UK Health Officials Warn of Drug-Resistant Shigella Outbreak Linked to Sexual Transmission

The UK Health Security Agency (UKHSA) is tracking a significant increase in cases of Shigella sonnei, a bacterium causing severe gastrointestinal illness, which is spreading primarily through sexual contact. According to the UKHSA, this specific strain is increasingly resistant to common antibiotics, posing a distinct public health threat because standard treatments may fail to clear the infection.

Understanding the Spread of Drug-Resistant Shigellosis

Shigellosis is an infection of the intestines caused by Shigella bacteria. While typically associated with contaminated food or water, the UKHSA has identified a pattern of transmission among men who have sex with men (MSM), though the agency notes the bacteria can affect any sexually active person regardless of orientation.

The current concern centers on antimicrobial resistance (AMR). Many of the cases identified in the UK are resistant to ciprofloxacin, a primary antibiotic used to treat the infection. When the bacteria resist these drugs, the illness lasts longer and increases the likelihood of the patient spreading the pathogen to others. This genomic epidemiology—the study of how the bacteria’s genetic code changes as it moves through a population—shows a rapid spread of these resistant strains across England.

Identifying Symptoms and Risk Factors

The infection manifests as acute gastroenteritis. According to health reports from the UKHSA and clinical guidelines, the primary symptoms include:

• Severe Diarrhoea: Often containing blood or mucus.
• Stomach Cramps: Intense abdominal pain and tenderness.
• Fever: High temperature and chills.

Transmission occurs via the fecal-oral route, which in this specific outbreak is occurring through sexual activity and the subsequent transfer of bacteria from the rectum to the mouth.

Treatment Challenges and Medical Guidance

Treatment for shigellosis usually involves fluid replacement and, in severe cases, antibiotics. However, the UKHSA warns that because of the high level of resistance in the current circulating strains, doctors must rely on stool culture and sensitivity testing to determine which antibiotic will actually work.

Health officials emphasize that individuals who have been infected should inform their sexual partners so they can be tested and treated, even if they aren't showing symptoms, to break the chain of transmission.

Preventative Measures and Public Health Response

The UKHSA recommends several concrete steps to reduce the risk of infection and transmission:

• Hand Hygiene: Thoroughly washing hands with soap and water after using the toilet and before handling food.
• Barrier Use: Using condoms and dental dams during sexual activity to reduce the risk of fecal-oral transfer.
• Partner Notification: Promptly notifying recent sexual partners of a positive diagnosis.
• Avoid Food Prep: Infected individuals should avoid preparing food for others until they are cleared by a healthcare provider.

Comparing Shigella to Other Gastrointestinal Pathogens

Unlike Norovirus, which is a virus and cannot be treated with antibiotics, Shigella is a bacterium. While both cause vomiting and diarrhoea, Shigella is more likely to cause high fever and bloody stools. The critical difference in this outbreak is the “drug-resistant” nature of the bacteria, which makes it more dangerous than seasonal stomach bugs that resolve on their own.