Shiga toxin producing Escherichia coli (STEC): Analysis of serotype changes over time in South Australia, 1997-2009

Background: Shiga toxin producing Escherichia coli (STEC) causes significant illness around the globe. South Australia enhanced the surveillance of STEC in 1996 following a serious outbreak of paediatric haemolytic uraemic syndrome (a severe complication of STEC infection) as a result of E. coli O111:H contaminated mettwurst. An analysis of the STEC surveillance data was conducted to assess changes in STEC serotypes over the period 1997 to 2009.

Methods: Routinely collected data were used to describe the epidemiology of STEC infection in South Australia from 1997 to 2009. General trends in STEC serotypes over time were described as well as specific trends in relation to age, sex, severity, seasonality, and location. Poisson regression was used to assess changes over time.

Results: The serotype most commonly identified was O157. This serotype showed a significant increase over time (p=<0.001) which contributed to the overall increase in STEC. Serotype O157 on average increased by 17% per year over the 13 year period. No other serotype documented a significant change during the study period.

Conclusions: Changes in the serotype distribution of STEC infection in South Australia is of public health significance as it may reflect epidemiological changes such as the introduction of an increasingly dominate strain. Identification of such strains is important as it may predict changes that will subsequently take place in neighbouring states or countries, or indicate novel sources of infection.

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Author (s): 

Amy E. Parry, A.Dyda, M.McCallum, M.McPherson, J.Raupach

Presenter (s): 
Ms. Amy Parry
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