Ionic binding of 3H-gentamicin and short-time bactericidal activity of gentamicin against Pseudomonas aeruginosa isolates with different lipopolysaccharide structures.

The clinical isolates of Pseudomonas aeruginosa can be roughly classified into long- and short-LPS strains and LPS-deficient strains. Ionic binding of 3H-gentamicin was the highest in the long-LPS strains followed in descending order by short-LPS and LPS-deficient strains. However, PAC605 strain, completely lacking in the repeated units of O-polysaccharide and also lacking in some of the neutral sugar residues of the core oligosaccharide region, highly bound to 3H-gentamicin and it is suggested that the negatively charged sites on the deep-core oligosaccharide region and/or on lipid A participated in the binding to 3H-gentamicin. This manner of binding may be also applied to P. aeruginosa No. 45 (LPS-deficient), a clinical isolate.