Effect of Antibiotic Class and Concentration on the Release of Lipopolysaccharide from Escherichia coli

Abstract

The ability of six antibiotics from different classes to release radiolabeled lipopolysaccharide (LPS) from a phenotypically smooth galE mutant of Escherichia coli O111:B4 was examined. Antibiotic concentrations were 0.0625-512 micrograms/mL. LPS release increased as a function of the antibiotic concentration, reaching a limit at or near the concentration that killed the majority of bacteria. The maximum amount of LPS released by polymyxin B was 40.6% +/- 0.9%, by gentamicin 58.2% +/- 2.5%, by ciprofloxacin 65.8% +/- 2.5%, by ceftazidime 73.1% +/- 0.9%, by tetracycline 75.3% +/- 10.0%, and by imipenem 79.7% +/- 2.3%. In timed experiments, ceftazidime released 61.9% +/- 1.2%, imipenem 51.1% +/- 8.8%, and tetracycline 39.7% +/- 4.4% of the LPS within the first hour of incubation, whereas polymyxin B released 13.5% +/- 1.9%, gentamicin 9.8% +/- 3.6%, and ciprofloxacin 12.7% +/- 2.6% of the LPS (P < .05). Fluoro-radiography and immunoblot analyses revealed similar migration patterns for antibiotic-released and cell-bound LPS on SDS-PAGE gels, suggesting similar O-polysaccharide content in the two LPS fractions. The amount and rate of LPS release from an E. coli strain was dependent upon antibiotic class and concentration.

Porins from Salmonella enterica serovar Typhimurium induce TNF-α, IL-6 and IL-8 release by CD14-independent and CD11a/CD18-dependent mechanisms

“…Endotoxin protein preparations have been shown to contain at least 12 proteins, ranging in size from 5 to 80 kDa (Goldman et al, 1981). The predominant proteins present in endotoxin preparations were the porins, protein II and lipoprotein (Goldman et al, 1981), the most abundant protein in the outer membrane of bacteria in the Enterobacteriaceae (Evans & Pollack, 1993 ;Sultzer & Goodman, 1976). The LPSassociated protein complex can probably use different mechanisms of cell activation, which may or may not include specific receptors, as a consequence of the prevailing amounts of LPS or porins in such a complex.…”

The Front Line of Enteric Host Defense against Unwelcome Intrusion of Harmful Microorganisms: Mucins, Antimicrobial Peptides, and Microbiota

“…Indeed, intracellular K ϩ and ATP depletion have also been observed in EHEC strain O157:H7 subjected to AMPs (10). Moreover, it has been reported that a release of LPS from the membrane of gram-negative pathogens is triggered by several antibiotics (99,179,278,381,393). Since AMPs are discharged from Paneth cells at effective microbiocidal concentrations into the small intestinal crypts (116)(117)(118), it is tempting to suggest that some commensal intestinal bacteria, including E. coli and Lactobacillus, may discharge antimicrobial substance(s) into ecological niches within the intestine and thus also contribute to the front line of the chemical defense against enteric pathogens.…”

Porins fromSalmonella entericaSerovar Typhimurium Activate the Transcription Factors Activating Protein 1 and NF-κB through the Raf-1-Mitogen-Activated Protein Kinase Cascade

“…Porins are integral components of the outer membranes of all gram-negative bacteria and are intimately associated with the LPS; they induce many cellular responses, including cellular activation (23) and cytokine release (17,19,20,28,30). LPS and porins are released by several bacteria during both in vitro (10) and in vivo (59) growth, and this release is significantly enhanced when the bacteria are lysed following exposure to antibiotics or human serum (10,12,35). Active concentrations of both LPS and porins are often reached at infection sites from either gramnegative bacteria outer membrane blebbing or bacterial lysis as a consequence of host defense (59).…”