What is the recommended treatment for streptococcus pyogenes skin infection?

Treatment for Streptococcus pyogenes Skin Infection

Penicillin remains the first-line treatment for all Streptococcus pyogenes skin infections, with 100% of strains maintaining susceptibility to this antibiotic. 1, 2

Treatment Selection Based on Infection Type

Impetigo and Ecthyma

For limited lesions:

• Topical mupirocin or retapamulin twice daily for 5 days is recommended 1
• Mupirocin is the superior topical agent, though resistance has been described 1
• Other topical agents like bacitracin and neomycin are considerably less effective 1

For numerous lesions or when topical therapy fails:

• Oral penicillin is the treatment of choice when cultures confirm streptococci alone 1
• A 7-day regimen with an agent active against S. aureus is recommended when cultures are not obtained or show mixed infection 1
• Dicloxacillin or cephalexin are recommended because S. aureus isolates from impetigo are usually methicillin-susceptible 1
• Treatment must continue for at least 10 days for any S. pyogenes infection to prevent acute rheumatic fever 3

Important caveat: The decision to use anti-staphylococcal coverage empirically is critical because beta-lactamase-producing S. aureus can protect S. pyogenes from penicillin in mixed infections, leading to treatment failure 4

Erysipelas

Penicillin, given either parenterally or orally depending on clinical severity, is the treatment of choice 1, 2

• Oral penicillin V is appropriate for mild cases 2
• Intravenous penicillin is indicated for moderate to severe infections with systemic signs 1

Cellulitis

For diffuse cellulitis unassociated with a defined portal (typically streptococcal):

• Penicillin is the preferred agent 1, 2
• However, because distinguishing streptococcal from staphylococcal cellulitis clinically is unreliable, a penicillinase-resistant semisynthetic penicillin or first-generation cephalosporin should be selected empirically 1, 5
• This approach covers both S. pyogenes and S. aureus 1, 5

For moderate infection with systemic signs:

• Oral beta-lactam antibiotics are appropriate 1

For severe infection with failed oral treatment, systemic signs, or immunocompromise:

• Intravenous therapy is required 1

Alternative Regimens for Penicillin-Allergic Patients

For non-immediate hypersensitivity:

• First-generation cephalosporins (cephalexin) are recommended 2

For immediate-type penicillin allergy:

• Erythromycin or other macrolides (azithromycin) 2, 6
• Clindamycin for severe infections 2
• Note: Macrolide resistance is increasing (8-9% in the US), and clindamycin resistance can reach up to 50% in some regions 2

Treatment Duration

• Minimum 48-72 hours beyond symptom resolution or evidence of bacterial eradication 2, 3
• At least 10 days of treatment for any S. pyogenes infection to prevent acute rheumatic fever 1, 3
• Some infections may require several weeks of therapy 3
• Clinical and/or bacteriological follow-up for several months after cessation may be necessary 3

Special Considerations

During outbreaks of poststreptococcal glomerulonephritis:

• Systemic antimicrobials should be used to help eliminate nephritogenic strains of S. pyogenes from the community 1
• Note: No data demonstrate that treatment of impetigo prevents glomerulonephritis in individual patients 1

When MRSA is suspected or confirmed in mixed infections:

• Doxycycline, clindamycin, or trimethoprim-sulfamethoxazole are recommended 1

For necrotizing fasciitis caused by S. pyogenes:

• Penicillin plus clindamycin is recommended 1
• Urgent surgical debridement is mandatory in addition to antibiotics 2

Common Pitfalls to Avoid

• Do not use penicillin monotherapy empirically for skin infections without culture confirmation because mixed infections with beta-lactamase-producing S. aureus will fail treatment 4
• Do not use agents with poor activity against common co-pathogens (dicloxacillin, cephalexin, erythromycin have poor activity against Pasteurella in bite wounds) 1
• Do not discontinue treatment before 10 days for confirmed S. pyogenes infections due to rheumatic fever risk 1, 3
• Aspiration of cellulitis is unhelpful in 75-80% of cases, and blood cultures are rarely positive (<5%) 1