Abstract
The nosocomial multidrug resistant bacteria (MDR), are rapidly circulating from water surfaces to humans away from the clinical setting, forming a cyclical breeding ground of resistance, causing worldwide infections, and thus requiring urgent responses. The combination of chitosan and zinc oxide (CZNPs), with proven bactericidal effects on some MDRs, was further studied to set the stage for a broad-spectrum in vivo utilization of CZNPs. Toward ensuring CZNPs' uniformity and potency, when it faces not only biofilms but also their extracellular polymeric substances (EPS) defense mechanism, the size, zeta potential, and polydispersity index (PDI) were determined through dynamic light scattering (DLS). Furthermore, the efficacy of CZNPs was tested on the inhibition of MDR Gram-negative Escherichia coli BAA-2471 and Gram-positive Enterococcus faecium 1449 models, co-cultured in an Alvatex 3D fiber platform as a biofilm-like structure. The Biotek Synergy Neo2 fluorescent microplate reader was used to detect biofilm shrinkage. The biofilm protection mechanism was elucidated through detection of EPS using 3D confocal and transmission electronic microscopy. Results indicated that 200 μl/mL of CZNPs, made with 50 nm ZnO and 10,000 Da chitosan (N = 369.1 nm; PDI = 0.371; zeta potential = 22.8 mV), was the most promising nanocomposite for MDR biofilm reduction, when compared to CZNPs enclosing ZnO, 18 or 100 nm. This study depicts that CZNPs possess enough potency and versatility to face biofilms' defense mechanism in vivo.
Highlights
During recent decades, interest in nanotherapeutics in the United States and worldwide has met an unprecedented progress in biomedical and food safety fields (Ponce et al, 2018)
While this study focuses on the multifunctional capability of CZNPs as a broad spectrum antimicrobial through different levels of intricacies and habitats, the gastrointestinal tract (GIT) is mentioned in this study as model for treatment due to its highest levels of complexity, with the rationale that if CZNPs can be optimized as a nanotherapeutic for the GIT, it will be less difficult to repurpose it to treat infections in organ systems of a lower level of complexity
The average polydisperity index for the CZNPs formulations made with 50 nm ZnO and with 100 nm ZnO is 0.393 ± 0.078 and 0.428 ± 0.045, respectively, whereas the average value for the formulation made with 18 nm ZnO is substantially higher, i.e., 0.828 ± 0.128
Summary
Interest in nanotherapeutics in the United States and worldwide has met an unprecedented progress in biomedical and food safety fields (Ponce et al, 2018). Among the MDR pathogens, some strains of multidrug resistant fecal bacteria (MRFs), including both Gram-positive Enterococcus faecium and Gram-negative Escherichia coli, are the main causatives of hospital-acquired infections. The considerable phenotypical elasticity and antigenic variance of this “Superbug" generate out from it an enormous “factory" of continuous antibiotic resistance production Owing to these increasing public health risks, it is deemed imperative to develop an alternative antimicrobial over conventional antibiotics that is broad-spectrum and costefficient in order to suppress both Gram-positive and Gramnegative MDR strains with minimal side effects and a high safe threshold toxicity. Among the most promising nanotherapeutics, the newly designed CZNPs have been proven to have an extraordinary inhibitive potential against a substantial number of pathogens and MDR strains primarily nosocomial multidrug resistant Enterococcus faecium, Esherchia coli, and Pseudomonas spp. Among the most promising nanotherapeutics, the newly designed CZNPs have been proven to have an extraordinary inhibitive potential against a substantial number of pathogens and MDR strains primarily nosocomial multidrug resistant Enterococcus faecium, Esherchia coli, and Pseudomonas spp. (Limayem et al, 2015a,b; Mehta et al, 2019; Mohapatra and Limayem, 2019)
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