Key Takeaway:
- Drug-Resistant Shigella is spreading: Sexual contact is an increasingly important transmission route for the bacteria that cause severe diarrhea.
- Treatment options are shrinking: Extensively drug-resistant strains are making some infections harder to treat with antibiotics.
- Prevention and testing matter: Avoid sexual contact during diarrhea, practice good hygiene, and seek medical advice for severe or persistent symptoms.
Drug-resistant Shigella infections are raising public health concerns as sexual transmission increases, with U.S. surveillance data showing drug-resistant strains reached 8.5% of tested samples in 2023, limiting treatment options.
Shigella Cases Rise as Sexual Transmission Expands
Drug-resistant Shigella, a highly contagious bacterium that causes shigellosis, can trigger diarrhea, stomach cramps, fever and, in severe cases, bloody stools. The infection has traditionally spread through contaminated food and water, but sexual contact has become an increasingly important transmission route, particularly among gay, bisexual and other men who have sex with men.
The United States records an estimated 450,000 shigellosis infections annually, according to reporting by ScienceAlert. The disease can affect anyone, regardless of sexual orientation, and spreads when microscopic amounts of infected fecal matter enter the mouth, including during sexual activity.
A recent U.S. Centers for Disease Control and Prevention analysis found that extensively drug-resistant Shigella isolates increased from zero in 2011 to 8.5% in 2023. These strains resist five commonly used antibiotics, making infections more difficult to treat.
Shangxin Yang, a molecular biologist at the University of California, Los Angeles, told CIDRAP News that the hospital was seeing approximately one extensively drug-resistant Shigella case per month, compared with one case throughout 2022. “It’s almost like an explosion of this pathogen in the community,” Yang said.
Antibiotic Resistance Narrows Treatment Options
The threat extends beyond the United States. England’s UK Health Security Agency reported 2,560 Shigella diagnoses in 2025 among cases potentially associated with sexual transmission, based on surveillance of people with no reported recent international travel or an unknown travel history.
Among the relevant samples tested in England in 2025, 86% of Shigella sonnei isolates and 94% of Shigella flexneri isolates showed resistance to at least some antibiotics. More than half of the tested S. sonnei isolates were classified as extensively drug-resistant.
Kate Baker, a geneticist at the University of Cambridge and senior author of a study published in The Lancet Infectious Diseases, warned that treatment options are becoming increasingly limited.
“This disease has gone from being relatively treatable with off-the-shelf drugs to being close to untreatable over the course of the last decade or so,” Baker said in a July university statement.
Researchers have also investigated how antibiotic use for other infections may contribute to resistance in Shigella. This process, known as bystander resistance, can occur when antibiotics prescribed for one pathogen affect other bacteria, potentially favoring resistant strains.
The findings do not mean every Shigella infection is drug-resistant or that all patients require antibiotics. Many cases resolve without them, while severe infections may require medical treatment guided by laboratory testing.
Health Experts Urge Prevention and Early Testing
Public health authorities recommend precautions to reduce transmission, including avoiding sexual activity when experiencing diarrhea and for a period after symptoms resolve, following local medical guidance. Using barriers during oral and anal sex and washing hands and the genital and anal areas before and after sexual activity can also reduce exposure.
People experiencing persistent or bloody diarrhea, fever, or severe abdominal cramps should seek medical advice. Patients should tell health care professionals about relevant sexual contact and recent travel so clinicians can consider Shigella testing and select appropriate treatment.
Daniel Richardson, a consultant in sexual health at University Hospitals Sussex, said clinicians should ask patients with dysentery about possible sexual transmission of Drug-Resistant Shigella and provide appropriate advice.
He also stressed that sexually transmitted Shigella may involve greater antibiotic resistance than infections acquired through other routes.
Experts say improved surveillance, timely diagnosis, and responsible antibiotic prescribing will be important in limiting the spread of resistant strains. The growing number of cases highlights the need to recognize Shigella as both a foodborne infection and a sexually transmissible health threat.
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