Is it effective to use Augmentin (amoxicillin-clavulanate) and Keflex (cephalexin) together to treat a skin infection in an adult patient?

Using Augmentin and Keflex Together for Skin Infection

Combining Augmentin (amoxicillin-clavulanate) and Keflex (cephalexin) for skin infections is unnecessary and represents inappropriate polypharmacy—you should use one beta-lactam agent, not both simultaneously. 1

Why Combination is Inappropriate

Both Augmentin and Keflex are beta-lactam antibiotics with overlapping spectra of activity against the primary pathogens in skin infections: beta-hemolytic streptococci and methicillin-sensitive Staphylococcus aureus (MSSA). 2, 1 Using both agents together provides no additional antimicrobial coverage beyond what either agent achieves alone, while doubling the risk of adverse effects and unnecessarily increasing antibiotic exposure. 1

Beta-lactam monotherapy is the standard of care for typical uncomplicated cellulitis, with a 96% success rate. 1 The Infectious Diseases Society of America explicitly recommends single-agent therapy with penicillin, amoxicillin, amoxicillin-clavulanate, dicloxacillin, cephalexin, or clindamycin for nonpurulent cellulitis. 2, 1

Choosing Between Augmentin and Keflex

When to Use Keflex (Cephalexin)

Use cephalexin 500 mg orally every 6 hours for typical nonpurulent cellulitis without specific risk factors. 1 Cephalexin provides excellent coverage against streptococci and MSSA, which are the primary pathogens in 96% of typical cellulitis cases. 1, 3 Cephalexin has demonstrated cure rates of 90% or higher in streptococcal and staphylococcal skin infections over 12 years of clinical experience. 3

Cephalexin is appropriate when:

• The cellulitis is nonpurulent (no drainage or exudate) 1
• No MRSA risk factors are present (no penetrating trauma, injection drug use, or known MRSA colonization) 1
• No systemic inflammatory response syndrome (SIRS) is present 1

When to Use Augmentin (Amoxicillin-Clavulanate)

Use Augmentin 875/125 mg twice daily specifically for bite-associated cellulitis (animal or human bites). 2, 1 Augmentin provides single-agent coverage for the polymicrobial oral flora commonly found in bite wounds, including Pasteurella multocida and anaerobes. 2

Augmentin is appropriate when:

• The infection is associated with an animal or human bite 2, 1
• Polymicrobial coverage including anaerobes is needed 2
• The patient cannot take other beta-lactams due to specific contraindications 2

Treatment Duration

Treat for 5 days if clinical improvement occurs; extend only if symptoms have not improved within this timeframe. 1 This applies to both cephalexin and Augmentin when used appropriately. 1 Traditional 7-14 day courses are no longer necessary for uncomplicated cases. 1

When MRSA Coverage is Actually Needed

If MRSA coverage is required (penetrating trauma, purulent drainage, injection drug use, or MRSA risk factors), neither Augmentin nor Keflex alone is adequate. 1 In these scenarios:

• Use clindamycin 300-450 mg orally four times daily as monotherapy (covers both streptococci and MRSA) 1, 4
• Or combine trimethoprim-sulfamethoxazole 1-2 double-strength tablets twice daily PLUS a beta-lactam 1
• Or use doxycycline 100 mg twice daily PLUS a beta-lactam 1

Common Pitfall to Avoid

Do not combine multiple antibiotics when monotherapy is appropriate, as this increases adverse effects without improving outcomes. 1 The reflexive addition of multiple agents represents overtreatment and contributes to antibiotic resistance. 1 Choose the single most appropriate agent based on the specific clinical scenario—bite wound versus typical cellulitis—and use that agent alone. 1