, but only 41% actually had positive urine cultures 6
• Overdiagnosis of UTI and underdiagnosis of STI is extremely common, leading to unnecessary antibiotics and missed partner treatment 6, 7
• Research demonstrates that concurrent bacterial UTI and STI is unlikely—they are typically distinct entities 5

Treatment Implications

UTI Management

• Treat with antibiotics targeting enteric organisms: amoxicillin-clavulanate, fluoroquinolones, or second/third-generation cephalosporins 1, 3
• Duration: 1-2 weeks for cystitis, 4 weeks for acute prostatitis, 6-12 weeks for chronic bacterial prostatitis 4
• Partner notification is NOT required for typical UTIs 2

STI/Urethritis Management

• Doxycycline 100 mg orally twice daily for 7 days is the recommended regimen for NGU 1
• Alternative: Azithromycin 1 g orally as single dose 1
• For gonorrhea, use CDC-recommended cephalosporin-based regimens 1
• Mandatory partner evaluation and treatment to prevent reinfection and ongoing transmission 1, 2

Special Considerations in Males

• Young sexually active men with dysuria should be evaluated for urethritis/STI first, as UTIs are uncommon in this population without anatomic abnormalities 3, 4
• Men over 35 years with epididymitis typically have enteric bacterial causes related to UTI, while men 14-35 years have STI-related epididymitis from C. trachomatis or N. gonorrhoeae 8
• Receptive anal intercourse is a common site for initial chlamydial or gonococcal infection causing proctitis, which requires STI-specific treatment 1, 9
• Insertive anal intercourse followed by vaginal contact can increase UTI risk, and men practicing insertive anal intercourse may develop epididymitis from enteric organisms 2, 9

Algorithm for Clinical Decision-Making

1. Assess sexual history and age: Young sexually active males → suspect STI/urethritis first
2. Examine for urethral discharge: Present → perform Gram stain and NAAT for STIs
3. If no discharge but dysuria: Obtain urethral swab for Gram stain (≥5 WBCs = urethritis) 1
4. If urethritis confirmed: Treat for STI and mandate partner notification 1, 2
5. If no urethritis: Consider UTI, obtain urine culture, evaluate for anatomic abnormalities 1, 3
6. Never rely on urinalysis alone to distinguish UTI from STI 5, 6, 7