Transfer of Salmonella Enteritidis to four types of surfaces after cleaning procedures and cross-contamination to tomatoes

The objectives of the present study were to evaluate the spread of Salmonella Enteritidis to different cutting boards (wood, triclosan-treated plastic, glass, and stainless steel) from contaminated poultry skin (5 log CFU/g) and then to tomatoes and to analyze the effect of different protocols used to clean these surfaces to control contamination. The following procedures were simulated: (1) no cleaning after handling contaminated poultry skin; (2) rinsing in running water; (3) cleaning with dish soap and mechanical scrubbing; and (4) cleaning with dish soap and mechanical scrubbing, followed by disinfection with hypochlorite. The pathogen was recovered from all surfaces following procedure 1, with counts ranging from 1.90 to 2.80 log, as well as from the tomatoes handled on it. Reduced numbers of S. Enteritidis were recovered using the other procedures, both from the surfaces and from the tomatoes. Counts were undetectable after procedure 4. From all surfaces evaluated, wood was the most difficult to clean, and stainless steel was the easiest. The use of hypochlorite as a disinfecting agent helped to reduce cross-contamination. (C) 2011 Elsevier Ltd. All rights reserved.

Effect of disinfectant agents on dimensional stability of elastomeric impression materials.

STATEMENT OF PROBLEM: Difficulties in sterilizing impressions by traditional methods have led to chemical disinfection as an alternative, and some studies have shown that disinfectants may adversely affect impressions. PURPOSE: This study investigated the effect of disinfection methods on the dimensional stability of 6 elastomeric materials. MATERIAL AND METHODS: Impression materials were submitted to the following treatments: immersion in 5.25% sodium hypochlorite solution for 10 minutes, immersion in 2% glutaraldehyde solution for 30 minutes, and no immersion (control). After treatments, impressions were poured, and respective stone casts were measured with a Nikon Profile projector and compared with the master model. RESULTS: The elastomeric materials had different reproduction capacities, and the disinfecting treatments did not differ from the control.

Performance of constructed wetland system for public water supply

The project is being conducted in the town of Analândia, São Paulo, Brazil. The constructed wetlands system for water supply consists of a channel with floating aquatic macrophytes, HDS system (Water Decontamination with Soil - Patent PI 850.3030), chlorinating system, filtering system and distribution. The project objectives include investigating the process variables to further optimize design and operation factors, evaluating the relation of nutrients and plants development, biomass production, shoot development, nutrient cycling and total and fecal coliforms removal, comparing the treatment efficiency among the seasons of the year; and moreover to compare the average values obtained between February and June 1998 (Salati et al., 1998) with the average obtained for the same parameters between March and June 2000. Studies have been developed in order to verify during one year the drinking quality of the water for the following parameters: turbidity, color, pH, dissolved oxygen, total of dissolved solids, COD, chloride, among others, according to the Ministry of Health's Regulation 36. This system of water supply projected to treat 15 L s-1 has been in continuous operation for 2 years, it was implemented with support of the National Environment Fund (FNMA), administered by the Center of Environmental Studies (CEA-UNESP), while the technical supervision and design were performed by the Institute of Applied Ecology. The actual research project is being supported by FAPESP.

Lack of genotoxicity of formocresol, paramonochlorophenol, and calcium hydroxide on mammalian cells by comet assay

Formocresol, paramonochlorophenol, and calcium hydroxide are widely used in dentistry because of their antibacterial activities in root canal disinfection. However, the results of genotoxicity studies using these materials are inconsistent in literature. The goal of this study was to examine the genotoxic potential of formocresol, paramonochlorophenol, and calcium hydroxide using mouse lymphoma cells and human fibroblasts cells in vitro by the comet assay. Data were assessed by Kruskal-Wallis nonparametric test. The results showed that all compounds tested did not cause DNA damage for the tail moment or tail intensity parameters. These findings suggest that formocresol, paramonochlorophenol, and calcium hydroxide do not promote DNA damage in mammalian cells and that the comet assay is a suitable tool to investigate genotoxicity.

Effect of microwave treatments on dimensional accuracy of maxillary acrylic resin denture base

Microwave energy has been used as an alternative method for disinfection and sterilization of dental prostheses. This study evaluated the influence of microwave treatment on dimensional accuracy along the posterior palatal border of maxillary acrylic resin denture bases processed by water-bath curing. Thirty maxillary acrylic bases (3-mm-thick) were made on cast models with Clássico acrylic resin using routine technique. After polymerization and cooling, the sets were deflasked and the bases were stored in water for 30 days. Thereafter, the specimens were assigned to 3 groups (n=10), as follows: group I (control) was not submitted to any disinfection cycle; group II was submitted to microwave disinfection for 3 min at 500 W; and in group III microwaving was done for 10 min at 604 W. The acrylic bases were fixed on their respective casts with instant adhesive (Super Bonder®) and the base/cast sets were sectioned transversally in the posterior palatal zone. The existence of gaps between the casts and acrylic bases was assessed using a profile projector at 5 points. No statistically significant differences were observed between the control group and group II. However, group III differed statistically from the others (p<0.05). Treatment in microwave oven at 604 W for 10 min produced the greatest discrepancies in the adaptation of maxillary acrylic resin denture bases to the stone casts.

Photocatalytic and photoelectrochemical treatment effects on the killing of escherichia coli cells

In this study, we report the efficiency of photocatalytic and photoelectrochemical treatment using titanium dioxide as semiconductor and its applications in water disinfection. It was compared the efficiency of the two methods on the killing of E.coli cells. The photoelectrochemical treatment with electric field enhancement showed a good result and could be a new technology to water treatment.

Effect of disinfectants on the hardness and roughness of reline acrylic resins

Purpose: Potential effects on hardness and roughness of a necessary and effective disinfecting regimen (1% sodium hypocholorite and 4% chlorhexidine) were investigated for two hard chairside reline resins versus a heat-polymerizing denture base acrylic resin. Materials and Methods: Two standard hard chairside reliners (Kooliner and Duraliner II), one heat-treated chairside reliner (Duraliner II +10 minutes in water at 55°C), and one standard denture base material (Lucitone 550) were exposed to two disinfecting solutions (1% sodium hypochlorite; 4% chlorhexidine gluconate), and tested for two surface properties [Vickers hardness number (VHN, kg/mm2); Roughness (Ra, μm)] for different times and conditions (1 hour after production, after 48 hours at 37 ± 2°C in water, after two disinfection cycles, after 7 days in disinfection solutions, after 7 days in water only). For each experimental condition, eight specimens were made from each material. Data were analyzed by analysis of variance followed by Tukey's test, and Student's t-test (p= 0.05). Results: For Kooliner (from 6.2 ± 0.3 to 6.5 ± 0.5 VHN) and Lucitone 550 (from 16.5 ± 0.4 to 18.4 ± 1.7 VHN), no significant changes in hardness were observed either after the disinfection or after 7 days of immersion, regardless of the disinfectant solution used. For Duraliner II (from 4.0 ± 0.1 to 4.2 ± 0.1 VHN), with and without heat treatment, a small but significant increase in hardness was observed for the specimens immersed in the disinfectant solutions for 7 days (from 4.3 ± 0.2 to 4.8 ± 0.5 VHN). All materials showed no significant change in roughness (Kooliner: from 0.13 ± 0.05 to 0.48 ± 0.24 μm; Duraliner II, with and without heat treatment: from 0.15 ± 0.04 to 0.29 ± 0.07 μm; Lucitone 550: from 0.44 ± 0.19 to 0.49 ± 0.15 μm) after disinfection and after storage in water for 7 days. Conclusions: The disinfectant solutions, 1% sodium hypochlorite and 4% chlorhexidine gluconate, caused no apparent damage on hardness and roughness of the materials evaluated. Copyright © 2006 by The American College of Prosthodontists.

Candida albicans inactivation and cell membrane integrity damage by microwave irradiation

In indicating the microwave irradiation for disinfecting dentures it is necessary to see how this procedure influences Candida albicans integrity and viability. The aim of this study was to evaluate the ability of microwaves to inactivate C. albicans and damage cell membrane integrity. Two 200-ml C. albicans (ATCC 10231) suspensions were obtained. A sterile denture was placed in a beaker containing the Experimental (ES) or the Control suspension (CS). ES was microwaved at 650 W for 6 min. Suspensions were optically counted using methylene blue dye uptake as indicative of membrane-damaged cells; spread on Agar Sabouraud dextrose (ASD) for viability assay; or spectrophotometrically measured at 550 nm. Cell-free solutions were submitted to content analyses of protein (Bradford and Pyrogallol red methods); Ca++ (Cresolftaleine complexone method); DNA (spectrophotometer measurements at 260 nm) and K + (selective electrode technique). Data were analysed by Student's t- or Wilcoxon z-tests (α = 0.05). All ES cells demonstrated cell membrane damage. Viable cells were non-existent in the ES ASD plates. No significant difference in optical density between ES and CS was observed (P = 0.272). ES cells released significantly high protein (P < 0.001, Bradford; P = 0.005, Pyrogallol red), K+ (P < 0.001), Ca++ (P = 0.012) and DNA (P = 0.046) contents. Microwaves inactivated C. albicans and damaged cell membrane integrity. © 2007 The Authors.

Micropropagación de Pothomorphe umbellata (L.) Miq. vía organogénesis directa

The present research was aimed at standardizing the protocol of seed disinfection, seed germination and organogenesis via callus of Pothomorphe umbellata (L.) Miq.The germinated seeds were inoculated in different concentrations of BAP (benzylamine purine) and NAA (naphthalene acetic acid) in order to stimulate the callus induction. After 60 days of culture, the calluses with some shoots were taken to an organogenesis medium (GA3 0.1 mg.L -1, BAP 0.5 mg.L-1) during 40 days, to be transferred later to a development medium. Finally, the plantules were acclimatized, presenting a good index of survival.

Comportamento cinético do cloro livre em meio aquoso e formação de subprodutos da desinfecção

One indirect approach to predict the disinfection by-product (DBP) formation potential for a given water source is by evaluation of the kinetic behavior of free chlorine in the liquid phase and chlorine demand determination for different operation conditions of the chlorination process. The objective of this work was to evaluate the kinetic behavior of free chlorine in water or a number of different raw water sources, as well as to investigate the impact of the coagulation process on chlorine demand reduction and DBP formation. It was observed that the higher the total organic carbon (TOC) removal efficiency through coagulation, the lower the liquid phase chlorine demand. Regarding trihalomethane (THM) formation, a ratio of 28 ug/L formed per mg/L of applied chlorine was observed for the waters employed in the experimental investigation.

Effectiveness of six different disinfectants on removing five microbial species and effects on the topographic characteristics of acrylic resin

Purpose: The aim of this study was to evaluate the effectiveness of disinfectant solutions (1% sodium hypochlorite, 2% chlorhexidine digluconate, 2% glutaraldehyde, 100% vinegar, tabs of sodium perborate-based denture cleanser, and 3.8% sodium perborate) in the disinfection of acrylic resin specimens (n = 10/group) contaminated in vitro by Candida albicans, Streptococcus mutans, S. aureus, Escherichia coli, or Bacillus subtilis as measured by residual colony-forming unit (CFU). In a separate experiment, acrylic resin was treated with disinfectants to monitor potential effects on surface roughness, Ra (μm), which might facilitate microbial adherence. Materials and Methods: Three hundred fifty acrylic resin specimens contaminated in vitro with 1×10 6 cells/ml suspensions of standard strains of the cited microorganisms were immersed in the disinfectants for 10 minutes; the control group was not submitted to any disinfection process. Final counts of microorganisms per ml were performed by plating method for the evaluation of microbial level reduction. Results were compared statistically by ANOVA and Tukey's test (p ≤ 0.05). In a parallel study aiming to evaluate the effect of the tested disinfectant on resin surface, 60 specimens were analyzed in a digital rugosimeter before and after ten cycles of 10-minute immersion in the disinfectants. Measurements of superficial roughness, Ra (μm), were compared statistically by paired t-test (p ≤ 0.05). Results: The results showed that 1% sodium hypochlorite, 2% glutaraldehyde, and 2% chlorhexidine digluconate were most effective against the analyzed microorganisms, followed by 100% vinegar, 3.8% sodium perborate, and tabs of sodium perborate-based denture cleanser. Superficial roughness of the specimens was higher after disinfection cycles with 3.8% sodium perborate (p = 0.03) and lower after the cycles with 2% chlorhexidine digluconate (p = 0.04). Conclusion: Within the limits of this experiment, it could be concluded that 1% sodium hypochlorite, 2% glutaraldehyde, 2% chlorexidine, 100% vinegar, and 3.8% sodium perborate are valid alternatives for the disinfection of acrylic resin. © 2008 by The American College of Prosthodontists.

Evaluation of dimensional change and detail reproduction in silicones for facial prostheses.

The aim of this study was to evaluate the dimensional stability and detail reproduction of two silicones used for facial prosthesis, under the influence of chemical disinfection and storage time. Twenty-eight test specimens were obtained, half made of Silastic MDX 4-4210 silicone, and the other half of Silastic 732 RTV silicone. The test specimens were divided into 4 groups: Silastic 732 RTV and Silastic MDX 4-4210, with disinfection 3 times a week with Efferdent and without disinfection. Dimensional change was analyzed using an electronic comparison microscope and detail reproduction was observed under a stereo microscope, immediately and 2 months after the test specimens were made. Once the results were obtained, an analisis of variance (ANOVA) was applied, followed by the Tukey's Test with 1% confidence. The storage time factor had a statistical influence on dimensional stability: Silastic MDX 4-4210 had less contraction than Silastic 732 RTV. Chemical disinfection did not significantly alter the dimensional stability of the materials used. Regarding detail reproduction, no alteration of values was observed in any of the materials analyzed, regardless of storage period or disinfection.

Effect of sodium bicarbonate on Candida albicans adherence to thermally activated acrylic resin

The purpose of this study was to evaluate the effect of 5% sodium bicarbonate on the adherence of Candida albicans to thermally activated acrylic resin. Fifty 4 mm specimens of acrylic resin were obtained using a metallic matrix. The specimens received chemical polishing, were sterilized and then immersed in Sabouraud broth, inoculated with Candida albicans standardized suspension. After 24 hours of incubation at 37°C, the specimens were divided into four groups according to the substance used for disinfection (5% sodium bicarbonate, 0.12% digluconate chlorhexidine, vinegar and Corega Tabs). A control group was included, in which distilled water was used. The adhered microorganisms were dispersed, diluted and plated onto culture media to determine the number of colony-forming units (cfu/mL). The results were analyzed through the Mann-Whitney statistical test at the 5% level of significance. Only 0.12% digluconate chlorhexidine and 5% sodium bicarbonate presented a statistically significant difference (p = 0.0010 and p = 0.0156, respectively) compared to the control group, decreasing the number of cfu/mL. However, when the different disinfecting solutions were compared with each other, only 0.12% digluconate chlorhexidine presented a statistically significant difference in the reduction of cfu/mL. It was concluded that although 0.12% digluconate chlorhexidine was more effective in the reduction of Candida albicans adherence values to thermally activated acrylic resin, 5% sodium bicarbonate also proved to be a viable alternative.

Evaluación de la deformación de dos siliconas para prótesis faciales, influencia de la pigmentación y desinfección química

The purpose of present study was to analyze the effect of pigmentation and chemical disinfection on the initial and the permanent deformation of two silicones (Silved Selant and Brascoved) for facial prosthesis. Initial and permanent deformation tests samples (20 mm × 12.5 mm) were made following the manufacturer's instructions. For each silicone (n= 40), ten samples were used for pigmentation with make up power, ten with iron oxide, ten with ceramics power and tem were tested without pigmentation. Five samples of each group were submitted to chemical disinfection using a 2 % Chlorhexidine spray. All samples were immersed in physiological saline and stored in an oven at 35 ° ± 1 °C. After 90 days, the samples were submitted to initial and permanent deformation tests using a dial indicator. For both properties, data were analyzed by Tukey's test (a= 0.05). The results showed that all the materials had initial and permanent deformation regardless of pigmentation and chemical disinfection. The groups were used for pigmentation with iron oxide showed less initial and permanent deformation when were submitted to the chemical disinfection regardless the silicone used.

Avaliação das condutas de biossegurança em laboratórios de prótese dentária de João Pessoa, PB, Brasil

Objective: To evaluate the biosecurity measures adopted in dental prosthesis laboratories of the city of João Pessoa, PB, Brazil with respect to prosthetic works sent by dentists. Method: Twenty-five dental prosthesis technicians (DPT) of the city of João Pessoa, PB, filled out a questionnaire referring to their knowledge of the biosecurity principles, disinfection of impressions and other prosthetic items, and the use of individual protection equipment (IPE). Results: Although 92% of the interviewees believed in the possible occurrence of cross-infection between dental prosthesis laboratories and dental offices, 64% declared that the prosthetic works received in their laboratories do not undergo any disinfection procedure. It was also observed that, for disinfection of impressions and stone casts, the chemical substances are not used as recommended by the manufacturers or are innocuous to microorganisms. Regarding the use of IPE, 60% of the DPT used mask, but only 4% used gowns. With respect to the measures taken regarding the impressions received from dental offices, 56% of the interviewees only wash them in running tap water, and 56% of the stone casts that arrive at the laboratory are not disinfected in any way. Conclusion: There is a need for more motivation and instructions to DPT regarding the prevention of cross-contamination during sending and receiving of prosthetic works between dental prosthesis laboratories and dental offices because the DPT evaluated in this study were found negligent with respect to disinfection procedures.