Release of endotoxic lipopolysaccharide by sensitive strains ofEscherichia coli submitted to the bactericidal action of human serum

Demonty, J; Graeve, J. De

doi:10.1007/bf02123317

Cited by 23 publications

(9 citation statements)

References 24 publications

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“…Airborne endotoxins may exist in a bound or free state (Demonty and Grawe, 1982). Bound endotoxins remain bound to the bacterial outer membrane, whereas free endotoxins are shed from membrane complexes containing phospholipids, proteins, and LPS.…”

Section: Airborne Endotoxin Analysismentioning

confidence: 99%

Inactivation of airborne bacteria using different UV sources: Performance modeling, energy utilization, and endotoxin degradation

Wang

Zhang

2019

Science of The Total Environment

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Airborne bacteria-containing bioaerosols have attracted increased research attention on account of their adverse effects on human health. Ultraviolet germicidal irradiation (UVGI) is an effective method to inactivate airborne microorganisms. The present study models and compares the inactivation performance of three UV sources in the UVGI for aerosolized Escherichia coli. Inactivation efficiency of 0.5, 2.2 and 3.1 logarithmic order was obtained at an exposure UV dose of 370 J/m 3 under UVA (365 nm), UVC (254 nm) and UVD (185 nm) sources, respectively. A Beer-Lambert law-based model was developed and validated to compare the inactivation performances of the UV sources, and modeling enabled prediction of inactivation efficiency and analysis of the sensitivity of several parameters. Low influent E. coli concentrations and high UV doses resulted in high energy consumption (EC). The change in airborne endotoxin concentration during UV inactivation was analyzed, and UVC and UVA irradiation showed no marked effect on endotoxin degradation. By contrast, both free and bound endotoxins could be removed by UVD treatment, which is attributed to the ozone generated by the UVD source. The results of this study can provide a better understanding of the air disinfection and airborne endotoxin removal processes.

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Section: Airborne Endotoxin Analysismentioning

confidence: 99%

Inactivation of airborne bacteria using different UV sources: Performance modeling, energy utilization, and endotoxin degradation

Wang

Zhang

2019

Science of The Total Environment

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“…The endotoxin may exist bound to the bacterial outer membrane or as shed membrane complexes containing phospholipid, protein, and LPS (9, 29). Since bacteria often are found in low numbers in blood and experimental studies have shown that bacteria are rapidly cleared from the circulation by the reticuloendothelial system, a major contribution to the induced symptoms may come from endotoxin shed by the bacteria or released by lysis (9,32,36). Such smaller membrane fragments may penetrate to areas of tissues which could be poorly reached by bacteria.…”

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confidence: 99%

Endotoxin shedding by enterobacteria: free and cell-bound endotoxin differ in Limulus activity

et al. 1991

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The endotoxin activities of gram-negative bacteria and their lipopolysaccharides (LPS) have been quantitated by a chromogenic Limulus amoebocyte lysate (CLAL) assay. When bacterial cells exposing various cell surface structures were compared, the highest Limulus activities were found in R strains of Escherichia coli and Salmonella typhimurium mutants. E. coli with K antigens did not differ from K-negative strains. By measuring 0-hydroxymyristic acid (3-OH tetradecanoic acid, D-OHC14:0), it was possible to compare the CLAL activities of LPS bound to bacterial cells, LPS shed into the culture medium, and purified LPS. After 16 h of growth, the cell-free culture supernatants of three E. coli OlKl strains and S. typhimurium showed CLAL activities 14.3 to 20.3 times higher than did the corresponding bacterial cell suspensions in relation to their I-OHC14:0 contents. Four other E. coli strains (0 serotypes 014, 024, and 075) and the S. typhimurium 395 R mutants MR5 and MR6 showed CLAL values 2.8 to 7.9 times higher in their culture supernatants. LPS of E. coli OlKl and S. typhimurium had lower CLAL activities than the culture supernatants (1/10 and 1/4, respectively). Although the jI-OHC14:0 concentrations of the culture supernatants were approximately half those of the corresponding bacterial cells, all had CLAL values that were 2 to 21 times higher. The bacterial cell suspension, culture supernatant, and purified LPS of S. typhimurium MS were compared by CLAL assay and a quantitative enzyme-linked immunosorbent assay based on monoclonal antibodies to the 05 antigen. Endotoxin shed into the culture medium was the most CLAL-active form of LPS, while purified LPS was the most antigen-active form. The results emphasize the importance of appropriate standards when quantifying endotoxin in various states. In conclusion, E. coli and S. typhimurium bacteria shed significant amounts of endotoxin into the surrounding medium during growth. This form of LPS is more CLAL active than the cell-bound or purified LPS.

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“…First, a common observation in previous studies is the dissociation between lethality and an increase in the endotoxin concentration; that is, the period of maximal increase in endotoxin followed the period of cell death by 1 h (3) and by up to 3 h (13). This contrasts with the release of lipopolysaccharide from serum-affected bacteria, which as 51Cr-labeled lipopolysaccharide is 80% complete within 7 min (10) and 99% complete within 15 min (37) of cell death and as activity in the LAL assay is more than 90% complete within 12 min of cell death, although neither cell death nor lipopolysaccharide release is seen with heat-inactivated serum (8). The findings in this study support this dissociation between lethality and the maximal increase in endotoxin concentration after antibiotic exposure.…”

Section: Discussionmentioning

confidence: 87%

Antibiotic-induced release of endotoxin in chronically bacteriuric patients

Hurley

Louis

Tosolini

et al. 1991

Antimicrob Agents Chemother

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A novel in vivo model for the study of antibiotic-induced release of endotoxin from gram-negative bacteria is described. The model uses the chronically colonized urinary tracts of patients whose spinal cords have been injured. At baseline, the organisms were present in the range of 1 x i03 to 2 x i07 CFU/ml, and the concentration of endotoxin ranged from 2 x 10-1 to 1 x 103 ng/ml in 44 studies. tion. The intention of the studies was to develop a novel model for the study of antibiotic action in vivo, with the purpose of comparing antibiotics which differ in their modes of antibacterial activity. In each study, the effects on endotoxin concentration, which were determined by using a novel kinetic Limulus amoebocyte lysate (LAL) assay (16-18) and bacterial viability, were monitored. The reason for performing these studies in patients with spinal cord injuries is that because of their neurogenic injury, their urinary tracts are dilated and, hence, could be expected to resemble the chemostat culture apparatus. MATERIALS AND METHODSStudy design. The Austin Hospital, where these studies were performed, is a referral center for patients with spinal injuries for southeastern Australia. The study was approved by the Austin Hospital Ethics Review Committee.A total of 44, studies were performed on 11 volunteer patients who had given informed consent. Each study consisted of repeated samplings of urine for up to 3 h after administration of 6 mg of furosemide intramuscularly at time -20 min, followed by antibiotic (or no treatment) at time zero. In each patient, the individual studies were separated by a minimum interval of 3 days and a maximum interval of 14 days.Volunteer patients were selected from the spinal cord injury rehabilitation ward by the following criteria: an indwelling urinary catheter was present, the most recent routine weekly catheter urine culture revealed the growth of not more than two different gram-negative bacteria, and in the previous 7 days the patient had not been treated with either antibiotics or urinary antiseptics. The study period lasted for up to 4 weeks. Patients were suspended from the study if, during that time, therapy with antibiotics or urinary antiseptics was commenced.

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Release of endotoxic lipopolysaccharide by sensitive strains ofEscherichia coli submitted to the bactericidal action of human serum

Cited by 23 publications

References 24 publications

Inactivation of airborne bacteria using different UV sources: Performance modeling, energy utilization, and endotoxin degradation

Inactivation of airborne bacteria using different UV sources: Performance modeling, energy utilization, and endotoxin degradation

Endotoxin shedding by enterobacteria: free and cell-bound endotoxin differ in Limulus activity

Antibiotic-induced release of endotoxin in chronically bacteriuric patients

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