Modeling Persistent <em>Pseudomonas aeruginosa</em> Infection in Wounded Zebrafish Larvae

Pseudomonas aeruginosa is a major human pathogen, particularly in chronic wound infections and chronic pulmonary infections (especially in patients with cystic fibrosis (CF)). Chronic bacterial infections are refractory to antibiotic treatments and there is an urgent need for in vivo chronic infection models amenable to drug screening to develop efficient therapies. Here, we describe a protocol of infection by a P. aeruginosa clinical isolate from a CF patient, expressing constitutively the Green Fluorescent Protein (GFP), for generating a persistent wound infection in zebrafish larvae. Tail fin-injured embryos are immersed in a bacterial suspension for 1.5 h, washed, and monitored for bacterial load for 3 days. The bacterial burden was quantified daily by counting fluorescent colony-forming units (CFU) from lysed infected larvae, which allowed a persistent infection. Moreover, persistent P. aeruginosa bacteria were refractory to antibiotic treatment. This novel in vivo model of persistent P. aeruginosa infection offers opportunities to evaluate the efficacy of innovative treatments against chronic infections.