Jumbo phages are active against extensively-drug-resistant eyedrop-associated Pseudomonas aeruginosa infections.

Antibiotic resistant bacteria present an emerging challenge to human health as the pressure instituted on the microbial world through the liberal use of antibiotics has resulted in their emergence across the globe. Those bacteria that acquire mobile genetic elements such as plasmids are especially concerning because those plasmids may be shared readily with other microbes that then can also become antibiotic resistant. Serious infections have recently been related to contamination of preservative-free eyedrops with extensively drug resistant (XDR) isolates of Pseudomonas aeruginosa, already resulting in three deaths. These drug-resistant isolates cannot be managed with most conventional antibiotics. We sought to identify alternatives to conventional antibiotics for lysis of these XDR isolates, and identified multiple bacteriophages (viruses that attack bacteria) that killed them efficiently. We found both jumbo phages (>200kb in genome size) and non-jumbo phages that were active against these isolates, the former killing more efficiently. Jumbo phages effectively killed the 3 separate XDR P. aeruginosa isolates both on solid and liquid medium. Given the ongoing nature of the XDR P. aeruginosa eyedrop outbreak, the identification of phages active against them provides physicians with several novel potential alternatives for treatment.