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Published: 21 February 2017

Vale Sue Dixon

By George Davey

Friends and colleagues of Sue Dixon were saddened to hear of her passing in August 2016 after a short illness.

Sue was born on 10 January 1928 in Malvern, Adelaide. After graduating from Unley High School she commenced her career in microbiology as a laboratory assistant cleaning test tubes at the then recently established Institute of Medical and Veterinary Science (IMVS). Sue was awarded a cadetship by the IMVS to study at Adelaide University where she graduated with a BSc in 1949. From 1949 to 1952 Sue worked as a bacteriologist at the IMVS and then resigned to start a family. After rejoining the IMVS in 1960 Sue assumed responsibility for the National Salmonella Reference Centre established by her mentor and good friend the eminent Dr Nancy Atkinson. From 1967 until her retirement in 1983 Sue was the head of the Salmonella Reference Laboratory (SRL) and Food Hygiene Laboratory at the IMVS.

Sue was one of a number of formidable and influential female Australian microbiologists of her generation who played leading roles in transforming the profession of food microbiology in this country. Her contemporaries included Margaret Dick (Kraft Foods, Melbourne), Jenny Taplin (MDU The University of Melbourne), Dr Barbara Keogh (CSIRO Dairy Research Laboratories, Melbourne), Professor Nancy Millis (The University of Melbourne) and Dr Phillis Rountree (Royal Prince Alfred Hospital, Sydney).

In 1977 Sue and her colleague Jenny Taplin at the Microbiological Diagnostic Unit (MDU) identified infant formula as the likely cause of a widespread national outbreak of infant gastroenteritis from Salmonella bredeney. However, it was only through Sue’s forensic and innovative approach to microbiological analysis of foods that the source was ultimately confirmed and traced to contaminated milk powder ingredient, which was something no other Australian food testing laboratory was able to achieve. Her work in this area greatly influenced future approaches to investigations of outbreaks of food borne disease and the methods adopted by regulatory authorities and the Australian dairy industry to prevent Salmonella contamination of dried milk products. This development was especially important in meeting food safety requirements for valuable export markets for Australian dried milk products. As a consequence of the national media attention to this investigation Sue became widely reported as ‘Salmonella Sue’!

The discovery in 1977 of S. bredeney in infant formula and the detection around the same time of S. adelaide in calcium caseinate in a range of dried dairy based food products such as invalid diet supplements and slimming diets highlighted the importance of a national Salmonella typing system. This led to a collaboration between the SRL, MDU, the Commonwealth Department of Health and the Australian Society for Microbiology (ASM) in establishing a National Salmonella Surveillance Scheme (NSSS). Sue played a key role in the development of the NSSS which has been a major tool in the epidemiological investigations of salmonellosis and early warning to health authorities of food-borne disease from Salmonella.

Sue was an active member of the ASM where she served on the Membership Committee from 1979 to 1981 and the working party to investigate the establishment of a Fellowship category (FASM) from 1982 to 1983. She was also President of the South Australian Branch of ASM from 1979 to 1981. In 1983 Sue was elected to Honorary Life Membership of ASM.

Sue was also active in the Australian Institute of Food Science and Technology (AIFST). In 1974 she participated in the inaugural AIFST/CSIRO/UNSW Specialist course for the food Industry: Food-borne microorganisms of public health significance, where with good humour and diplomacy she taught the teachers some basics in food microbiological techniques. For subsequent courses (1976 and 1979) Sue co-authored with George Davey chapters in Food-borne microorganisms of public health significance (the ‘Green Book’) on serological techniques for the identification of Salmonella species.

Prior to the establishment of Food Standards Australia New Zealand (FSANZ) and its predecessor organisation the National Food Authority (NFA), microbiological specifications for foods were developed by the National Health and Medical Research Council (NHMRC), Food Microbiology Sub-committee. Sue served on this committee from around 1979 to 1983.

Sue played a significant role in helping both government and industry Australian food microbiological testing laboratories to improve testing methodologies and performance. She was a member of Standards Australia Committee FT/4 Methods for the Microbiological Analysis of Foods from around 1976 to 1983 and a member of the National Association of Testing Authorities (NATA) Biological Testing Advisory Committee from 1982 to 1987.

Apart from the important part Sue played in developing national microbiological food standards, improving laboratory testing methodologies and procedures, assisting in the epidemiological investigations of food-borne disease and surveillance of Salmonella, Sue was a role model and mentor to many young aspiring food microbiologists. She was always willing to offer her guidance and wisdom with humour and empathy. Sue is sadly missed.

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