How do I distinguish epididymitis from acute bacterial prostatitis and what are the recommended antibiotic regimens for each condition?

Distinguishing Epididymitis from Acute Bacterial Prostatitis

Epididymitis presents with gradual onset of unilateral posterior scrotal pain with palpable epididymal swelling and tenderness, while acute bacterial prostatitis presents with pelvic pain, systemic symptoms (fever, chills, malaise), and a tender, boggy prostate on digital rectal examination. 1, 2

Clinical Differentiation

Epididymitis Key Features

• Pain location and onset: Gradual onset over hours to days of unilateral posterior scrotal pain, typically beginning at the lower pole of the epididymis and progressing upward 3, 1
• Physical examination: Palpable swelling and tenderness localized to the epididymis with the testis in anatomically normal position; positive Prehn sign (pain relief with scrotal elevation) 3, 4
• Associated symptoms: May have urethral discharge, dysuria, or urinary frequency in younger men with STI-related disease 5
• Systemic symptoms: Usually absent unless severe complications develop 3

Acute Bacterial Prostatitis Key Features

• Pain location: Pelvic pain, perineal discomfort, or suprapubic pain—not primarily scrotal 2
• Physical examination: Digital rectal exam reveals tender, enlarged, or boggy prostate; avoid vigorous prostatic massage as it may precipitate bacteremia 2
• Systemic symptoms: Fever, chills, nausea, emesis, and malaise are common and often prominent 2
• Urinary symptoms: Dysuria, urinary frequency, urgency, and potentially urinary retention due to prostatic inflammation blocking urinary flow 6, 2

Critical Diagnostic Pitfall

• Always exclude testicular torsion first in any patient presenting with acute scrotal pain, especially with sudden onset, severe pain, or in adolescents—this is a surgical emergency requiring intervention within 4-6 hours to preserve testicular viability 3, 4

Diagnostic Workup

For Suspected Epididymitis

• Urethral Gram stain: Look for ≥5 polymorphonuclear leukocytes per oil immersion field indicating urethritis 5
• Nucleic acid amplification test (NAAT): Obtain from urethral swab or first-void urine for N. gonorrhoeae and C. trachomatis 5, 3
• Urine culture: Examine first-void uncentrifuged urine for leukocytes and culture for Gram-negative bacteria, particularly in men >35 years 5, 3
• Age-specific approach: In men <35 years, urethral swab testing is essential as urinalysis alone misses most STI-related cases; in men ≥35 years, urine culture is more diagnostic 4

For Suspected Acute Bacterial Prostatitis

• Urinalysis and urine culture: Mandatory in all patients to identify the causative organism and guide antibiotic selection 2
• Digital rectal examination: Assess for tender, enlarged, or boggy prostate, but avoid vigorous massage 2
• Additional labs based on severity: Complete blood count, blood cultures if systemically ill, and consider prostate-specific antigen (though it will be elevated acutely) 2

Antibiotic Regimens

Epididymitis Treatment (Age-Based)

Men <35 Years (Sexually Transmitted Etiology)

Recommended regimen: Ceftriaxone 250 mg IM single dose PLUS doxycycline 100 mg orally twice daily for 10 days 5, 3

• This dual therapy covers both N. gonorrhoeae (ceftriaxone) and C. trachomatis (doxycycline) 3, 1
• Doxycycline monotherapy is insufficient for gonorrhea and will lead to treatment failure 3

Men Who Practice Insertive Anal Intercourse

Recommended regimen: Ceftriaxone 250 mg IM single dose PLUS levofloxacin 500 mg orally once daily for 10 days 3, 1

• This covers both STI pathogens and enteric organisms such as E. coli 3

Men ≥35 Years (Enteric Organism Etiology)

Recommended regimen: Levofloxacin 500 mg orally once daily for 10 days OR ofloxacin 300 mg orally twice daily for 10 days 5, 3, 1

• Fluoroquinolones provide excellent tissue penetration and cover Gram-negative enteric bacteria, particularly E. coli 3, 7

Acute Bacterial Prostatitis Treatment

Outpatient Management (Mild-Moderate Cases)

Recommended regimen: Fluoroquinolone therapy—ciprofloxacin or levofloxacin—for 4-6 weeks 6, 2

• The prolonged duration (4-6 weeks) is necessary for adequate prostatic tissue penetration and eradication of infection 6
• Alternative: Ceftriaxone PLUS doxycycline can be used, though fluoroquinolones are preferred for prostatic penetration 2

Inpatient Management (Severe Cases)

Hospitalization criteria: Systemic illness with high fever, inability to urinate voluntarily, inability to tolerate oral intake, or risk factors for antibiotic resistance 2

Recommended IV regimen: Broad-spectrum therapy with ceftriaxone PLUS doxycycline, ciprofloxacin IV, or piperacillin/tazobactam 2

• Transition to oral fluoroquinolone once clinically improved to complete 4-6 weeks total 6, 2

Adjunctive Measures and Follow-Up

For Epididymitis

• Supportive care: Bed rest, scrotal elevation, scrotal supporter, and analgesics until fever and inflammation resolve 3, 4
• Reassessment at 72 hours: If no improvement, re-evaluate diagnosis and consider alternative diagnoses (abscess, tumor, torsion) or change antibiotics based on culture results 3, 4
• Partner management: All sexual partners from the preceding 60 days must be evaluated and treated empirically for STIs; abstain from sexual activity until both patient and partners complete therapy 5, 3

For Acute Bacterial Prostatitis

• Bladder drainage: May require urethral or suprapubic catheterization if urinary retention develops 6
• Follow-up: Monitor clinical response; persistent symptoms after appropriate therapy warrant investigation for prostatic abscess or chronic bacterial prostatitis 6, 2

Common Pitfalls to Avoid

• Failing to exclude testicular torsion in any acute scrotal pain presentation—maintain high suspicion with sudden onset or severe pain 3, 4
• Using inadequate antibiotic duration for prostatitis—4-6 weeks is required, not the 10 days used for epididymitis 6, 2
• Monotherapy in young men with epididymitis—single-agent therapy fails to cover both gonorrhea and chlamydia 3
• Relying solely on urinalysis in men <35 years—urethral swab testing is essential as STI-related epididymitis often presents without significant pyuria 4
• Vigorous prostatic massage in acute bacterial prostatitis—this may precipitate bacteremia 2