Shift In Microflora Research Articles

Colonization of construction materials by microbial flora of the oral cavity and its significance for prosthetics

Today there is no unified personalized approach to the selection of construction materials in orthopedic dentistry, hence it is necessary to introduce and further study the effect of construction materials on the microbiota of the oral cavity. In particular, principles of microbial adhesion to various construction materials, development of biofilm and bacterial colonization of concrete construction materials need to be analysed. The article provides a review of literature devoted to the description of the adhesive properties of oral microbiota to orthopedic materials from the groups of polymers, metals and ceramic constructions as well as the development of the negative impact of the construction material on the microbiota of a particular group of teeth and the general condition of the microflora of the oral cavity, increase of the risks of dental plaque formation, biofilms formation and a shift of microflora towards the predominance of cariogenic one.

Rhizosphere responses to environmental conditions in Radix pseudostellariae under continuous monoculture regimes

The root exudates of Radix pseudostellariae, working as a rhizospheric intermediary between plants and microbes, can deteriorate the microbial community in the rhizosphere in a consecutive monoculture system. We assessed the effects of artificially applied R. pseudostellariae root exudates on R. pseudostellariae seedling growth, rhizosphere soil microbial communities, and soil physicochemical properties. We found that phenolic acids and organic acids acted as a driver of changes in the microbial community. High-throughput sequencing and qRT-PCR analysis demonstrated that treatment with phenolic acids significantly decreased the relative abundance of Trichoderma, Penicillium, Pseudomonadales, Xanthomonadales, and Streptomycetales. Organic acids had a significant negative effect on the relative abundance of Pseudomonadales and Streptomycetales and significantly increased the abundance of Fusarium, Xanthomonadales, Micrococcales, and Gemmatimonadales. Analysis based on the noninvasive microtest technique indicated that root exudates increased H+ efflux and plasma membrane H+-ATPase activity in the pathogenic fungi and decreased them in the beneficial fungi. These phenomena created an acidic environment for the inhibition of beneficial bacteria and accumulation of specialized plant pathogens. This study explains the mechanisms underlying the shift in microflora and structural disorder caused by root exudates in continuously monocultured R. pseudostellariae rhizosphere soil through responses to environmental conditions.

Can the oral microflora affect oral ulcerative mucositis?

Oral mucositis is one of the most prevalent toxicities after hematopoietic stem cell transplantation. Mucositis is initiated by the chemotherapy or radiotherapy preceding the transplantation. It is commonly accepted that microorganisms play a role in the process of oral mucositis. Despite the upcoming techniques to determine the whole oral bacterial ecosystem, the exact role of the microflora in mucositis is not yet understood. This article provides an overview of the state-of-the-art research on the oral microflora and mucositis. A shift in microflora, in both the intestine and the oral cavity, can be found after chemotherapy or radiation therapy. The presence of oral ulcerative mucositis coincides with the presence of periodontitis-associated bacteria, in particular Porphyromonas gingivalis. Moreover, this bacterium can inhibit wound healing processes in an in-vitro model. We come to realize that some diseases are associated with a shift in the microflora. The role of the microflora in oral and intestinal mucositis is gaining more attention in recent literature. In the oral cavity, periodontitis-associated bacteria may influence the healing of ulcerations and the role they play in mucositis may be more subtle and complicated than was previously thought.

Toward Early Safety Alert Endpoints: Exploring Biomarkers Suggestive of Microbicide Failure

Several microbicides, including nonoxynol-9 (N-9) and cellulose sulfate (CS), looked promising during early trials but failed in efficacy trials. We aimed to identify Phase I mucosal safety endpoints that might explain that failure. In a blinded, randomized, parallel trial, 60 healthy premenopausal sexually abstinent women applied Universal HEC placebo, 6% CS or 4% N-9 gel twice daily for 13½ days. Endpoints included immune biomarkers in cervicovaginal lavage (CVL) and endocervical cytobrushes, inflammatory infiltrates in vaginal biopsies, epithelial integrity by naked eye, colposcopy, and histology, CVL anti-HIV activity, vaginal microflora, pH, and adverse events. Twenty women enrolled per group. Soluble/cellular markers were similar with CS and placebo, except secretory leukocyte protease inhibitor (SLPI) levels decreased in CVL, and CD3(+) and CD45(+) cells increased in biopsies after CS use. Increases in interleukin (IL)-8, IL-1, IL-1RA, and myeloperoxidase (MPO) and decreases in SLPI were significant with N-9. CVL anti-HIV activity was significantly higher during CS use compared to N-9 or placebo. CS users tended to have a higher prevalence of intermediate Nugent score, Escherichia coli, and Enterococcus and fewer gram-negative rods. Most Nugent scores diagnostic for bacterial vaginosis were in N-9 users. All cases of histological inflammation or deep epithelial disruption occurred in N-9 users. While the surfactant N-9 showed obvious biochemical and histological signs of inflammation, more subtle changes, including depression of SLPI, tissue influx of CD45(+) and CD3(+) cells, and subclinical microflora shifts were associated with CS use and may help to explain the clinical failure of nonsurfactant microbicides.

Modifying the gastrointestinal ecology in alternatively raised poultry and the potential for molecular and metabolomic assessment

Consumer demand for nonconventional poultry products continues to increase in the United States. In pasture flock and organic poultry production, probiotics and prebiotic feed additives have potential advantages because they are thought to promote intestinal health and may offer a replacement for current intervention strategies that are not considered acceptable for these production systems. Prebiotics have been demonstrated to produce effects on the gastrointestinal tract including modulation of microflora by promoting selective increases in beneficial bacteria concomitant with decreases in undesirable bacteria. In-depth assessment of microbial community changes during host growth and development as well as the establishment of beneficial microbial species by adding biologicals such as probiotics and prebiotics is important to achieve predictable and consistent improvements in chicken health and productivity. To analyze microflora shifts and metabolites produced by bacteria in the gut as well as host responses to biological additives, sophisticated molecular techniques are now available and are becoming more widely used. Polymerase chain reaction assays, denaturing gradient gel electrophoresis, and temperature gradient gel electrophoresis offer approaches for detecting microbial shifts in the gut. Likewise, the employment of microarrays and molecular analysis of gut tissues can reveal insight into gut physiological and responses to dietary and other changes. Recent application of 16S rDNA sequencing and analysis utilizing basic local alignment search tool (BLAST) and FASTA databases on poultry gut samples have the potential to provide a much more in-depth assessment of the gut microbiome. Utilizing ultra pressure liquid chromatography-mass spectroscopy profiling, metabolomic assessment of gut contents will also allow for parallel comparisons of changes in the gut contents with microbiome and physiological responses. Combining all these technologies will provide a plenary understanding of poultry gut health in alternative production systems.

Calcium effects on bodyweight appear to be mediated in part by changes in gut microflora and altered by dietary matrix

Calcium (Ca) intake variably affects bodyweight (BW) regulation. Delivery matrix may affect Ca effects. Gut microflora is now a considered variable in BW regulation. Three isonitrogenous, isocaloric, 45 kcal% fat diets were fed to male C57/BL6J mice (n=10/group) in two diet‐induced obesity tests. Isolated soy protein was used for diets containing adequate (0.5 wt%, D1) or high (1.5 wt%, D2) amounts of Ca as CaCO3, while non‐fat dry milk was used in a second 1.5 wt% Ca diet (NFDM), providing 0.5 wt% Ca as intrinsic dairy Ca. Test 1: 5 wk old mice were fed test diets for 12 wks. Mice fed D1 and NFDM consumed similar amounts of feed, but NFDM fed mice gained less BW and body fat (p<0.05). Mice fed D2 consumed the most feed, gained the most BW and body fat (p <0.05). Gut microflora community structure was determined by 16SrRNA pyrosequencing of feces collected during the last 48 hrs of study. UniFrac analysis and PCA clustering of mice with similar microflora clearly separated D1, D2, and NFDM at the genera level. Test 2: Test 1 protocol, except that mice were pre‐fed D1 for 12wks prior to being fed D1, D2, or NFDM for an additional 8wk period. Similar responses in feed intake, BW, body fat and microflora shifts were seen. Dairy was most effective in obesity prevention (Test 1) and its effects were correlated to changes in gut microflora. 1.5 wt% CaCO3 increased obesogenic tendencies. Funded by the Dairy Research Institute.

Clinical case of a child with Rhabdomyosarcoma (RMS), embryonic type, with oral complications post radiation therapy and chemotherapy

SUMMARY Case of a 7 years old female, with significant medical history of embrional type of RMS, diagnosed 2,5 years ago in left parapharingeal area. After surgical removal of the tumor, the area is radiated with 50Gy for 6 weeks and also has 3 courses of chemotherapy. By now the child is clinically healthy of RMS, but she has developed serious side effects of radiation therapy: erosive caries to all primary teeth, hyposalivation and total lost of function of the left parotid gland, delayed development of the teeth, facial asymmetry, caused by the arrested growth of left side mandibule. Acute and chronic complications of radiation therapy act to the dynamic changes of the oral environment in a phase of active growth, dental eruptions and incomplete mineralization. The potential risk of osteoradionecrosis and radiation caries, resulted in the sequel of xerostomia and a cariogenic shift in micro flora, requires a prophylactic and heeling program to modulate the oral environment and to prevent or at lease, minimize the side effects and should be integral part of the treatment. Frequent dental follow – up should be scheduled throughout the treatment period to reinforce the importance of continued oral hygiene and to deal with the complications for a lifelong period of time. Key word: Rhabdomyosarcoma (RMS) embryonic,

Shift Towards Pro-inflammatory Intestinal Bacteria Aggravates Acute Murine Colitis via Toll-like Receptors 2 and 4

BackgroundGut bacteria trigger colitis in animal models and are suspected to aggravate inflammatory bowel diseases. We have recently reported that Escherichia coli accumulates in murine ileitis and exacerbates small intestinal inflammation via Toll-like receptor (TLR) signaling.Methodology and Principal FindingsBecause knowledge on shifts in the intestinal microflora during colitis is limited, we performed a global survey of the colon flora of C57BL/10 wild-type (wt), TLR2-/-, TLR4-/-, and TLR2/4-/- mice treated for seven days with 3.5% dextrane-sulfate-sodium (DSS). As compared to wt animals, TLR2-/-, TLR4-/-, and TLR2/4-/- mice displayed reduced macroscopic signs of acute colitis and the amelioration of inflammation was associated with reduced IFN-gamma levels in mesenteric lymph nodes, lower amounts of neutrophils, and less FOXP3-positive T-cells in the colon in situ. During acute colitis E. coli increased in wt and TLR-deficient mice (P<0.05), but the final numbers reached were significantly lower in TLR2-/-, TLR4-/- and TLR2/4-/- animals, as compared to wt controls (P<0.01). Concentrations of Bacteroides/ Prevotella spp., and enterococci did not increase during colitis, but their numbers were significantly reduced in the colon of DSS-treated TLR2/4-/- animals (P<0.01). Numbers of lactobacilli and clostridia remained unaffected by colitis, irrespective of the TLR-genotype of mice. Culture-independent molecular analyses confirmed the microflora shifts towards enterobacteria during colitis and showed that the gut flora composition was similar in both, healthy wt and TLR-deficient animals.Conclusions and SignificanceDSS-induced colitis is characterized by a shift in the intestinal microflora towards pro-inflammatory Gram-negative bacteria. Bacterial products exacerbate acute inflammation via TLR2- and TLR4-signaling and direct the recruitment of neutrophils and regulatory T-cells to intestinal sites. E. coli may serve as a biomarker for colitis severity and DSS-induced barrier damage seems to be a valuable model to further identify bacterial factors involved in maintaining intestinal homeostasis and to test therapeutic interventions based upon anti-TLR strategies.

Role of Vaginal Flora As a Barrier to HIV Acquisition.

Recent evidence has linked bacterial vaginosis with acquisition of sexually transmitted diseases, including HIV infection. Prospective data show that women with bacterial vaginosis are at a significantly higher risk for HIV infection than those without bacterial vaginosis. The hallmark of bacterial vaginosis is the shift in the microbiology of the vaginal flora away from a lactobacilli-predominant milieu. In particular, lactobacilli that produce hydrogen peroxide are notably absent. Hydrogen peroxide-producing lactobacilli have been shown in vitro to be virucidal to HIV. Thus, the lack of these apparently protective bacteria, along with other local changes resulting from the shift in microflora, is thought to represent a biological risk factor for HIV acquisition.

Microbial ecology of dental plaque and its significance in health and disease.

Dental plaque forms naturally on teeth and is of benefit to the host by helping to prevent colonization by exogenous species. The bacterial composition of plaque remains relatively stable despite regular exposure to minor environmental perturbations. This stability (microbial homeostasis) is due in part to a dynamic balance of both synergistic and antagonistic microbial interactions. However, homeostasis can break down, leading to shifts in the balance of the microflora, thereby predisposing sites to disease. For example, the frequent exposure of plaque to low pH leads to inhibition of acid-sensitive species and the selection of organisms with an aciduric physiology, such as mutans streptococci and lactobacilli. Similarly, plaque accumulation around the gingival margin leads to an inflammatory host response and an increased flow of gingival crevicular fluid. The subgingival microflora shifts from being mainly Gram-positive to being comprised of increased levels of obligately anaerobic, asaccharolytic Gram-negative organisms. It is proposed that disease can be prevented or treated not only by targeting the putative pathogens but also by interfering with the processes that drive the breakdown in homeostasis. Thus, the rate of acid production following sugar intake could be reduced by fluoride, alternative sweeteners, and low concentrations of antimicrobial agents, while oxygenating or redox agents could raise the Eh of periodontal pockets and prevent the growth and metabolism of obligately anaerobic species. These views have been incorporated into a modified hypothesis (the "ecological plaque hypothesis") to explain the relationship between the plaque microflora and the host in health and disease, and to identify new strategies for disease prevention.

The Role of Chemostats in the Evaluation of Antimicrobial Agents for Use in Dental Products

Dental plaque develops naturally on teeth and forms part of the natural defence systems of the mouth by acting as a barrier to colonisation by exogenous species. 10 Plaque preferentially forms at stagnant or retentive sites and, unless removed by diligent oral hygiene, it can predispose a site to either caries or periodontal diseases. In disease, the balance ofthe resident microflora shifts. In caries, there is an increase in acidogenic and aciduric species (e.g. mutans streptococci, lactobacilli) at the expense of many acid-sensitive species (e.g. Streptococcus sanguis, S. oralis ), while in periodontal diseases there is an increase both in plaque mass and in the proportions of several obligately anaerobic and capnophilic species. For many subjects, the customary oral hygiene of tooth brushing is usually insufficient by itself over long periods to provide a level of plaque control compatible with oral health. Consequently, the incorporation of antimicrobial agents into dental products as a means of controlling plaque and disease has been advocated for a number of years.'' There are several important differences in the way antimicrobial agents function in the mouth compared to the treatment of most medical infections. Agents for plaque control are applied topically, and are usually delivered by toothpaste or mouthwash. Inhibitors are present at concentrations greater than minimum inhibitory concentrations (MICs) of target organisms for a relatively short time (perhaps minutes), and function thereafter for much longer periods (hours) at sub-MIC levels. Also, antimicrobial agents in dental products are required to produce clinical benefit without disrupting the natural ecology of the resident microflora. The longterm use of these agents is intended, therefore, to control rather than eliminate plaque, and to preserve the beneficial properties of plaque. 10,11 The conventional methods of evaluating antimicrobial agents for use in dental products still centre around those used in medical microbiology, such as determining the MIC. As discussed above (and elsewhere in this workshop), the MIC is not particularly relevant to the mode of action of antimicrobials in the mouth. It is also difficult to extrapolate from such simple tests to predict the likely behaviour of an inhibitor in vivo , so more stringent methods for the laboratory assessment of potential antimicrobial agents have been sought. Of particular value has been the use of continuous culture techniques to grow oral bacteria for prolonged periods, under defined and relevant conditions, in pure and mixed culture.

The Role of Chemostats in the Evaluation of Antimicrobial Agents for Use in Dental Products

Dental plaque develops naturally on teeth and forms part of the natural defence systems of the mouth by acting as a barrier to colonisation by exogenous species. 10 Plaque preferentially forms at stagnant or retentive sites and, unless removed by diligent oral hygiene, it can predispose a site to either caries or periodontal diseases. In disease, the balance ofthe resident microflora shifts. In caries, there is an increase in acidogenic and aciduric species (e.g. mutans streptococci, lactobacilli) at the expense of many acid-sensitive species (e.g. Streptococcus sanguis, S. oralis ), while in periodontal diseases there is an increase both in plaque mass and in the proportions of several obligately anaerobic and capnophilic species. For many subjects, the customary oral hygiene of tooth brushing is usually insufficient by itself over long periods to provide a level of plaque control compatible with oral health. Consequently, the incorporation of antimicrobial agents into dental products as a means of controlling plaque and disease has been advocated for a number of years.'' There are several important differences in the way antimicrobial agents function in the mouth compared to the treatment of most medical infections. Agents for plaque control are applied topically, and are usually delivered by toothpaste or mouthwash. Inhibitors are present at concentrations greater than minimum inhibitory concentrations (MICs) of target organisms for a relatively short time (perhaps minutes), and function thereafter for much longer periods (hours) at sub-MIC levels. Also, antimicrobial agents in dental products are required to produce clinical benefit without disrupting the natural ecology of the resident microflora. The longterm use of these agents is intended, therefore, to control rather than eliminate plaque, and to preserve the beneficial properties of plaque. 10,11 The conventional methods of evaluating antimicrobial agents for use in dental products still centre around those used in medical microbiology, such as determining the MIC. As discussed above (and elsewhere in this workshop), the MIC is not particularly relevant to the mode of action of antimicrobials in the mouth. It is also difficult to extrapolate from such simple tests to predict the likely behaviour of an inhibitor in vivo , so more stringent methods for the laboratory assessment of potential antimicrobial agents have been sought. Of particular value has been the use of continuous culture techniques to grow oral bacteria for prolonged periods, under defined and relevant conditions, in pure and mixed culture.

Effect of flooding on activities of soil dehydrogenases and alcohol dehydrogenase in rice (Oryza SativaL.) Roots

Dehydrogenase activity and redox potential were monitored over a period of 100 days in flooded and drained soils in which rice was grown. The activity of the enzyme alcohol dehydrogenase (ADH) was measured in the roots of the rice plants. The immediate decrease in soil redox potential and rapid increase in soil dehydrogenase activity upon flooding indicated a shift of microflora from aerobic to predominantly anaerobic microorganisms. Soil dehydrogenase activity remained elevated as long as the soil continued to be flooded, but was negligible in soils allowed free drainage. The rice roots only initially experienced anaerobiosis during flooding. Root ADH activity was stimulated upon flooding but declined by day 47 to levels similar to those measured in plants grown in a drained soil. The development of aerenchyma (air-space) tissue in the continuously flooded plants may have provided a pathway for oxygen movement to the roots which allowed aerobic metabolism to proceed in spite of the reduced amount of subs...

The predominant cultivable subgingival flora of beagle dogs following ligature placement and metronidazole therapy.

Ligature‐induced periodontitis was evaluated microbiologically in 8 beagle dogs. Gingival health was established by repeated cleaning. At day 0 subgingival plaque was sampled from individual sites in two quadrants. All teeth in one quadrant were then ligated at the CEJ, and the other quadrant served as a non‐ligated control which was cleaned three times each week. At day 14, four dogs were given metronidazole for seven days. Plaque was cultured anaerobically on nonselcctive media, and the predominant cultivable flora was characterized. At day 0 Gram‐negative facultative rods represented 56.8 % of the flora. with motile and surface translocating organisms predominating. At day 14 Bacteroides asaccharolyticus, including catalase positive B.asaccharolyticus‐like organisms, increased at ligated sites to 34.7 % of the cultivable flora. After metronidazole therapy the total bacterial count decreased, and Gram‐negative anaerobic rods became non‐detectable. Gram negative facultative bacteria which were motile or surface translocating represented 52.7 % of the cultivable flora after metronidazole treatment.In the beagle dog ligature placement was associated with a shift in the flora from Gram‐negative facultative rods to Gram‐negative anaerobic rods. Metronidazole treatment reduced the total cultivable flora and selectively reversed the microflora shifts which followed ligature placement.

RADIATION PASTEURIZATION OF FRESH AND BLANCHED TROPICAL SHRIMPS

SUMMARY— The storage life of fresh, peeled and deveined tropical shrimps at 10—12°C is extended to 10—14 and 18—21 days with 0.15 and 0.25 Mrad, respectively, as against spoilage of unirradiated samples within 4 days. Blanching treatment (steaming for 4 min) with or without brine (3.0% NaCl) extends the storage life up to 30 days at lo—12°C. the former retaining the shell‐fish flavor. However, the blanched products develop musty odor and slimy texture during storage; subjected to irradiation (0.15 Mrad) these are devoid of undesirable attributes and are acceptable for 60 and 130 days, respectively, at 10—1°C and 2—4°C. Bacterial counts exceeding 108/g and high levels of TMAN and TVBN concur with spoilage of unirradiated shrimps. In contrast, low levels of TMAN and TVBN, despite high TBC, corroborate with high acceptability of radiation processed shrimps. In blanched as well as in blanched and irradiated shrimps TBC, TMAN and TVBN are low. Samples subjected to blanching only have low acceptability as against the improvement in quality by irradiation. These alterations in storage property have been discussed in the light of shifts in microflora.