Salmonella is one of the most dangerous and common food-borne pathogens. The overuse of antibiotics for disease prevention has led to the development of multidrug resistant Salmonella. Now, more than ever, there is a need for new antimicrobial drugs to combat these resistant bacteria. Aptamers have grown in popularity since their discovery, and their properties make them attractive candidates for therapeutic use. In this work, we describe the selection of highly specific DNA aptamers to S. enteritidis and S. typhimurium. To evolve species-specific aptamers, twelve rounds of selection to live S. enteritidis and S. typhimurium were performed, alternating with a negative selection against a mixture of related pathogens. Studies have shown that synthetic pools combined from individual aptamers have the capacity to inhibit growth of S. enteritidis and S. typhimurium in bacterial cultures; this was the result of a decrease in their membrane potential.

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The present study envisages synthesis of silver and zinc oxide nanobactericides from phytogenic source Bupleurum aureum. The synthesized nanobactericides were subjected to biophysical characterization and evaluated for biofunctionalization onto bacterial cellulose membrane which was synthesized by Komagataeibacter xylinus B-12068 culture strain. The synthesis was initially confirmed with UV -visible spectroscopy which conferred maximum absorbance at 415 nm for silver nanobactericides and 280 nm for zinc nanobactericides. The molecular binding and stabilization were predicted using FTIR which confirmed the presence of functional moieties. The XRD analysis revealed the crystalline nature and morphological characteristics was studied using TEM which confirmed the poly-dispersity of nanobactericides with the average size being 20-25 nm. The nanobactericides were tested against seven multi-drug resistant pathogens which were clinically isolated from patients suffering from myriad microbial infections. The tested pathogens were having antimicrobial resistant to ten different antibiotics and are reported to be members of ESKAPE pathogen group which are the major cause of drugresistance. The nanobactericides displayed significant activity against test pathogens with silver nanobactericides showed the highest activity against Escherichia coli strain 55 with 24 mm zone of inhibition and zinc oxide nanobactericides displayed the highest activity against Methicillin-resistant Staphylococcus aureus with 20 mm inhibition zone. The nanobactericides embedded onto bacterial cellulose to develop nanobactericides incorporated films which were characterized using SEM along with physicochemical analysis. The bacterial films with nanobactericides were evaluated against test pathogens which showed activity against all the pathogens. The results obtained in the present investigation attributes towards growing scientific knowledge on drug resistance during the post drug-resistance era.

The recent research on nanomaterials as antibacterials agents have gained significant importance in recent decades. The sustainable development of bio-nanobactericides from biogenic sources have resulted as one of the potent bactericidal agents at nanoscale. Bio-nanobactericides generously offers low toxic profiles in comparison with nanomaterials synthesized from conventional routes. The biological components mediate the synthesis and act as stabilizing agent to participate in the desired activity. These nanobactericides offers efficient alternatives to combat drug resistant pathogens with their unique mode of actions. Owing to their size dependent properties, they can be one of the most attractive tools against both gram +ve and gram −ve pathogens which are resistant to most of the available antibiotics. Based on these keys fundamental facts and considerations, the present mini review is designed to compile the recently published studies on nanomaterials bearing antibacterial activity against clinically important test pathogens.