Heterogeneity of Lipopolysaccharide Chain Size of Pseudomonas aeruginosa Isolated from Different Clinical Sources

With Reference to Gentamicin-Susceptibility and Serotype

Abstract

Lipopolysacchride (LPS) compositions of P. aeruginosa isolated from different clinical sources such as blood, urine, pus, sputum, and feces were analyzed by sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE), and aminoglycoside-susceptibility and serotype of these isolates were investigated in this study.
Fifty-nine isolates tested were divided into three groups according to the difference in their LPS compositions; 35 strains with the long-LPS chain (B-band LPS), 14 strains with the short chain (A-band LPS) and 10 LPS-deficient strains.
The relationship between the LPS compositions and their sources of 59 strains were investigated. The majority of clinical isolates (12 of the 13 strains) from the blood samples possessed the long-LPS chain (B-band LPS) and the remaining possessed the short-LPS chain (A-band LPS). About 67% each of the isolates from urine and feces possessed the long-LPS chain, and the minor part of both groups possessed the short-LPS chain. In isolates from both sputum and pus samples, the long-and chort-LPS chains were found at almost the same rate, and the LPS-deficient isolates were found in the sputum samples at a considerably high rate of 42%.
The 19 of the 35 isolates with the long-LPS chain were susceptible to gentamicin (54%) and 12 isolates were resistant (34%). On the other hand, the 14 isolates with the short chain were divided roughly into three groups, gentamicin-resistant, and-susceptible groups and intermediate groups. It was also notable that 7 of the 10 LPS-deficinet isolates were resistant to gentamicin.
Serotypes of 35 isolates with the long-LPS chain were classified into A, B, C, E, G and H types, but not into M type or non-typable groups, respectively. However, 12 and 2 of the 14 isolates with the short-LPS chain were classified into M type and non-typable groups, respectively, and also 8 and 2 of the 10 LPS-deficient isolates were classified into non-typable and M type groups, respectively.
These results indicate that the frequency of P. aeruginosa isolates with the long-and short-LPS and without LPS differed among the clinical sources used for the bacterial isolation. It was also clarified that heterogeneity of the LPS-chain size of P. aeruginosa isolates affected the differences in their susceptibility to gentamicin and serotype.