What is the treatment for Streptococcus pseudoporcinus infection in the throat?

Treatment of Streptococcus pseudoporcinus Throat Infection

Treat Streptococcus pseudoporcinus pharyngitis with the same antibiotics used for Group A Streptococcus (GAS) pharyngitis, with penicillin or amoxicillin as first-line therapy for 10 days, recognizing that multidrug-resistant strains may require vancomycin, linezolid, or clindamycin if the patient fails to respond or has severe invasive disease. 1

First-Line Treatment for Non-Allergic Patients

• Penicillin V remains the treatment of choice due to its proven efficacy, narrow spectrum, safety profile, and low cost 2

  • Adults: 250 mg four times daily OR 500 mg twice daily for 10 days 2
  • Children: 250 mg two or three times daily for 10 days 2

• Amoxicillin is equally effective and more palatable, particularly for young children who may not tolerate penicillin suspension 2

  • Dosing: 50 mg/kg once daily (maximum 1000 mg) OR 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days 2
  • The once-daily dosing may enhance adherence while maintaining equivalent efficacy 2

• Intramuscular benzathine penicillin G should be used when adherence to oral therapy is unlikely 2

  • Dosing: <60 lbs: 600,000 units; ≥60 lbs: 1,200,000 units as a single injection 2

Treatment for Penicillin-Allergic Patients

Non-Immediate (Non-Anaphylactic) Allergy

• First-generation cephalosporins are preferred for patients without immediate hypersensitivity reactions 2, 3
  • Cephalexin: 20 mg/kg per dose twice daily (maximum 500 mg per dose) for 10 days 2, 3
  • Cefadroxil: 30 mg/kg once daily (maximum 1 gram) for 10 days 2, 3
  • Cross-reactivity risk with penicillin is less than 3% in non-immediate reactions 4

Immediate (Anaphylactic) Allergy

• Avoid all beta-lactams including cephalosporins due to up to 10% cross-reactivity risk 2, 3

• Clindamycin is the preferred alternative with approximately 1% resistance rate in the United States 2, 3

  • Dosing: 7 mg/kg per dose three times daily (maximum 300 mg per dose) for 10 days 2, 5
  • Particularly effective for chronic carriers and has excellent streptococcal eradication rates 3

• Azithromycin is an acceptable alternative with the advantage of shorter duration 2

  • Dosing: 12 mg/kg once daily (maximum 500 mg) for 5 days 2, 3
  • The 5-day course is possible due to prolonged tissue half-life 2, 3
  • Caution: Macrolide resistance among streptococci is 5-8% in the United States and varies geographically 2, 3

• Clarithromycin is another option 2

  • Dosing: 7.5 mg/kg per dose twice daily (maximum 250 mg per dose) for 10 days 2, 3

Critical Considerations for Multidrug-Resistant Strains

• If the patient fails initial therapy or presents with severe invasive disease, consider that S. pseudoporcinus can be multidrug-resistant 1

  • Empiric choices for suspected resistant strains: vancomycin, linezolid, daptomycin, levofloxacin, clindamycin, or tetracycline 1
  • These agents should be used until antimicrobial susceptibility results are available 1

• Recognize that S. pseudoporcinus can cause fatal disseminated infections, particularly in immunocompromised patients or those with underlying conditions like decompensated liver cirrhosis 1

Treatment Duration Requirements

• All antibiotics except azithromycin require a full 10-day course to achieve maximal pharyngeal eradication and prevent complications 2, 3

  • Shortening the course by even a few days results in appreciable increases in treatment failure rates 3
  • The 10-day duration is necessary to prevent acute rheumatic fever, even though symptoms typically resolve within 3-4 days 3

• Therapy can be safely postponed up to 9 days after symptom onset and still prevent acute rheumatic fever 3

Common Pitfalls to Avoid

• Do not use tetracyclines, sulfonamides, or trimethoprim-sulfamethoxazole as they do not effectively eradicate streptococci from the pharynx 2

• Do not use older fluoroquinolones (ciprofloxacin) due to limited activity against streptococci 2

• Do not prescribe cephalosporins to patients with immediate/anaphylactic penicillin reactions due to the 10% cross-reactivity risk 2, 3

• Do not routinely perform follow-up throat cultures or rapid antigen tests in asymptomatic patients who have completed therapy 2, 3

• Do not assume all penicillin-allergic patients cannot receive cephalosporins—only those with immediate/anaphylactic reactions should avoid them 3

Adjunctive Therapy

• Acetaminophen or NSAIDs (ibuprofen) can be used for moderate to severe symptoms or high fever 3

• Avoid aspirin in children due to the risk of Reye syndrome 3

• Corticosteroids are not recommended as adjunctive therapy 3

Special Circumstances

• Chronic carriers generally do not require treatment as they are unlikely to spread infection or develop complications 2, 3

• Treatment of asymptomatic household contacts is not routinely recommended unless special circumstances exist (outbreak in closed community, history of acute rheumatic fever, excessive anxiety, or consideration of tonsillectomy) 2