Multi - drug resistant shigella alert

20 December 2018

The Communicable Disease Control Branch (CDCB) has identified a recent increase in cases of multi-drug resistant (MDR) Shigella sonnei biotype G in metropolitan Adelaide among men who have sex with men (MSM). 

Shigellosis is highly infectious and spread by direct faecal-oral transmission, or indirectly via contaminated food, water, or fomites. The infectious dose can be as low as 10-100 organisms. The incubation period is 1-3 days. Cases present with diarrhoea (which may contain blood and mucus), stomach cramps, fever and vomiting. Duration of illness is usually 3-4 days, but bacteria can be shed for up to four weeks after resolution of symptoms. This presents a high risk of ongoing transmission, particularly where additional risk factors for transmission occur.

Recently identified strains of MDR Shigella have been resistant to all recommended oral antibiotics, and inpatient management with IV antibiotics has been required. Shigellosis is one of the few situations where antibiotic treatment of gastroenteritis is recommended, both because of the potential for severe illness (dysentery), and to reduce shedding and limit outbreaks; antibiotic treatment reduces shedding from up to 4 weeks to about 3 days.

Doctors are asked to:

  • Ensure culture and sensitivity testing (not just PCR) is requested on faecal specimens from all persons presenting with diarrhoea who identify as MSM.
  • Persons identifying as MSM who present with severe illness or are HIV+ve should be admitted to hospital for IV therapy with ceftriaxone whilst awaiting sensitivities.
  • MSM with milder illness who are not HIV+ve should be given 1 gram ceftriaxone IV / IM after a faecal specimen has been collected for culture, and reviewed if necessary.
  • Patients with proven MDR Shigella infection should have faecal samples re-tested by culture (not PCR) at least 48 hours post completion of treatment regardless of whether they have ongoing symptoms. It is important that the clinical notes on the lab request  indicate that this is for test of clearance, otherwise specimens will not be processed.
  • Encourage people to use good personal hygiene and hand washing to reduce the risk of transmission.
  • Advise cases to not have sex (especially where there is any contact with the anus) until no longer infectious (at least one week after symptoms resolve).
  • Advise cases not to prepare food, share utensils or linen/towels while unwell.
  • Advise cases not to swim in public pools until diarrhoea-free for 24 hours.
  • Exclude people with diarrhoea from school, childcare and workplace until diarrhoea-free for at least 24 hours.
  • Exclude commercial food handlers from work until diarrhoea-free for at least 48 hours.
  • Notify cases to CDCB (see link below).

Dr Ann Koehler – Acting Director, Communicable Disease Control Branch