S. aureus has evolved strategies to manipulate host-pathogen interactions to its own ends and avoid killing by professional phagocytes. The pathogen evades killing by subverting one or more of the internalisation and intracellular processes to escape from cells or to establish an optimal microenvironment for its intracellular survival. Internalisation processes bear many interesting features that make them an integral part of decision making process in inflammatory responses. We are using light fluorescence and confocal microscopy to track bacterial fate inside professional phagocytes and developing transgenic zebrafish lines to specifically mark intracellular compartments of interest.

Additionally, S. aureus strains are stained before injection with pH-sensitive and insensitive fluorescent dyes to assess the stage of endosome maturation by pH decrease – important factor of disruptive environment and intracellular killing. The incorporation of plasmid carrying fluorescent protein allows us to track bacterial growth and formation of an abscess. The project aims to combine informative abilities of different imaging approaches to target both: pathogen and host strategies in order to shed light on the key process and its timing in S. aureus infection.