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The Microbiological Diagnostic Unit Public Health Laboratory (MDU PHL), part of the University of Melbourne’s Department Microbiology and Immunology at the Doherty Institute, regularly conducts whole-genome sequencing of bacterial samples submitted from food imported into Australia, as part of the Government’s Imported Food Inspection Scheme.

As part of this routine genomic surveillance program, scientists at MDU PHL discovered a new strain of Vibrio alginolyticus, a bacterium commonly found in marine environments, in cooked prawns imported from overseas.

In a study published in Microbiology Spectrum, they found that this new variant carries a particular gene capable of triggering resistance to carbapenem antibiotics, which are a last resort treatment option for severe infections in humans.

University of Melbourne’s Dr Jacqueline Morris, Research Fellow at MDU PHL at the Doherty Institute and lead author of the study, says this discovery is a concern for public health globally.

“This gene is typically found in a group of bacteria commonly found in the human digestive system, so we did not expect to find it in cooked seafood,” Dr Morris says.

“This is very concerning due the potential of gene transmission to other bacteria, which could lead to the emergence of highly drug-resistant strains of bacteria that are difficult to treat, posing a serious threat to public health.”

The detection of V. alginolyticus is not a notifiable condition, and although notifiable in foods, it is under detected, therefore this new strain is potentially still entering the country undetected, increasing the risk of transmission of the resistance gene in our food, particularly imported foods.

University of Melbourne’s Professor Ben Howden, Director of MDU PHL at the Doherty Institute and senior author of the paper, says the study highlighted the importance of strong surveillance programs and calls for increased in genomic testing that is still lacking in some regions.

“To monitor this new threat, we need to include V. alginolyticus in surveillance activities, particularly when screening seafood from aquaculture systems, which are a vital industry for food security, but also a potential AMR hot spot,” Professor Howden said.

“Traditional methods alone would not have detected the AMR determinant in this sample. It is thanks to whole-genome sequencing that we were able to discover the AMR gene. This study really emphasised the crucial role of genomic surveillance in the fight against this rising threat.”

Peer review: Microbiology Spectrum https://doi.org/10.1128/spectrum.04176-22
Funding: The MDU PHL is funded by the Victorian Government.