What is the issue?
The rise in the number of cases of shigellosis resistant to multiple antibiotics has caused the department to change its recommendations, in line with the therapeutic guidelines, to minimise the use of antibiotics. Previously, the department recommended antibiotic treatment for all confirmed cases of shigellosis. It is still important, however, to ensure all suspected cases of shigellosis have stool samples sent for culture and antibiotic sensitivity testing.
Who is at risk?
High risk populations for contracting shigellosis include men who have sex with men and all travellers to countries with high rates of endemic disease.
Symptoms and transmission
Transmission of Shigella is by the faecal-oral route requiring only a small infectious dose; the incubation period is usually one to three days.
Shigellosis is characterised by an acute onset of diarrhoea, fever, nausea, vomiting and abdominal cramps. Typically stools contain blood, mucus and pus, although some people will present with watery diarrhoea without these features. Shigellosis is usually a self-limited infection, although in vulnerable individuals, such as the immunocompromised, it is potentially serious.
Cases remain infectious while bacteria are continuing to be shed in the faeces, which can last for up to four weeks after symptoms resolve. Although appropriate antibiotic treatment usually reduces the period of carriage to a few days, high rates of antibiotic resistance have prompted the department to recommend reserving antibiotics for priority cases only.
Prevention of onward transmission
Reinforce good hygiene practices including cleaning of kitchen and bathroom surfaces, handwashing after going to the toilet and before eating or preparing food. Cases should not prepare food for others until 48 hours after symptoms resolve. A safer sex message should be given for both men and women:
- Abstain from sex while symptomatic and for seven days after symptoms completely resolve.
- Use barrier protection (condoms, dental dams) for vaginal, anal, oral-anal and oral sex for a further 2 weeks.
- Avoid faecal-oral exposure during sex Wash body and hands before and after sex (e.g. showering), especially after removing condoms.
Food handlers, healthcare workers, staff of residential facilities and childcare workers should be advised to not work pending advice from the department. Those living in residential facilities should be isolated (including cohorting with other ill residents, if necessary) to reduce onward transmission. Others with shigellosis should be advised against visiting residential facilities and vulnerable people. Children must be excluded from childcare and primary school until 24 hours after cessation of symptoms.
Supportive treatment, including plenty of fluids, is all that is required for most people. Anti-motility drugs are contraindicated.
Who should receive antibiotics?
Antibiotics reduce the period of transmissibility to a few days, however their use should be restricted to priority groups where possible and informed by acquisition source and antibiotic sensitivities. To reduce transmission especially amongst vulnerable people, the following priority groups should receive antibiotics:
- food handlers
- healthcare workers
- childcare workers
- people living or working in aged care facilities, prisons, disability group homes and other residential facilities
- children younger than 6 years.
To reduce the extent of disease, those with severe disease or who are immunocompromised should also receive antibiotics. Those who are HIV positive generally only require antibiotics if their CD4 count is low – the advice of an infectious diseases physician should be sought.
If indicated, what antibiotics should be used?
Empirical antibiotic treatment is recommended in these priority groups but should be informed by acquisition source (below) until susceptibilities are known. If diagnosis was by PCR alone, empirical treatment should be completed. Note that antimicrobial resistance is increasing in Victoria against some antibiotics recommended in the Therapeutic Guidelines. The department has recently issued antimicrobial sensitivity data to assist with empirical therapy choice. The department recommends that clinicians seek advice from an infectious diseases physician, where appropriate, as well as their diagnostic laboratory on the results of antibiotic susceptibility testing in each instance for their patient.
Levels of antimicrobial resistance in Shigella species are high overseas – priority cases whose disease was not acquired in Australia should be treated empirically with azithromycin until sensitivities are known.
There are very high levels of antimicrobial resistance among Shigella species circulating in the MSM community, therefore there is no suitable oral empirical antibiotic of choice for those who have acquired shigellosis through MSM contact. Personal hygiene and safer sex messages should be emphasised as a matter of urgency and antibiotics considered only after sensitivities are known. The exceptions are MSM cases with severe shigellosis or who are immunocompromised, for whom parenteral ceftriaxone or similar third generation cephalosporins are among the limited empirical options. It is particularly important that priority groups who have acquired shigellosis through MSM contact are excluded from work or isolated if living in a residential facility until advised otherwise by the department.
Under the Public Health and Wellbeing Regulations (2009), medical practitioners must notify cases of shigellosis to the Department of Health and Human Services within five days of initial diagnosis. Notifications can be made online or faxed on 1300 651 170. More information about managing cases - for example, workplace exclusion or isolation in residential facilities - may be obtained by phoning the department on 1300 651 160.
Better Health Channel – Gastroenteritis – shigella
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