Brace yourselves: superbug strains of Shigella, which are known to cause diarrhea, are becoming a more pressing issue.
In a recent report by the Centers for Disease Control and Prevention, federal and state health officials highlighted a worrying trend. Since 2011, there’s been a noticeable increase in Shigella cases across the country showing significant resistance to commonly prescribed antibiotics. They emphasize that more needs to be done to prevent, monitor, and develop treatments for this escalating public health concern.
“The emergence of [extensively drug-resistant] Shigella infections is a growing worry in the United States,” the authors noted in their paper, published just last week in the Morbidity and Mortality Weekly Report (MMWR).
Resilient bacteria
Over time, antibiotic resistance has become a significant public health threat. Antibiotic-resistant bacteria are now believed to be responsible for over 1.2 million deaths globally each year. Projections suggest that by 2050, this figure might soar to 10 million, making it comparable to cancer-related deaths.
Among various superbugs, extensively drug-resistant (XDR) Shigella stands out as particularly concerning. This strain can resist all major classes of antibiotics, which means that common medications like azithromycin, ceftriaxone, and ciprofloxacin are ineffective. Currently, no oral antibiotic is authorized to treat these tough infections.
A Shigella infection, also known as shigellosis, is classified as a nationally notifiable disease; doctors must report cases to health departments. Officials from the CDC and local health entities have observed a rise in XDR shigellosis cases since at least 2015. However, the complete picture of this trend didn’t come together until recently.
The researchers reviewed data from PulseNet, a national network that tracks bacteria responsible for food and waterborne outbreaks. They looked closely at samples of Shigella collected from laboratories across the U.S. between 2011 and 2023.
The findings were alarming: there were no samples of XDR Shigella between 2011 and 2015, yet by 2023, 8.5% of submitted samples exhibited extensive resistance. Notably, two-thirds of these isolates were Shigella sonnei, the most prevalent cause of shigellosis, while the remainder was Shigella flexneri. Interestingly, about three-quarters of these cases had no recent travel history, indicating that they were likely contracted locally. Of those with recorded data, one-third ended up hospitalized, although no fatalities were documented.
A rising threat
Shigellosis can be quite debilitating, with symptoms like diarrhea, fever, and stomach cramps. Typically, the infection resolves on its own within a week, even without antibiotics. That said, antibiotics are crucial for severe cases or for those in high-risk categories, such as individuals with weakened immune systems.
About 450,000 Americans are infected with Shigella bacteria annually. While it’s usually spread through contaminated food and water, close sexual contact, especially involving anal sex, is also a transmission route. This factor appears to contribute to recent surges of XDR Shigella infections among men who have sex with men.
It’s not only the superbugs themselves that pose a threat; their resistance genes can potentially be shared with other gut bacteria. This risk, combined with the highly contagious nature of these pathogens, makes them even more concerning from a public health perspective.
Health professionals are encouraged to utilize lab testing to inform treatment decisions for suspected Shigella infections whenever feasible and to report cases of XDR promptly to help contain outbreaks. Additionally, it’s critical to identify or develop effective antibiotics to combat these stubborn infections.
