Formulation of selenium nanoparticles encapsulated by alginate-chitosan for controlled delivery of Vibrio Cholerae LPS: A novel delivery system candidate for nanovaccine

The lipopolysaccharide (LPS) of Vibrio cholerae plays a significant role in stimulating primary protection and immune responses. LPS delivery has been limited by the stimulation of inflammatory cytokines. This work aimed to report the synthesis and performance of this formulation in modulating immune responses and protecting LPS against acidic gastric medium. Alg-Cs-LPS-SeNPs composite was fabricated by an ionic cross-linking/in situ reduction method. Cytokines TNF-α, IL-6, IL-10, and TGF-β were assessed after cells were incubated with different compounds of the system. The main outcomes revealed that encapsulation of LPS-loaded SeNPs in the alginate-chitosan complex was associated with a high entrapment efficiency and could effectively protect LPS against acidic GIT medium. Kinetic profiling revealed that LPS was more slowly released from LPS-loaded Alg-Cs-LPS-SeNPs at pH 1.2, 7.4, and 6.8. These results indicated that Alg-Cs-LPS-SeNPs composite was able to significantly increase anti-inflammatory cytokines and reduce the release of pro-inflammatory cytokines. Thus, these findings show that this system for LPS delivery could be easily biosynthesized and encapsulated for use in the pharmaceutical industry. This study provides proof of the potential for future use of oral LPS vaccines, concomitantly inducing immunomodulatory effects.

Sensitivity of levofloxacin in combination with ampicillin-sulbactam and tigecycline against multidrug-resistant Acinetobacter baumannii

BACKGROUND AND OBJECTIVES

The selection of alternative treatment options with antibiotic combinations may be used for successful managing of multidrug-resistant Acinetobacter baumannii. The aim of this study was to determine the synergistic effects of ampicillin-sulbactam combined with either levofloxacin or tigecycline against MDR A. baumannii.

MATERIALS AND METHODS

A total 124 of A.baumannii isolates collected from clinical samples of hospitalized patients which assessed for antibiotic susceptibility using disk diffusion method. E-test was used on 10 MDR A. baumannii isolates to determine the minimum inhibitory concentration (MIC) of ampicillin-sulbactam, levofloxacin and tigecycline. Any synergistic effects were evaluated at their own MIC using E-test assay at 37°C for 24 hours. Synergy was defined as a fractional inhibitory concentration index (FICI) of ≤0.5.

RESULTS

Levofloxacin plus ampicillin-sulbactam combination was found to have synergistic effects (FIC index: ≤0.5) in 90% of the isolates, but there was no synergistic effect for ampicillin-sulbactam/tigecycline and tigecycline/levofloxacin combination. The antagonist effect in 50% of isolates (FIC index: >2) showed in combination of levofloxacin/tigecycline.

CONCLUSION

The emergence of multidrug A. baumannii isolates requires evaluating by combination therapy. The combination of levofloxacin plus a bactericidal antibiotic such as ampicillin-sulbactam is recommended. Results should be confirmed by clinical studies.