Public Health Alert – XDR Shigella sonnei in Ontario

Issue

Shigellosis is an acute infectious diarrheal disease characterized by severe abdominal cramps, tenesmus, fever and malaise, nausea, vomiting, and watery or bloody diarrhea which may contain mucus. It is highly infectious and a common cause of travel-associated diarrhea. Treatment includes rehydration and electrolyte replacement when indicated, and usually does not require antibiotics. Vulnerable individuals may experience complications requiring additional treatment.

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

There have been at least 10 known cases of XDR Shigella sonnei in Ontario between March 29, 2022 and January 31, 2023, with nine in Toronto and one in the Region of Waterloo. The predominant route of transmission has been sexual contact between men who have sex with men (MSM), and four cases had travelled abroad during their incubation period.

Action required

• Maintain awareness of XDR Shigellosis in patients with symptoms consistent with Shigellosis and when providing specialized care or clinics for patients who are gay, bisexual, and other men who have sex with men
  • Inquire about travel abroad, social history including sexual activities, housing status, and use of substances
  • Exclude from work symptomatic patients who are food handlers, healthcare providers, caregivers or daycare attendees pending a negative stool sample or rectal swab collected at least 24 hours after cessation of symptoms, OR 48 hours after completion of antibiotic therapy when indicated
  • If antibiotics are required, therapy should be guided by antimicrobial susceptibility testing, and in consultation with an infectious disease specialist or clinician knowledgeable in treating antibiotic-resistant bacteria
• Be aware of other immunocompromising conditions e.g. HIV
  • Counsel patients related to sexual activity:
  • Avoid sexual activity from symptom onset until at least seven days after symptoms stop
  • Avoid faecal-oral contact for 4-6 weeks
  • Hygiene measures:
    • Wash genital and anal areas and hands before and after sexual activity
    • Use latex gloves for fingering or fisting and dental dams during oral-anal sex
    • Refrain from sharing sex toys, clean and disinfect after use and between partners
    • Change condoms between anal and oral sex
  • Reinforce safer sex to reduce the risk of other STIs including HIV, Hepatitis B and C

For more information, please see the memo from Dr. Yaffe, Associate Chief Medical Officer of Health for Ontario: XDR Shigella sonnei: Possible Sexual Transmission.

Contact:
Dr Kit Young Hoon
Medical Officer of Health
Northwestern Health Unit