What is the management and treatment of Yersinia pestis infection?

Management and Treatment of Yersinia pestis Infection

Dual antimicrobial therapy with a fluoroquinolone plus an aminoglycoside is the recommended treatment for all forms of plague (pneumonic, septicemic, bubonic, or pharyngeal), administered for 10-14 days. 1

Clinical Presentation

Yersinia pestis presents in several forms:

• Bubonic plague: Characterized by painful, swollen lymph nodes (buboes), fever, headache, and weakness
• Pneumonic plague: Severe respiratory illness with fever, headache, weakness, and rapidly developing pneumonia
• Septicemic plague: Fever, chills, extreme weakness, abdominal pain, shock, and bleeding into skin and organs
• Pharyngeal plague: Pharyngitis, cervical lymphadenopathy, and fever

Treatment Algorithm

First-line Treatment (Adults)

• Fluoroquinolone (one of the following):
  • Ciprofloxacin: 400 mg IV every 8 hours or 500 mg PO every 8 hours 2, 1
  • Levofloxacin: 750 mg IV or PO every 24 hours 2, 1, 3
  • Moxifloxacin: 400 mg IV or PO every 24 hours 1, 4

PLUS

• Aminoglycoside (one of the following):
  • Gentamicin: 5 mg/kg IV or IM every 24 hours (preferred over streptomycin) 2, 1
  • Streptomycin: 1 g IV or IM every 12 hours 2, 1

Alternative Agents (if first-line agents unavailable)

• Chloramphenicol: 12.5-25 mg/kg IV every 6 hours (maximum 1 g/dose) 2
• Doxycycline: 200 mg loading dose IV, then 100 mg every 12 hours IV or PO 2
• Trimethoprim-sulfamethoxazole: 5 mg/kg (trimethoprim component) every 8 hours IV or PO 2

Treatment Duration

• Continue treatment for 10-14 days 2, 1

Special Populations

Pediatric Patients

• Fluoroquinolones:
  • Ciprofloxacin: 10 mg/kg every 8 or 12 hours IV; 15 mg/kg every 8 or 12 hours PO (max 400 mg/dose IV, 500 mg/dose PO) 2
  • Levofloxacin: 8 mg/kg every 12 hours (if <50 kg) or adult dosing if ≥50 kg 2, 3

PLUS

• Aminoglycosides:
  • Gentamicin: 4.5-7.5 mg/kg every 24 hours IV or IM 2
  • Streptomycin: 15 mg/kg every 12 hours IV or IM (maximum 1 g/dose) 2

Pregnant Women

• Gentamicin is preferred over streptomycin due to lower risk of fetal ototoxicity 2
• Fluoroquinolones remain first-line therapy despite pregnancy 1

Prophylaxis

For individuals exposed to Y. pestis:

First-line Prophylaxis (Adults)

• Ciprofloxacin: 500 mg every 8 hours PO or 750 mg every 12 hours PO 2
• Levofloxacin: 750 mg every 24 hours PO 2
• Doxycycline: 100 mg every 12 hours PO 2

Duration of Prophylaxis

• Pre-exposure prophylaxis: Continue until 48 hours after last exposure 2
• Post-exposure prophylaxis: 7 days 2

Important Clinical Considerations

1. Early treatment is critical: Initiate therapy immediately upon suspicion of plague. Studies show significantly higher survival rates when treatment begins early 5, 6

2. Isolation precautions: Pneumonic plague requires strict respiratory isolation to prevent transmission 1

3. Beta-lactam caution: Beta-lactam antibiotics (cephalosporins, penicillins) have shown poor efficacy in pneumonic plague with bacteremia and may even accelerate mortality compared to controls 5

4. Bioterrorism considerations: In cases of suspected bioterrorism, dual therapy should be maintained until susceptibility testing confirms absence of engineered resistance 1

5. Intracellular efficacy: Streptomycin and ciprofloxacin demonstrate comparable efficacy against both intracellular and extracellular Y. pestis, while gentamicin and doxycycline may be less effective against intracellular bacteria 7

6. Monitoring therapy: For aminoglycosides, check drug concentrations as appropriate and adjust dose accordingly 2

Common Pitfalls to Avoid

• Delaying treatment while awaiting confirmation (plague is rapidly fatal if untreated)
• Using monotherapy in suspected bioterrorism cases
• Inadequate duration of treatment (less than 10 days)
• Failing to implement proper isolation for pneumonic plague
• Relying solely on beta-lactam antibiotics, especially in bacteremic patients