Nanoemulsions of essential oils against multi-resistant microorganisms: An integrative review.

Microbial resistance to drugs continues to be a global public health issue that demands substantial investment in research and development of new antimicrobial agents. Essential oils (EO) have demonstrated satisfactory and safe antimicrobial action, being used in pharmaceutical, cosmetic, and food formulations. In order to improve solubility, availability, and biological action, EO have been converted into nanoemulsions (NE). This review identified scientific evidence corroborating the antimicrobial action of nanoemulsions of essential oils (NEEO) against antibiotic-resistant pathogens. Using integrative review methodology, eleven scientific articles evaluating the antibacterial or antifungal assessment of NEEO were selected. The synthesis of evidence indicates that NEEO are effective in combating multidrug-resistant microorganisms and in the formation of their biofilms. Factors such as NE droplet size, chemical composition of essential oils, and the association of NE with antibiotics are discussed. Furthermore, NEEO showed satisfactory results in vitro and in vivo evaluations against resistant clinical isolates, making them promising for the development of new antimicrobial and antivirulence drugs.

Chemical composition, cytotoxicity, antimicrobial, antibiofilm, and anti-quorum sensing potential of Mentha Piperita essential oil against the oral pathogen Streptococcus mutans.

Dental caries is a highly prevalent oral disease affecting billions of individuals globally. The disease occurs chemically as a result of breakdown of the tooth surface attributed to metabolic activity in colonizing biofilm. Biofilms, composed of exopolysaccharides and proteins, protect bacteria like Streptococcus mutans, which is notable for its role in tooth decay due to its acid-producing abilities. While various antimicrobial agents may prevent biofilm formation, these drugs often produce side effects including enamel erosion and taste disturbances. This study aimed to examine utilization of the Mentha piperita essential oil as a potential antibiofilm activity agent against S. mutans. M. piperita oil significantly (1) reduced bacterial biofilm, (2) exhibited a synergistic effect when combined with chlorhexidine, and (3) did not induce cell toxicity. Chemical analysis identified the essential oil with 99.99% certainty, revealing menthol and menthone as the primary components, constituting approximately 42% and 26%, respectively. Further, M. piperita oil eradicated preformed biofilms and inhibited biofilm formation at sub-inhibitory concentrations. M. piperita oil also interfered with bacterial quorum sensing communication and did not produce any apparent cell toxicity in immortalized human keratinocytes (HaCaT). M. piperita represented an alternative substance for combating S. mutans and biofilm formation and a potential combination option with chlorhexidine to minimize side effects. An in-situ performance assessment requires further studies.

Brazilian scientists: much to learn from the microbial biofilm lifestyle (a resistant, resilient, well-orchestrated, and dynamic organization) / Cientistas brasileiros: muito a aprender com o estilo de vida do biofilme microbiano (uma organização resistente, resiliente, bem orquestrada e dinâmica)

Abstract In the present perspective, some parallels are drawn between a career as a scientist in Brazil and the ability of microorganisms to form a biofilm. Do these connections really exist? Definitely the answer is YES. Over billions of years, microbial biofilms have evolved in order to form a cohesive, well-structured, organized and dynamic community, which is characterized by its resistant/resilient profile to several environmental stressors. Adapting to constant change is a necessary attribute for survival and perpetuation of all live organisms, which are key signatures present in the hereditary molecule. Brazilian scientists are faced with many stressful situations along their journey in academia, which requires constant adaptability, reorganization and, above all, resilience. Can we take some lessons from what we know about the biofilm lifestyle developed by microorganisms? The answer is yes!

Resumo Na perspectiva atual, alguns paralelos são traçados entre a carreira de cientista no Brasil e a capacidade dos microrganismos de formarem biofilme. Essas conexões realmente existem? Definitivamente a resposta é SIM. Ao longo de bilhões de anos, os biofilmes microbianos evoluíram para formar uma comunidade coesa, bem estruturada, organizada e dinâmica, que se caracteriza por seu perfil de resistência/resiliência a diversos estressores ambientais. Adaptar-se a mudanças constantes é um atributo necessário para a sobrevivência e perpetuação de todos os organismos vivos, que são assinaturas-chave presentes na molécula de hereditariedade. Nesse sentido, os cientistas brasileiros se deparam com diversas situações estressantes ao longo de suas trajetórias na academia, exigindo constante adaptabilidade, reorganização e, acima de tudo, resiliência. Podemos tirar algumas lições do que sabemos sobre o estilo de vida do biofilme desenvolvido por microrganismos? A resposta é sim!

Degradation of Staphylococcus aureus Biofilm Using Hydrolytic Enzymes Produced by Amazonian Endophytic Fungi.

Microbial biofilms can cause serious health problems, since, due to their persistent character, they often function as spreaders of contaminants. Hydrolytic enzymes have a number of industrial applications and have been indicated as an alternative to the traditional chemical methods that are used to eradicate microbial biofilms. In this study, we evaluated the ability of enzymatic extracts produced by endophytic fungi isolated from the Amazonian species Myrcia guianensis to remove Staphylococcus aureus biofilms. After culture in liquid medium, the fungal hydrolytic extracts showed amylase (3.77 U/mL), lipase (3.84 U/mL), protease (3.63 U/mL), and xylanase (2.91 U/mL) activity. A 24 h mature S. aureus ATCC6538 biofilm was exposed to each enzyme extract with standardized enzyme activities for 10, 30, and 60 min. The optical density at 630 nm was used to calculate the growth rate (GR%) and the residual biofilm rate (RBR%). The most promising solutions were used in combination, based on a 24 factorial design for 0, 10, 20, and 30 min of exposure. Lipase and protease solutions, when applied separately, were the most effective, and promoted the complete removal of S. aureus biofilms in t10 (lipase) and t30 and t60 (lipase and protease). Of the combined treatments using 1.0 U/mL protease and 0.4 U/mL lipase, total biofilm degradation was observed for all exposure times. Thus, the hydrolases produced by the Amazonian endophytic fungi evaluated here are highlighted as an interesting tool in the fight against microbial biofilms.

Alternative method in Galleria mellonella larvae to study biofilm infection and treatment.

In vivo studies are crucial decision-maker step in order to translate in vitro data to an applied therapy. Considering this we describe a simple method that analyzes and quantifies biofilm formation inside the Galleria mellonella larvae. Toothbrush bristles were employed as an abiotic surface to mimic a medical device. A standardized inoculum of Staphylococcus aureus was systemically injected in the larvae together with the insertion of a bristle in the last proleg pair. After incubation adhered cells were detached from bristles and quantified by colony-forming units (CFU) counting using staphylococci-selective medium. About 3 × 106 CFU of S. aureus were recovered from bristles and scanning electron microscopy (SEM) images confirmed biofilm formation. Control group did not show adherent bacteria, as demonstrated by absence of CFU counting and SEM images, indicating that the insertion procedure is free of bacterial contamination. We present a feasible method to evaluate bacterial biofilm formation in vivo that in the near future can be used to evaluate antibiofilm compounds.

Dispersal of potentially pathogenic bacteria by plastic debris in Guanabara Bay, RJ, Brazil.

Analyses of thermotolerant coliform and heterotrophic bacteria as well as Escherichia coli and Vibrio species were carried out on plastic samples and in the surrounding waters of Guanabara Bay to evaluate plastic debris as vehicles of bacterial dispersal. Chemical characterizations of plastics were performed using Fourier transform infrared spectroscopy (FTIR). Plastic debris with high coliform contents were found, while their respective water samples had only low titers. No correlations were observed, however, between the amounts of bacteria and the chemical compositions of the plastic debris. Forty-four bacterial strains were PCR-confirmed as E. coli pathotypes, and 59 strains of Vibrio spp. (with 12 being identified as Vibrio cholerae [6], Vibrio vulnificus [5], and Vibrio mimicus [1]). These findings suggest these plastics can function as a substrate for bacterial biofilms (including pathogens). These debris, in turn, can be dispersed in aquatic environments not otherwise showing recent fecal bacterial contamination.

Genomic identification of microbial species adhering to maxillofacial prostheses and susceptibility to different hygiene protocols.

This study investigated the microbial colonization of maxillofacial prostheses and support tissues using the Checkerboard DNA-DNA hybridization method, and the efficacy of 0.12% chlorhexidine gluconate, 10% Ricinus communis solutions, or brushing, on colony forming unit (CFU) reduction in monospecies biofilms (Candida glabrata, Staphylococcus aureus, Streptococcus mutans, Escherichia coli, Enterococcus faecalis, and Pseudomonas aeruginosa) formed on two silicones (MDX 4-4210 and Bio-Skin). Biofilm was harvested from 43 maxillofacial prosthesis wearers for detection of 38 species of microorganisms. The CFU counts of the six above mentioned species were recorded after using the hygiene protocols. All 38 investigated species were identified in prostheses and tissues, with a higher prevalence in the prostheses. 0.12% chlorhexidine gluconate immersion showed the greatest antimicrobial effectiveness, followed by mechanical brushing protocols. MDX 4-4210 silicone produced lower CFU counts than Bio-Skin.

Biological activities of a mixture of biosurfactant from Bacillus subtilis and alkaline lipase from Fusarium oxysporum

In this study, we investigate the antimicrobial effects of a mixture of a biosurfactant from Bacillus subtilis and an alkaline lipase from Fusarium oxysporum (AL/BS mix) on several types of microorganisms, as well as their abilities to remove Listeria innocua ATCC 33093 biofilm from stainless steel coupons. The AL/BS mix had a surface tension of around 30 mN.m-1, indicating that the presence of alkaline lipase did not interfere in the surface activity properties of the tensoactive component. The antimicrobial activity of the AL/BS mix was determined by minimum inhibitory concentration (MIC) micro-assays. Among all the tested organisms, the presence of the mixture only affected the growth of B. subtilis CCT 2576, B. cereus ATCC 10876 and L. innocua. The most sensitive microorganism was B. cereus (MIC 0.013 mg.mL-1). In addition, the effect of the sanitizer against L. innocua attached to stainless steel coupons was determined by plate count after vortexing. The results showed that the presence of the AL/BS mix improved the removal of adhered cells relative to treatment done without the sanitizer, reducing the count of viable cells by 1.72 log CFU.cm-2. However, there was no significant difference between the sanitizers tested and an SDS detergent standard (p<0.05).

Biological Activities of a Mixture of Biosurfactant from Bacillus subtilis and Alkaline Lipase from Fusarium oxysporum.

In this study, we investigate the antimicrobial effects of a mixture of a biosurfactant from Bacillus subtilis and an alkaline lipase from Fusarium oxysporum (AL/BS mix) on several types of microorganisms, as well as their abilities to remove Listeria innocua ATCC 33093 biofilm from stainless steel coupons. The AL/BS mix had a surface tension of around 30 mN.m(-1), indicating that the presence of alkaline lipase did not interfere in the surface activity properties of the tensoactive component. The antimicrobial activity of the AL/BS mix was determined by minimum inhibitory concentration (MIC) micro-assays. Among all the tested organisms, the presence of the mixture only affected the growth of B. subtilis CCT 2576, B. cereus ATCC 10876 and L. innocua. The most sensitive microorganism was B. cereus (MIC 0.013 mg.mL(-1)). In addition, the effect of the sanitizer against L. innocua attached to stainless steel coupons was determined by plate count after vortexing. The results showed that the presence of the AL/BS mix improved the removal of adhered cells relative to treatment done without the sanitizer, reducing the count of viable cells by 1.72 log CFU.cm(-2). However, there was no significant difference between the sanitizers tested and an SDS detergent standard (p<0.05).

Biological activities of a mixture of biosurfactant from Bacillus subtilis and alkaline lipase from Fusarium oxysporum

In this study, we investigate the antimicrobial effects of a mixture of a biosurfactant from Bacillus subtilis and an alkaline lipase from Fusarium oxysporum (AL/BS mix) on several types of microorganisms, as well as their abilities to remove Listeria innocua ATCC 33093 biofilm from stainless steel coupons. The AL/BS mix had a surface tension of around 30 mN.m-1, indicating that the presence of alkaline lipase did not interfere in the surface activity properties of the tensoactive component. The antimicrobial activity of the AL/BS mix was determined by minimum inhibitory concentration (MIC) micro-assays. Among all the tested organisms, the presence of the mixture only affected the growth of B. subtilis CCT 2576, B. cereus ATCC 10876 and L. innocua. The most sensitive microorganism was B. cereus (MIC 0.013 mg.mL-1). In addition, the effect of the sanitizer against L. innocua attached to stainless steel coupons was determined by plate count after vortexing. The results showed that the presence of the AL/BS mix improved the removal of adhered cells relative to treatment done without the sanitizer, reducing the count of viable cells by 1.72 log CFU.cm-2. However, there was no significant difference between the sanitizers tested and an SDS detergent standard (p 0.05).