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PubMed2000

Granulysin, a T cell product, kills bacteria by altering membrane permeability.

Granulysin, a protein located in the acidic granules of human NK cells and cytotoxic T cells, has antimicrobial activity against a broad spectrum of microbial pathogens. A predicted model generated from the nuclear magnetic resonance structure of a related protein, NK lysin, suggested that granulysin contains a four alpha helical bundle motif, with the alpha helices enriched for positively charged amino acids, including arginine and lysine residues. Denaturation of the polypeptide reduced the alpha helical content from 49 to 18% resulted in complete inhibition of antimicrobial activity. Chemical modification of the arginine, but not the lysine, residues also blocked the antimicrobial activity and interfered with the ability of granulysin to adhere to Escherichia coli and Mycobacterium tuberculosis. Granulysin increased the permeability of bacterial membranes, as judged by its ability to allow access of cytosolic ss-galactosidase to its impermeant substrate. By electron microscopy, granulysin triggered fluid accumulation in the periplasm of M. tuberculosis, consistent with osmotic perturbation. These data suggest that the ability of granulysin to kill microbial pathogens is dependent on direct interaction with the microbial cell wall and/or membrane, leading to increased permeability and lysis.

Amino Acid Sequence↗
PubMed2005

Estimation of salivary bacteria capable of inhibiting and stimulating Streptococcus mutans and its correlation to dental caries and untreated carious teeth.

Bacteriocins are bacteriocidal proteinaceous molecules produced by the Gram-positive bacteria not active against the produced strain. Many investigations have revealed that certain bacteria using antibacterial or the inhibitory substance inhibit some other bacteria. A study was conducted in a group of 60 children to ascertain whether any correlation exists between the proportion of salivary bacteria inhibiting and stimulating Streptococcus mutans and the oral health indices (DMFT, deft and Community Periodontal Index of Treatment Needs). A definite inverse correlation was observed between the percentage of salivary inhibiting S. mutans and untreated carious teeth (UCT).

Adolescent↗
PubMed1978

Pretreatment with colistin and Proteus sensitivity to other agents.

The effects of pretreatment with colistin (polymyxin E) on the sensitivity of Proteus mirabilis, P. vulgaris and P. morganii strains to tris and sodium deoxycholate (DOC) have been studied. Pretreatment of two P. mirabilis strains (NCTC 60 and 4199) with low concentrations (0.25 approximately 1 microgram/ml) of colistin rendered them sensitive to lysis by tris (0.05M) or DOC (250 approximately 1,000 microgram/ml) although DOC induced lysis of control (non-colistin-treated) suspensions also. In contrast, the other P. mirabilis strains, as well as the P. vulgaris and P. morganii strains were little affected by tris (0.2M) or DOC (10,000 microgram/ml) even after exposure of the cells to high colistin concentrations (up to 500 microgram/ml). Colistin-pretreated or control cells of P. mirabilis NCTC 60 rapidly lost viability when suspended in water but not when held in 0.16M sodium chloride solution. Ethylenediamine tetraacetate-pretreated cells of strains 60 and 4199 were fairly sensitive to tris, although the extent of the lysis was less than when colistin was used as pretreating agent. One strain of P. vulgaris (NCTC 4175) became sensitive to tris and to DOC following exposure of the cells to ampicillin.

Colistin↗
PubMed1999

Interaction between specific hydrological and microbial activity leading to extensive mucilage formation in the northern Adriatic Sea.

The massive formation of marine snow and the senescent stage of it, the mucilage, is a phenomenon largely restricted to the Adriatic Sea. In this contribution the major environmental factors potentially leading to the formation of this mucilage are discussed. It is proposed that the specific hydrological conditions in combination with severe phosphorus depletion lead to excessive formation of colloidal organic matter by phytoplankton. This colloidal organic matter coagulates to marine snow due to the low-turbulence regimes prevailing in the water column. Subsequently, this marine snow is colonized by bacteria which, in turn, produce and release copious amounts of capsular polymers into the matrix of marine snow. It is speculated that a significant fraction of the later stages of marine snow (mucilage) consists of bacterial-derived organic matter which has been shown to be semi-labile to refractory for further bacterial utilization. The marine snow matrix acts as efficient adsorption site and allows the bacteria to utilize scavenged molecules from the ambient water. Thus it is proposed that the matrix ages without significant biotic degradation.

Colloids↗
PubMedDate not supplied

[Synthesis of anabiosis autoinducers in non-spore-forming bacteria as a mechanism regulating their activity in soil and subsoil sedimentary rocks].

Non-spore-forming bacteria of the genera Arthrobacter and Micrococcus, isolated from permafrost subsoil, were found to produce greater amounts of the d1 extracellular factor than closely related collection strains isolated from soil. The effect of this factor, responsible for cell transition to anabiosis, was not species-specific. Thus, the d1 crude preparation isolated from the culture liquid of the permafrost isolate Arthrobacter globiformis 245 produced an effect on the collection strain Arthrobacter globiformis B-1112 and also on Micrococcus luteus and Bacillus cereus. The crude d1 preparation from the permafrost isolate of Arthrobacter differed from the chemical analogue of this factor, 4n-hexylresorcinol, in the level of the induced cell response, which may have resulted from different cell sensitivity to various homologs of alkylhydroxybenzenes contained in the d1 preparation. Thus, additional evidence was obtained indicating that autoregulation of bacterial growth and development is implemented at the level of intercellular interactions in microbial communities. Abundant production of the d1 anabiosis-inducing factors by bacteria isolated from permafrost subsoil is probably a result of special antistress mechanisms responsible for the survival of these bacteria under extreme conditions of natural deep cooling.

Arctic Regions↗
PubMed1979

Influence of potassium chloride upon the binding and antibacterial activity of chlorhesidine diacetate and (ethoxy)5 octyl phenol (Triton X45) towards Bacillus megaterium KM-.

Chlorhexidine (0.5-0.65 microM) and Triton X45 (30-40 microM) added to exponential phase Bacillus megaterium KM- cultures was growth inhibitory. The presence of KCl (0.05-0.35 M) in the medium did not significantly affect growth rate in the absence of drug, yet reduced the growth inhibitory activity of the chlorhexidine and enhanced that of Triton X45. These effects were maximal at KCl concentrations of 0.2 M and above, when complete protection towards chlorhexidine and lysis of the cultures in the presence of Triton X45 were observed. Time-survivor curves in the presence of chlorhexidine (0.7-1.0 microM) gave LT90 values of 1.5-2.0 h in the absence of KCl, yet its inclusion (0.35 M) totally inhibited this low level bactericidal activity. Drug absorption by whole cell and isolated cell wall preparations was determined in the presence and absence of KCl (0.35 M). Chlorhexidine uptake by intact cells was reduced by approximately 50% in the presence of salt whereas that of Triton X45 increased by a similar fraction. Uptake of chlorhexidine by the cell wall fraction accounted for approximately 50% of that for the whole cells and was relatively unaffected by the presence of KCl. Conversely, absorption of Triton X45 by the cell wall fraction accounted for most of the uptake by whole cells and increased markedly in the presence of salts.

Bacillus megaterium↗
PubMedDate not supplied

Using host response modifiers in the treatment of periodontal disease.

Periodontal disease is the result of a complex interaction between microbial plaque, the host's inflammatory response to the plaque, and host modifying factors (e.g., smoking, diabetes, genetics) that may have an impact on the disease process. It is known that plaque initiates periodontal disease but that the host response is responsible for the destruction of periodontal tissues. This article describes why host response modifiers may be used to help control inflammation and tissue destruction as part of the initial phase of periodontal therapy in selected patient groups.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2003

[Effect of disinfectants on surface hydrophobicity and mobility in Salmonella enterica serovar Typhimurium DT104].

The paper evaluated antibacterial efficacy of 12 disinfectants on the basis of quaternary ammonium compounds (KAZ) on the isolates of Salmonella enterica serovar Typhimurium of the definitive phage type 104 (DT104). One isolate--5551/99--represented the multiresistant phenotype, resistant to ampicillin (A), chloramphenicol (C), streptomycin (S), and tetracycline (T). The second isolate--577/99--was sensitive to all antibiotics tested. The present study further examined the capability of sub-MIC concentrations of disinfectants to intervene into surface hydrophobicity and motility of the strains tested. The results showed that all disinfectants under study exhibited high antibacterial activity. It is of interest that the isolate resistant to antibiotics was more sensitive to disinfectants in comparison with the isolate resistant to antibiotics. The most effective substances against strain 5551/99 (R-type) were Sokrena, Triquart, Hexaquart plus, ID213, and Microbac forte, and those most effective against strain 577/99 (S-type) were Benzalkonium chloride and Hexaquart plus (MIC 0.09-0.19 microliter/ml). Surface hydrophobicity of both tested strains after the action of sub-MIC (1/16, 1/8, 1/4 of MIC) of disinfectants was not influenced in a more marked way. In the case of strain 5551/99, the highest percentage of inhibition of adherence to xylene, to 69.5% versus the control, was produced by 1/4 of MIC of the substance Triquart and, in the whole concentration range, by the substance Microbac forte. After the action of most substances to strain 577/99, stimulation of adherence took place. Only substance ID213 induced inhibition of adherence in the whole concentration range. The salt-aggregative capabilities of both strains were not influenced in a more marked way. The only exceptions were the action of 1/4 of MIC of the substances Cetrimid, Sokrena, ID212, Forten, and 1/8 of MIC of Hexaquart S on strain 577/99, where a decrease in hydrophobicity was observed. A moderate inhibition of motility was found after the action of 1/4 of MIC of Benzalkonium chloride (to 87.5%) and A.D.L. 007 (to 85.2%) on strain 5551/99. In the case of sensitive isolate 577/99, the most markedly manifested inhibition effect was that of Sokrena within the whole concentration range and that of 1/4 of MIC ID213. The results can be used in the selection of a suitable disinfectant for decontamination of solid surfaces. The effect of substances under study on surface hydrophobicity and motility of the important, food-transferred pathogen in the sense of inhibition or stimulation points out to intervention into its pathogenic potential.

Bacterial Adhesion↗
PubMed2003

[Mechanisms of plant disease resistance induced by arbuscular mycorrhizal fungi].

In recent years, the induced disease resistance of plant by Arbuscular Mycorrhizal Fungi (AMF) has become a hot spot in chemo-ecological study and in biocontrol of plant disease. There were many reports indicating that AMF had antagonistic function to soilborne disease pathogen, or could suppress the growth of pathogen, and increase the resistance or tolerance of mycorrhizal plants to soilborne disease. In mycorrhizosphere, there are interactions among microbial community, in which, AMF could suppress the growth of pathogen and promote the growth of beneficial microbe. Thus, AMF may use as biocontrol fungi with other antagonism microbe. There were several hypotheses about the mechanisms of the increased resistance in mycorrhizal plants: (1) improvement of plant nutrient status; (2) competition; (3) changed roots morphology and structure; (4) changed microbial flora in rhizosphere; (5) induced resistance or systematic resistance in plant. After colonized by AMF, phenolic compounds accumulate in plant, and local defense response or systemic defense response occurs. It is necessary to do intensive research on the mechanisms of increased resistance in mycorrhizal plants, because it may help us understand the function of disease resistance of mycorrhiza correctly, and let us use AMF as a new biocontrol method to control soilborne disease in eco-agriculture in the near future.

Ecology↗
PubMed2004

[Effect of growth conditions on cell surface hydrophobicity of multiresistant Pseudomonas aeruginosa strains].

Bacterial cell surface hydrophobicity (CSH) may promote colonization. The aim of this study was evaluation of the influence of growth conditions and sensitivity to selected antibiotics on hydrophobic properties of multiresistant P. aeruginosa strains by means of salt aggregation test (SAT) and bacterial adhesion to hydrocarbons (BATH). 30 multiresistant P. aeruginosa strains were included in this study. The variables were: microbiological media type (trypticase-soy agar, trypticase-soy agar with 5% sheep blood and trypticase-soy broth), growth temperature (22, 30 and 37 degrees C) and growth time (24 and 48 h). Most of the investigated strains presented hydrophilic properties in both methods. Cultivation in trypticase-soy broth caused statistically relevant decrease of CSH. Growth temperature did not influence CSH. 48 hours of incubation caused statistically relevant drop of the CSH when compared with 24 h incubation. The sensitivity to selected antibiotics did not vary investigated strains, except form cefepime sensitive and intermediate sensitive strains.

Agar↗
PubMed2005

The effect of ethambutol on mycobacterial cell wall permeability to hydrophobic compounds.

Ethambutol (EMB), the first line drug in the treatment of tuberculosis, is an inhibitor of the biosynthesis of the cell wall compound - arabinogalactan. It was found that EMB at sub-inhibitory concentration increases the permeability of the M. vaccae cell wall, which was monitored by cell sensitization to erythromycin and rifampicin. The high permeability of the cell wall to hydrophobic compounds allows enhanced intracellular bioconversion of beta-sitosterol to 4-androsten-3,17-dione (AD) and 1,4-androstadien-3,17-dione (ADD).

Anti-Bacterial Agents↗
PubMed1991

[The adhesion of pathogenic microflora on carbon sorbents].

The adsorbing activity of granulated carbonic sorbents SKN and KAU, as well as their oxidated forms, containing protogenic carboxylic and phenolic groups with respect to Shigella flexneri, Salmonella typhimurium, Escherichia coli, Streptococcus aureus and Pseudomonas aeruginosa pathogenic strains has been studied. As shown in this study, the process of interaction between microorganisms and carbonic sorbents has two stages. At the first stage the main role is played by long-distance electrostatic forces and at the second stage, by Van der Waals short-distance forces, as well as bonds formed between cell structures and surface groupings of carbonaceous materials. In the mechanism of interaction between microbial cells and carbons the geometry of carbon surface plays an important role. KAU(0)-1 exhibits the highest degree of adhesion with respect to pathogenic bacteria.

Adsorption↗
PubMed1990

Ultrastructural comparative distribution of carbohydrates in human tracheal and frog palate mucosa using neuraminidase and lectin-colloidal gold complexes.

We have compared, at the ultrastructural level, the carbohydrate structure of glycoconjugates of the different types of secretory cells of the human tracheal mucosa (HTM) and the frog palate mucosa (FPM), proposed as a model for studying bacterial adherence to mucus-coated respiratory epithelium. In addition to reactivity with Concanavalin A and Lens cullinaris agglutinin, reactivity of Epon-embedded HTM and FPM secretory granules was studied by transmission electron microscopy using neuraminidase-gold complex and colloidal gold-adsorbed lectins with affinity for sugar residues of human mucins, namely the following: Helix pomatia, Lotus tetragonolobus, Ricinus communis II, Wheat germ and Limax flavus agglutinins. The affinity of HTM and FPM mucous and serous cells for the different colloidal-gold complexes was very similar, however Limax flavus agglutinin labelled only HTM and not FPM secretory granules. The FPM mucous and serous secretory granules were nevertheless intensely labelled by the neuraminidase-gold complex, demonstrating the presence of sialic acid residues. The close ultrastructural and histochemical similarities between HTM and FPM suggest that the FPM may be a valuable model for studying the specific interaction between microbial lectins and mucus glycoproteins in the bacterial adherence phenomenon.

Animals↗
PubMed1989

[A supplement study on the in vitro activity of sulfadimethoxine on Mycobacterium avium complex--combined effect with other antituberculosis drugs].

Previously the author observed that sulfadimethoxine is most effective among sulfa drugs against Mycobacterium avium complex strains (Tsukamura, M.: Kekkaku 58: 247-250, 1983) and used this drug in the treatment of pulmonary infection caused by M. avium complex (Tsukamura, M.: Kekkaku 59: 33-37, 1983). In the present study, some supplemental observations were carried out on the in vitro activity of this drug. In vitro susceptibility testing of sulfadimethoxine by the use of Ogawa egg medium was influenced by the number of viable bacteria (colony-forming units) used in the susceptibility testing. By the use of small inocula (50 to 100 colony-forming units), minimal inhibitory concentration (MIC) was determined as 0.8 to 3.13 micrograms/ml, whereas, by the use of large inocula, the MIC was determined as 6.25 to 25 micrograms/ml. Furthermore, the prolongation of incubation time resulted in the elevation of the MIC. The finding shows that the activity of this drug is only to delay the growth. Comparing various combinations with low concentrations of other drugs, combinations with p-aminosalicylate, isoniazid and pyrazinamide seemed to be antagonistic, and combinations with the other drugs seemed to be additive. The influence of the inoculation size on the reading of MICs were compared in Mycobacterium tuberculosis and M. avium complex strains. The susceptibility testings to most drugs were influenced by the inoculation size. However, the testings to ethionamide, ethambutol and isoniazid in M. tuberculosis strains were less influenced by the inoculation size. In contrast, the susceptibility testings to ethionamide and isoniazid in M. avium complex strains seemed to be more influenced.(ABSTRACT TRUNCATED AT 250 WORDS)

Antitubercular Agents↗
PubMed1987

Interaction of clavulanic acid, sulbactam and cephamycin antibiotics with beta-lactamases.

The inhibitory effects of clavulanic acid, sulbactam and cephamycin antibiotics on chromosomally-mediated or plasmid-mediated beta-lactamases were investigated. The inhibition constants were determined by a non-linear regression analysis. Clavulanic acid and sulbactam had high affinities for the purified plasmid-mediated beta-lactamases such as SHV-1, TEM-1 and PSE-4, and were potent inhibitors as shown by their low Ki values. Except for Bacteroides beta-lactamase, which is sensitive to inhibition by cephamycin antibiotics, clavulanic acid and sulbactam were found not to be as effective against chromosomally-mediated beta-lactamases. The cephamycin antibiotics were better inhibitors of chromosomally-mediated beta-lactamases than those that are plasmid mediated. Except for P99 beta-lactamase, against which sulbactam and clavulanic acid were inactive, the cephamycin antibiotics were less effective inhibitors than sulbactam and clavulanic acid.

Anti-Bacterial Agents↗