Plug-and-play evolution of the Klebsiella pneumoniae capsule locus enables serotype exchange across genetic backgrounds

Researchers at the Institut Pasteur have discovered that the capsule locus of Klebsiella pneumoniae, a major cause of hospital-acquired infections, evolves through a 'plug-and-play' mechanism. This modularity allows the bacteria to swap its protective outer capsule (serotype) with other strains with minimal impact on its growth or internal gene regulation. This finding explains the pathogen's high ecological versatility and its ability to rapidly evade vaccines and phage therapies that target specific serotypes. The study suggests that virulence traits can be seamlessly transferred across diverse genetic backgrounds, complicating efforts to control the spread of multi-drug resistant lineages.