Drug-Resistant Shigella Spreads as Sexually Transmitted Infection Across England, Genomic Study Reveals
Key Insights
A nationwide genomic study of 3,514 Shigella (search) samples found sexually transmitted strains spread an average of 117 km versus 46 km for non-sexually transmitted strains in England.
Seventy percent of sexually transmitted Shigella (search) strains were resistant to at least one clinically relevant antibiotic, compared with 40% of non-sexually transmitted cases.
UKHSA figures show more than 2,500 cases of sexually transmitted Shigella (search) in England in 2025, up from just over 2,000 in 2023.
A nationwide genomic epidemiology study published in The Lancet Infectious Diseases has revealed that sexually transmitted Shigella sonnei (search) is spreading faster, over greater geographic distances, and with higher transmission intensity than non-sexually transmitted strains across England. The research, led by the University of Cambridge and the UK Health Security Agency (search) (UKHSA), provides the most detailed mapping to date of how Shigella (search) — traditionally known as a food and water-borne intestinal infection — has evolved into a rapidly circulating, drug-resistant sexually transmitted infection (STI).
The study analyzed 3,514 samples of Shigella (search) from people over the age of 16 in the UK between 2004 and 2020. Over a two-and-a-half-year period, sexually transmitted Shigella strains spread an average distance of 117 km, compared with just 46 km for non-sexually transmitted strains, underscoring the heightened transmission dynamics within sexual networks.
Rising Case Numbers and Antibiotic Resistance
UKHSA figures show that there were more than 2,500 cases of sexually transmitted Shigella (search) in England in 2025, up from just over 2,000 in 2023 — a trajectory that signals an escalating public health challenge. The study also found that 70% of sexually transmitted Shigella strains were resistant to at least one clinically relevant antibiotic, compared with 40% of non-sexually transmitted cases and 49% of cases contracted while travelling.
Shigella (search), most commonly found in feces and contracted through contaminated food, can cause severe diarrhea, fever, and stomach cramps. The infection primarily affects sexual networks of gay, bisexual, and other men who have sex with men, according to the study.
Limitations of Current Prevention Strategies
Historically, public health agencies relied on basic hygiene messages — such as washing hands and avoiding contaminated food or water — to curb outbreaks. However, researchers, including Dr. Lewis Mason, Lecturer in Biological Sciences at Kingston University, stress that these standard infection-prevention measures are largely ineffective against the sexual transmission of Shigella (search) via direct or indirect oral-anal contact during sex.
"We have found a worrying increase in cases of antibiotic-resistant Shigella (search) being transmitted sexually, and there isn't enough public awareness or effective interventions out there currently to stop the spread of this infection — particularly with Shigella becoming resistant to more antibiotics," Dr. Mason said.
The Call for New Interventions
To control the spread of drug-resistant shigellosis, the researchers concluded that alternative interventions — including effective vaccines, microbiological clearance pathways, and tailored treatment guidelines — must be urgently developed in partnership with patient communities. Dr. Mason highlighted the need to better manage antimicrobial stewardship across pathogens at a public health level.
The findings arrive amid growing global concern over antimicrobial resistance (AMR), which is estimated to contribute to nearly five million deaths each year and could claim ten million deaths annually by 2050 if left unchecked. While the impact is global, the heaviest toll is borne by low- and middle-income countries, where factors including overuse of antibiotics, substandard medicines, and shortcomings in sanitation and diagnostic testing compound the crisis.
Broader AMR Context and Prevention Efforts
Alongside the development of new treatments, researchers are exploring how artificial intelligence can help predict how resistant pathogens emerge and spread, as well as designing more effective surveillance techniques. GSK has more than 30 medicine and vaccine developments underway to address AMR, including a £45 million commitment to the Fleming Initiative, which uses large-scale data to identify new drug targets and improve antibiotic use in clinical settings.
Prevention is increasingly viewed as central to the AMR response. Established vaccines for diseases like influenza, pneumonia, and meningitis already play a crucial role in reducing infections and therefore the use of antibiotics for secondary bacterial infections. Next-generation vaccines, including combination formulations designed to protect against multiple pathogens in a single dose, aim to broaden coverage while streamlining delivery in resource-constrained settings.
The study from Cambridge and UKHSA reinforces the urgency of these efforts, demonstrating that drug-resistant Shigella (search) is not only spreading more rapidly through sexual transmission but also outpacing the conventional public health tools designed to contain it.