Purpose: Enterohemorrhagic Escherichia coli O157:H7 (EHEC) is known to cause sporadic and epidemic gastrointestinal infections and many children infected by E. coli O157:H7 had developed a hemolytic-uremic syndrome (HUS). HUS is believed to be caused by Shiga toxins (Stx) and lipopolysaccharides (LPS) released by E. coli O157:H7. The current antibiotic therapy (which includes Sulfa-containing or β-lactam antibiotics) is generally not recommended for EHEC infections because the treatment may increase the production of LPS and Stx in patients. The purpose of this study is to investigate the role of arginine anchored nanoglobule in inhibiting the growth of EHEC and capturing released LPS.
Methods: Arginine anchored nanoglobules were prepared using lauryl arginate ethyl (LAE) loaded self nano-emulsifying preconcentrate composed of medium chain triglycerides (MCT) and Kolliphor HS15. Effect of LAE concentration on particle size, zeta potential and minimum inhibitory concertation (MIC) against E. coli (Luria-Bertani (LB) broth) was evaluated and optimized. The binding of LPS on the nanoparticle was estimated by analyzing particle size, zeta potential and turbidity at various LAE: LPS ratio. LPS mediated aggregation and separation of nanoglobules were evaluated using coumarin-6 as a fluorescent probe. For quantitative estimation of binding, a kinetic chromogenic Limulus Amebocyte Lysate (LAL) test was used according to manufacturer's instructions.
Results: LAE loaded self-nanoemulsifying preconcentrate spontaneously formed nanoglobules of 105 ± 5 nm in contact with an aqueous medium. A gradual decrease in zeta potential from +54.7 mV to +0.505 mV with the addition of LPS, increase in the polydispersity index (0.3 to 0.718) and increase in turbidity clearly indicated binding of LPS on nanoparticle surface and LPS induced aggregation of the particles (Fig. 1). MIC test demonstrated that the nanoglobules with LAE of concentration range from 1 mg/mL to 0.125 mg/mL has strong antimicrobial activity against E. coli with MIC of 0.125 mg/mL. As shown in Fig. 2, quantitative LAL assay showed that 90 % of LPS was captured.
Conclusion: Arginine anchored nanocarrier can kill E. Coli and efficiently capture released LPS. Thus, it can be a very novel and promising approach in the treatment of pathogenic E. Coli infection by averting systemic toxicities of E. Coli.
Manali Patki– student, St. John's University, New York
Jing Kong– St. John's University
Sabesan Yoganathan– St. John's University
Ketankumar Patel– Assistant Professor, St. John's university, Jamaica, New York