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Surface contamination by pathogenic and deteriorating microorganisms is a constant concern in the food industry. Therefore, in this study we evaluated the antimicrobial activity of silver nanoparticles (AgNPs), produced using the essential oil of Lippia origanoides Kunth and ethanolic extract of Hymenaea martiana Hayne, against bacteria used in milk processing. For this, AgNPs were synthesized and their antimicrobial activity was evaluated for minimum inhibitory and bactericidal concentrations, time-kill, interference on the biofilm, and application on the surfaces of different materials. AgNPs showed bacteriostatic and bactericidal activity against Staphylococcus aureus (ATCC 25923), Staphylococcus aureus (ATCC 33591), Escherichia coli (ATCC 25922), Salmonella enterica subsp. enterica serovar Choleraesuis (ATCC 10708), Listeria monocytogenes, Escherichia coli, Salmonella spp.,andPseudomonas aeruginosa,and interfered with biofilm formation more than with consolidated biofilms. A 1hour period was sufficient to reduce the bacterial cells, whereas a Minimum Duration for Killing (MDK) of 99% was reached after approximately 30 min. AgNPs were effective against bacteria attached to stainless steel and polyethylene, but ineffective on tile surfaces. Thus, owing to the growing microbial resistance and the need to develop new products based on the concepts of green chemistry, these AgNPs are presented as a new possibility for cleaning processes in the food industry [ABSTRACT FROM AUTHOR]

Given the need for alternative therapies for bovine mastitis, an infectious disease of high prevalence and significant economic impact in dairy farms, this study evaluated the in vivo antimicrobial efficacy of an intramammary formulation based on soluble polypyrrole (PPy), a promising conductive polymer for biomedical applications, especially as an effective antimicrobial agent. In this assay, mammary quarters of healthy Holstein Friesian cows (n = 8) were inoculated with Staphylococcus aureus and treated, via the intramammary route, with an experimental formulation based on soluble PPy (5%) and a commercial formulation based on gentamicin sulfate. The effect of these treatments was evaluated based on milk cultures, Total Bacterial Count (TBC), Somatic Cell Count (SCC), and milk composition analysis of mammary quarter samples in seven experimental moments. In addition, hematological evaluations of the animals were also performed. The intramammary application of three levels of the experimental formulation based on soluble PPy resulted in higher log/mL of the TBC and SCC compared to a positive control group and a group that received gentamicin sulfate. The experimental formulation did not induce changes in milk composition or in hematological parameters. Certain factors related to pharmacokinetics, such as the type of carrier used in the formulation and the pharmacodynamics of soluble PPy, may have contributed to the antimicrobial ineffectiveness of the experimental formulation. The results of this study neither define nor decrease the antimicrobial potential of soluble PPy. Further research is required to develop formulations that enable the antibacterial action of soluble PPy in the intramammary environment of dairy cows. [ABSTRACT FROM AUTHOR]