Purpose: To determine the role of smooth or rough lipopolysaccharide on adherence of Pseudomonas aeruginosa bacteria to the rat cornea in vitro and on contact lenses of differing types.
Methods: Adherence of a smooth (AK957) and isogenic rough strain (AK1012) of P. aeruginosa bacteria to rat corneas that were either normal, traumatized using a 20-gauge needle or treated for 15 min with 0.1N sodium hydrochloric acid was assessed by homogenization and viable counting. Adherence of these organisms to 43 unworn contact lenses representing the four Food and Drug Administration lens groups was also assessed using viable counts.
Results: Attachment to contact lenses was greater for the smooth strain for all four lens types (P < 0.001). No variation in adherence to the different lens types was observed. Smooth bacteria also adhered to the cornea to a greater extent than the rough strain, regardless of trauma type (P < 0.001). Adherence to traumatized corneas was greater than to nontraumatized corneas for both strains of P. aeruginosa bacteria (P < 0.01). Measurement of surface hydrophobicity of the two bacterial strains revealed that the smooth strain was more hydrophobic than the rough strain (P < 0.001), perhaps accounting for the adherence pattern.
Conclusions: These results indicate that bacterial surface characteristics may be important determinants of adherence and could explain the propensity of certain bacterial strains to infect the cornea.