Rising cases of antibiotic-resistant Shigella bacteria are causing widespread concern

By Lisa Marie Basile | Fact-checked by Barbara Bekiesz
Published March 7, 2023

Key Takeaways

  • Cases of infection with extensively drug-resistant (XDR) Shigella bacteria are rising.

  • Shigella is an enteric infection that causes abdominal pain, fever and diarrhea. There are currently no antimicrobial treatments.  

  • Shigella is transmitted more frequently in people experiencing homelessness, travelers, children, individuals with HIV and men who have sex with men.

The Centers for Disease Control and Prevention (CDC) recently sounded an alarm warning healthcare providers and the public about an easily transmissible, extensively drug-resistant (XDR) bacteria, Shigella. Here's what you need to know.[]

The bacteria is responsible for shigellosis, an enteric infection that comes on quickly. According to Kenneth J. Perry, M.D., FACEP, “The most common symptoms are abdominal pain, fever and diarrhea. The diarrhea can last for a number of days and even have blood within it.” Tenesmus may also occur. Diarrhea typically lasts longer than three days.[] 

The uptick in XDR shigellosis— none of the reported infections in 2015 were XDR strains, while that number grew to 22 percent in 2022—is a cause for concern, as there are limited antimicrobial treatment strategies available. The bacteria is resistant to all commonly recommended antibiotics, including trimethoprim-sulfamethoxazole (TMP-SMX), azithromycin, ciprofloxacin, ceftriaxone, and ampicillin. 

How Shigella spreads

Shigella spreads like other bacteria. “The common route of transmission is the fecal-oral route,” Perry says. “The bacteria that has been shed through the gastrointestinal system ends up finding its way back into the oral mucosa of the next host.” 

Certain groups of people are more susceptible to it, Perry explains. “It is common for outbreaks to occur in daycare and preschool settings,” he notes. “Travelers can also be affected, too, as the water treatment quality may not be suitable.” Additionally, the CDC says people experiencing homelessness and people with weaker immune systems—especially those with HIV infection—are at greater risk.  

Sexual intercourse—anal, vaginal, and oral—can lead to infection as well. According to a study in Lancet Infectious Diseases, some strains of Shigella have been associated with transmission in men who have sex with men.[] 

Specifically, the investigators found that transmission was seen more in people with “high numbers of sexual partners who were often met through geospatial dating applications, or at private sex parties or commercial sex-on-premises venues.” Additionally, a literature review found that drug use was associated with Shigella spread in men who have sex with men.[] []

Among XDR Shigella cases reported to the CDC over the last eight years (232 cases with available information), 82 percent were men, 13 percent were women, and 5 percent were children. Of the 41 patients asked about their recent sexual histories, 88 percent were men who reported sexual contact with men. 

It is important to note that all people, including children, are at risk for developing Shigella, and both the medical community and the public should avoid framing it as an infection that mainly impacts men who have sex with men.

Treating Shigella

The CDC states, “Currently, there are no data from clinical studies of treatment of XDR Shigella to inform recommendations for the optimal antimicrobial treatment of these infections. As such, CDC does not have recommendations for optimal antimicrobial treatment of XDR Shigella infections.”

However, the CDC did cite recent research from the United Kingdom indicating a treatment course for XDR shigellosis that included “oral pivmecillinam and fosfomycin (for patients with prolonged symptoms or as oral step-down after intravenous treatment) or IV carbapenems and colistin (for hospitalized patients with severe infections or complications).” Fortunately, the CDC notes XDR Shigella isolates in the United States typically do not carry resistance mechanisms for fosfomycin or carbapenems. Unfortunately, pivmecillinam is not commercially available for use in the US.

Shigellosis typically requires rehydration and generally clears up without medical intervention within five to six days. Patients with XDR Shigella may need to be given other drugs, including fluoroquinolones, azithromycin, and ceftriaxone says the CDC. Shigellosis may be fatal for patients with severely weakened immune systems if the infection spreads to the blood.[][] 

Perry warns physicians against using certain drugs. “Supportive care should usually avoid antidiarrheal medications [like loperamide], as it can prolong the infection and possibly make things worse,” he says. 

What to do if you suspect a patient is infected with Shigella

If you suspect a patient has an XDR Shigella infection, order a stool culture to confirm. Refer the patient to a specialist in antibiotic-resistant bacteria if necessary. 

Educating your patients—especially those in high-risk groups—is also crucial. “The best option [for patients] is prevention,” Perry says. “Fastidious hand washing and cleaning of surfaces that may harbor the bacteria is an important step to reducing transmission of shigella.” Anyone who has had diarrhea within the past two weeks should be encouraged to avoid sexual activity. 

The CDC says that physicians should be vigilant when reporting infections. You can learn more about the spread of XDR Shigella infections in the US by visiting the National Antimicrobial Resistance Monitoring System for Enteric Bacteria (NARMS). 

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