Development of effective anti-microbial therapeutics has been hindered by the emergence of bacterial strains with multi-drug resistance and biofilm formation capabilities. In this article, we report an efficient green synthesis of silver nanoparticle (AgNP) by in situ reduction and capping with a semi-synthetic polysaccharide-based biopolymer (carboxymethyl tamarind polysaccharide). The CMT-capped AgNPs were characterized by UV, DLS, FE-SEM, EDX and HR-TEM. These AgNPs have average particle size of ~20–40 nm, and show long time stability, indicated by their unchanged SPR and Zeta-potential values. These AgNPs inhibit growth and biofilm formation of both Gram positive (B. subtilis) and Gram negative (E. coli and Salmonella typhimurium) bacterial strains even at concentrations much lower than the minimum inhibitory concentration (MIC) breakpoints of antibiotics, but show reduced or no cytotoxicity against mammalian cells. These AgNPs alter expression and positioning of bacterial cytoskeletal proteins FtsZ and FtsA. CMT-capped AgNPs can effectively block growth of several clinical isolates and MDR strains representing different genera and resistant towards multiple antibiotics belonging to different classes. We propose that the CMT-capped AgNPs can have potential bio-medical application against multi-drug-resistant microbes with minimal cytotoxicity towards mammalian cells.
Multidrug resistant
(MDR) bacteria have emerged as a major clinical
challenge. The unavailability of effective antibiotics has necessitated
the use of emerging nanoparticles as alternatives. In this work, we
have developed carbohydrate-coated bimetallic nanoparticles (Au-AgNP,
30–40 nm diameter) that are nontoxic toward mammalian cells
yet highly effective against MDR strains as compared to their monometallic
counterparts (Ag-NP, Au-NP). The Au-AgNP is much more effective against
Gram-negative MDR Escherichia coli and Enterobacter
cloacae when compared to most of the potent antibiotics.
We demonstrate that in vivo, Au-AgNP is at least
11000 times more effective than Gentamicin in eliminating MDR Methicillin
Resistant Staphylococcus aureus (MRSA) infecting
mice skin wounds. Au-AgNP is able to heal and regenerate infected
wounds faster and in scar-free manner. In vivo results
show that this Au-AgNP is very effective antibacterial agent against
MDR strains and does not produce adverse toxicity. We conclude that
this bimetallic nanoparticle can be safe in complete skin regeneration
in bacteria infected wounds.
Investment in SARS-CoV-2 sequencing in Africa over the past year has led to a major increase in the number of sequences generated, now exceeding 100,000 genomes, used to track the pandemic on the continent. Our results show an increase in the number of African countries able to sequence domestically, and highlight that local sequencing enables faster turnaround time and more regular routine surveillance. Despite limitations of low testing proportions, findings from this genomic surveillance study underscore the heterogeneous nature of the pandemic and shed light on the distinct dispersal dynamics of Variants of Concern, particularly Alpha, Beta, Delta, and Omicron, on the continent. Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve, while the continent faces many emerging and re-emerging infectious disease threats. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century.
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