High hydrostatic pressure treatment for the inactivation of Staphylococcus aureus in human blood plasma.

For the past 30years, pressure inactivation of microorganisms has been developed in biosciences, in particular for foods and more recently for biological products, including pharmaceutical ones. In many past studies, the effect of high hydrostatic pressure (HHP) processes on pathogens focused mainly on the effect of an increase of the pressure value. To assure the safety of pharmaceutical products containing fragile therapeutic components, development of new decontamination processes at the lowest pressure value is needed to maintain their therapeutic properties. The aim of this study was therefore to evaluate the impact of the process parameters characterizing high-pressure treatments [such as the pressurization rate (PR) and the application mode (AM)] on the inactivation of pathogens, in particular to determine how these parameters values could help decrease the pressure value necessary to reach the same inactivation level. The effect of these physical parameters was evaluated on the inactivation of Staphylococcus aureus ATCC 6538 which is an opportunistic pathogen of important relevance in the medical, pharmaceutical and food domains. Human blood plasma was chosen as the suspension medium because of its physiological importance in the transfusion field. It was shown that the optimization of all the selected parameters could lead to a high inactivation level (≈5log(10) decrease of the initial bacterial load) at a pressure level as low as 200MPa, underlining some synergistic effects among these parameters. Complete inactivation of the initial bacterial population was achieved for the following conditions: PR=50MPas(-1), AM=5×2min, T≈-5°C and P=300MPa.