Conditional role of O-specific antigen expression in Pseudomonas aeruginosapathogenicity

In chronic biofilm-associated infections, variations in motility and LPS structure are commonly observed adaptive traits. Here, we identified the expression of the O-antigen biosynthetic cluster as a key driver of motility variation among a large number of clinical PA14 clade isolates.

Although flagellar presence and function remain intact, increased hydrophobicity in O-specific antigen (OSA)-deficient mutants enhances surface attachment, which limits surface motility but promotes biofilm formation. The modified lipopolysaccharide structure with a lack of OSA also results in increased serum sensitivity, reduced phagocytic uptake, increased aminoglycoside resistance, and enhanced expression of the type III secretion system.