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Introduction: The coronavirus disease 2019 (COVID-19) is a viral disease that affects several human organs and systems. Preventive or prophylactic treatments are specifically useful in emerging infectious diseases such as COVID-19 because they reduce the need for hospitalization and public health spending. Although the SARS-CoV-2 preventive effect of several therapeutic agents (e.g., hydroxychloroquine/chloroquine, remdesivir, lopinavir, and ritonavir) has been extensively evaluated, none of them have demonstrated significant clinical efficacy. Method: We aim to address and discuss the recently published studies on the chemoprophylactic potential of quercetin against SARS-CoV-2. A literature search was carried out on different databases, such as PubMed/MEDLINE, Scielo, Scopus, Web of Science, Cochrane Library, and Clinical Trials.gov. Studies that report the effect of quercetin against SARS-CoV-2 or other types of coronaviruses were included and critically evaluated. Results: Studies have shown that quercetin, an FDA-approved flavonoid used as an antioxidant and anti-inflammatory agent, inhibits the entry of coronavirus (SARS-CoV) into the host cell. Moreover, an in silico study showed that quercetin is a potent inhibitor of the SARS-CoV-2 main protease (Mpro), suggesting that this flavonoid is also active against COVID-19. Conclusions: Because quercetin might prevent and lessen the duration of SARS-CoV-2 infections, it is plausible to assume that the prophylactic use of this flavonoid produces several clinical benefits. However, this preliminary evidence needs to be confirmed by in vitro assays and, posteriorly, in randomized clinical trials.

The expression of virulence factors, such as biofilm formation, in association with the acquisition of resistance to multiple drugs, has evidenced the need for new and effective antimicrobial agents against Staphylococcus aureus. The evaluation of the pharmacological properties of plant-derived compounds is a promising alternative to the development of new antimicrobials. In this study, we aimed to evaluate the antibacterial, antibiofilm, and the synergistic and cytotoxic effects of netzahualcoyonol isolated from Salacia multiflora (Lam.) DC. roots. Netzahualcoyonol presented bacteriostatic (1.56–25.0 µg/mL) and bactericidal (25.0–400.0 µg/mL) effects against Gram-positive bacteria, disrupted the biofilm of S. aureus, and presented a synergistic effect after its combination with β-lactams and aminoglycosides. The low cytotoxicity of netzahualcoyonol (Selectivity Index (SI) for S. aureus (2.56), S. saprophyticus (20.56), and Bacillus subtilis (1.28)) suggests a good security profile. Taken together, these results show that netzahualcoyonol is promising for the development of a new effective antibacterial agent. Graphical abstract

Introduction: Mechanical-associated pneumonia (VAP) is identified as an implicit cause of mortality in patients hospitalized in Intensive Care Units (ICU). Pseudomonas aeruginosa is an important VAP agent that has multiple resistance to antimicrobials, being considered a serious public health problem. In this context, polymyxin antimicrobials are considered the best therapeutic option for the treatment of these diseases. Objective: To analyze the susceptibility profile and mechanisms of resistance to polymyxins in granting of P. aeruginosa causing VAP. Methods: A systematic review was conducted according to the Cochrane Handbook and the research and analysis of the articles followed the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA). Results: 22 articles were included and most were published from 2015, highlighting the year 2017 (22.7%), especially in Asian countries. 1,490 P. aeruginosa isolates recovered from ICU patients (16 pediatric ICUs) were analyzed. The susceptibility profile of the isolates to polymyxin B and/or colistin was determined by microdilution (40.9%) and Kirby-Bauer methods. 2.57% of the P. aeruginosa isolates were resistant to colistin and a lower resistance (1.87%) was observed for polymyxin B. Conclusion: No study investigated the presence of the plasmid gene encoding resistance to polymyxins (mcr) among the isolates, although this gene has already been reported in this species. Therefore, further research is needed to monitor the resistance and resistance mechanisms of P. aeruginosa to polymyxins, in order to preserve the therapeutic efficacy of this class of antibiotic. Introducción: Neumonía asociada al ventilador (NAVM) se identifica como una causa importante de mortalidad en pacientes hospitalizados en Unidades de Cuidados Intensivos (UCI). Pseudomonas aeruginosa es un importante agente NAVM que ha mostrado múltiples resistencias a los antimicrobianos, considerándose un grave problema de salud pública. En este contexto, los antimicrobianos de polimixina se consideran la mejor opción terapéutica para el tratamiento de estas infecciones. Objetivo: Analizar el perfil de susceptibilidad y mecanismos de resistencia a polimixinas en la concesión de NAVM causante de P. aeruginosa. Métodos: Se realizó una revisión sistemática de acuerdo con el Cochrane Handbook y la investigación y el análisis de los artículos siguieron las pautas del PRISMA. Resultados: Incluyeron 22 artículos y la mayoría fueron publicados a partir de 2015, destacando el año 2017 (22,7%), especialmente en países asiáticos. 1.490 aislados de P. aeruginosa recuperados de pacientes de UCI (de los cuales 16 son UCI pediátricos). El perfil de susceptibilidad de los otorgados a polimixina B y/o colistina se determinó mediante microdilución (40,9%) y métodos de Kirby-Bauer. 2,57% de los aislados fueron resistentes a la colistina y se observó una resistencia menor (1,87%) para la polimixina B. Conclusión: Ningún trabajo investigó la presencia del gen del plásmido que codifica la resistencia como polimixinas (mcr) entre las resistentes, aunque el gen ya ha sido reportado en esta especie. Por lo tanto, se necesita más investigación para monitorear la resistencia y los mecanismos de resistencia de P. aeruginosa como polimixinas, consolidando la efectividad de esta clase de antibiótico. Introdução: Pneumonia associada à ventilação mecânica (PAVM) é apontada como uma causa significativa de mortalidade em pacientes internados em Unidades de Terapia Intensiva (UTI). Pseudomonas aeruginosa é um importante agente de PAVM que tem apresentado resistência múltipla aos antimicrobianos, sendo considerado um grave problema de saúde pública. Neste contexto, antimicrobianos da classe das polimixinas são considerados a melhor opção terapêutica para o tratamento dessas infecções. Objetivo: Analisar o perfil de susceptibilidade e os mecanismos de resistência às polimixinas em isolados de P. aeruginosa causando PAVM. Métodos: Foi conduzida uma revisão sistemática de acordo a Cochrane Handbook e a pesquisa e análise dos artigos seguiram as normas do Preferred ReportingItems for Systematic Reviews and Meta-Analyses (PRISMA). Resultados: Foram incluídos 22 artigos e a maioria foi publicada a partir de 2015, destacando o ano de 2017 (22,7%), sobretudo em países asiáticos. 1.490 isolados de P. aeruginosa recuperados de pacientes em UTI (sendo 16 UTIs pediátricas) foram analisados. O perfil de susceptibilidade dos isolados a polimixina B e/ou colistina foi determinado pelos métodos de microdiluição (40,9%) e Kirby-Bauer. 2,57% dos isolados de P. aeruginosa foram resistentes a colistina e resistência menor (1,87%) foi observada para polimixina B. Conclusão: Nenhum trabalho investigou a presença do gene plasmidial que codifica resistência as polimixinas (mcr) entre os isolados, apesar deste gene já ter sido relatado nesta espécie. Com isso, tornam-se necessárias mais pesquisas que monitorem a resistência e os mecanismos de resistência de P. aeruginosa as polimixinas, visando preservar a eficácia terapêutica desta classe de antibiótico.