Non-mammalian infection models have been developed over
the last two decades, which is a historic milestone to understand
the molecular basis of bacterial pathogenesis. They also
provide small-scale research platforms for identification of
virulence factors, screening for antibacterial hits, and evaluation
of antibacterial efficacy. The fruit fly, Drosophila melanogaster
is one of the model hosts for a variety of bacterial
pathogens, in that the innate immunity pathways and tissue
physiology are highly similar to those in mammals. We here
present a relatively simple protocol to assess the key aspects
of the polymicrobial interaction in vivo between the human
opportunistic pathogens, Pseudomonas aeruginosa and Staphylococcus
aureus, which is based on the systemic infection
by needle pricking at the dorsal thorax of the flies. After infection,
fly survival and bacteremia over time for both P.
aeruginosa and S. aureus within the infected flies can be monitored
as a measure of polymicrobial virulence potential.
The infection takes ~24 h including bacterial cultivation. Fly
survival and bacteremia are assessed using the infected flies
that are monitored up to ~60 h post-infection. These methods
can be used to identify presumable as well as unexpected phenotypes
during polymicrobial interaction between P. aeruginosa
and S. aureus mutants, regarding bacterial pathogenesis
and host immunity.