69 research outputs found

    Effect of surface roughness of biomaterials on Staphylococcus epidermidis adhesion

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    Background: Implant-related infections are caused by adhesion of bacteria to the surface of biomaterials. In this in vitro research, we evaluated the ability of Staphylococcus epidermidis (ATCC35984) to adhere to the surface of solid biomaterials at different levels of roughness below 30 nm Ra and investigated the minimum level of roughness required to promote bacterial adhesion on five kinds of biomaterials: oxidized zirconium-niobium alloy (Oxinium), cobalt-chromium-molybdenum alloy (Co-Cr-Mo), titanium alloy (Ti-6Al-4 V), commercially pure titanium (Cp-Ti) and stainless steel (SUS316L), samples of which were categorized into a fine group and a coarse group according to surface roughness. The test specimens were physically analyzed and the viable bacterial density of the adhered bacteria was quantitatively determined (n = 20).Results: The amount of bacteria that adhered to the biomaterials in the coarse group was higher than those in the fine group. Oxinium, Ti-6Al-4 V and SUS316L in particular demonstrated statistically significant differences between the two groups (P < 0.05). Of the materials, the Co-Cr-Mo specimens exhibited significantly lower amounts of adhered bacteria than the Ti-6Al-4 V, Cp-Ti and SUS316L specimens in the fine group. Similarly, the Co-Cr-Mo specimens in the coarse group exhibited significantly lower values than the other four materials.Conclusions: These results suggest that minimum level of roughness affecting initial bacterial adherence activity differs according to the type of biomaterial used, and that even a surface roughness of below 30 nm Ra in Oxinium, Ti-6Al-4 V and SUS316L can promote bacterial adhesion. Relative hydrophobic Co-Cr-Mo surfaces were less susceptible to bacterial adherence

    Early Staphylococcal Biofilm Formation on Solid Orthopaedic Implant Materials: In Vitro Study

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    Biofilms forming on the surface of biomaterials can cause intractable implant-related infections. Bacterial adherence and early biofilm formation are influenced by the type of biomaterial used and the physical characteristics of implant surface. In this in vitro research, we evaluated the ability of Staphylococcus epidermidis, the main pathogen in implant-related infections, to form biofilms on the surface of the solid orthopaedic biomaterials, oxidized zirconium-niobium alloy, cobalt-chromium-molybdenum alloy (Co-Cr-Mo), titanium alloy (Ti-6Al-4V), commercially pure titanium (cp-Ti) and stainless steel. A bacterial suspension of Staphylococcus epidermidis strain RP62A (ATCC35984) was added to the surface of specimens and incubated. The stained biofilms were imaged with a digital optical microscope and the biofilm coverage rate (BCR) was calculated. The total amount of biofilm was determined with the crystal violet assay and the number of viable cells in the biofilm was counted using the plate count method. The BCR of all the biomaterials rose in proportion to culture duration. After culturing for 2-4 hours, the BCR was similar for all materials. However, after culturing for 6 hours, the BCR for Co-Cr-Mo alloy was significantly lower than for Ti-6Al-4V, cp-Ti and stainless steel (P0.05). These results suggest that surface properties, such as hydrophobicity or the low surface free energy of Co-Cr-Mo, may have some influence in inhibiting or delaying the two-dimensional expansion of biofilm on surfaces with a similar degree of smoothness

    Risk Factors of Diarrheal Disease Among Children in the East African Countries of Burundi, Rwanda and Tanzania

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    Diarrheal diseases are a leading cause of childhood morbidity and mortality globally and in East Africa. Determining diarrheal disease risk factors and their strength of association to diarrheal disease in this region is necessary to identify and prioritize future research questions and interventions. Demographic and Health Surveys (DHS) Program Data on child health in Burundi, Rwanda, and Tanzania from 2010 were used and simple and multiple logistic regressions were completed to determine factors that predicted diarrheal disease. Diarrhea that occurred in the two weeks prior to data collection was reported for 24.80% of Burundian, 13.1% of Rwandan, and 13.91% of Tanzanian children under five. In Burundian children, increased risk of diarrhea was associated with unimproved sanitation, young mothers, and the mother’s education level (secondary school or less). In Rwandan children, increased risk of diarrhea was associated with more than 30-minute travel time to water source, rainy season, young mothers, mother’s lack of education, and low wealth index. In Tanzanian children, increased risk of diarrhea was associated with rainy season and young mothers. The impact of improved water source and sanitation facility on diarrheal disease is not consistent across the literature or results of this study. Future research should include information on hygiene practices, type of water storage container and types of household water treatment. Further, pathogen specific research, such as molecular fingerprinting, would assist to link the source to the disease. These additions would provide a more comprehensive understanding of risk factors for and sources of diarrheal disease globally and in East Africa

    Biosand Water Filter Evaluation: Pilot Study of Field Use Indicators

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    Diarrheal diseases are a global public health burden, killing 1.8 million people annually. Diarrhea disproportionately affects children and those in poverty. Most diarrheal cases can be prevented through safe drinking water, basic hygiene and/or sanitation measures, with drinking water interventions having the most impact on reducing diarrheal disease. A meta-evaluation was completed of studies evaluating a specific household water treatment method, the biosand water filter. Results from the meta-evaluation illustrate that biosand water filters improve drinking water quality and reduce diarrheal disease. However, there is no generally agreed upon field method for determining biosand water filter effectiveness that is useable in low-resource communities. A pilot study was conducted of potential field use indicators, including the Colilert coliform Presence/ Absence test, hydrogen sulfide, alkalinity, hardness, pH, and fluorescently-labeled latex microspheres. The study included both laboratory and field testing. The Colilert Presence/ Absence test had the highest correlation to the United States Environmental Protection Agency standard method (IDEXX Quanti-trays), but more data is needed before making a recommendation. This study adds to understanding about evaluation of biosand water filters and provides preliminary data to address the need for a field use indicator for biosand water filters

    Review of Biosand Water Filters

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    Diarrhoeal diseases are a global public health burden, killing 1.8 million people annually. Diarrhoea disproportionately affects children and those in poverty. Most diarrhoeal cases can be prevented through safe drinking water and basic hygiene and sanitation measures, with drinking water interventions having the most impact on reducing diarrhoeal disease. A metaevaluation of studies assessing a specific household water treatment method, the biosand water filter, was completed. Results from the meta-evaluation illustrated that biosand water filters improve drinking water quality and reduce diarrhoeal disease. However, short follow-up times and inconsistent measures are a concern. Furthermore, there is no generally accepted field method for determining biosand water filter effectiveness that is useable in low-resource communities. This study adds to understanding of biosand water filters

    Use of the Aquatic Oligochaetes Lumbriculus Variegatus and Tubifex Tubifex for Assessing the Toxicity of Copper and Cadmium in Spiked-Sediment Toxicity Bioassay

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    A sediment toxicity test using the freshwater oligochaetes Lumbriculus variegatus and Tubifex tubifex was performed. We evaluated acute and chronic toxicity affects of copper and cadmium on reproduction in both species and the bioaccumulation of both metals by L. variegatus using artificial sediment. L. variegatus bioconcentrated copper 22‐fold and cadmium 16‐fold after a 14‐day exposure to spiked artificial sediments with 0.02% organic content. The EC50 for T. tubifex varied depending upon endpoint from 2.7 to 2.8 mg/L for cadmium and from 8.4 to 8.9 mg/L for copper. The EC50 for L. variegatus was 2.2 mg/L for cadmium and 3.9 mg/L for copper. Based on these results, L. variegatus appears to be more sensitive to metal toxicity in artificial sediments than T. tubifex
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