Rise in Drug-Resistant Shigella Bacteria Highlights Urgent Need for New Antibiotics
CDC alert underscores serious threat posed by increasingly hard-to-treat strain
Cases of a dangerous, extensively drug-resistant (XDR) strain of shigella—an easily transmissible bacteria that results in serious, potentially life-threatening gastrointestinal infections—are on the rise in the United States, according to a recent health advisory from the federal Centers for Disease Control and Prevention. Although shigella causes an estimated 450,000 infections in the U.S. each year, none had been linked to the highly resistant strain before 2015. Since then, infections with the XDR strain have been reported in 29 states and now make up about 5% of all cases nationwide.
The new strain has proved resistant to all five commonly recommended antibiotics: azithromycin, ciprofloxacin, ceftriaxone, trimethoprim-sulfamethoxazole, and ampicillin. Without these antibiotic options, there is currently no clinical data on what treatment options might work. Amplifying the threat, these bacteria not only spread easily from person to person (requiring only a small number of bacteria to make someone ill), but the resistance genes can also spread readily to other types of bacteria.
What Is Shigellosis?
The infection caused by the shigella bacteria, known as shigellosis, usually causes inflammatory diarrhea that can be bloody and lead to fever, abdominal cramping, and other potentially uncomfortable symptoms. Although many patients recover without the help of any medicine, some need antibiotic treatment to prevent complications or to shorten the duration of illness.
According to CDC, people of all ages can get shigellosis; however, children under the age of 5 are most likely to get the infection because of the frequency of outbreaks in child care and early education settings. Infection can then easily spread from young children to family members and other people in their communities. Other individuals whom CDC identifies as most likely to get shigellosis include people traveling to places where water and food may be unsafe because of poor sanitation, men who have sex with men, people who are experiencing homelessness, and people with weakened immune systems.
Unfortunately, XDR shigella is not the only alarming recent development in the growing threat of antibiotic-resistant bacteria. Already this year, the nation has seen an outbreak of drug-resistant bacteria associated with eye medication and the discovery of a novel strain of antibiotic-resistant gonorrhea. These types of emerging threats highlight the critical need for new antibiotics.
Despite that urgent need, the latest data from the World Health Organization shows a stagnant antibiotic pipeline, with fewer than 50 antibiotics in global clinical development. Alarmingly, just a handful of those drugs are targeted against the pathogens that present the most urgent threats, and based on historical data, most will likely never make it to Food and Drug Administration approval, in large part because of the stark financial disincentives to invest in their development.
Policymakers can spur the development of these essential drugs by passing the Pioneering Antimicrobial Subscriptions to End Upsurging Resistance (PASTEUR) Act. The bipartisan PASTEUR Act would help to reinvigorate the antibiotics pipeline by providing sizable, subscription-based government contracts for access to new, high-priority antibiotics that address an unmet medical need. Although pharmaceutical revenue is typically tied to how much of a drug is sold, these contracts would instead pay for new antibiotics based on their value to public health. This approach incentivizes development of new types of antibiotics while addressing a core issue confronting the market: the pressing need for innovative drugs that don’t have high sales potential.
This critical piece of legislation also would provide support for antibiotic stewardship programs at health care facilities throughout the country. These programs—designed to ensure that essential, lifesaving drugs are used appropriately—are a critical part of the fight against superbugs. They can help to slow the emergence of resistance and preserve the effectiveness of existing drugs. At the same time, they can improve patient outcomes and lower health care costs.
Increasing resistance to antibiotics poses numerous societal risks. Drug-resistant shigellosis can be serious, and the next drug-resistant bug could be worse. Congress should act this year to pass the PASTEUR Act and address the pervasive and growing threat of antibiotic-resistant bacteria.
David Hyun, M.D., directs The Pew Charitable Trusts’ antibiotic resistance project.
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