What is the recommended antibiotic prophylaxis regimen for a typical adult with a fresh stab wound, including indications, first‑line agents, alternatives, tetanus management, and considerations for MRSA?

Antibiotic Prophylaxis for Stab Wounds

For fresh stab wounds, antibiotic prophylaxis is NOT universally recommended—only high-risk wounds require antibiotics, with amoxicillin-clavulanate 875/125 mg twice daily for 3–5 days as first-line therapy. 1

Indications for Antibiotic Prophylaxis

Most simple stab wounds do NOT require prophylactic antibiotics. The infection rate in clean, simple wounds is extremely low (approximately 1%), and universal prophylaxis is not recommended. 2, 1

High-Risk Wounds Requiring Antibiotics:

Prophylactic antibiotics are indicated for stab wounds with the following characteristics:

• Deep wounds penetrating periosteum, joint capsule, or involving significant tissue depth 3, 1
• Critical anatomic locations: hands, feet, face, genitals, or areas near joints 2, 3
• Significant contamination with soil, debris, or fecal matter 4
• Pre-existing or resultant edema at the wound site 3, 1
• Moderate to severe injuries with extensive tissue damage 2, 1

Patient-Specific Risk Factors:

• Immunocompromised patients (including those on immunosuppressive drugs) 2, 1
• Asplenic patients 1
• Advanced liver disease 1
• Patients with prosthetic implants (artificial heart valves, joint prostheses) 2

Timing Considerations:

• Antibiotics should NOT be given if the patient presents ≥24 hours after injury without signs of infection 2
• For indicated wounds, start antibiotics as soon as possible, ideally within 3 hours of injury 3, 5

First-Line Antibiotic Regimen

Amoxicillin-clavulanate 875/125 mg orally twice daily for 3–5 days is the first-line agent for high-risk stab wounds. 2, 3, 1

This combination provides coverage against:

• Staphylococcus aureus (including some methicillin-sensitive strains) 2
• Streptococcus species 2
• Anaerobic bacteria (Bacteroides, Prevotella, Fusobacterium) 2
• Gram-negative organisms commonly found in contaminated wounds 2

Duration of Therapy:

• High-risk wounds: 3–5 days 2, 3, 1
• Contaminated wounds requiring therapeutic (not prophylactic) antibiotics: 48–72 hours 3, 1

Alternative Regimens

For β-Lactam Allergy:

Oral options:

• Doxycycline 100 mg twice daily PLUS metronidazole 500 mg three times daily 2, 1
• Moxifloxacin 400 mg once daily (provides both aerobic and anaerobic coverage as monotherapy) 2
• Levofloxacin 750 mg once daily PLUS metronidazole 500 mg three times daily 2

For Severe/Hospitalized Patients:

Intravenous options:

• Ampicillin-sulbactam 1.5–3.0 g every 6 hours 2
• Piperacillin-tazobactam 3.37 g every 6–8 hours 2
• Ceftriaxone 1 g every 12 hours PLUS metronidazole 500 mg every 8 hours 2

MRSA Considerations

Empiric MRSA coverage is NOT routinely required for simple stab wounds. 2

Indications for Empiric MRSA Coverage:

Consider adding MRSA-active therapy in the following scenarios:

• Prior history of MRSA infection or colonization 2
• High local prevalence of MRSA in your community or hospital 2
• Clinically severe infection with systemic toxicity 2
• Purulent drainage from the wound (suggests abscess formation) 2
• Failure to respond to initial β-lactam therapy 2

MRSA-Active Agents (if indicated):

Oral options:

• Trimethoprim-sulfamethoxazole (TMP-SMX) 1–2 double-strength tablets twice daily 2
• Doxycycline 100 mg twice daily 2
• Clindamycin 300–450 mg three times daily 2
• Linezolid 600 mg twice daily 2

Important caveat: TMP-SMX and doxycycline lack reliable streptococcal coverage, so if β-hemolytic streptococci are a concern, add amoxicillin 500 mg three times daily or use clindamycin or linezolid as monotherapy. 2

Intravenous options for hospitalized patients:

• Vancomycin (dose based on weight and renal function) 2
• Linezolid 600 mg IV twice daily 2
• Daptomycin 4 mg/kg IV once daily 2

Tetanus Management

All patients with stab wounds require tetanus prophylaxis assessment. 2

Tetanus Toxoid Administration:

• Administer tetanus toxoid if the patient has not received vaccination within 10 years 2
• Tdap (tetanus, diphtheria, pertussis) is preferred over Td if the patient has not previously received Tdap 2

Tetanus Immune Globulin (TIG):

For contaminated or deep wounds in patients with:

• Unknown or incomplete primary tetanus vaccination series (fewer than 3 doses)
• Last tetanus booster >5 years ago

Give TIG 250 units intramuscularly in addition to tetanus toxoid. 2

Wound Management Principles

Antibiotics are NOT a substitute for proper wound care. 1

Essential Wound Care Steps:

• Thorough irrigation with copious amounts of normal saline (avoid high-pressure irrigation in deep wounds, as this may drive bacteria deeper) 2
• Debridement of devitalized tissue and removal of foreign bodies 2
• Primary closure is appropriate for most fresh, clean stab wounds presenting within 6–12 hours 6
• Delayed closure should be considered for heavily contaminated wounds or those presenting >12–24 hours after injury 2

Common Pitfalls to Avoid

• Do NOT prescribe antibiotics for clean, simple stab wounds—this contributes to antimicrobial resistance without clinical benefit 1, 6
• Do NOT continue antibiotics beyond 3–5 days for prophylaxis—longer courses do not reduce infection rates and increase resistance 2, 4
• Do NOT give antibiotics to wounds presenting >24 hours after injury without signs of infection—prophylaxis is ineffective at this point 2
• Do NOT rely on antibiotics alone—inadequate wound cleaning and debridement cannot be compensated by antimicrobial therapy 1
• Do NOT add rifampin as monotherapy or adjunctive therapy for stab wounds—it is not recommended 2

Culture Recommendations

Obtain wound cultures in the following situations:

• Purulent drainage or abscess formation 2
• Signs of systemic infection (fever, tachycardia, hypotension) 2
• Failure to respond to initial antibiotic therapy 2
• Immunocompromised patients 2

Technique: After cleansing and debriding the wound, obtain tissue specimens by scraping the wound base with a sterile scalpel or curette, or aspirate purulent material with a sterile needle and syringe. Send for aerobic and anaerobic culture. 2