Scientists from the University of Southern California (USC) recently found that an old antibiotic, rifabutin, maybe a new tool for fighting a deadly superbug called Acinetobacter baumannii.
Acinetobacter baumannii reared its ugly head for the first time during the Iraq War. Troops in medical treatment facilities were getting pneumonia, meningitis, and blood infection. Every year, 99,000 people died in U.S. hospitals from infections they got while hospitalized. According to the Centers for Disease Control (CDC), of those 99,000, 2% were caused by Acinetobacter baumannii
According to the first author and assistant professor of molecular microbiology and immunology at Keck School of Medicine at USC, "Rifabutin has been around for more than 35 years, and no one has ever studied it for Acinetobacter infections before. Going forward, we may find many new antibiotics that have been missed over the last 80 years because the screening tests used to discover them were suboptimal."
Rifabutin is used to treat tuberculosis in HIV/AIDS patients, because those individuals can’t tolerate a similar drug, called rifampin. Rifabutin is on the World Health Organization’s (WHO’s) List of Essential Medicines. Rifabutin, until now, had not been studied against superbugs due to current screen methods. Since the 1940s, new or existing antibiotics are tested against bacteria grown in “culture-rich media.”
"But bacteria grow very differently inside the human body," said Brad Spellberg, chief medical officer at the Los Angeles County-USC Medical Center and senior author of the study. Accordingly, the researchers designed a new type of media that is "nutrient-limited" that better simulates conditions inside the body.
The scientists found that rifabutin tricks the bacteria into importing the antibiotic inside itself, getting past the defense system of the bacteria. This mechanism isn’t seen in culture-rich media because the high levels of iron and amino acids suppress it.
"Rifabutin can be used immediately to treat such infections because it is already FDA-approved, cheap and generic, and on the market," Spellberg said. "But we would like to see randomized controlled human trials to prove its efficacy, so we know for sure one way or the other."
The study is published in Nature Microbiology.