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.
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.
Authors: Deborah A Williamson; Courtney R Lane; Marion Easton; Mary Valcanis; Janet Strachan; Mark G Veitch; Martyn D Kirk; Benjamin P Howden Journal: Antimicrob Agents Chemother Date: 2018-01-25 Impact factor: 5.191