Salmonella typing in New South Wales: current methods and application of improved epidemiological tools.

Salmonellosis caused by enteropathogens of the genus Salmonella is a major public health concern in Australia. Serotyping is usually performed in enteric reference laboratories for the initial characterisation and differentiation of Salmonella species. Further strain identification within serovars may be achieved by phage typing and this is used as an epidemiological tool for outbreak investigations. Phage typing has limited discriminatory ability and the necessity of sending specimens interstate from NSW for this test causes delays in recognising outbreaks and reduces the likelihood of identifying the source. Multilocus variable-number tandem-repeat analysis has a high discriminatory power and faster turnaround time, and is the method of choice for outbreak investigation. Additionally, a newly developed multiplex PCR-based reverse line blot hybridisation system is able to identify most of the phage types prevalent in NSW. Combining these last two molecular methods will significantly enhance outbreak investigations and surveillance of Salmonella infections in NSW.