Antibiotic Prophylaxis for Stab Wound to the Knee
For a stab wound to the knee, administer amoxicillin-clavulanate 875/125 mg orally twice daily for 3-5 days, starting as soon as possible after injury. 1
Rationale for Antibiotic Treatment
Knee wounds are high-risk and warrant antibiotic prophylaxis because they involve areas near joints, which are critical anatomical locations with elevated infection risk and potential for devastating complications including septic arthritis. 2
The knee joint proximity makes this a contaminated wound requiring therapeutic antibiotics rather than simple prophylaxis, as infection at this site could lead to permanent joint damage. 2
Antibiotics should be initiated within 3 hours of injury, as delays beyond this timeframe significantly increase infection risk. 2, 1
First-Line Antibiotic Selection
Amoxicillin-clavulanate is the preferred oral antibiotic for traumatic open wounds, providing broad coverage against Staphylococcus aureus, streptococci, and gram-negative organisms commonly found in these wounds. 1
Standard adult dosing is 875/125 mg twice daily or 500/125 mg three times daily. 1
This agent is superior to first-generation cephalosporins alone, which should be avoided as monotherapy for contaminated wounds due to poor activity against common wound pathogens. 1
Alternative Options for Penicillin Allergy
For patients with penicillin allergy, doxycycline 100 mg twice daily is the recommended alternative. 1
Ciprofloxacin may also be considered due to its broad-spectrum coverage, bactericidal activity, and good oral bioavailability. 2, 1
Moxifloxacin or levofloxacin can serve as alternatives for patients with multiple antibiotic allergies. 1
Duration of Therapy
Continue antibiotics for 3-5 days depending on wound severity, contamination level, and clinical response. 2, 1
This duration is appropriate for fresh, deep wounds in critical bodily areas such as joints. 2
Essential Wound Management
Perform thorough wound irrigation with normal saline before antibiotic administration—this is critical for removing foreign bodies and reducing bacterial load. 1
Deep irrigation under pressure is not recommended as it may spread bacteria into deeper tissue layers. 2
Surgical debridement of any necrotic tissue should be performed to mechanically reduce pathogen burden. 2
Common Pitfalls to Avoid
Do not delay antibiotic administration beyond 3 hours post-injury, as this significantly increases infection risk. 2, 1
Avoid using first-generation cephalosporins (like cephalexin), penicillinase-resistant penicillins, macrolides, or clindamycin as monotherapy for this contaminated wound—they have inadequate coverage for gram-negative organisms commonly present. 1
Do not withhold antibiotics if the patient presents within 24 hours of injury with a deep wound near a joint, even if no signs of infection are present yet. 2
Target Pathogen Coverage
The primary pathogens requiring coverage are Staphylococcus aureus (including beta-lactamase-producing strains), streptococci, and aerobic gram-negative bacilli. 2, 3
For grossly contaminated wounds (soil, fecal matter), consider adding anaerobic coverage, which amoxicillin-clavulanate already provides. 1