Cytotoxicity evaluation, antibacterial effect, and degree of conversion of QAM-containing adhesives

Abstract The aim of this study was to evaluate the influence of adding quaternary ammonium methacrylates (QAMs) to experimental adhesives by assessing the degree of conversion (DC), cytotoxicity against keratinocytes and fibroblasts, and antibacterial activity against biofilm formation. Two QAMs were added to an experimental adhesive: dimethylaminododecyl methacrylate bromododecane (DMADDM) or dimethylaminododecyl methacrylate bromohexadecane (DMAHDM) at three concentrations each: 1, 2.5, and 5 wt.%. Experimental adhesive without QAMs (control group) and commercially available Transbond XT Primer (3M Unitek, Monrovia, California, USA) were used for comparisons. The adhesives were tested for DC, cytotoxicity against keratinocytes and fibroblasts, and antibacterial activity against biofilm formation. DC, cytotoxicity against fibroblasts, and antibacterial activity were analyzed using one-way ANOVA and Tukey's multiple comparisons. Cytotoxicity against keratinocytes was evaluated using the Kruskal Wallis and Dunn's post-hoc (α = 5%) tests. Transbond showed lower DC as compared to 5% DMAHDM, 1% DMADDM, and 5% DMADDM (p < 0.05). However, all groups presented proper DC when compared to commercial adhesives in the literature. In the evaluation of cytotoxicity against keratinocytes, Transbond induced higher viability than 2.5 wt.% groups (p < 0.05). Against fibroblasts, Transbond induced higher viability as compared to 5 wt.% groups (p < 0.05). DMAHDM at 5 wt.% reduced biofilm formation when compared to all the other groups (p < 0.05). Despite their cytotoxic effect against keratinocytes, gingival fibroblasts showed higher viability. DMAHDM at 5 wt.% decreased Streptococcus mutans viability. The incorporation of DMAHDM at 5 wt.% may be a strategy for reducing the development of white spot lesions.

Research progress on root canal irrigation disinfection drugs / 口腔疾病防治

@#Endodontic infection control is crucial to successful root canal treatment. Irrigation is the key step in endodontic procedures, and the application of root canal irrigation and disinfection medications play an important role. How to enhance antibacterial effects and functions in removing tissues while maintaining biocompatibility is a hot topic in endodontics. Currently, insights to address this issue can be split into two categories: one, the modification or combination of conventional endodontic irrigation solutions, and two, the development of novel endodontic irrigation solutions with new technologies and materials, for instance, nanomaterials and natural exacts. However, conventional endodontic irrigation solutions, such as sodium hypochlorite and chlorhexidine, are still the first choice in clinical practice. Most novel endodontic irrigation solutions remain at the pre-clinical laboratory stage. Clinical research and relevant data are required to determine whether various methods can improve endodontic irrigation. From basic research to clinical application is the direction for advancing to the next stage. The present article focuses on research progress on endodontic irrigation, especially concerning its antibacterial mechanism, characteristics and efficacy, to provide a reference for future clinical translation.

Evaluation of current disinfection practice of transvaginal ultrasound probes in a Philippine Tertiary Referral Hospital: A comparative study on the performance of manual reprocessing methods

Objectives@#There are no standard infection control regulations in transvaginal ultrasound probe disinfection followed in the most prominent local public tertiary referral hospital. Likewise, no studies have evaluated the efficacy of the current method that uses an inexpensive multipurpose antiseptic spray solution. This study aims to evaluate the efficacy of the current practice of manual disinfection of TVS probes and compare it with the performance of an acceptable manual reprocessing method. @*Methods@#A prospective, randomized, controlled study was carried out using a crossover, quasi-experimental design, collecting 119 total samples from the ultrasound transducers before (35 samples) and after disinfection with two manual reprocessing methods, either a locally manufactured multipurpose antiseptic spray (A-Septic® Multipurpose Antiseptic Spray) that is currently used for disinfection or Mikrozid Sensitive®, a ready to use impregnated wipes (42 samples each arm). Disinfection efficacy was evaluated based on microbial culture results. @*Results@#Before disinfection, bacterial growth was observed in 77.1% (27/35) of the probes. After disinfection, 80.95% (34/42) remained contaminated with the antiseptic spray and 21.43% (9/42) with the wipes. The cultures revealed many environmental and pathogenic bacterial isolates, including Burkholderia, Staphylococcus, Acinetobacter, Diphtheroids, and Pseudomonas. @*Conclusions@#The currently used method for disinfecting transvaginal transducers in the division is not adequate for decontamination and decreasing the risk of cross contamination among patients. The results call for aggressive disinfection measures and highlight the need to update local standards and formulate and institutionalize these recommendations.

Physicochemical properties and biological effects of quaternary ammonium methacrylates in an experimental adhesive resin for bonding orthodontic brackets

Abstract Fixed orthodontic appliances may lead to biofilm accumulation around them that may increase caries risk. This study aimed to evaluate the influence of quaternary ammonium methacrylates (QAMs) on the physicochemical properties, cytotoxicity, and antibacterial activity of adhesive resins for orthodontic purposes. Methodology: A base resin was prepared with a comonomer blend and photoinitiator/co-initiator system. Two different QAMs were added to the base adhesive: dimethylaminododecyl methacrylate at 5 wt.% (DMADDM) or dimethylaminohexadecyl methacrylate (DMAHDM) at 10 wt.%. The base adhesive, without QAMs, (GC) and the commercial Transbond™ XT Primer 3M (GT) were used as control. The resins were tested immediately and after six months of aging in the water regarding the antibacterial activity and shear bond strength (SBS). The antibacterial activity was tested against Streptococcus mutans via metabolic activity assay (MTT test). The groups were also tested for the degree of conversion (DC) and cytotoxicity against keratinocytes. Results: The resins containing QAM showed antibacterial activity compared to the commercial material by immediately reducing the metabolic activity by about 60%. However, the antibacterial activity decreased after aging (p<0.05). None of the groups presented any differences for SBS (p>0.05) and DC (p>0.05). The incorporation of DMADDM and DMAHDM significantly reduced the keratinocyte viability compared to the GT and GC groups (p<0.05). Conclusion: Both adhesives with QAMs showed a significant reduction in bacterial metabolic activity, but this effect decreased after water aging. Lower cell viability was observed for the group with the longer alkyl chain-QAM, without significant differences for the bonding ability and degree of conversion. The addition of QAMs in adhesives may affect the keratinocytes viability, and the aging effects maybe decrease the bacterial activity of QAM-doped materials.

Resistência aos compostos de amônio quaternário (QACs) de uso doméstico e hospitalar em patógenos prioritários multirresistentes / Resistance to quaternary ammonium compounds (QACs) for domestic and hospital use in multiresistant priority pathogens

Compostos de amônio quaternário (QACs) têm sido amplamente utilizados como desinfetantes e antissépticos, sendo essenciais na prevenção e controle de infecções bacterianas na medicina humana e veterinária. Embora patógenos prioritários multirresistentes têm sido muito bem caracterizados quanto ao perfil de suscetibilidade e contexto genético da resistência aos antibióticos, dados de resistência aos QACs são limitados. Assim, o objetivo do presente estudo foi avaliar a atividade in vitro dos QACs de uso doméstico e hospitalar [cloreto de benzalcônio (BAC), cloreto de cetilpiridinio (CPC) e brometo de cetiltrimetilamônio (CTAB)], contra patógenos prioritários multirresistentes, identificando os principais genes de resistência associados. Foram estudadas 100 cepas multirresistentes previamente sequenciados usando as plataformas Illumina MiSeq e NextSeq representativas de diferentes hospedeiros (humanos e animais) e fontes (ambientes e alimentos). As cepas foram identificadas como Klebsiella pneumoniae (n= 24), Escherichia coli (n= 30); Pseudomonas aeruginosa (n= 10), Enterobacter spp, (n= 8), Acinetobacter baumannii (n= 11) e Salmonella spp. (n= 17). Genes de resistência aos QACs foram identificados in silico através do alinhamento dos contigs obtidos de cada cepa sequenciada com genes de referência obtidos do GenBank, utilizando o programa Geneious versão 8 (Biomatters Ltd). A identidade de cada gene foi analisada utilizando o programa BLASTx, no qual um critério baseado em ≥90% identidade resultou na identificação dos genes mdfA (77%), qacE (44%), qacEΔ1 (43%), sugE(c) (29%), emrE (21%), qacA (19%), sugE(p) (5%), qacF (7%), qacH (7%) e qacL (7%) em 85 cepas; enquanto que 15 cepas não possuíam nenhum gene de resistência aos QACs. A concentração inibitória mínima (CIM) dos QACs para as 100 cepas foi determinada pelo método de microdiluição em caldo. Os resultados sugeriram que a resistência em patógenos prioritários circulando na interface humano-ambiente-animal não é restrita aos antibióticos, uma vez que a elevada ocorrência de genes qacE, qacEΔ1 e mdfA poderia estar associada com uma redução da suscetibilidade para QACs. Consequentemente, a resistência aos QACs poderia também contribuir para a persistência e adaptação destes patógenos nos seres humanos e outros animais, assim como em ambientes impactados antropogenicamente

Quaternary ammonium compounds (QACs) have been widely used as disinfectants and antiseptics, being applied as essential compounds in the prevention and control of bacterial infections in human-and veterinary hospital medicine. Although multiresistant priority pathogens have been well characterized with respect to their susceptibility profile and their genetic context of resistance for antibiotics, studies of resistance to QACs are limited. Thus, the objective of the present study was to evaluate the in vitro activity of QACs [(benzalkonium chloride (BAC), cetylpyridinium chloride (CPC) and cetyltrimethylammonium bromide (CTAB)] for household and hospital use against multiresistant priority pathogens, identifying the main resistance genes associated. A hundred multiresistant isolates (previously sequenced using the Illumina MiSeq and NextSeq platforms), representative of different hosts (humans and animals) and sources (environment and food) were studied. Isolates were identified as Klebsiella pneumoniae (n=24), Escherichia coli (n=30), Pseudomonas aeruginosa (n=10), Enterobacter spp. (n=8), Acinetobacter baumannii (n=11) and Salmonella spp. (n=17). In silico analysis for identification of genes conferring resistance to QACs were performed by aligning the contigs obtained from the strains with reference genes deposited in GenBank, using the Geneious version program (Biomatters Ltd). Similarities were analyzed using the BLASTx online program, considering the alignment criteria based on ≥ 90% identity. The result of these analysis revealed the presence of the following QAC genes: mdfA (77%), qacE (44%), qacEΔ1 (43%), sugE(c) (29%), emrE (21%), qacA (19%), sugE (p) (5%), qacF (7%), qacH (7%) e qacL (7%); while 15 strains showed no resistance genes for QACs. Determination of QACs minimum inhibitory concentration (MIC) for the 100 isolates, by the broth microdilution method. These results suggest that resistance to QACs in priority pathogens, circulating at the human-environment-animal interface, is not restricted to antibiotics, since the high occurrence of genes qacE, qacEΔ1 and mdfA were associated with a reduced susceptibility to QACs. Consequently, resistance to QACs could also contribute to the persistence and adaptation of these pathogens in humans and othes animals, as well as in anthropogenically impacted environments

Eficácia do álcool etílico e quaternário de amônio na desinfecção de equipamentos médicos hospitalares / Efficacy of ethyl alcohol and quaternary ammonium in hospital medical equipment disinfection / Eficacia del alcohol etílico y cuaternario de amonio en la desinfección de equipos médicos hospitalarios

Justificativa e Objetivos: Os ambientes hospitalares podem albergar microrganismos patogênicos e oportunistas, sendo o processo de limpeza e desinfecção importante para o controle das Infecções relacionadas à Assistência à Saúde (IRAS). Assim, o objetivo deste trabalho foi avaliar a eficácia do álcool etílico e do quaternário de amônio no processo de desinfecção de equipamentos médicos hospitalares previamente contaminados com Staphylococcus aureus (S. aureus). Métodos: descontaminação de 10 equipamentos médicos hospitalares contaminados com uma suspensão de S. aureus ATCC 25923. A descontaminação ocorreu com álcool etílico nas concentrações de 46,2%, 70% e 99% e com o quaternário de amônio de 1ª e de 5ª geração. Após a descontaminação, foram colhidas amostras da superfície dos equipamentos para cultura bacteriana. Resultados: foi verificado crescimento bacteriano em 80% dos equipamentos descontaminados com álcool 46,2% e 99%. Não houve crescimento bacteriano na superfície dos equipamentos descontaminados com álcool 70% e quaternários de amônio. Conclusão: os processos de desinfecção com álcool 70% e quaternário de amônio de 1ª e 5ª geração foram eficazes no controle do S. aureus, comprovando a ação efetiva destes produtos na desinfecção dos equipamentos médicos hospitalares.(AU)

Background and Objectives: Hospital environments may harbor pathogenic and opportunistic microorganisms, and the cleaning and disinfection process is important for the control of Health Care Related Infections (IRAS). Thus, the objective of this work to evaluate compare the efficacy of ethyl alcohol and quaternary ammonium in the disinfection of hospital medical equipment against Staphylococcus aureus (S. aureus). Methods: decontamination of 10 hospital medical equipment contaminated with a suspension of S. aureus ATCC 25923. The decontamination occurred with ethyl alcohol at concentrations of 46.2%, 70% and 99% and with the quaternary ammonium of 1st generation and 5th generation. After the decontamination, samples were harvested from the surface of the equipment for bacterial culture. Results: bacterial growth was verified in 80% of the equipment decontaminated with alcohol 46.2% and 99%. There was no bacterial growth on the surface of equipment decontaminated with alcohol 70% and quaternary ammonium. Conclusions: the disinfection processes with alcohol 70% and quaternary ammonium 1st and 5th generation were effective in the control of S. aureus, proving the effectiveness of these products in the disinfection of hospital medical equipment.(AU)

Justificación y objetivos: Los ambientes hospitalarios pueden albergar microorganismos patógenos y oportunistas, siendo el proceso de limpieza y desinfección importante para el control de las Infecciones relacionadas a la Asistencia a la Salud (IRAS). Así, el objetivo de este trabajo evaluar comparar la eficacia del alcohol etílico y del cuaternario de amonio en el proceso de desinfección de equipos médicos hospitalarios previamente contaminados con Staphylococcus aureus (S. aureus). Métodos: la descontaminación de 10 equipos médicos hospitalarios contaminados con una suspensión de S. aureus ATCC 25923. La descontaminación ocurrió con alcohol etílico en las concentraciones de 46,2%, 70% y 99% y con el cuaternario de amonio de 1ª y de 5ª generación. Después de la descontaminación, se tomaron muestras de la superficie de los equipos para cultivo bacteriano. Resultados: se verificó crecimiento bacteriano en el 80% de los equipos descontaminados con alcohol 46,2% y 99%. No hubo crecimiento bacteriano en la superficie de los equipos descontaminados con alcohol 70% y cuaternarios de amonio. Conclusión: los procesos de desinfección con alcohol 70% y cuaternario de amonio de 1ª y 5ª generación fueron eficaces en el control del S. aureus, comprobando la acción efectiva de estos productos en la desinfección de los equipos médicos hospitalarios.(AU)

Consecuencias del amonio en la fatiga central en atletas, posible efecto neuroprotector del ejercicio / Ammonium consequences in athletes' central fatigue and its possible neuroprotection effect thanks to physical activity / Consequências do amônio na fadiga central em atletas, possível efeito neuroprotetor do exercício

Introducción. La fatiga central en el deporte está asociada a los efectos del amonio. La principal fuente de producción de amonio durante el ejercicio es el músculo esquelético. El amonio se genera como consecuencia del metabolismo energético, debido a la oxidación de aminoácidos y a la desaminación del nucleótido de adenosin trifosfato. Objetivo. Presentar una reflexión sobre el efecto del amonio durante el ejercicio de alta intensidad y su relación con la fatiga central en atletas. Discusión. Durante el ejercicio, la concentración de amonio alcanza valores superiores a 200µM (micromolar); sin embargo, en un adulto promedio se considera que valores superiores a 60µM en sangre manifiestan un trastorno por hiperamonemia. El amonio influye en la disminución del rendimiento en atletas y está asociado con los efectos nocivos para la salud en pacientes con encefalopatía hepática. Conclusiones. La práctica del ejercicio físico genera neuroprotección contra las altas concentraciones de amonio en el cerebro, pues, durante el ejercicio con altas concentraciones de amonio, los atletas no presentan los síntomas de pacientes con encefalopatía hepática, lo que implica adaptaciones metabólicas que juegan un papel importante en el metabolismo del amonio en el cerebro. [Porras-Álvarez J. Consecuencias del amonio en la fatiga central en atletas, posible efecto neuroprotector del ejercicio. MedUNAB. 2018;21(1): 115-121 doi: 10.29375/01237047.3394].

Introduction. Central fatigue in sports training is associated with ammonium effects within the human body. The ammonium main production source during physical training is located in skeletal muscles and it is generated as a result of energy metabolism. This process is caused by amino acids oxidation and adenosine triphosphate nucleotide deamination. Objective. This article's objective is to present an analysis regarding ammonium effects when high intensity sports are performed and its relation with central fatigue in athletes. Discussion. When high intensity sport practices are performed, ammonium concentration levels can reach values higher than 200 µM (micromolar). However, it is considered that an average adult with ammonium levels higher than 60µM evidences a hyperammonemia disorder. Ammonium has direct influence in the decline of athletic performance and it is associated with harmful effects for hepatic encephalopathy patients. Conclusions. Physical activity practice creates neuroprotection against high-quantities of ammonium in the brain. Although in physical practices athletes have high amounts of ammonium, they do not show symptoms related to hepatic encephalopathy; thus, this situation implies that metabolic adaptations have an important role within ammonium metabolism in the brain. [Porras-Álvarez J. Ammonium consequences in athletes' central fatigue and its possible neuroprotection effect thanks to physical activity. MedUNAB. 2018;21(1):115-121doi: 10.29375/01237047.3394].

Introdução. A fadiga central no esporte está associada aos efeitos do amônio. A fonte de produção do amônio mais importante durante o exercício é o músculo esquelético. O amônio é gerado como consequência do metabolismo energético, devido à oxidação dos aminoácidos e à desaminação do trifosfato de adenosina. Objetivo. Apresentar uma reflexão sobre o efeito do amônio durante o exercício de alta intensidade e sua relação com a fadiga central em atletas. Discussão. Durante o exercício, a concentração do amônio atinge valores superiores a 200µM (micromol); no entanto, em um adulto médio, considera-se que valores superiores a 60µM no sangue mostram um distúrbio por hiperamonemia. O amônio influencia a diminuição do desempenho em atletas e está associado a efeitos nocivos para a saúde em pacientes com encefalopatia hepática. Conclusões. A prática de exercício físico gera neuroproteção contra altas concentrações do amônio no cérebro, pois, durante o exercício com altas concentrações do amônio, os atletas não apresentam sintomas de encefalopatia hepática, o que implica adaptações metabólicas que desempenham um papel importante no metabolismo do amônio no cérebro. [Porras-Álvarez J. Consequências do amônio na fadiga central em atletas, possível efeito neuroprotetor do exercício. MedUNAB. 2018;21(1):115-121doi: 10.29375/01237047.3394].

Use of green fluorescent protein labeled non-tuberculous mycobacteria to evaluate the activity quaternary ammonium compound disinfectants and antibiotics

Abstract Although infections with NonTuberculous Mycobacteria have become less common in AIDS patients, they are important opportunistic infections after surgical procedures, likely because they are ubiquitous and not efficiently killed by many commonly used disinfectants. In Venezuela there have recently been many non-tuberculous mycobacteria soft tissue infections after minor surgical procedures, some apparently related to the use of a commercial disinfectant based on a Quaternary Ammonium Compound. We studied the activity of this and other quaternary ammonium compounds on different non-tuberculous mycobacteria by transforming the mycobacteria with a dnaA-gfp fusion and then monitoring fluorescence to gauge the capacity of different quaternary ammonium compounds to inhibit bacterial growth. The minimum inhibitory concentration varied for the different quaternary ammonium compounds, but M. chelonae and M. abscessus were consistently more resistant than M. smegmatis, and M. terrae more resistant than M. bovis BCG.

The cytotoxicity of methacryloxylethyl cetyl ammonium chloride, a cationic antibacterial monomer, is related to oxidative stress and the intrinsic mitochondrial apoptotic pathway

Antibacterial monomers incorporated in dentin bonding systems may have toxic effects on the pulp. Thus, the cytotoxicity of antibacterial monomers and its underlying mechanisms must be elucidated to improve the safety of antibacterial monomer application. The influence of an antibacterial monomer, methacryloxylethyl cetyl ammonium chloride (DMAE-CB), on the vitality of L929 mouse fibroblasts was tested using MTT assay. Cell cycle progression was studied using flow cytometry. Production of intracellular reactive oxygen species (ROS) after DMAE-CB treatment was measured using 2,7-dichlorodihydrofluorescein diacetate staining and flow cytometry analysis. Loss of mitochondrial membrane potential, disturbance of Bcl-2 and Bax expression, as well as release of cytochrome C were also measured using flow cytometry analysis or Western blot to explore the possible involvement of the mitochondrial-related apoptotic pathway. DMAE-CB elicited cell death in a dose-dependent manner and more than 50 percent of cells were killed after treatment with 30 µM of the monomer. Both necrosis and apoptosis were observed. DMAE-CB also induced G1- and G2-phase arrest. Increased levels of intracellular ROS were observed after 1 h and this overproduction was further enhanced by 6-h treatment with the monomer. DMAE-CB may cause apoptosis by disturbing the expression of Bcl-2 and Bax, reducing the mitochondrial potential and inducing release of cytochrome C. Taken together, these findings suggest that the toxicity of the antibacterial monomer DMAE-CB is associated with ROS production, mitochondrial dysfunction, cell cycle disturbance, and cell apoptosis/necrosis.

Trypanosoma cruzi ribosomal protein S4: characterization of its coding locus, analysis of transcripts, and antigenicity of the protein

Two allelic genomic fragments containing ribosomal protein S4 encoding genes (rpS4) from Trypanosoma cruzi (CL-Brener strain) were isolated and characterized. One allele comprises two complete tandem repeats of a sequence encoding an rpS4 gene. In the other, only one rpS4 gene is found. Sequence comparison to the accessed data in the genome project database reveals that our two-copy allele corresponds to a variant haplotype. However, the deduced aminoacid sequence of all the gene copies is identical. The rpS4 transcripts processing sites were determined by comparison of genomic sequences with published cDNA data. The obtained sequence data demonstrates that rpS4 genes are expressed in epimastigotes, amastigotes, and trypomastigotes. A recombinant version of rpS4 was found to be an antigenic: it was recognized by 62.5 percent of the individuals with positive serology for T. cruzi and by 93.3 percent of patients with proven chronic chagasic disease.

The presence of qacA/B gene in Brazilian methicillin-resistant Staphylococcus aureus

A total of 74 methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from three government hospitals in 2002 and 2003 were examined concerning the distribution of qacA/B gene, which is the determinant of resistance to quaternary ammonium compounds largely employed in hospital disinfection. By polymerase chain reaction the qacA/B gene was found in 80 percent of the isolates, which is a significant result considering it is the first time that qacA/B gene is being reported for Brazilian MRSA strains and it is presented at a high rate.

Study on Quaternary Ammonium Compounds Resistance among Staphylococcus spp in Disinfected Public Environment / 环境与健康杂志

50 g/ml by MIC. Nine isolates contained the qacA/B, and 1 isolate contained the smr gene. No qacG,qacH and qacE?1 was detected. Conclusion The disinfect resistance of Staphylococcu spp isolated from hospital disinfectant environment is markedly high. Resistance monitoring should be strengthened,and the rational use of disinfect should be emphasized.

Estudo das variações do coeficiente fenólico e diluição de uso de diversos tipos de desinfetantes aplicados normalmente na desinfecção hospitalar / Study of variations in the phenolic coefficient and dilution of the use of different types of disinfectants normally applied in hospital disinfection

Foi feito um estudo dos princípios ativos de desinfetantes normalmente utiliza dos em hospitais (hipoclorito de cálcio, compostos de amônio quaternário, fenóis, formaldeído, Irgasan DP-300). São apresentadas tabelas demonstrando a relação entre o coeficiente fenólico e a diluição de uso de cada desinfetante. É ressaltado que há diluições de desinfetantes que são próprias para áreas específicas, tais como: centros cirúrgicos, berçários, unidades de terapia intensiva etc (AU).