Rapid assessment of changes in phage bioactivity using dynamic light scattering.

Phages are promising for use in treating antibiotic-resistant infections, but their decay over time in refrigerated storage and higher temperatures has been a difficult barrier to overcome. This is in part because there are no suitable methods to monitor phage activity over time, especially in clinical settings. Here, we show that Dynamic Light Scattering (DLS) can be used to measure the physical state of phage preparations, which provides accurate and precise information on their lytic function - the key parameter underlying clinical efficacy. This study reveals a "structure-function" relationship for lytic phages and establishes DLS as a method to optimize the storage, handling, and clinical use of phages.