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.
Subject(s)
Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial , Salmonella typhi/drug effects , Typhoid Fever/microbiology , Adolescent , Adult , Aged , Aged, 80 and over , Asia, Southeastern , Australia/epidemiology , Child , Child, Preschool , Drug Resistance, Multiple, Bacterial , Female , Humans , Incidence , Infant , Infant, Newborn , Logistic Models , Male , Microbial Sensitivity Tests , Middle Aged , Nalidixic Acid/pharmacology , Retrospective Studies , Salmonella typhi/isolation & purification , Typhoid Fever/epidemiology , Young AdultABSTRACT
A national scheme of Salmonella surveillance emerged in Australia as a direct result of high-profile outbreaks in 1977. A typing laboratory in Victoria put together a working model using the computer technology available at the time. The evolving information-gathering system has stood the test of time and has provided an invaluable bank of information covering isolations from humans and other sources. The databases have been used effectively in detecting trends and outbreaks and have assisted in the solution of public health problems--even extending internationally. The way in which this has been done and the lessons learned are described.
