What antibiotics are recommended for a patient with a scrotal injury, considering potential allergies and underlying conditions?

Antibiotic Management for Scrotal Injury

For pure traumatic scrotal injury without signs of infection, antibiotics are not indicated—treatment consists of bed rest, scrotal elevation, and analgesics. 1 However, you must immediately rule out bacterial infection, as any evidence of urethritis, pyuria, or fever mandates treatment as bacterial epididymo-orchitis rather than simple trauma. 1

Critical Initial Assessment

Before deciding on antibiotics, you must distinguish between pure trauma and infectious etiology:

Mandatory Diagnostic Steps

• Obtain urethral swab or first-void urine for Gram stain (looking for >5 polymorphonuclear leukocytes per oil immersion field), culture, and nucleic acid amplification testing for Chlamydia trachomatis and Neisseria gonorrhoeae 1, 2
• Check midstream urine for culture, nitrite, and leukocytes 2
• Assess for urethral discharge indicating urethritis 1, 2
• Rule out testicular torsion immediately if pain onset is sudden and severe, particularly in adolescents—this is a surgical emergency requiring urgent exploration, not antibiotics 2, 1

Signs That Mandate Antibiotic Treatment

If any of the following are present, treat as bacterial infection, not pure trauma:

• Fever (>38°C) 2
• Urethral discharge or urethritis 1, 2
• Pyuria or positive urine culture 1
• Systemic inflammatory response (tachycardia >90 bpm, tachypnea >24/min, WBC >12,000 or <4,000) 2

Antibiotic Regimens When Infection Is Confirmed

Age-Based Treatment Algorithm

For men under 35 years (sexually transmitted pathogens likely):

• Ceftriaxone 1000 mg IM or IV single dose PLUS doxycycline 100 mg orally twice daily for 10 days 2, 1, 3
• This covers N. gonorrhoeae and C. trachomatis, the most common pathogens in this age group 2

For men over 35 years (enteric organisms predominate):

• Levofloxacin 500 mg orally once daily for 10 days OR ofloxacin 300 mg orally twice daily for 10 days 1, 2
• Fluoroquinolones provide coverage against Enterobacterales (E. coli, Klebsiella), which are more common in older men 2
• Do not use doxycycline alone in this age group, as it lacks adequate coverage for enteric organisms 2

Severe Infection Requiring Parenteral Therapy

If the patient has severe systemic toxicity, hypotension, or extensive tissue involvement suggesting necrotizing infection (Fournier's gangrene):

• Piperacillin-tazobactam 4.5 g IV every 6-8 hours PLUS vancomycin 15 mg/kg IV every 12 hours 2
• Alternative: Meropenem 1 g IV every 8 hours or imipenem-cilastatin 1 g IV every 6-8 hours 2
• Immediate surgical consultation is mandatory—antibiotics alone are insufficient for necrotizing soft tissue infections 2

Conservative Management for Pure Trauma (No Infection)

If all microbiological testing is negative and no signs of infection exist:

• Bed rest until local inflammation subsides 1, 2
• Scrotal elevation using rolled towels or supportive underwear 1, 2
• Oral analgesics for pain control 1, 4
• No antibiotics indicated 1

Critical Reassessment Timeline

Patients must return within 72 hours if no improvement occurs. 1, 5 Failure to improve mandates:

• Re-evaluation of diagnosis (consider testicular torsion, tumor, abscess, testicular cancer) 1, 2
• Scrotal ultrasound to rule out abscess formation 2
• Blood cultures and complete blood count if sepsis is suspected 5
• Surgical evaluation if necrotizing infection is possible 5

Special Populations

Immunocompromised or HIV-Positive Patients

• Use the same initial antibiotic regimens (age-based as above) 6, 2
• Maintain higher suspicion for atypical organisms (fungi, mycobacteria, Mycoplasma) if treatment fails 6, 2
• Consider broader diagnostic workup including fungal and mycobacterial cultures if no response after 72 hours 2

Penicillin-Allergic Patients

For sexually transmitted epididymitis in penicillin-allergic patients:

• Levofloxacin 500 mg daily for 10 days (covers both gonorrhea and chlamydia) 2
• Alternative: Azithromycin 1 g single dose for chlamydia coverage, but requires separate gonorrhea treatment 6

Common Pitfalls to Avoid

1. Do not assume all scrotal swelling after trauma requires antibiotics—pure traumatic injury without infection does not benefit from antimicrobials 1

2. Do not delay surgical evaluation if necrotizing infection is suspected—7.3% of severe genitourinary infections progress to urosepsis, and mortality is high without prompt debridement 5, 7

3. Do not use doxycycline alone in men over 35—enteric organisms predominate and require fluoroquinolone coverage 2

4. Do not miss testicular torsion—if diagnostic uncertainty exists, urgent surgical exploration takes precedence over antibiotics 2, 1

5. Do not prescribe antibiotics for chronic scrotal pain syndrome—only 22% of these cases have clinically relevant bacteria, and widespread antibiotic use is not justified 8