Many Gram-negative bacteria secrete outer-membrane vesicles (OMVs) into their surrounding environment. OMVs deliver effect or molecules to nearby cells and play important roles in bacterial survival and pathogenesis. Klebsiella pneumoniae is a prominent opportunistic pathogen, but its production of OMVs and the roles that OMVs play in its biology have not been clearly elucidated. This study examined the secretion and protein profiles of K. pneumoniae OMVs. K. pneumoniae ATCC 13883 secreted OMVs into the extracellular environment. The OMVs were associated with 159 different proteins, including many outer-membrane proteins and relatively few inner-membrane proteins. They also included proteins involved in the production of vesicles, the elimination of toxins and phages, the intercellular transport of genetic material and proteins, the targeting of host cells, and the modulation of host defenses. This study will help to reveal the functions of OMVs in K. pneumoniae in order to generate new vaccines and therapies for multi-drug resistant K. pneumoniae strains.
