Why Concerns Are Growing About Drug-Resistant Shigella Infections

The healthcare community is increasingly concerned about Shigella bacteria infections that have shown drug resistance.

The Centers for Disease Control and Prevention (CDC) issued a health alert last week about an increase in infections caused by a drug-resistant strain of Shigella, bringing new attention to a pathogen that is likely unknown to many in the United States. United.

As the CDC noted in its alert, 5% of Shigella cases in 2022 were caused by extremely drug-resistant bacterial infections called XDR infections. This marked an increase from when no cases were considered XDR infections in 2015.

“We have received increasing reports of XDR infections from our state health partners in multiple areas of the United States, and then we have also received multiple communications from physicians, IV physicians in particular , who were learning about treatment options for these really difficult cases,” CDC Medical Officer Naeemah Logan told The Hill.

CDC officials said it’s unclear if some areas of the United States are seeing more Shigella cases than others, as not all areas have the same level of surveillance and reporting data. may be late. But the increase in drug-resistant Shigella infections is notable.

CDC physician Louise Francois Watkins noted that XDR infections with other bacteria could take decades to increase from zero to five percent of cases, but Shigella accomplished that in just a few years.

“We don’t see a single strain of Shigella causing this emerging phenomenon. What we are seeing is the development of this resistance in a number of different strains that are happening across the country and in fact all over the world,” said François Watkins.

According to François Watkins, the increase in cases of XDR indicates a certain selective pressure that pushes the Shigella bacterium to develop resistance to antibiotics. She noted that a common driver of antibiotic resistance is the use of antibiotics not only in humans, but also in animals and environmental settings.

“We think some of the best ways to tackle this problem is to really have what we call judicious use, or conscientious use, of antibiotics in all these different settings,” said François Watkins.

George Garcia, professor and chair of medicinal chemistry at the University of Michigan College of Pharmacy, told The Hill that labs like his are studying treatments that block a pathogen’s ability to infect instead to target the pathogen itself. According to Garcia, these potential methods, targeting so-called “virulence factors,” would put less pressure on bacteria to become resistant to antibiotics.

Shigella is a close relative of the better known E. coli bacteria and can also be spread through contaminated food and water, but also through oral contact with feces. What distinguishes Shigella from E. coli is its extremely high virulence, with as few as 10 microorganisms in the bacterium able to cause infection.

In comparison, other common causes of gastrointestinal infections require hundreds or even thousands of bacterial organisms to cause illness.

Symptoms of Shigella infections include diarrhea – which can be bloody – as well as fever and abdominal cramps. Most cases of Shigella infection resolve on their own without medical intervention.

Garcia noted that blood in the stool or diarrhea can be a telltale indication for some that they have contracted Shigella.

“A lot of diarrheal diseases don’t quite do that, but Shigella does,” Garcia said. “It’s not unique to Shigella, but it would definitely be a red flag for me.”

The CDC noted in its health alert that it had observed an increase in Shigella cases among men who have sex with men, which Garcia attributed to bacteria accumulating in the intestines and the prevalence and anal sex among this demographic.

Francois Watkins said Shigella’s potential as a sexually transmitted disease was under-recognized in the medical community.

“We think that oftentimes its reputation within the medical community is more of a foodborne and person-to-person mode of transmission that happens like in young children in day care centers and things like that,” Francois Watkins said. . “So we think it’s underrecognized as a sexually transmitted disease, but in the medical literature it’s been known for many years that it’s a possibility.”

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