Substrate For Growth Of Microorganisms Research Articles

Role of vacuum assisted closure in the management of infected wound in orthopaedics

Background and objective: Wounds are a major source of morbidity, lead to considerable disability, and are associated with increased mortality; therefore, they have a significant impact on public health and the expenditure of healthcare resources [1]. Vacuum-assisted closure (VAC) uses negative pressure to assist wound healing. Negative pressure drains fluid from the wound, thus removing the substrate for growth of microorganisms. Negative pressure may also accelerate granulation tissue formation and promote angiogenesis. The mechanical stimulation of cells by tensile forces may also play a role by increasing cellular proliferation and protein synthesis. Negative pressure wound therapy (NPWT) involves the use of a negative pressure therapy or suction device to aspirate and remove fluids, debris, and infectious materials from the wound bed to promote the formation of granulation tissue. Materials and Methods: A total of 30 post-operative infected wound cases presented in between December 2019 to August 2021 were taken for study. Each case was examined clinically in systematic manner as per the proforma drafted. VAC dressing was done and all cases were followed up to discharge and subsequently for a follow up on 10th day. Results: In our clinical study of 30 cases managed by VAC dressing, 30% of the cases were of post-operative infected wounds of radius & ulna, 13.3% humerus, 23.3% femur, 23.3% tibia, 3.3% spine, 3.3% calcaneum, 3.3% metatarsals. By the completion of VAC therapy none of the cases required a revision surgery or implant removal. There is a progression of healthy healing in all the cases (100%). Commonest organisms isolated were Staphylococcus, Pseudomonas and Proteus. Interpretation and conclusion: In our study VAC therapy enhanced granulation tissue formation leading to better wound healing, and faster recovery. VAC is thus a promising new technology in the field of wound healing with multiple applications in a variety of wounds and can be used in both acute and chronic wounds, salvage procedures or as an adjuvant therapy to improve the results of various surgical procedures.

Role of vacuum assisted closure in the management of infected wound in Orthopaedics

Background and Objective: Wounds are a major source of morbidity, lead to considerable disability, and are associated with increased mortality; therefore, they have a significant impact on public health and the expenditure of healthcare resources. Vacuum-assisted closure (VAC) uses negative pressure to assist wound healing. Negative pressure drains fluid from the wound, thus removing the substrate for growth of microorganisms. Negative pressure may also accelerate granulation tissue formation and promote angiogenesis. The mechanical stimulation of cells by tensile forces may also play a role by increasing cellular proliferation and protein synthesis. Negative pressure wound therapy (NPWT) involves the use of a negative pressure therapy or suction device to aspirate and remove fluids, debris, and infectious materials from the wound bed to promote the formation of granulation tissue. Materials and Methods: A total of 30 post-operative infected wound cases presented in between December 2016 to August 2018 were taken for study. Each case was examined clinically in systematic manner as per the proforma drafted. VAC dressing was done and all cases were followed up to discharge and subsequently for a follow up on 10th day. Results: In our clinical study of 30 cases managed by VAC dressing, 30% of the cases were of post-operative infected wounds of radius & ulna, 13.3% humerus, 23.3% femur, 23.3% tibia, 3.3% spine, 3.3% calcaneum, 3.3% metatarsals. By the completion of VAC therapy none of the cases required a revision surgery or implant removal. There is a progression of healthy healing in all the cases (100%). Commonest organisms isolated were Staphylococcus, Pseudomonas and Proteus. Interpretation and Conclusion: In our study VAC therapy enhanced granulation tissue formation leading to better wound healing, and faster recovery. VAC is thus a promising new technology in the field of wound healing with multiple applications in a variety of wounds and can be used in both acute and chronic wounds, salvage procedures or as an adjuvant therapy to improve the results of various surgical procedures.

Surfactant Mediated Biodegradation of Aromatic Hydrocarbons Using Rhamnolipid Producing Bacterial Isolate

Aromatic hydrocarbons (toluene and xylene) are highly water soluble and their contamination with groundwater is a serious issue. Hydrocarbons are growth substrates for microorganisms which use them as a sole source of carbon and energy. Surfactants increase the solubility and dissolution of hydrocarbons thus making them susceptible to degradation. In this study, biodegradation of toluene and xylene using a soil bacterium was evaluated in the presence of chemical surfactant. The colonies that were tested positive for xylene and toluene degradation in the primary screening were analyzed by 16s rRNA sequencing and identified as <i>Bacillus Cereus</i>. The presence of chemical surfactant enhanced the growth of bacterial isolate and its bioremediation activity indicated the possible role of the tween in bioremediation process. It was observed that pH of the medium has reached near neutral from initial pH of 8.2 at the end of 21 days cultivation period. Addition of hydrocarbons in the mineral salt medium (MSM) has enhanced the bacterial growth as confirmed by increasing optical density throughout the cultivation period. Increase in protein content of bacterial isolate indicated its metabolic activity in the presence of hydrocarbons. Similarly, increase in the rhamnolipid concentration of <i>B. cereus</i> grown in MSM along with hydrocarbons and chemical surfactant indicated the role of rhamnolipids during the biodegradation of xylene and toluene.

Sonochemical Coating of Textiles with Hybrid ZnO/Chitosan Antimicrobial Nanoparticles

Textiles are good substrates for growth of microorganisms especially under moisture and temperature conditions found in hospitals. Microbial shedding from the body occurs continuously at contact of the patient with textile materials used in medical practices, contributing to the occurrence of hospital acquired infections. Thus, the use of efficient antimicrobial textiles is necessary to prevent the transfer of pathogens and the infection incidence. In this work, hybrid antimicrobial coatings were generated on cotton fabrics by means of a one-step simultaneous sonochemical deposition of ZnO nanoparticles (NPs) and chitosan. The process was further optimized in terms of reagents concentration and processing time in order to improve the antibacterial properties of the fabric and ensure their biocompatibility. The highest antibacterial activity of the fabrics against two medically relevant bacterial species was achieved in a 30 min sonochemical coating process using 2 mM ZnO NPs suspension. When chitosan was simultaneously deposited with the same amount of ZnO, the obtained hybrid NPs coating displayed higher by 48 and 17% antibacterial activity against Staphylococcus aureus and Escherichia coli, respectively. The presence of biopolymer also improved the durability of the antimicrobial effect of the coatings by 21% for Staphylococcus aureus and 40% for Escherichia coli, evaluated after applying multiple washing cycles at hospital laundering regimes. Finally, 87% biocompatibility improvement supported by fibroblast viability was observed for the hybrid ZnO/chitosan coating compared to the steady decrease of cells viability over one week in contact with the fabrics coated with ZnO alone.

Factors Affecting Quality and Safety of Fresh-Cut Produce

The quality of fresh-cut fruit and vegetable products includes a combination of attributes, such as appearance, texture, and flavor, as well as nutritional and safety aspects that determine their value to the consumer. Nutritionally, fruit and vegetables represent a good source of vitamins, minerals, and dietary fiber, and fresh-cut produce satisfies consumer demand for freshly prepared, convenient, healthy food. However, fresh-cut produce deteriorates faster than corresponding intact produce, as a result of damage caused by minimal processing, which accelerates many physiological changes that lead to a reduction in produce quality and shelf-life. The symptoms of produce deterioration include discoloration, increased oxidative browning at cut surfaces, flaccidity as a result of loss of water, and decreased nutritional value. Damaged plant tissues also represent a better substrate for growth of microorganisms, including spoilage microorganisms and foodborne pathogens. The risk of pathogen contamination and growth is one of the main safety concerns associated with fresh-cut produce, as highlighted by the increasing number of produce-linked foodborne outbreaks in recent years. The pathogens of major concern in fresh-cut produce are Listeria monocytogenes, pathogenic Escherichia coli mainly O157:H7, and Salmonella spp. This article describes the quality of fresh-cut produce, factors affecting quality, and various techniques for evaluating quality. In addition, the microbiological safety of fresh-cut produce and factors affecting pathogen survival and growth on fresh-cut produce are discussed in detail.

A simple approach to modeling microbial biomass in the rhizosphere

Microorganisms make an important contribution to the degradation of contaminants in bioremediation as well as in phytoremediation. An accurate estimation of microbial concentrations in the soil would be valuable in predicting contaminant dissipation during various bioremediation processes. A simple modeling approach to quantify the microbial biomass in the rhizosphere was developed in this study. Experiments were conducted using field column lysimeters planted with Eastern gamagrass. The microbial biomass concentrations from the rhizosphere soil, bulk soil, and unplanted soil were monitored for six months using an incubation–fumigation method. The proposed model was applied to the field microbial biomass data and good correlation between simulated and experimental data was achieved. The results indicate that plants increase microbial concentrations in the soil by providing root exudates as growth substrates for microorganisms. Since plant roots are initially small and do not produce large quantities of exudates when first seeded, the addition of exogenous substrates may be needed to increase initial microbial concentrations at the start of phytoremediation projects.

Characterization of anthracite

Abstract Examination of the surface properties of anthracite provides information of assistance in the interpretation of in situ behaviour and use of the material as a micronized fuel and as an inexpensive support substrate for growth of micro-organisms. The characteristics of anthracite particles (&lt;10 μm) produced by crushing and grinding larger material (obtained from Cynheidre Colliery, South Wales UK) are reported. Mineral particles, liberated from this anthracite matrix, subsequent to radiofrequency-induced plasma (RFIP) oxidation, were found to constitute 2 wt%, 0.6vol% of that matrix. X-Ray fluorescence analysis and analytical transmission electron microscopy of these particles indicated silicon, aluminium and iron to be the predominant electropositive elements present, with calcium the only other element detected at a level greater than 5wt% of the mineral component. X-Ray diffractometry (XRD) of this component indicated that hematite, pyrite, siderite and a variety of aluminosilicate minerals were present in the original matrix. Mineral particles liberated by RFIP oxidation of the planar (cut) surface of anthracite were initially captured in plastic replica films and thence transferred to carbon films. Electron microscopic examination of these films indicated that mineral particles present in the anthracite matrix possessed diverse chemistries, were submicron in size and suggested their distribution throughout the carbonaceous matrix to be homogeneous. Estimates of the surface area of &lt;10μm anthracite particles (107 ± 15 m 2 g −1 ) made using nitrogen adsorption/desorption (BET) analysis, were significantly greater than those predicted for non-porous particles of this size. Equilibration of the surface with nitrogen was reached ≈1.2 × 10 4 s after the imposition of changes in pressure. Hysteresis of the adsorption/desorption isotherms was pronounced, suggesting that the material contained 9% v/v pores, of which 75% were estimated to be ≈2 nm diameter. Potentiometric (aqueous, acid/base, batchwise) titration of the material, at a variety of ionic strengths ( I ), indicated long equilibration times between H + /OH − and the surface (≈3 × 10 5 s). The dependence of the analytical surface charge density (σ a ) on pH and I were found to be significant though small, with points of zero titration (pH pzt ) in the range 4 &lt; pH pzt &lt; 7 which increased with I . at pH &lt; pH &lt; 9, σ a was virtually independent of I , suggesting a point of zero salt effect to be located in this region or that solute ions were unable to penetrate the surface. The range of σ a (based on the surface area determined by BET) was found to be small (−7 &lt; σ a &lt; 6 μC cm −2 ) and its nature consistent with that of surfaces of minerals shown and identified by electron microscopy and XRD analysis to be present at low concentration within (and exposed at the surface of) the carbonaceous matrix.