lipid-a and Enterobacteriaceae-Infections

Topics: Anti-Bacterial Agents; Colistin; Drug Resistance, Bacterial; Enterobacter; Enterobacteriaceae Infections; Humans; Lipid A; Microbial Sensitivity Tests; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Tandem Mass Spectrometry

Edwardsiella tarda is a causative agent of edwardsiellosis in freshwater and marine fish. Extracellular enzymic, haemolytic, hydrophobic and serum resistance activities, haemagglutination, autoagglutination and siderophores of high- and low- virulent E. tarda strains were examined. The results revealed different haemagglutination, autoagglutination, haemolytic, hydrophobic and serum resistance activities in different strains. Analysis of extracellular proteins (ECPs) and outer membrane proteins (OMPs) demonstrated several major, low molecular weight, virulent-strain-specific proteins, which could be virulence-related. Based on the database search with MALDI-TOF MS data, the closest homologies of the three protein bands Ed1, Ed2 and Ed3 were phosphotransferase enzyme family protein, nitrite reductase [NAD(P)H], large subunit and ATP-dependent Lon protease, respectively. A comparison of pathogenicity of purified lipopolysaccharide (LPS) and lipid A from virulent and avirulent strains demonstrated that LPS was one of the virulence factors of the E. tarda isolates, and lipid A was a biologically active determinant of LPS.

Topics: Animals; Edwardsiella tarda; Electrophoresis, Polyacrylamide Gel; Enterobacteriaceae Infections; Fish Diseases; Lipid A; Lipopolysaccharides; Oncorhynchus mykiss; Phenotype; Virulence Factors

Lipid A is the toxic component of endotoxin in gram-negative bacteria. Antibodies to lipid A are not usually found in healthy persons (or only at a low titer) without a corresponding history of infection. Even gram-negative septicemia is found to be accompanied by only low titers. A completely different situation is seen in patients with chronic or recurrent infections due to Enterobacteriaceae and other gram-negative bacteria. Here it is notable that the antibody titer varies with the type of disorder (e. g. cystitis and pyelonephritis). A severe would infection, e. g. due to Pseudomonas aeruginosa, also leads to measurable lipid A antibody titers. Varying antibody titers can be observed in cystic fibrosis, Crohn's disease, and severe surgical infections. One can conclude that a significantly elevated antibody titer develops during an extensive tissue involvement of long duration and indeed is caused by tissue inhibition by endotoxin. Based on clinical experience, it can be assumed that lipid A antibodies present in the body have a protective effect in septic shock.

Topics: Adolescent; Adult; Antitoxins; Bacterial Infections; Child; Enterobacteriaceae Infections; Humans; Immunoglobulin G; Lipid A; Pyelonephritis; Sepsis; Urinary Tract Infections; Wound Infection