Commons, Robert J., McBryde, Emma, Valcanis, Mary, Powling, Joan, Street, Alan, and Hogg, Geoff (2012) Twenty-six years of enteric fever in Australia: an epidemiological analysis of antibiotic resistance. Medical Journal of Australia, 196 (5). pp. 332-336.

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Abstract

Objectives: To determine incidence and trends in antibiotic resistance in Australian Salmonella enterica subspecies enterica serovars Typhi (S. Typhi) and Paratyphi (S. Paratyphi) isolates over the past 26 years.

Design: A retrospective analysis of consecutive microbiologically confirmed enteric fever isolates.

Participants and setting: All S. Typhi and S. Paratyphi isolates from patients diagnosed with enteric fever in Australia between 1985 and 2010.

Main outcome measures: Incidence and variation in antibiotic resistance over time and according to country of origin.

Results: We analysed 2551 isolates, which originated from 74 countries or regions, mainly India (33%) and Indonesia (22%). The incidence among Australian residents increased from four to five before 2003 to seven cases per million person-years after 2003. Multidrug resistance (chloramphenicol, ampicillin, trimethoprim) and nalidixic acid resistance emerged rapidly from the early 1990s, with nalidixic acid resistance increasing to 70% in 2009–2010, while multidrug resistance was relatively stable at between 4% and 11%. Nalidixic acid and multidrug resistance rates are highest in isolates from the Indian subcontinent. Some countries in South-East Asia, such as Indonesia, had very low rates of resistance; however, this varied across the region.

Conclusions: Nalidixic acid resistance has become widespread in enteric fever isolates from the Indian subcontinent and some parts of South-East Asia, justifying the use of ceftriaxone or azithromycin rather than ciprofloxacin as first-line treatment. However, resistance in some countries remains rare, potentially allowing treatment to be adjusted according to country of origin.

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