What is the drug of choice for bubonic plague?

Drug of Choice for Bubonic Plague

For bubonic plague, the first-line treatment options include fluoroquinolones (ciprofloxacin, levofloxacin, or moxifloxacin), doxycycline, or aminoglycosides (gentamicin or streptomycin), with no single agent prioritized over the others according to the most recent CDC guidelines. 1

Treatment Approach

The 2021 CDC MMWR guidelines explicitly state that antimicrobials are not listed in order of preference within the first-line category for bubonic plague 1. This represents an important shift from historical practice where streptomycin was considered the "gold standard."

First-Line Options for Adults:

• Ciprofloxacin: 400 mg IV every 8 hours OR 750 mg PO every 12 hours
• Levofloxacin: 750 mg IV or PO every 24 hours
• Moxifloxacin: 400 mg IV or PO every 24 hours
• Doxycycline: 200 mg loading dose, then 100 mg every 12 hours IV or PO
• Gentamicin: 5 mg/kg IV or IM every 24 hours
• Streptomycin: 1 g IV or IM every 12 hours

Treatment duration: 10-14 days 1

Key Clinical Considerations

Monotherapy vs. Dual Therapy

Monotherapy is recommended for naturally occurring bubonic plague, although dual therapy can be considered for patients with large buboes 1. This differs from pneumonic or septicemic plague, where dual therapy with two distinct antimicrobial classes is recommended for severe cases 1.

Evidence Supporting Multiple First-Line Agents

The guidelines reflect modern evidence showing comparable efficacy across drug classes:

• Gentamicin and doxycycline demonstrated 94% and 97% favorable response rates respectively in a randomized clinical trial in Tanzania 2
• Fluoroquinolones showed superior killing compared to streptomycin in pharmacodynamic models, with no resistance selection 3
• Historical data showed streptomycin reduced mortality dramatically, but modern alternatives are now equally or more effective 4, 5

Practical Advantages of Different Agents

Fluoroquinolones (ciprofloxacin, levofloxacin, moxifloxacin):

• Excellent oral bioavailability allows transition from IV to PO
• Broad availability compared to streptomycin
• No resistance amplification in studies 3

Doxycycline:

• Widely available and inexpensive
• Oral and IV formulations readily accessible
• Proven efficacy in clinical trials 2

Gentamicin:

• Once-daily dosing convenient
• Proven in randomized trials 2
• Requires monitoring of renal function and drug levels

Streptomycin:

• Historical gold standard but limited availability in many countries 1, 3
• Resistance can develop 3

Common Pitfalls to Avoid

1. Delaying treatment: Start empiric therapy immediately when plague is suspected—mortality increases dramatically with delayed treatment 6, 7

2. Assuming streptomycin is required: While historically the gold standard, streptomycin is no longer superior to modern alternatives and may not be available 3

3. Using penicillin: Penicillin has no protective effect against plague and should be avoided 5

4. Inadequate treatment duration: Complete the full 10-14 day course even if clinical improvement occurs earlier 1

Pediatric Dosing

For children, the same first-line agents apply with weight-based dosing. For example, ciprofloxacin 10 mg/kg IV every 8-12 hours (max 400 mg/dose) or doxycycline 2.2 mg/kg every 12 hours for children <45 kg 1.

The choice among first-line agents should be based on drug availability, route of administration preference (oral vs. IV), patient-specific factors (renal function, pregnancy), and local antimicrobial susceptibility patterns rather than a rigid hierarchy of preference.