Adherence of Serratia marcescens, Serratia liquefaciens, Pseudomonas aeruginosa and Staphylococcus epidermidis to blood transfusion bags (CPD-SAGMAN sets).

The adherence of 4 isolates of Serratia marcescens, 1 isolate of Serratia liquefaciens, 1 of Pseudomonas aeruginosa, and 2 of Staphylococcus epidermidis to blood transfusion sets (CPD-SAGMAN) consisting of bags and connecting tubing was tested. All strains adhered well to the connecting tubes (polyvinyl chloride) from the transfusion sets from 3 manufacturers. Three isolates from a Swedish outbreak of septicaemia associated with contaminated blood bags showed greater adherence than an isolate from a urinary tract infection. There was no significant adherence of S. marcescens to the blood bags. In general, there were no significant differences in the adherence of a given isolate to the plastics from different manufacturers. Appropriate hygienic procedures for the production of transfusion sets appear to be of greater importance than differences in the plastic material as regards the incidence of transfusion-related bacteremia.

Studies of the binding activity of phage G13 to synthetic trisaccharides analogous to binding structures in Salmonella typhimurium and Escherichia coli C core saccharide. Correlation between conformation and binding activity.

Phage G13 binds to the carbohydrate part of lipopolysaccharides from rough mutants of Salmonella and Escherichia coli as the first event of infection. Equilibrium dialysis inhibition studies with native and synthetic trisaccharides as inhibitors suggested that phage G13 recognizes branched oligosaccharides having 6-O-alpha- or 7-O-alpha-glycosyl groups with alpha-Man(1----3) [alpha-Man(1----6)]Man (Man[Man]Man) and alpha-Glc(1----3)-[alpha-Hep(1----7)] alpha-Hep(1----3) alpha-Hep(1----5)Kdo as the smallest saccharides with inhibitory activity (Wollin et al., 1989). Of four synthetic analogues to Man[Man]Man only Man(1----3)[alpha-Gal(1----6)]alpha-Man-OMe (Man[Gal]-Man) and alpha-Glc(1----3)[alpha-Hep(1----7)]alpha-Hep-OMe (Glc[Hep]Hep) inhibited the binding of labelled E. coli C core nonasaccharide ligand to G13 with activities which were 10- and 15-fold lower than Man[Man]Man. The trisaccharides alpha-Man(1----3)[alpha-Glc(1----6)[alpha-Man-OMe (Man[Glc]Mann) and alpha-Man(1---3)[alpha-Tal(1----6)]alpha-Man-OMe (Man[Tal]Man) showed no inhibition at concentrations 75-fold higher than Man[Man]Man. Minimum energy conformation calculations of the saccharides using the GESA method showed that the 6-O-alpha-Man group in Man[Man]Man and the 7-O-alpha-Hep group SL805 pentasaccharide expose their OH-2 and OH-3 groups in a similar way and these are postulated to be key structural features for binding activity. The importance of hydroxy groups at certain positions is implied from the fact that both manno- and galacto-isomers are active. We also conclude that the O6-C6-C5-O5-C1 region of the 3-O-alpha-glycosyl group in the Man[Man]Man trisaccharide, or part of it, is important for the G13 binding activity.

Interaction between phage G13 and its oligosaccharide receptor studied by equilibrium dialysis.

The reversible binding of phage G13, a phi X174-like single-strand DNA phage, to a 3H-labelled nonasaccharide from the lipopolysaccharide of its natural host Escherichia coli C was studied with equilibrium dialysis. The binding constant (Ka) was determined to 1.3 x 10(7) M-1 in Scatchard and Lineweaver-Burk plots. Approximately one saccharide bound per G13 phage particle which suggests that only one of the 12 spikes in each G13 virion was engaged in the phage/receptor saccharide interaction. Equilibrium dialysis inhibition experiments with saccharides from lipopolysaccharides of an isogenic series of Salmonella typhimurium mutants showed that hepta- and pentasaccharides from two G13-sensitive bacteria, i.e., with efficiencies of plating of 0.1-1.0 compared to E. coli C, were efficient inhibitors with Ka-values greater than or equal to 1.2 x 10(7) M-1. The octa- and hexasaccharides from two G13 resistant strains, with efficiency of plating less than or equal to x 10(-4), were either greater than 1000-fold or greater than 15-fold less efficient as inhibitors with Ka-values less than or equal to 8.8 x 10(5) M-1. The results show that phage G13 binds in a specific and reversible way to penta-, hepta-, and nonasaccharides from G13 sensitive bacteria with the specificity residing in the hexose and heptose region of the core lipopolysaccharide.

The conformation of core oligosaccharides from Escherichia coli and Salmonella typhimurium lipopolysaccharides as predicted by semi-empirical calculations.

The preferred conformation of the hexose and heptose regions of core saccharides from Enterobacteriaceae lipopolysaccharides was calculated. The Hard Sphere Exo Anomeric (HSEA) approach was used and the minimum energy conformation of the Salmonella typhimurium and Escherichia coli R1, R2, R3, R4 and K12 cores calculated. The results indicate that most of the cores are sterically crowded, with small degrees of freedom, and that the hexose and heptose parts form two separate regions. The core structures exhibit a 'front'-side and a 'back'-side, the former being similar for all the structures and the latter being characteristic for each core type.

Definition of the phage G13 receptor as structural domains of trisaccharides in Salmonella and Escherichia coli core oligosaccharides.

The interaction between phage G13 and different bacterial and synthetic oligosaccharides has been studied using equilibrium dialysis inhibition. The results, and conformational analysis of the oligosaccharides, make us conclude that the phage G13 carbohydrate receptor is a conformational domain involving three sugar residues. The following trisaccharide elements contain the domain: alpha-D-Galp-(1----3)-[alpha-D-Galp-(1----6)]-alpha-D-Glcp, alpha-D-Manp-(1----3)-[alpha-D-Manp-(1----6)-alpha-D-Manp , and alpha-D-Glcp-(1----3)-[L-gly-alpha-D-man-Hepp-(1----7)]-L-gly-alph a-D- man-Hepp. Thus two structures, either a hexose substituted with alpha-D-glycopyranosyl groups in the 3- and 6-positions, or a heptose substituted with such groups in the 3- and 7-positions are functional G13 binding sites. Such domains are present in several cores of lipopolysaccharides from Salmonella and Escherichia coli species. Some cores, e.g. those from S. typhimurium chemotypes Ra, Rb1 and Rb2, contain two such domains. The identification of two G13 receptor domains within different core saccharides could explain the broad host range of this phage.