Division of Microbiology and Infectious Diseases (DMID)

Off-Patent Antibiotics for the Treatment of Pneumonic Plague

Scanning electron micrograph depicting a mass of Yersinia pestis bacteria. Credit: Rocky Mountain Laboratories, NIAID, NIH.

The U.S. Department of Homeland Security has designated plague as a potential bioterror threat. Pneumonic plague, the most deadly form of plague, can be spread from person to person. It occurs when Yersinia pestis bacteria infect the lungs and cause pneumonia.

Until recently, only a few antibiotics were licensed to treat plague. These drugs, approved more than 40 years ago, were indicated to treat plague in general, but not specifically for pneumonic plague.

Can Existing Antibiotics Work Against Pneumonic Plague?

In collaboration with the Food and Drug Administration (FDA), NIAID is supporting animal studies to determine whether newer antibiotics approved for other uses are also effective against pneumonic plague.

NIAID research services have been instrumental in advancing existing antibiotics toward new label indications. Beginning in 2003, NIAID/DMID preclinical services were used to establish the natural history of disease in non-human primates. Since then, NIAID has provided additional preclinical services to evaluate the pharmacokinetics, tolerability, and efficacy of widely available antibiotics in monkeys exposed to aerosolized Y. pestis.  

Drug Approved for Emergency Use Against Plague

Data from NIAID-supported studies played a major role in FDA approval of the first drug for pneumonic plague. In April 2012, an FDA Advisory Committee unanimously recommended FDA approval of ciprofloxacin and levofloxacin as treatments for pneumonic plague. Soon afterwards, FDA approved levofloxacin to treat and prevent pneumonic plague, making it the first antibiotic approved under a regulatory approach known as the Animal Rule. (The FDA decision on ciprofloxacin is pending.)  

This approach sets a precedent for FDA approval of other medical countermeasures under the Animal Rule (e.g., additional antibiotics for pneumonic plaque and other potential bioterror threats like Francisella tularensis). Approving existing antibiotics to treat pneumonic plague will enable the U.S. government to dispense and use such antibiotics from the Strategic National Stockpile to respond to public health emergencies. It will also inform and guide healthcare providers’ treatment decisions in endemic areas and public health emergencies.