Rapid identification of Vibrio vulnificus by Raman spectroscopy

The autochthonous estuarine bacterium Vibrio vulnificus (V. vulnificus) is an opportunistic human pathogen acquired through consumption of raw shellfish or open wound infections. The infections caused by this Gram-negative bacterium are a significant health threat in susceptible individuals and can lead to septicemia. Traditional identification methods using selective-differential media for V. vulnificus are time consuming and lack the sensitivity to detect low numbers of bacteria. Therefore, developing technologies for rapid identification and enumeration of V. vulnificus in the environment has become a major concern for safe consumption of shellfish. In this study, Raman spectroscopy was applied to characterise the chemical properties of V. vulnificus, showing distinct changes in biochemical composition as the bacteria progress through their life cycle. Spectra from micro-colonies of V. vulnificus were compared against a principal component linear discriminant analysis model constructed from four species of planktonic bacteria, including V. vulnificus, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. This preliminary analysis achieved a classification accuracy of 67%, which demonstrates the potential for rapid identification of this pathogen in shellfish and water. This non-destructive, and reagentless spectroscopic technique holds great potential for the next generation of tools to investigate the prevalence and ecology of V. vulnificus.