What is the treatment for Yersinia infection?

Treatment of Yersinia Pestis Infection

Dual antimicrobial therapy with a fluoroquinolone (ciprofloxacin, levofloxacin, or moxifloxacin) plus an aminoglycoside (gentamicin or streptomycin) for 10-14 days is the most effective treatment for Yersinia pestis infection, significantly reducing mortality across all clinical forms of plague. 1

First-Line Treatment Options

For Severe Pneumonic or Septicemic Plague:

• Dual therapy with two distinct classes of antimicrobials is required:

  • Fluoroquinolones:
    • Ciprofloxacin: 400 mg every 8 hrs IV or 750 mg every 12 hrs PO
    • Levofloxacin: 750 mg every 24 hrs IV or PO
    • Moxifloxacin: 400 mg every 24 hrs IV or PO

  PLUS

  • Aminoglycosides:
    • Gentamicin: 5 mg/kg every 24 hrs IV or IM
    • Streptomycin: 15 mg/kg every 12 hrs IM (maximum 1 g/dose) 2, 1

For Uncomplicated Bubonic Plague:

• Monotherapy may be sufficient with:
  • Streptomycin: 15 mg/kg every 12 hrs IM (maximum 1 g/dose)
  • Doxycycline: 200 mg loading dose, then 100 mg every 12 hrs PO 1, 3

Treatment Duration

• Continue treatment for 10-14 days or until patient is afebrile for at least 48 hours 2, 1

Special Populations

Children:

• Same first-line agents as adults with adjusted dosing:
  • For children <45 kg: Ciprofloxacin 15 mg/kg every 12 hrs IV or IM (maximum 1g/dose)
  • Doxycycline dosing: Body weight <45 kg: 4.4 mg/kg loading dose, then 2.2 mg/kg every 12 hrs IV or PO 2
• Note: Doxycycline should only be used in children <8 years when other options are unavailable due to dental staining risk 1

Pregnant Women:

• Fluoroquinolones remain first-line despite pregnancy
• Gentamicin is an acceptable alternative but requires monitoring 1
• Dual therapy recommended with distinct classes of antimicrobials 2

Post-Exposure Prophylaxis

• Recommended for individuals exposed to Y. pestis:
  • Ciprofloxacin: 500 mg every 8 hrs PO or 750 mg every 12 hrs PO
  • Levofloxacin: 750 mg every 24 hrs PO
  • Doxycycline: 100 mg every 12 hrs PO
• Duration: 7 days 2, 1

Infection Control Measures

• Patients with bubonic plague should be kept in respiratory isolation for the first 48 hours of effective treatment
• Patients with pneumonic plague require strict respiratory isolation for 48 hours after starting effective therapy 1

Treatment Efficacy and Monitoring

• Early treatment is crucial - mortality decreases from 50% untreated to 5-10% with appropriate therapy
• Survival rates with appropriate treatment:
  • Aminoglycosides: 83-91% survival
  • Tetracyclines: 95-98% survival
  • Fluoroquinolones: 100% survival (limited data) 1
• Monitor for clinical improvement within 24-48 hours
• Check aminoglycoside levels as indicated
• Adjust therapy based on culture and sensitivity results when available 1

Important Caveats

• Beta-lactam antibiotics should be avoided due to potential poor efficacy and accelerated mortality 1
• Intracellular Y. pestis may be less susceptible to certain antibiotics like gentamicin or doxycycline, while streptomycin and ciprofloxacin maintain similar efficacy against both intracellular and extracellular bacteria 4
• Common treatment pitfalls include delayed treatment initiation, inappropriate monotherapy in severe cases, inadequate treatment duration, and improper isolation 1
• In bioterrorism scenarios, consider the possibility of engineered resistance and adjust therapy accordingly 1