What is the treatment for Yersinia (Y) pestis infection?

Treatment of Yersinia pestis Infection

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

First-Line Treatment Options

Recommended Dual Therapy

• Fluoroquinolone + Aminoglycoside combination:

  • Ciprofloxacin (400 mg IV every 8 hours or 750 mg PO every 12 hours) plus
  • Gentamicin (5 mg/kg IV/IM every 24 hours) or
  • Streptomycin (15 mg/kg IM every 12 hours, maximum 1 g/dose) 1

• Alternative fluoroquinolones:

  • Levofloxacin (750 mg IV/PO every 24 hours) 2
  • Moxifloxacin (400 mg IV/PO every 24 hours) 3

Treatment Duration

• Continue treatment for 10-14 days or until the patient has been afebrile for at least 48 hours 1
• Early initiation of therapy is critical as mortality rates can reach 50% without treatment but decrease to 5-10% with timely treatment 1

Treatment Based on Clinical Form

Bubonic Plague

• Dual therapy as outlined above
• Place patient in respiratory isolation for the first 48 hours of effective treatment to prevent secondary transmission of pneumonic plague 1
• Monitor for clinical improvement within 24-48 hours 1

Pneumonic or Septicemic Plague

• Immediate initiation of dual therapy is critical
• Strict respiratory isolation for 48 hours after starting effective therapy 1
• More aggressive supportive care may be needed due to higher mortality rates

Special Populations

Pregnant Women

• Fluoroquinolones remain first-line despite pregnancy
• Gentamicin is an acceptable alternative but requires monitoring 1

Children

• Same first-line agents as adults with adjusted dosing
• Doxycycline should only be used in children <8 years when other options are unavailable due to dental staining risk 1

Bioterrorism Considerations

• In the event of a bioterrorism attack using a strain of Y. pestis engineered for resistance, dual therapy with distinct classes of antimicrobials is strongly recommended 4
• Levofloxacin and moxifloxacin have demonstrated efficacy in animal models of pneumonic plague, which supports their use in bioterrorism scenarios 2, 3

Monitoring and Adjustments

• Monitor patients for clinical improvement within 24-48 hours
• Check aminoglycoside levels as indicated to prevent toxicity
• Adjust therapy based on culture and sensitivity results when available 1
• Be aware that 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 5

Common Pitfalls to Avoid

• Delayed treatment initiation (treatment should begin within 24 hours of symptom onset)
• Using monotherapy in severe cases or suspected bioterrorism
• Inadequate duration of treatment
• Failure to consider plague in differential diagnosis
• Improper isolation procedures
• Using beta-lactam antibiotics as monotherapy due to potential poor efficacy 1

Post-Exposure Prophylaxis

• For individuals exposed to Y. pestis, post-exposure prophylaxis with ciprofloxacin, levofloxacin, or doxycycline for 7 days is recommended 1