Multidrug-resistant Escherichia coli strains isolated from swine manure biofertilizer in Brazil.

Escherichia coli is one of the key bacteria responsible for a variety of diseases in humans and livestock-associated infections around the globe. It is the leading cause of mortality in neonatal and weaned piglets in pig husbandry, causing diarrhea and significant harm to the industry. Furthermore, the frequent and intensive use of antimicrobials for the prevention of diseases, particularly gastrointestinal diseases, may promote the selection of multidrug-resistant (MDR) strains. These resistant genotypes can be transmitted through the excrement of animals, including swine. It is common practice to use porcine manure processed by biodigesters as fertilizer. This study aimed to examine the antimicrobial susceptibility, the presence of virulence genes frequently associated with pathotypes of intestinal pathogenic E. coli (InPEC), and antimicrobial resistance genes (ARGs) of 28 E. coli isolates collected from swine manure fertilizers. In addition, the enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) technique was used to investigate the genetic relationship among the strains. Using disk diffusion, the antimicrobial susceptibility profiles of the strains were determined. Using polymerase chain reaction (PCR), 14 distinct virulence genes associated with the most prevalent diarrhea and intestinal pathogenic E. coli (DEC/InPEC) and five ARGs were analyzed. All isolates tested positive for multidrug resistance. There was no detection of any of the 14 virulence genes associated with InPECs, indicating the presence of an avirulent commensal microbiota. Molecular classification by ERIC-PCR revealed that the majority of isolates (27 isolates) coalesced into a larger cluster with a genetic similarity of 47.7%; only one strain did not cluster in this cluster, indicating a high level of genetic diversity among the analyzed isolates. Thus, it is of the utmost importance to conduct epidemiological surveillance of animal breeding facilities in order to determine their microbiota and formulate plans to reduce the use of antimicrobials and improve animal welfare.

Green Synthesis, Characterization and Antimicrobial Evaluation of Silver Nanoparticles for an Intracanal Dressing.

Green chemistry has been applied in different areas due to the growing demands for renewable processes and one of them is nanotechnology. The aim of this study was to characterize a formulation containing silver nanoparticles (AgNPs) produced by a green synthesis and to evaluate its antimicrobial activity. The formulation will be used as an intracanal dressing exploiting the AgNPs' antimicrobial properties, which are crucial to prevent infections and bacterial reinfections that can compromise endodontic treatments. In the green synthesis, silver nitrate was employed as the precursor salt, maltose as a reducing agent, and gelatin as a stabilizing agent. The formulation was prepared mixing 50 % of a liquid containing the AgNPs and 50 % of hydroxyethylcellulose gel at 1.5 % with proper evaluation of the process inherent parameters. Techniques such as molecular absorption spectrometry and dynamic light scattering were used in characterization step. The antimicrobial activity of the AgNPs against Escherichia coli ATCC 25922, Enterococcus faecalis NCTC 775, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923 and Streptococcus mutans ATCC 25175 was verified according to National Comittee for Clinical Laboratory Standards (NCCLS) by determining minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). The obtained results indicated the formulation containing AgNPs produced by a green synthesis was properly characterized by the selected techniques. Furthermore, the formulation assessment proved that it is suitable for the proposal as well as it has potential to be used as an intracanal dressing since presented antimicrobial activity against all bacterial strains evaluated.

Green synthesis, characterization and antimicrobial evaluation of silver nanoparticles for an intracanal dressing

Abstract Green chemistry has been applied in different areas due to the growing demands for renewable processes and one of them is nanotechnology. The aim of this study was to characterize a formulation containing silver nanoparticles (AgNPs) produced by a green synthesis and to evaluate its antimicrobial activity. The formulation will be used as an intracanal dressing exploiting the AgNPs' antimicrobial properties, which are crucial to prevent infections and bacterial reinfections that can compromise endodontic treatments. In the green synthesis, silver nitrate was employed as the precursor salt, maltose as a reducing agent, and gelatin as a stabilizing agent. The formulation was prepared mixing 50 % of a liquid containing the AgNPs and 50 % of hydroxyethylcellulose gel at 1.5 % with proper evaluation of the process inherent parameters. Techniques such as molecular absorption spectrometry and dynamic light scattering were used in characterization step. The antimicrobial activity of the AgNPs against Escherichia coli ATCC 25922, Enterococcus faecalis NCTC 775, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923 and Streptococcus mutans ATCC 25175 was verified according to National Comittee for Clinical Laboratory Standards (NCCLS) by determining minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). The obtained results indicated the formulation containing AgNPs produced by a green synthesis was properly characterized by the selected techniques. Furthermore, the formulation assessment proved that it is suitable for the proposal as well as it has potential to be used as an intracanal dressing since presented antimicrobial activity against all bacterial strains evaluated.

Resumo A química verde tem sido aplicada em diferentes áreas devido à crescente demanda por processos renováveis e uma delas é a nanotecnologia. O objetivo deste estudo foi caracterizar uma formulação contendo nanopartículas de prata (AgNPs) produzidas por meio de síntese verde e avaliar sua atividade antimicrobiana. A formulação será usada como curativo intracanal explorando as propriedades antimicrobianas das AgNPs que são cruciais para prevenir infecções e reinfecções bacterianas que podem comprometer os tratamentos endodônticos. Na síntese verde, nitrato de prata foi empregado como sal precursor, maltose como agente redutor e gelatina como agente estabilizador. A formulação foi preparada misturando-se 50% do líquido contendo as AgNPs e 50% de gel de hidroxietilcelulose a 1,5% com avaliação adequada dos parâmetros inerentes ao processo. Técnicas como espectrometria de absorção molecular e espalhamento dinâmico de luz foram usadas na etapa de caracterização. A atividade antimicrobiana das AgNPs contra Escherichia coli ATCC 25922, Enterococcus faecalis NCTC 775, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923 e Streptococcus mutans ATCC 25175 foi verificada de acordo com o National Comittee for Clinical Laboratory Standards (NCCLS), determinando-se a concentração inibitória mínima (MIC) e a concentração bactericida mínima (MBC). Os resultados obtidos indicaram que a formulação contendo AgNPs produzidas por meio de síntese verde foi devidamente caracterizada pelas técnicas selecionadas. Além disso, a avaliação da formulação provou que ela é adequada para a proposta, bem como tem potencial para ser utilizada como curativo intracanal já que apresentou atividade antimicrobiana contra todas as cepas bacterianas avaliadas.