Lipopolysaccharide and Wzi retain capsular polysaccharide at the Klebsiella pneumoniae cell surface and promote bloodstream infection fitness

LPS and the outer-membrane protein Wzi jointly retain Klebsiella pneumoniae capsular polysaccharide on the cell surface, linked to bloodstream infection fitness in a murine bacteremia model.

• Why it matters: Capsule research has emphasized CPS synthesis and whether capsules are present, but how CPS is retained on the bacterial surface—and why that retention matters during infection—remains underexplored.
• What they did: The study identified CPS-retention components in K. pneumoniae and tested how LPS core-oligosaccharide and Wzi extracellular regions, plus divalent cation availability, affect surface CPS retention.
• The result: Surface CPS retention is important for survival in serum and for bacterial fitness at secondary infection sites in mice, supporting that CPS retention beyond synthesis contributes to bacteremia fitness.

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