Cytotoxicity of Brazilian plant extracts against oral microorganisms of interest to dentistry

Background: With the emergence of strains resistant to conventional antibiotics, it is important to carry studies using alternative methods to control these microorganisms causing important infections, such as the use of products of plant origin that has demonstrated effective antimicrobial activity besides biocompatibility. Therefore, this study aimed to evaluate the antimicrobial activity of plant extracts of Equisetum arvense L., Glycyrrhiza glabra L., Punica granatum L. and Stryphnodendron barbatimam Mart. against Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus mutans, Candida albicans, Candida tropicalis, and Candida glabrata, and to analyze the cytotoxicity of these extracts in cultured murine macrophages (RAW 264.7).Methods: Antimicrobial activity of plant extracts was evaluated by microdilution method based on Clinical and Laboratory Standards Institute (CLSI), M7-A6 and M27-A2 standards. The cytotoxicity of concentrations that eliminated the microorganisms was evaluated by MTT colorimetric method and by quantification of proinflammatory cytokines (IL-1β and TNF-α) using ELISA.Results: In determining the minimum microbicidal concentration, E. arvense L., P. granatum L., and S. barbatimam Mart. extracts at a concentration of 50 mg/mL and G. glabra L. extract at a concentration of 100 mg/mL, were effective against all microorganisms tested. Regarding cell viability, values were 48% for E. arvense L., 76% for P. granatum L, 86% for S. barbatimam Mart. and 79% for G. glabra L. at the same concentrations. About cytokine production after stimulation with the most effective concentrations of the extracts, there was a significant increase of IL-1β in macrophage cultures treated with S. barbatimam Mart. (3.98 pg/mL) and P. granatum L. (7.72 pg/mL) compared to control (2.20 pg/mL) and a significant decrease of TNF-α was observed in cultures treated with G. glabra L. (4.92 pg/mL), S. barbatimam Mart. (0.85 pg/mL), E. arvense L. (0.83 pg/mL), and P. granatum L. (0.00 pg/mL) when compared to control (41.96 pg/mL).Conclusions: All plant extracts were effective against the microorganisms tested. The G. glabra L. extract exhibited least cytotoxicity and the E. arvense L. extract was the most cytotoxic. © 2013 de Oliveira et al.; licensee BioMed Central Ltd.

Control of microorganisms of oral health interest with Arctium lappa L. (burdock) extract non-cytotoxic to cell culture of macrophages (RAW 264.7)

Objectives: To evaluate the antimicrobial activity of Arctium lappa L. extract on Staphylococcus aureus, S. epidermidis, Streptococcus mutans, Candida albicans, C. tropicalis and C. glabrata. In addition, the cytotoxicity of this extract was analyzed on macrophages (RAW 264.7).Design: By broth microdilution method, different concentrations of the extract (250-0.4 mg/mL) were used in order to determine the minimum microbicidal concentration (MMC) in planktonic cultures and the most effective concentration was used on biofilms on discs made of acrylic resin. The cytotoxicity A. lappa L. extract MMC was evaluated on RAW 264.7 by MTT assay and the quantification of IL-1 beta and TNF-alpha by ELISA.Results: The most effective concentration was 250 mg/mL and also promoted significant reduction (log(10)) in the biofilms of S. aureus (0.438 +/- 0.269), S. epiderrnidis (0.377 +/- 0.298), S. mutans (0.244 +/- 0.161) and C. albicans (0.746 +/- 0.209). Cell viability was similar to 100%. The production of IL-beta was similar to the control group (p > 0.05) and there was inhibition of TNF-alpha (p < 0.01).Conclusions: A. lappa L. extract was microbicidal for all the evaluated strains in planktonic cultures, microbiostatic for biofilms and not cytotoxic to the macrophages. (C) 2014 Elsevier Ltd. All rights reserved.

The effect of conventional mechanical periodontal treatment on red complex microorganisms and clinical parameters in Down syndrome periodontitis patients: a pilot study

Periodontal disease (PD) is induced by a complex microbiota, such as Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola (together called the red complex), which triggers intense inflammatory reaction. Down syndrome (DS) individuals demonstrate a high prevalence of PD compared with those who are otherwise chromosomally normal (euploids). This pilot study aimed to evaluate the effect of non-surgical periodontal treatment in DS chronic periodontitis patients on clinical and microbiological parameters. Patients with chronic periodontitis, 23 DS and 12 euploids (control group), were submitted to non-surgical mechanical periodontal treatment, followed by maintenance for 45 days. Clinical parameters after periodontal treatment were similar in diseased and healthy sites, independent of the genetic background. Diseased sites of DS and control patients harbored similar levels of P. gingivalis and T. forsythia at baseline, but significantly higher levels of T. denticola were found in DS patients. Increased levels of P. gingivalis at healthy sites were found in DS individuals. Non-surgical periodontal therapy decreased the levels of red complex microorganisms and improved the tested clinical parameters of diseased sites in both groups. However, the levels of red complex bacteria were higher in diseased sites of DS patients after the periodontal treatment. We conclude in this pilot study that, although the mechanical periodontal treatment seemed to be effective in DS subjects over a short-term period, the red complex bacteria levels did not decrease significantly in diseased sites, as occurred in controls. Therefore, for DS patients, it seems that the conventional non-surgical periodontal therapy should be improved by utilizing adjuvants to reduce the presence of periodontopathogens.

Comparison of different irrigants in the removal of endotoxins and cultivable microorganisms from infected root canals

This study was conducted to compare the effectiveness of different irrigants used to remove endotoxins and cultivable microorganisms during endodontic therapy. Forty root canals were contaminated and divided into groups according to the irrigant: 2% NaOCl + surfactant, 2% CHX, 2.5% NaOCl, and pyrogen-free saline solution (control). Samples were collected after root canal contamination (S1), after instrumentation (S2), and 7 days after instrumentation (S3). Microorganisms and endotoxins were recovered from 100% of the contaminated root canals (S1). At S2, 2% NaOCl + surfactant, 2% CHX, and 2.5% NaOCl were able to completely eliminate cultivable microorganisms. At S3, both 2% CHX and 2.5% NaOCl were effective in preventing C. albicans and E. coli regrowth, but E. faecalis was still detected. No microorganism species was recovered from root canals instrumented with 2% NaOCl + surfactant. At S2, a higher percentage value of endotoxin reduction was found for 2% NaOCl + surfactant (99.3%) compared to 2% CHX (98.9%) and 2.5% NaOCl (97.18%) (p < 0.05). Moreover, at S3, 2% NaOCl + surfactant (100%) was the most effective irrigant against endotoxins. All irrigants tested were effective in reducing microorganisms and endotoxins from root canals. Moreover, 2% NaOCl + surfactant was the most effective irrigant against endotoxins and regrowth of microorganisms.

Biossorção & biodegradação de azo corante: desenvolvimento de processos utilizando resíduos como fonte de microorganismos = Azo dye biosorption & biodegradation : process development with residues as source of microorganisms

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

MICROORGANISMS OF THE COCCIDIA SUBCLASS: RESISTANCE AND IMPLICATIONS FOR THE ASEPTIC PROCESSING OF HEALTHCARE PRODUCTS

This theoretical study proposes a reflection on the intrinsic resistance of the subclass Coccidia, particularly the genus Cryptosporidium, considered to be potential pathogens for immunocompromised patients, and the implications for nursing practice. Currently, the international and national guidelines support the chemical disinfection of digestive system endoscopes after their cleansing as a safe and effective procedure. However, studies show that microorganisms of the subclass Coccidia, namely Cryptosporidium, responsible for enteric infection, are more resistant than mycobacteria and are not inactivated by high-level disinfectants, except for hydrogen peroxide 6% and 7.5%, which are not currently available in Brazil. We conclude that the legislation should include this agent among test microorganisms for approving high-level disinfectants. Health authorities should make efforts to ensure that healthcare institutions have access to effective disinfectants against Cryptosporidium.

Photodynamic inactivation of microorganisms present on complete dentures. A clinical investigation

The aim of this study was to evaluate the effectiveness of photodynamic therapy (PDT) for the disinfection of complete dentures. Biofilm samples were collected from dentures of 60 denture users who were randomly divided into four experimental groups (n = 15 each): subjects whose maxillary dentures were sprayed with 50 and 100 mg/l of PhotogemA (R) suspension (groups P50S and P100S) and patients whose maxillary dentures were treated with 50 and 100 mg/l of PhotogemA (R) gel (groups P50G and P100G). Dentures with photosensitizers were left in the dark for 30 min (pre-irradiation time) and then irradiated with blue LED light at 37.5 J/cm(2) (26 min). Denture samples were taken with sterile cotton swab before (left side surfaces) and after (right side surfaces) PDT. All microbial material was diluted and plated on selective media for Candida spp., Staphylococcus mutans spp., streptococci and a non-selective media. After incubation (48 h/37A degrees C), the number of colony-forming units (cfu/ml) was counted. Microorganisms grown on selective media were identified using biochemical methods before and after PDT. The data were submitted to McNemar and Kruskal-Wallis tests (alpha = 0.05). No growth after PDT was observed in 60, 53, 47, and 40% of dentures from P100G, P50G, P100S, and P50S groups, respectively. When evidence of microorganisms' growth was observed, PDT regimens eliminated over 90% of microorganisms on dentures. This clinical study showed that PDT was effective for disinfecting dentures.

Colonization with resistant microorganisms in patients transferred from abroad: who needs to be screened?

BACKGROUND While multi-drug resistant organisms (MDRO) are a global phenomenon, there are significant regional differences in terms of prevalence. Traveling to countries with a high MDRO prevalence increases the risk of acquiring such an organism. In this study we determined risk factors for MDRO colonization among patients who returned from a healthcare system in a high-prevalence area (so-called transfer patients). Factors predicting colonization could serve as screening criteria to better target those at highest risk. METHODS This screening study included adult patients who had been exposed to a healthcare system abroad or in a high-prevalence region in Switzerland over the past six months and presented to our 950-bed tertiary care hospital between January 1, 2012 and December 31, 2013, a 24-month period. Laboratory screening tests focused on Gram-negative MDROs and methicillin-resistant Staphylococcus aureus (MRSA). RESULTS A total of 235 transfer patients were screened and analyzed, of which 43 (18 %) were positive for an MDRO. Most of them yielded Gram-negative bacteria (42; 98 %), with only a single screening revealing MRSA (2 %); three screenings showed a combination of Gram-negative bacteria and MRSA. For the risk factor analysis we focused on the 42 Gram-negative MDROs. Most of them were ESBL-producing Escherichia coli and Klebsiella pneumoniae while only two were carbapenemase producers. In univariate analysis, factors associated with screening positivity were hospitalization outside of Europe (p < 0.001), surgical procedure in a hospital abroad (p = 0.007), and - on admission to our hospital - active infection (p = 0.002), antibiotic treatment (p = 0.014) and presence of skin lesions (p = 0.001). Only hospitalization outside of Europe (Odds Ratio, OR 3.2 (95 % CI 1.5- 6.8)) and active infection on admission (OR 2.7 (95 % CI 1.07- 6.6)) remained as independent predictors of Gram-negative MDRO colonization. CONCLUSION Our data suggest that a large proportion of patients (i.e., 82 %) transferred to Switzerland from hospitals in high MDRO prevalence areas are unnecessarily screened for MDRO colonization. Basing our screening strategy on certain criteria (such as presence of skin lesions, active infection, antibiotic treatment, history of a surgical procedure abroad and hospitalization outside of Europe) promises to be a better targeted and more cost-effective strategy.

Rules and regulations relating to viruses, serums, toxins and analogous products, and to certain organisms and vectors, effective March 1, 1949.

Mode of access: Internet.

Effective Cell-Centred Time-Domain Maxwell's Equations Numerical Solvers

This research work analyses techniques for implementing a cell-centred finite-volume time-domain (ccFV-TD) computational methodology for the purpose of studying microwave heating. Various state-of-the-art spatial and temporal discretisation methods employed to solve Maxwell's equations on multidimensional structured grid networks are investigated, and the dispersive and dissipative errors inherent in those techniques examined. Both staggered and unstaggered grid approaches are considered. Upwind schemes using a Riemann solver and intensity vector splitting are studied and evaluated. Staggered and unstaggered Leapfrog and Runge-Kutta time integration methods are analysed in terms of phase and amplitude error to identify which method is the most accurate and efficient for simulating microwave heating processes. The implementation and migration of typical electromagnetic boundary conditions. from staggered in space to cell-centred approaches also is deliberated. In particular, an existing perfectly matched layer absorbing boundary methodology is adapted to formulate a new cell-centred boundary implementation for the ccFV-TD solvers. Finally for microwave heating purposes, a comparison of analytical and numerical results for standard case studies in rectangular waveguides allows the accuracy of the developed methods to be assessed.