Metabolic changes associated with biofilm formation in an undisturbed Mediterranean stream

Respiratory activity (ETS), ectoenzymatic activity (-glucosidase and -xylosidase) and photosynthetic ¹⁴C-bicarbonate incorporation in the biofilm were measured in a shaded stream during a colonization sequence (43 days) on artificial substrates (unglazed clay tiles) and compared with older (aged) tiles. In the first five days bacterial densities and ectoenzyme activities showed a sharp increase. After two weeks, algal density, chlorophyll and productivity increased moderately. Chlorophyll did not reach similar values to those of the aged biofilms until the last day of colonization. Photosynthetic activity seemed to be relevant to the heterotrophs metabolism during substrate colonization, as could be deduced from the significant correlation between -glucosidase and ¹⁴C-bicarbonate incorporation, algal cell densities and chlorophyll. Respiratory activity (ETS) decreased in the older biofilms, accordingly to their higher algal and bacterial density. Younger biofilms (up to 8 days old) showed higher ETS activity per cell, indicating a fast response of microorganisms to substrate availability.     

Twitching motility and biofilm formation are associated with tonB1 in Xylella fastidiosa

A mutation in the Xylella fastidiosa tonB1 gene resulted in loss of twitching motility and in significantly less biofilm formation as compared with a wild type. The altered motility and biofilm phenotypes were restored by complementation with a functional copy of the gene. The mutation affected virulence as measured by Pierce's disease symptoms on grapevines. The role of TonB1 in twitching and biofilm formation appears to be independent of the characteristic iron-uptake function of this protein. This is the first report demonstrating a functional role for a tonB homolog in X. fastidiosa .     

Genetic variability in beta-defensins is not associated with susceptibility to Staphylococcus aureus bacteremia

Introduction

Human beta-defensins are key components of human innate immunity to a variety of pathogens, including Staphylococcus aureus. The aim of the present study was to investigate a potential association between gene variations in DEFB1 and DEFB103/DEFB4 and the development of S. aureus bacteremia (SAB) employing a case-control design.

Methods

Cases were unique patients with documented SAB, identified with the National S. aureus Bacteremia Register, a comprehensive dataset of all episodes of community associated-SABs (CA-SAB) occurring in children (≤20 yrs) in Denmark from 1990 to 2006. Controls were age-matched healthy individuals with no history of SAB. DNA obtained from cases and controls using the Danish Newborn Screening Biobank were genotyped for functional polymorphisms of DEFB1 by Sanger sequencing and copy number variation of the DEFB103 and DEFB4 genes using Pyrosequencing-based Paralogue Ratio Test (P-PRT).

Results

193 ethnic Danish SAB cases with 382 age-matched controls were used for this study. S. aureus isolates represented a variety of bacterial (i.e., different spa types) types similar to SAB isolates in general. DEFB1 minor allele frequencies of rs11362 (cases vs. controls 0.47/0.44), rs1800972 (0.21/0.24), and rs1799946 (0.32/0.33) were not significantly different in cases compared with controls. Also, DEFB4/DEFB103 gene copy numbers (means 4.83/4.92) were not significantly different in cases compared with controls.

Conclusions

Using a large, unique cohort of pediatric CA-SAB, we found no significant association between DEFB1 genetic variation or DEFB4/DEFB103 gene copy number and susceptibility for SAB.     

Differential biofilm formation and motility associated with lipopolysaccharide/exopolysaccharide-coupled biosynthetic genes in Stenotrophomonas maltophilia

Stenotrophomonas maltophilia WR-C is capable of forming biofilm on polystyrene and glass. The lipopolysaccharide/exopolysaccharide-coupled biosynthetic genes rmlA, rmlC, and xanB are necessary for biofilm formation and twitching motility. Mutants with mutations in rmlAC and xanB display contrasting biofilm phenotypes on polystyrene and glass and differ in swimming motility.     

Stenotrophomonas maltophilia flagellin is involved in bacterial adhesion and biofilm formation

Stenotrophomonas maltophilia is an emerging drug-resistant pathogen and an important opportunistic pathogen. S. maltophilia flagellin was purified using serial ultracentrifugation. The purity of flagellin was checked by SDS-PAGE. The antibodies were raised in rabbits. The presence of anti-flagellin and the titer of flagellin were detected by immunoblotting and bacterial agglutination techniques. Two methods (viable bacterial count and spectrophotometric methods) were applied to evaluate bacterial adhesion and biofilm formation. Pretreatment of S. maltophilia with dilutions of anti-flagellin (from 1/40 to 1/640) reduced the ability of S. maltophilia to adhere and form biofilms on polystyrene (P < 0.05). In the present study, the inhibition of bacterial adhesion to polystyrene was dose-dependent. The positive correlation was observed between the antibody dilutions and bacterial adhesion (CFU/mL) (r > +0.5, P < 0.05), while, the negative correlation (r < ?0.5, P < 0.05) was observed between the percentage of adhesion inhibition and anti-flagellin dilutions. The current study proved the direct role of S. maltophilia flagellin in bacterial adhesion to and biofilm formation on polystyrene.     

Factors associated with the adherence and biofilm formation by Aeromonas caviae on glass surfaces

AIMS: Knowledge on factors of Aeromonas caviae promoting the formation of biofilms on surfaces. METHODS AND RESULTS: In nutrient broth under agitation, A. caviae LMG 13455 was able to form biofilms on the surfaces of glass flasks, but such biofilm formation was inconsistent. A derivative of this strain, called M12, promoted the rapid formation of reliable and strongly adherent biofilms with about half of the cells being adhered. In contrast with its parent, M12 was hydrophobic, displayed auto-aggregation in liquid medium, synthesized very little polysaccharides and was defective in swimming and swarming motilities, together with the appearance of a characteristic phenotype on motility soft agar. Further analyses demonstrated that most of these properties were related to a hyperpiliation of the cells through the presence of type IV pili, and suggested that a mechanism of genetic variation, by altering the nature of motility appendages, allows the variant bacteria to attach on inert surfaces. CONCLUSIONS: M12 is a stabilized variant of the parental strain, promoting strongly adherent biofilms through the type IV pili. SIGNIFICANCE AND IMPACT OF THE STUDY: The wild-type strain A. caviae LMG 13455 include subpopulations that are likely implicated in its adaptation to different environmental changes.     

Pulsed field gel electrophoresis and random amplified polymorphic DNA molecular characterization of Ralstonia pickettii isolates from patients with nosocomial central venous catheter related bacteremia

Over a period of 18 months 3 clusters of central venous catheter-related Ralstonia pickettii bacteremia occurred in 3 different units of the same hospital. In order to investigate the relatedness of the clinical isolates we studied 15 strains using pulsed-field gel electrophoresis (PFGE) and randomly amplified polymorphic DNA (RAPD) techniques. The combined analysis of the results obtained by these two methods led us to conclude that all the patients except one were infected by a single clone comprising two variants circulating in the units. Only one case was due to a different strain, probably originating outside the ward. PFGE and RAPD appear to be discriminatory techniques to study the clonal relationship among the isolates and can represent a good tool to perform the epidemiological investigation of an outbreak.     

miR-499 rs3746444 polymorphism is associated with cancer development among Asians and related to breast cancer susceptibility

To derive a more precise estimation of the relationship between miR-499 rs3746444 polymorphism (A>G) and cancer risk, a meta-analysis was performed. A total of 9 studies including 6,077 cases and 7,199 controls were involved in this meta-analysis. Overall, no significantly elevated cancer risk was associated with miR-499 G allele when all studies were pooled into the meta-analysis (AG vs. AA: OR?=?1.14, 95?% CI?=?0.98–1.32; GG vs. AA: OR?=?1.12, 95?% CI?=?0.95–1.33; dominant model: OR?=?1.13, 95?% CI?=?0.99–1.29; recessive model: OR?=?1.05, 95?% CI?=?0.83–1.33). In the subgroup analysis by ethnicity, significantly increased risk was only found for Asians (dominant model: OR?=?1.22, 95?% CI?=?1.02–1.46). When stratified by study design, no statistically significantly elevated risks were found in hospital-based studies or population-based studies. In the subgroup analysis by cancer type, significant cancer risk change was only found for breast cancer when miR-499 G allele was included (dominant model: OR?=?1.13, 95?% CI?=?1.01–1.26). In conclusion, this meta-analysis suggests that the miR-499 rs3746444 polymorphism (A>G) is a low-penetrant risk factor for cancer development among Asians and may contribute to breast cancer susceptibility.     

Competitive interaction of thymol with cviR inhibits quorum sensing and associated biofilm formation in Chromobacterium violaceum

International Microbiology - Biofilm formation associated with quorum sensing (QS) is a community behaviour displayed by many gram-negative pathogenic bacteria that provide survival advantages in...     

Urinary catheter indwelling clinical pathogen biofilm formation,exopolysaccharide characterization and their growth influencing parameters

Self-reproducing microbial biofilm community mainly involved in the contamination of indwelling medical devices including catheters play a vital role in nosocomial infections. The catheter-associated urinary tract infection (CA-UTI) causative Staphylococcus aureus, Enterobacter faecalis, and Pseudomonas aeruginosa were selectively isolated, their phenotypic as well as genotypic biofilm formation, production and monomeric sugar composition of EPS as well as sugar, salt, pH and temperature influence on their in vitro biofilm formation were determined. From 50 culture positive urinary catheters S. aureus (24%), P. aeruginosa (18%), E. faecalis (14%) and others (44%) were isolated. The performed assays revealed their varying biofilm forming ability. The isolated S. aureus ica, E. faecalis esp, and P. aeruginosa cup A gene sequencing and phylogenetic analysis showed their close branching and genetic relationship. The analyzed sugar, salt, pH, and temperature showed that the degree of CA-UTI isolates biofilm formation is an environmentally sensitive process. EPS monosaccharide HPLC analysis showed the presence of neutral sugars (ng/μl) as follows: glucose (P. aeruginosa: 44.275; E. faecalis: 4.23), lactose (P. aeruginosa: 7.29), mannitol (P. aeruginosa: 2.53; S. aureus: 2.62; E. faecalis: 2.054) and maltose (E. faecalis: 7.0042) revealing species-specific presence and variation. This study may have potential clinical relevance for the easy diagnosis and management of CA-UTI.     

GREM1 is associated with metastasis and predicts poor prognosis in ER-negative breast cancer patients

The exposure of phosphatidylserine (PS) on the outer plasma membrane has long been considered a unique feature of apoptotic cells. Together with other “eat me” signals, it enables the recognition and phagocytosis of dying cells (efferocytosis), helping to explain the immunologically-silent nature of apoptosis. Recently, however, PS exposure has also been reported in non-apoptotic forms of regulated inflammatory cell death, such as necroptosis, challenging previous dogma. In this review, we outline the evidence for PS exposure in non-apoptotic cells and extracellular vesicles (EVs), and discuss possible mechanisms based on our knowledge of apoptotic-PS exposure. In addition, we examine the outcomes of non-apoptotic PS exposure, including the reversibility of cell death, efferocytosis, and consequent inflammation. By examining PS biology, we challenge the established approach of distinguishing apoptosis from other cell death pathways by AnnexinV staining of PS externalization. Finally, we re-evaluate how PS exposure is thought to define apoptosis as an immunologically silent process distinct from other non-apoptotic and inflammatory cell death pathways. Ultimately, we suggest that a complete understanding of how regulated cell death processes affect the immune system is far from being fully elucidated.     

Bacteremic meningitis is associated with inferior outcome in comparison to community acquired meningitis without bacteremia

Meningitis associated with bacteremia is rare. Bacteremic form of meningitis occurred in 28 of 201 cases of community acquired meningitis (14%) in Slovakia within last 17 years. Bacteremic meningitis was associated with diabetes (21.4% vs. 7.5%, p=0.02) and with higher treatment failures (32.1% vs. 9.5%, p=0.01) and higher mortality (25% vs. 12.4%, NS). In univariate analysis comparing 28 cases of bacteremic community acquired bacterial meningitis (BCBM) to all CBM, no significant risk factor concerning underlying disease (cancer, ENT infection, alcohol abuses, trauma, splenectomy, etc.) or etiology was observed apart of diabetes mellitus, which was more common among bacteremic meningitis (21.4% vs. 7.5%, p=0.02). Mortality (25% vs. 12.4%, NS) insignificantly but therapy failure (32.1% vs. 9.5%, p=0.01) was significantly more frequently observed among meningitis with bacteremia. N. meningitis was the commonest causative agent (8 of 28 cases) followed by Str. pneumoniae (6), gram-negative bacteria (6), S. aureus (4) and H. influenzae (2).     

Catheter related bacteremia in rats: A preliminary report on the effect of methylene blue coated catheter

The safety and efficacy of methylene blue (MB) coated indwelling jugular vein/cranial vena cava catheter made up of polyurethane material was tested in a rat model, receiving bacterial culture suspension of Pseudomonas aeruginosa, and Staphylococcus aureus. Daily blood samples were collected from the catheter and peripheral vein for bacterial culture. The clinical parameters (rectal temperature, respiratory rate, total white blood cell count, and loss in body weight) were not different between the groups. All the rats became bacteremic with similar changes in the number of colony forming units in the catheter and peripheral samples. Histopathological lesions were not different between the groups. The findings suggest that rats receiving MB coated catheters behaved similar to non-coated catheters. Based on the results it can be concluded that for this type of gross contamination, catheter coating alone may not eliminate infection/bacteremia.     

Smectite promotes probiotic biofilm formation in the gut for cancer immunotherapy

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Metabolic endotoxaemia related inflammation is associated with hypogonadism in overweight men

Background

Obesity is associated with both impaired testosterone production and a chronic state of low grade inflammation. Previously it was believed that this inflammation was mediated by a decline in the immunosuppressive action of testosterone. However, more recently an alternative hypothesis (GELDING theory) has suggested that inflammation originating from the passage of intestinal bacteria into the circulation (metabolic endotoxaemia) may actually be the cause of impaired testicular function in obese men. The aim of this study is to investigate if metabolic endotoxaemia, as quantified by serum Lipopolysaccharide Binding Protein (LBP), is associated with impaired testicular endocrine function.

Methods

A total of 50 men aged between 21 and 50 years (mean 35.1?±?6.8 years) were assessed for adiposity (BMI, waist circumference and % body fat using bio-impedance), inflammatory status (serum CRP, IL-1β, IL-6, TNFα and LBP) and testicular endocrine function (serum testosterone, estradiol, AMH, LH and FSH). Statistical analysis was performed using Pearson correlation analysis, with log transformation of data where appropriate, and multi-variate regression.

Results

Overall increasing adiposity (% body fat) was positively associated with metabolic endotoxaemia (LBP, r?=?0.366, p?=?0.009) and inflammation (CRP r?=?0.531, p?<?0.001; IL-6 r?=?0.463, p?=?0.001), while also being negatively correlated with serum testosterone (r?=??0.403, p?=?0.004). Serum testosterone levels were significantly negatively correlated with inflammation (CRP r?=??0.471, p?=?0.001; IL-6 r?=??0.516, p?<?0.001) and endotoxaemia (LBP) after adjusting for serum LH levels (p?=??0.317, p?=?0.03). Furthermore, serum IL-6 was negatively associated with AMH levels (r?=??0.324, p?=?0.023), with a negative trend between LBP and AMH also approaching significance (r?=??0.267, p?=?0.064).

Conclusions

Obesity and its associated metabolic endotoxaemia helps initiate a pro-inflammatory state characterised by raised serum IL-6 levels, which in turn is correlated with impairment of both Leydig (testosterone) and Sertoli cell function (AMH). These results open up the potential for new treatments of obesity related male hypogonadism that focus on preventing the endotoxaemia associated chronic inflammatory state.

     

Bacillus subtilis alpha-phosphoglucomutase is required for normal cell morphology and biofilm formation

Mutations designated gtaC and gtaE that affect alpha-phosphoglucomutase activity required for interconversion of glucose 6-phosphate and alpha-glucose 1-phosphate were mapped to the Bacillus subtilis pgcA (yhxB) gene. Backcrossing of the two mutations into the 168 reference strain was accompanied by impaired alpha-phosphoglucomutase activity in the soluble cell extract fraction, altered colony and cell morphology, and resistance to phages phi29 and rho11. Altered cell morphology, reversible by additional magnesium ions, may be correlated with a deficiency in the membrane glycolipid. The deficiency in biofilm formation in gtaC and gtaE mutants may be attributed to an inability to synthesize UDP-glucose, an important intermediate in a number of cell envelope biosynthetic processes.