Flies have also been used to differentiate virulence of P. aeruginosa strains, such as those isolated from the sputum of cystic fibrosis patients (who are particularly sensitive to infection by this pathogen) (Lutter et al., 2008; Salunkhe et al., 2005; Sibley et al., 2008) . For these assays, flies are either fed different strains of bacteria obtained from burn wounds or from cystic fibrosis patients, or bacteria are inoculated by wounding flies. Similar infection experiments can be performed to identify interactions between P. aeruginosa and other microbes present in sputum that could contribute to the virulence of this pathogen (Sibley et al., 2008) .