Abstract
We used SDS-polyacrylamide gel electrophoresis to investigate the outer membrane proteins (OMPs) band composition of 19 Escherichia coli K1 strains that have spontaneously lost the ability to form K1 polysaccharide capsule (E. coli K1−) and demonstrated different degrees of susceptibility to the bactericidal action of normal human serum. Presented results showed that there were differences between E. coli K1− strains in OMPs expressing capacity. The analysis performed on OMPs has not revealed a direct association between the different OMPs band composition and the susceptibility of these strains to the serum.
Highlights
We used SDS-polyacrylamide gel electrophoresis to investigate the outer membrane proteins (OMPs) band composition of 19 Escherichia coli K1 strains that have spontaneously lost the ability to form K1 polysaccharide capsule (E. coli K1−) and demonstrated different degrees of susceptibility to the bactericidal action of normal human serum
Uropathogenic Escherichia coli strains are the major cause of urinary tract infections (UTIs) and are responsible for approximately 70–95 % of community acquired and 50 % of nosocomial UTIs (Kucheria et al 2005)
The detailed results of susceptibility of E. coli K1+ strains to 50 % normal human serum (NHS) were previously published (Cisowska et al 2004); in Table 1 we presented only the survival percent after 3 h of incubation in NHS for K1+ strains in order to make the comparison between K1+ and K1− forms easier
Summary
We used SDS-polyacrylamide gel electrophoresis to investigate the outer membrane proteins (OMPs) band composition of 19 Escherichia coli K1 strains that have spontaneously lost the ability to form K1 polysaccharide capsule (E. coli K1−) and demonstrated different degrees of susceptibility to the bactericidal action of normal human serum. E. coli K1 strains are a important cause of neonatal meningitis (more than 80 % of the cases) and are commonly associated with neonatal septicaemia These pathogens are capable of invading the brain of the newborns as a complication of the bloodstream dissemination following the colonization of the gastrointestinal tract (Nassif et al 2002; Wooster et al 2006; Parthasarathy et al 2007). Pathogens presenting brain tropism must avoid the host’s innate defence mechanisms, such as the complement (C) system and opsonophagocytosis, to survive in the bloodstream This suggests that these microorganisms possess very specific virulence factors which are essential for meningeal invasion. The capsular polysaccharide produced by E. coli K1 strains is a homopolymer of α-2,8-linked sialic acid (N-acetylneuraminic acid, Neu5Ac, NeuAc) residues and is structurally and immunologically identical to the capsular polymer of Neisseria
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