What is the recommended treatment for a patient with a streptococcal (strep) skin infection?

Treatment of Streptococcal Skin Infections

For streptococcal skin infections, penicillin remains the first-line treatment, with intravenous penicillin G (2-4 million units every 4-6 hours for adults; 100,000 units/kg/day for children) recommended for moderate to severe infections. 1

First-Line Antibiotic Therapy

Parenteral Treatment (Moderate to Severe Infections)

• Penicillin G is the drug of choice: 2-4 million units IV every 4-6 hours for adults, or 100,000 units/kg/day for children 1
• For severe infections with systemic toxicity or necrotizing features, add clindamycin (600-900 mg IV every 8 hours for adults; 10-13 mg/kg every 8 hours for children) to penicillin, as clindamycin suppresses toxin production 1, 2

Oral Treatment (Mild Infections)

• Penicillin VK 250-500 mg every 6 hours for adults is appropriate for mild, non-systemic infections 1, 3
• Amoxicillin 500 mg every 12 hours or 250 mg every 8 hours for adults (25 mg/kg/day divided every 12 hours or 20 mg/kg/day divided every 8 hours for children) is an acceptable alternative 1, 4

Alternative Agents for Penicillin-Allergic Patients

Non-Severe Penicillin Reactions

• First-generation cephalosporins (cefazolin 1 g IV every 8 hours for adults; 33 mg/kg/dose for children) can be used unless there is a history of immediate hypersensitivity 1, 5
• Cephalexin 500 mg every 6 hours orally is effective for mild infections in penicillin-allergic patients without anaphylaxis history 6

Severe Penicillin Allergy

• Clindamycin 600 mg IV every 8 hours or 300-450 mg orally four times daily for adults (25-40 mg/kg/day IV in 3 divided doses or 30-40 mg/kg/day orally in 3 divided doses for children) 1, 7
• Vancomycin 15 mg/kg every 12 hours IV should be reserved for severe penicillin allergy or treatment failures 1, 5
• Other alternatives include linezolid (600 mg every 12 hours IV or orally), daptomycin (4 mg/kg every 24 hours IV), or ceftaroline (600 mg twice daily IV) 1

Treatment Duration and Monitoring

• Minimum treatment duration is 7 days, but therapy should be extended if infection has not improved within this timeframe 1
• For any Group A Streptococcus infection, treat for at least 10 days to prevent acute rheumatic fever 4, 7, 3
• Reevaluate patients within 24-48 hours to verify clinical response 5
• Treatment should continue for 48-72 hours beyond resolution of fever and clinical improvement 1

Severity-Based Treatment Algorithm

Mild Infections (No Systemic Signs)

• Outpatient oral therapy with penicillin VK or amoxicillin targeting streptococci 1
• Elevation of affected area and treatment of predisposing factors (edema, toe web abnormalities) 1

Moderate Infections (Systemic Signs Present)

• Systemic antibiotics are mandatory 1
• Consider adding coverage for methicillin-susceptible S. aureus (MSSA) as many clinicians encounter mixed infections 1
• Hospitalization if outpatient treatment fails or adherence concerns exist 1

Severe Infections (SIRS, Penetrating Trauma, or Necrotizing Features)

• Vancomycin plus piperacillin-tazobactam or a carbapenem for empiric broad-spectrum coverage 1
• For confirmed Group A Streptococcus necrotizing fasciitis: penicillin PLUS clindamycin is mandatory 1, 2
• Urgent surgical consultation and debridement for suspected necrotizing infection 1

Special Considerations

Abscess Management

• Incision and drainage is the primary intervention for any abscess formation 5
• Antimicrobial therapy should accompany drainage when systemic signs are present 5
• Obtain cultures from abscesses to guide therapy, especially in severe infections or treatment failures 5

Polymicrobial Infections

• When S. anginosus or other mixed flora are suspected, broader coverage with ampicillin-sulbactam or piperacillin-tazobactam may be necessary 5

Recurrent Infections

• After obtaining cultures, treat with a 5-10 day course of pathogen-directed antibiotics 1
• Consider 5-day decolonization regimen: intranasal mupirocin twice daily, daily chlorhexidine washes, and decontamination of personal items for recurrent S. aureus (not streptococcal) infections 1
• For patients with 3-4 episodes of cellulitis per year, prophylactic oral penicillin or erythromycin twice daily for 4-52 weeks, or intramuscular benzathine penicillin every 2-4 weeks should be considered 1

Common Pitfalls to Avoid

• Do not rely on oral therapy in patients with severe illness, nausea, vomiting, or gastrointestinal hypermotility, as absorption may be inadequate 3
• Never use β-lactam antibiotics alone for streptococcal toxic shock syndrome—clindamycin must always be included to suppress toxin production 2
• Do not obtain routine cultures for typical uncomplicated cellulitis, but do obtain blood cultures and consider tissue cultures in immunocompromised patients, neutropenia, or severe infections 1
• Avoid inadequate treatment duration—stopping before 10 days for Group A Streptococcus risks acute rheumatic fever 4, 7, 3
• Do not delay surgical intervention when necrotizing fasciitis is suspected—early debridement is paramount 2