RESUMEN
Colorectal cancer (CRC) is a significant global health burden with a rising incidence worldwide. Distinct bacterial populations are associated with CRC development and progression, and it is thought that the relationship between CRC and associated gut bacteria changes during the progression from normal epithelium to benign adenoma and eventually malignant carcinoma and metastasis. This study compared the interaction of CRC-associated species Enterotoxigenic Bacteroides fragilis, Enterococcus faecalis and Fusobacterium nucleatum and one probiotic species, Escherichia coli Nissle 1917 with a colorectal adenoma (S/RG/C2) and a colorectal adenocarcinoma (HCT116) derived cell line. Gentamicin protection assays showed that all species displayed higher attachment to benign tumour monolayers when compared to malignant monolayers. However, invasion of 3/4 species was higher in the HCT116 cells than in the adenoma cells. All species were found to persist within tumour cell monolayers for a minimum of 48 h under standard aerobic cell culture conditions, with persistence significantly higher in HCT116 cells. Downstream assays were performed to analyse the behaviour of S/RG/C2 and HCT116 cells post-infection and revealed that all species increased the tumour cell yield of both cell lines. The migratory and invasive potential of HCT116 cells was increased after infection with F. nucleatum; however, no species significantly altered these characteristics in S/RG/C2 cells. These results add to the growing evidence for the involvement of microorganisms in CRC progression and suggest that these interactions may be dependent on tumour cell-specific characteristics.
Asunto(s)
Adenoma , Neoplasias Colorrectales , Humanos , Células HCT116 , Neoplasias Colorrectales/patología , Bacterias , Proliferación Celular , Adenoma/patologíaRESUMEN
The quality and health of many of our vital freshwater systems are poor. To tackle this with ever increasing pressures from anthropogenic and climatic changes, we must improve water quality monitoring and devise and implement more appropriate water quality parameters. Recent research has highlighted the potential for Peak T fluorescence (tryptophan-like fluorescence, TLF) to monitor microbial activity in aquatic systems. The VLux TPro (Chelsea Technologies Ltd., UK), an in situ real-time fluorimeter, was deployed in different urban freshwater bodies within Kolkata (West Bengal, India) during March 2019. This study is the first to apply this technology in surface waters within a densely populated urban area. Spot-sampling was also undertaken at 13 sampling locations enabling physicochemical analysis, bacterial enumeration and determination of nutrient (nitrate and phosphate) concentrations. This case study has demonstrated the ability of an in situ fluorimeter, VLux TPro, to successfully identify both biological contamination events and potential elevated microbial activity, related to nutrient loading, in complex surface freshwaters, without the need for expensive and time-consuming laboratory analysis.
Asunto(s)
Monitoreo del Ambiente , Calidad del Agua , Fluorescencia , Agua Dulce , Triptófano/análisisRESUMEN
Aquatic dissolved organic matter (DOM) plays an essential role in biogeochemical cycling and transport of organic matter throughout the hydrological continuum. To characterise microbially-derived organic matter (OM) from common environmental microorganisms (Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa), excitation-emission matrix (EEM) fluorescence spectroscopy was employed. This work shows that bacterial organisms can produce fluorescent organic matter (FOM) in situ and, furthermore, that the production of FOM differs at a bacterial species level. This production can be attributed to structural biological compounds, specific functional proteins (e.g. pyoverdine production by P. aeruginosa), and/or metabolic by-products. Bacterial growth curve data demonstrates that the production of FOM is fundamentally related to microbial metabolism. For example, the majority of Peak T fluorescence (> 75%) is shown to be intracellular in origin, as a result of the building of proteins for growth and metabolism. This underpins the use of Peak T as a measure of microbial activity, as opposed to bacterial enumeration as has been previously suggested. This study shows that different bacterial species produce a range of FOM that has historically been attributed to high molecular weight allochthonous material or the degradation of terrestrial FOM. We provide definitive evidence that, in fact, it can be produced by microbes within a model system (autochthonous), providing new insights into the possible origin of allochthonous and autochthonous organic material present in aquatic systems.
Asunto(s)
Bacterias/metabolismo , Bacillus subtilis/metabolismo , Escherichia coli/metabolismo , Fluorescencia , Sustancias Húmicas , Pseudomonas aeruginosa/metabolismo , Especificidad de la Especie , Espectrometría de FluorescenciaRESUMEN
The main aim of this study was to assess the antimicrobial efficacy of electrochemically activated fog (ECAF) for reducing the microbial bio-burden on artificially inoculated fresh produce held under cooled (cucumber and vine tomatoes) or cold (rocket and broccoli) storage conditions. The ECAF treatment (1100 ± 5 mV ORP; 50 ± 5 mg L-1 free chlorine; 2.7 ± 0.1 pH) resulted in a significant log reduction in the potential pathogen E. coli recovered from rocket (2.644 Log10 CFU g-1), broccoli (4.204 Log10 CFU g-1), cucumber (3.951 Log10 CFU g-1) and tomatoes (2.535 Log10 CFU g-1) after 5 days. ECAF treatment also resulted in a significant log reduction in potential spoilage organisms, whereby a 3.533 Log10 CFU g-1, 2.174 Log10 CFU g-1 and 1.430 Log10 CFU g-1 reduction in presumptive Pseudomonads was observed for rocket, broccoli and cucumber respectively, and a 3.527 Log10 CFU g-1 reduction in presumptive Penicillium spp. was observed for tomatoes (after 5 days). No adverse visual effects on produce were recorded. The results of this study will inform industrial scale-up trials within commercial facilities (assessing shelf-life, microbial quality and organoleptic assessment) to assess the developed ECAF technology platform within a real food processing environment.
Asunto(s)
Aerosoles/química , Técnicas Electroquímicas/métodos , Conservación de Alimentos/métodos , Frutas/microbiología , Verduras/microbiología , Técnicas Electroquímicas/instrumentación , Escherichia coli O157/crecimiento & desarrollo , Contaminación de Alimentos/análisis , Contaminación de Alimentos/prevención & control , Microbiología de Alimentos , Conservación de Alimentos/instrumentación , Almacenamiento de Alimentos , Listeria monocytogenes/crecimiento & desarrolloRESUMEN
AIMS: To determine if bacterial species responsible for clinically relevant wound infection produce specific volatile profiles that would allow their speciation. METHODS AND RESULTS: Selected ion flow tube-mass spectrometry (SIFT-MS) in full mass scan mode was used to analyse headspace gases produced by wound-associated bacteria grown in vitro, so as to enable identification of bacterial volatile product ion profiles in the resulting mass spectra. Applying multivariate statistical analysis (hierarchical clustering and principal component analysis) to the resultant mass spectra enabled clear speciation. Moreover, bacterial volatile product ions could be detected from artificially contaminated wound dressing material, although the pattern of product ions detected was influenced by culture conditions. CONCLUSIONS: Using selected product ions from the SIFT-MS mass spectra it is possible to discriminate wound-associated bacterial species grown under specific in vitro culture conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study have shown that wound-associated bacteria can be discriminated using volatile analysis in vitro and that bacterial volatiles can be detected from wound dressing material. This indicates that volatile analysis of wounds or dressing material to identify infecting microbes has potential and warrants further study.
RESUMEN
The main aim of this study was to develop a standardized experimental assay to enable differential antimicrobial comparisons of test biocidal aerosols. This study represents the first chlorine-matched comparative assessment of the antimicrobial activities of aerosolized sodium hypochlorite, chlorine dioxide, and electrochemically activated solution (ECAS) to determine their relative abilities to decontaminate various surface-associated health care-relevant microbial challenges. Standard microbiological challenges were developed by surface-associating typed Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis spores, or a clinical methicillin-resistant S. aureus (MRSA) strain on stainless steel, polypropylene, or fabric. All test coupons were subjected to 20-min biocidal aerosols of chlorine-matched (100 ppm) sodium hypochlorite, chlorine dioxide, or ECAS within a standard aerosolization chamber using a commercial humidifier under defined conditions. Biocidal treatment type and material surface had a significant effect on the number of microorganisms recovered from various material surfaces following treatment exposure. Under the conditions of the assay, the order of antimicrobial efficacy of biocidal aerosol treatment was as follows: ECAS > chlorine dioxide > sodium hypochlorite. For all biocides, greater antimicrobial reductions were seen when treating stainless steel and fabric than when treating plastic-associated microorganisms. The experimental fogging system and assay protocol designed within this study were shown capable of differentiating the comparative efficacies of multiple chlorine-matched biocidal aerosols against a spectrum of target organisms on a range of test surface materials and would be appropriate for testing other biocidal aerosol treatments or material surfaces.
Asunto(s)
Bacillus subtilis/efectos de los fármacos , Compuestos de Cloro/farmacología , Desinfectantes/farmacología , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Óxidos/farmacología , Pseudomonas aeruginosa/efectos de los fármacos , Hipoclorito de Sodio/farmacología , Esporas Bacterianas/efectos de los fármacos , Aerosoles , Bacillus subtilis/crecimiento & desarrollo , Bioensayo/normas , Recuento de Colonia Microbiana , Técnicas Electroquímicas , Humedad , Staphylococcus aureus Resistente a Meticilina/crecimiento & desarrollo , Viabilidad Microbiana/efectos de los fármacos , Polipropilenos , Pseudomonas aeruginosa/crecimiento & desarrollo , Soluciones , Esporas Bacterianas/crecimiento & desarrollo , Acero InoxidableRESUMEN
Due to the limitations associated with the use of existing biocidal agents, there is a need to explore new methods of disinfection to help maintain effective bioburden control, especially within the healthcare environment. The transformation of low mineral salt solutions into an activated metastable state, by electrochemical unipolar action, produces a solution containing a variety of oxidants, including hypochlorous acid, free chlorine and free radicals, known to possess antimicrobial properties. Electrochemically activated solutions (ECAS) have been shown to have broad-spectrum antimicrobial activity, and have the potential to be widely adopted within the healthcare environment due to low-cost raw material requirements and ease of production (either remotely or in situ). Numerous studies have found ECAS to be highly efficacious, as both a novel environmental decontaminant and a topical treatment agent (with low accompanying toxicity), but they are still not in widespread use, particularly within the healthcare environment. This review provides an overview of the scientific evidence for the mode of action, antimicrobial spectrum and potential healthcare-related applications of ECAS, providing an insight into these novel yet seldom utilised biocides.
Asunto(s)
Desinfectantes/química , Desinfección/métodos , Técnicas Electroquímicas/métodos , Microbiología Ambiental , Soluciones/química , Desinfectantes/farmacología , Instituciones de Salud , Humanos , Soluciones/farmacologíaRESUMEN
OBJECTIVE: To compare the antimicrobial effectiveness of silver- and iodine-containing wound dressings against preformed mature biofilms of pathogenic wound bacteria grown in vitro. METHOD: Biofilms of Pseudomonas aeruginosa and Staphylococcus aureus were grown within an in vitro flat bed perfusion biofilm model. Mature biofilms were removed and exposed to wound dressings containing either silver or iodine (Aquacel Ag and Iodozyme) within a static diffusion method, for up to 24 hours. This method was designed to reflect certain key features that determine antimicrobial activity within the wound. The numbers of viable bacteria surviving in the biofilms were determined at set time intervals over the test period. RESULTS: Both test dressings exerted an antimicrobial effect against the target species biofilms, although the iodine dressing was more efficacious under the experimental conditions employed. CONCLUSION: There are large and potentially significant differences (as measured in vitro) in the effectiveness of wound dressings containing broad-spectrum antimicrobial agents such as silver and iodine against specific types of bacterial biofilms.
Asunto(s)
Vendas Hidrocoloidales , Biopelículas/efectos de los fármacos , Carboximetilcelulosa de Sodio/uso terapéutico , Compuestos de Yodo/uso terapéutico , Compuestos de Plata/uso terapéutico , Infección de Heridas/tratamiento farmacológico , Administración Tópica , Análisis de Varianza , Vendas Hidrocoloidales/normas , Técnicas de Cultivo de Célula , Recuento de Colonia Microbiana , Evaluación Preclínica de Medicamentos , Humanos , Modelos Lineales , Infecciones por Pseudomonas/tratamiento farmacológico , Infecciones Estafilocócicas/tratamiento farmacológico , Factores de Tiempo , Infección de Heridas/microbiologíaRESUMEN
AIMS: To develop an in vitro flat-bed perfusion biofilm model that could be used to determine the antimicrobial efficacy of topically applied treatments. METHODS AND RESULTS: Pseudomonas aeruginosa and Staphylococcus aureus biofilms were grown within continuously perfused cellulose matrices. Enumeration of the biofilm density and eluate was performed at various sampling times, enabling determination of the biofilm growth rate. Two antimicrobial wound dressings were applied to the surface of mature biofilms and periodically sampled. To enable real-time imaging of biofilm growth and potential antimicrobial kinetics, a bioluminescent Ps. aeruginosa biofilm was monitored using low-light photometry. Target species produced reproducible steady-state biofilms at a density of c. 10(7) per biofilm support matrix, after 24-h perfusion. Test dressings elicited significant antimicrobial effects, producing differing kill kinetic profiles. There was a good correlation between photon and viable count data. CONCLUSIONS: The model enables determination of the antimicrobial profile of topically applied treatments against target species biofilms, accurately differentiating bactericidal from bacteriostatic effects. Moreover, these effects could be monitored in real time using bioluminescence. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first in vitro biofilm model which can assess the antimicrobial potential of topical therapies in a dynamic growth environment.
Asunto(s)
Antibacterianos/administración & dosificación , Biopelículas/efectos de los fármacos , Infecciones por Pseudomonas/tratamiento farmacológico , Pseudomonas aeruginosa/fisiología , Infecciones Estafilocócicas/tratamiento farmacológico , Infección de Heridas/tratamiento farmacológico , Infección de Heridas/prevención & control , Administración Tópica , Vendajes , Humanos , Microscopía Electrónica de Rastreo , Modelos Biológicos , Infecciones por Pseudomonas/prevención & control , Pseudomonas aeruginosa/ultraestructura , Infecciones Estafilocócicas/prevención & control , Staphylococcus aureus/fisiología , Staphylococcus aureus/ultraestructura , Infección de Heridas/microbiologíaRESUMEN
A bioluminescent Pseudomonas aeruginosa was incorporated into an in vitro static diffusion method to determine whether light output could be used as a measure of wound dressing efficacy. A significant linear correlation was observed between viable counts and bioluminescence during exponential growth in planktonic culture (r(2) = 0.969). Exponential-phase cells were used to inoculate cellulose discs for integration into an in vitro wound model that incorporated a reservoir of serum. A significant linear correlation was found between bioluminescence (photon counts monitored by a low-light camera) and viable counts in this growth environment (r(2) = 0.982). Three antimicrobial wound dressings were applied to the surface of freshly prepared sample discs within the wound model, and the kill kinetics were codetermined by photon and viable counts. Quantifiable kill rates gave the same order of efficacy for the three wound dressings using both types of measurement, and a significant linear correlation was shown between photon and viable counts (r(2) = 0.873) within this killing environment. Under all defined conditions, a significant linear correlation between bioluminescence and viable counts was shown but the actual slope of the correlation was different, depending on the physicochemical environment of the cells. Hence, significantly more light per cell (P < 0.0001) was produced when cells in discs were exposed to a killing environment compared to a growing environment. As long as defined conditions are employed, the resulting linear correlation enables the state of the system to be continually monitored without disturbance, allowing more immediate and accurate calculations of kill rates without the need for viable counting.
Asunto(s)
Antibacterianos/administración & dosificación , Antibacterianos/uso terapéutico , Vendajes , Infecciones por Pseudomonas/prevención & control , Pseudomonas aeruginosa/efectos de los fármacos , Infección de Heridas/tratamiento farmacológico , Recuento de Colonia Microbiana , Interpretación Estadística de Datos , Indicadores y Reactivos , Luminiscencia , Pruebas de Sensibilidad Microbiana , Plásmidos/genética , Infecciones por Pseudomonas/microbiología , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/fisiología , Infección de Heridas/microbiologíaRESUMEN
OBJECTIVE: To determine the antimicrobial activity and efficacy of different formulations of novel bioxygenating hydrogel dressings (which deliver both iodine and oxygen into the wound) against various target organisms by means of an in vitro test system that more effectively mimics the conditions encountered when dressings are in contact with wounds. METHOD: Three bioxygenating hydrogels were tested: Oxyzyme, which releases low levels of iodine into the wound, and Iodozyme 402 and Iodozyme 401, which release higher levels of iodine, with Iodozyme 402 releasing twice the amount of 401. Cellulose filter disks (n = 32) were inoculated with indicator species and placed equidistant from each other as a matrix onto agar test beds. Cut squares of control or test dressings were placed on top of each disk. Kill curves were constructed from determinations of the numbers of survivors (log cfu per disk) over time by removing disk samples at various time points. RESULTS: Significant differences (p < 0.05) were observed between the controls and test samples. The order of sensitivity for Oxyzyme was Fusobacterium nucleatum, Bacteroides fragilis, Propionibacterium acnes, Staphylococcus epidermidis, methicillin-resistant Staphylococcus aureus (MRSA), Candida albicans and Pseudomonas aeruginosa. The order of efficacy of the three hydrogel dressings (Iodozyme 402, followed by Iodozyme 401 and then Oxyzyme) was the same regardless of the target species. CONCLUSION: The novel hydrogel skin surface wound dressings are broad-spectrum in activity, encompassing antibiotic-resistant organisms, anaerobes and yeasts; their antimicrobial function appears to be rapidly effective.
Asunto(s)
Antiinfecciosos Locales/farmacología , Bacterias/efectos de los fármacos , Vendas Hidrocoloidales/normas , Glucosa Oxidasa/farmacología , Compuestos de Yodo/farmacología , Administración Cutánea , Antiinfecciosos Locales/química , Antiinfecciosos Locales/uso terapéutico , Infecciones Bacterianas/tratamiento farmacológico , Infecciones Bacterianas/microbiología , Bacteroides fragilis/efectos de los fármacos , Candida albicans/efectos de los fármacos , Química Farmacéutica , Sistemas de Liberación de Medicamentos/métodos , Evaluación Preclínica de Medicamentos , Farmacorresistencia Bacteriana , Fusobacterium nucleatum/efectos de los fármacos , Glucosa Oxidasa/química , Glucosa Oxidasa/uso terapéutico , Humanos , Compuestos de Yodo/química , Compuestos de Yodo/uso terapéutico , Resistencia a la Meticilina , Pruebas de Sensibilidad Microbiana , Propionibacterium acnes/efectos de los fármacos , Pseudomonas aeruginosa/efectos de los fármacos , Staphylococcus aureus/efectos de los fármacos , Staphylococcus epidermidis/efectos de los fármacos , Infección de Heridas/tratamiento farmacológico , Infección de Heridas/microbiologíaRESUMEN
AIMS: To develop a simple, reproducible in vitro static diffusion method using cellulose disks and defined species to test antimicrobial efficacy of wound dressings. METHODS AND RESULTS: Cellulose disks were inoculated by immersion in cell suspensions of target species Staphylococcus epidermidis, Candida albicans and Fusobacterium nucleatum. Test and control wound dressings were cut into equal sized squares (25 x 25 mm) and applied to the surface of 10-mm thick tryptone yeast extract agar on test beds. Following a 2-h equilibration period, inoculated cellulose disks were inserted (one per dressing) at the interface between dressing and agar surface and a small weight applied over each square. At various sampling times, disks were removed and surviving cells enumerated by viable counts. Disk to disk variation for microbial loading was assessed using S. epidermidis for both initial (n = 16) and standard treatment (n = 16) conditions. The coefficient of variation was low (<5%) indicating good reproducibility for cell loading and treatment position on the test bed. Replicate assays (n = 6) using S. epidermidis and oxyzyme gels produced similar kill rates with low scatter (R2 > 0.9) indicating good reproducibility between assays. Significant differences (P < 0.05) in kill rates were observed for different target species, types of dressing and test bed conditions (+/-blood and nutrients). CONCLUSIONS: The method is reproducible and useful in tracking the death kinetics of test species, enabling the comparison of different types of dressing. SIGNIFICANCE AND IMPACT OF THE STUDY: The reported method has significant advantages over established test procedures; it can be applied equally across a wide range of target species (including anaerobes and yeasts), a wide range of conditions, and different types of surface dressings, including those relying upon oxygen diffusion.