XDR Shigella sonnei

Alert Date

The Windsor Essex County Health Unit (WECHU) is monitoring new provincial trends related to drug resistant (XDR) Shigella cases. There have been 11 cases of XDR Shigella sonnei reported in Ontario between March 29, 2022, and January 31, 2023. The cases are all male, ranging in age from 27 to 58 years old, and predominantly are men who have sex with men. Travel outside of the province has been identified as a risk factor for 36% of these cases. At this time, there are no reported cases in Windsor and Essex County.

Background on Shigellosis

Shigellosis is a reportable disease in Ontario. It is caused by a bacteria of the genus Shigella. There are four pathogenic species within the genus: Shigella dysenteriae (also known as serogroup A), Shigella flexneri (also known as serogroup B), Shigella boydii (also known as serogroup C) and Shigella sonnei (also known as serogroup D). XDR Shigella are strains that are resistant to all commonly recommended antibiotics.

Clinical Presentation

Signs and symptoms commonly arise 1 to 7 days after exposure and include diarrhea, fever, blood and/or mucus in stool, and abdominal cramps.

Mode of Transmission

The primary mode of transmission is fecal-oral; this includes ingestion of contaminated food and water and through sexual contact. The risk of transmission increases for individuals engaging in anal-oral sex and in settings where personal hygiene is limited.

At Risk Individuals

Individuals at risk for Shigella XDR include: men who have sex with men, those experiencing under housing, international travelers, immunocompromised persons, those living with HIV, and young children.

Drug Resistance

The XDR Shigella strain is currently defined as resistant to the following five antimicrobials: ampicillin, fluoroquinolones, third generation cephalosporins, azithromycin, and trimethoprim-sulfamethoxazole.

Recommended Action

It is recommended that clinicians keep shigellosis on their differential diagnosis when treating patients with enteric symptoms, especially for patients who are at higher risk. If shigellosis is suspected, a sexual history should be taken. Testing for STI and bloodborne infections, including HIV, syphilis, gonorrhea, chlamydia, hepatitis B and C should also be considered. Antibiotic therapy is recommended for patients with severe disease (e.g., hospitalized patients) or immunocompromised patients. In those who require antibiotics, therapy should be guided by antimicrobial susceptibility testing in consultation with an infectious disease specialist or other clinicians knowledgeable in treating antibiotic resistant bacteria.


Please continue to report all cases of Shigellosis to the Infectious Disease Department at WECHU using the reporting form. Reporting forms can be faxed to 226-783-2132. For questions or concerns please contact the WECHU at 519.258-2146 ext. 1420.