Repression of Staphylococcus aureus and Escherichia coli by Lactiplantibacillus plantarum Strain AG10 in Drosophila melanogaster In Vivo Model.

Probiotic bacteria exhibiting antagonistic activities against pathogenic bacteria are widely considered as potential options for the prevention and treatment of various infectious diseases and represent potential substitutes of antibiotics. Here we show that the L. plantarum AG10 strain represses the growth of Staphylococcus aureus and Escherichia coli in vitro and diminishes their negative effects in vivo in a Drosophila melanogaster model of survival on embryonic (larvae) and pupa stages. In an agar drop diffusion test, L. plantarum AG10 exhibited antagonistic properties against Escherichia coli, Staphylococcus aureus, Serratia marcescens and Pseudomonas aeruginosa, and repressed the growth of E. coli and S. aureus during milk fermentation. In a Drosophila melanogaster model, L. plantarum AG10 alone did not provide any significant effect, either during the embryonic stage or during further development of the flies. Despite this, it was able to restore the viability of groups infected with either E. coli and S. aureus, almost to the level of non-treated control at all stages of development (larvae, pupa and adult). Moreover, in the presence of L. plantarum AG10, pathogens-induced mutation rates and recombination events reduced 1.5-2-fold. The genome of L. plantarum AG10 was sequenced and deposited at NCBI under the accession number PRJNA953814 and consists of annotated genome and raw sequence data. It consists of 109 contigs and is 3,479,919 bp in length with a GC content of 44.5%. The analysis of the genome has revealed considerably few putative virulence factors and three genes responsible for the biosynthesis of putative antimicrobial peptides, with one of them exhibiting a high probability of antimicrobial properties. Taken together, these data allow the suggestion that the L. plantarum AG10 strain is promising for use in both dairy production and probiotics as a preservative from foodborne infections.

Consideration of childhood psychological factors at dental appointment.

OBJECTIVE: Introduction: Paediatric dentistry is a special field of dental practice. The scope of professional activities within this field covers not only high level of expertise and technical skills tailored to the needs of young patients, but requires searching and creating positive psychological environment and communicative management of each child in order to improve daily service methods. The aim of this study is to identify and describe the main psychological characteristics of the age developmental periods of child's personality that dental professionals should regard dealing with the paediatric patients. PATIENTS AND METHODS: Materials and methods: The study involved 124 paediatric participants aged 2,5 - 15 years, who were referred to get specialized dental care at the Department of Paediatric Dentistry at the Municipal Paediatric Dentistry Hospital, Poltava. We have collected and identified behavioural patterns of children of all age groups during their contacts with dentists at the dental offices as well as studied the characteristics of childhood psyche age periods through the available literature. The data obtained were thoroughly As a result of the analysis of the obtained data, the principles for managing paediatric patients' behaviour at the dental office have been elaborated and introduced into the practice. RESULTS: Results: Outer evaluation of the children's activities performed is perceived by children as an assessment of personality, so any negative doctor's remark can provoke anxiety, irritability, and discomfort, apathy. Therefore, the paediatric specialists should remain attentive to physical and emotional indicators of stress when dealing with young patients. CONCLUSION: Conclusions: Hence, among the key tasks of a paediatric dentist is to create the friendliest and most comfortable conditions for small patients, where they have the opportunity to play toys and receive little gifts for patience and courage.

Nutrient media optimization for simultaneous enhancement of the laccase and peroxidases production by coculture of Dichomitus squalens and Ceriporiopsis subvermispora.

Coculturing of two white-rot fungi, Dichomitus squalens and Ceriporiopsis subvermispora, was explored for the optimization of cultivation media for simultaneous augmentation of laccase and peroxidase activities by response surface methodology (RSM). Nutrient parameters chosen from our previous studies with the monocultures of D. squalens and C. subvermispora were used to design the experiments for the cocultivation study. Glucose, arabinose, sodium nitrate, casein, copper sulfate (CuSO4 ), and manganese sulfate (MnSO4 ) were combined according to central composite design and used as the incubation medium for the cocultivation. The interaction of glucose and sodium nitrate resulted in laccase and peroxidase activities of approximately 800 U/g protein. The addition of either glucose or sodium nitrate to the medium also modifies the impact of other nutrients on the ligninolytic activity. Both enzyme activities were cross-regulated by arabinose, casein, CuSO4 , and MnSO4 as a function of concentrations. Based on RSM, the optimum nutrient levels are 1% glucose, 0.1% arabinose, 20 mM sodium nitrate, 0.27% casein, 0.31 mM CuSO4 , and 0.07 mM MnSO4 . Cocultivation resulted in the production of laccase of 1,378 U/g protein and peroxidase of 1,372 U/g protein. Lignin (16.9%) in wheat straw was degraded by the optimized enzyme mixture.

Impact of silver-containing wound dressings on bacterial biofilm viability and susceptibility to antibiotics during prolonged treatment.

The long-term antimicrobial efficacy of silver dressings against bacterial biofilms was investigated in a 7-day treatment in vitro model where the protein-rich medium was refreshed daily in order to mimic the conditions found in a wound bed. The use of plate-to-plate transfer assays demonstrated measurable differences in the effectiveness of several silver dressings on the viability of biofilm bacteria and their susceptibility to antibiotics. Whereas after the first day of treatment, all dressings used resulted in a significant reduction in the number of viable cells in the biofilms and disruption of the biofilm colonies, during prolonged treatment, the efficacy of dressings with hydrophilic base materials diminished with daily transfers, and bacterial populations recovered. For dressings with hydrophobic base materials, the level of efficacy correlated with the silver species loaded. Biofilm bacteria, which survived the initial silver treatment, were susceptible to tobramycin, ciprofloxacin, and trimethoprim-sulfamethoxazole, in contrast to untreated biofilms, which were highly tolerant to the same antibiotics. This acquired susceptibility was unaffected by the longevity of pretreatment with the silver dressings but depended on the dressing used. The antimicrobial efficacy of the dressings correlated with the type of the dressing base material and silver species loaded.

Relation between the activity of anaerobic microbial populations in oil sands tailings ponds and the sedimentation of tailings.

Oil sands tailings ponds contain a variety of anaerobic microbes, including methanogens, sulfate- and nitrate-reducing bacteria. Methanogenic activity in samples from a tailings pond and its input streams was higher with trimethylamine (TMA) than with acetate. Methanogens closely affiliated to Methanomethylovorans hollandica were found in the TMA enrichments. Tailings sedimentation increased with methanogenic activity, irrespective whether TMA or acetate was used to stimulate methanogenesis. Increased sedimentation of autoclaved tailings was observed with added pure cultures under methanogenic, as well as under nitrate-reducing conditions, but not under sulfate-reducing conditions. Scanning electron microscopy and energy-dispersive X-ray spectroscopy indicated the presence of microbes and of extracellular polymeric substances in tailings particle aggregates, especially under methanogenic and nitrate-reducing conditions. Hence different classes of microorganisms growing in tailings ponds contribute to increased tailings aggregation and sedimentation. Because addition of nitrate is known to lower methane production by methanogenic consortia, these observations offer the potential to combine lower methane emissions with improved microbially-induced tailings sedimentation.

Staphylococcus aureus biofilm formation and tolerance to antibiotics in response to oscillatory shear stresses of physiological levels.

Bacterial infections in the blood system are usually associated with blood flow oscillation generated by some cardiovascular pathologies and insertion of indwelling devices. The influence of hydrodynamically induced shear stress fluctuations on the Staphylococcus aureus biofilm morphology and tolerance to antibiotics was investigated. Fluctuating shear stresses of physiologically relevant levels were generated in wells of a six-well microdish agitated by an orbital shaker. Numerical simulations were performed to determine the spatial distribution and local fluctuation levels of the shear stress field on the well bottom. It is found that the local biofilm deposition and morphology correlate strongly with shear stress fluctuations and maximum magnitude levels. Tolerance to killing by antibiotics correlates with morphotype and is generally higher in high shear regions.

Increased tolerance of Staphylococcus aureus to vancomycin in viscous media.

The increased viscosity observed in biofilms, adherent communities of bacterial cells embedded in a polymeric matrix, was hypothesized to induce increased tolerance of bacteria to antibiotics. To test this concept, planktonic Staphylococcus aureus cells were grown and exposed to vancomycin in media brought to specific viscosities in order to mimic the biofilm extracellular polymeric matrix. A viscous environment was observed to decrease the vancomycin susceptibility of planktonic S. aureus to levels seen for biofilms. Both planktonic S. aureus at a viscosity of 100 mPa s and staphylococcal biofilms were able to survive at >500 times the levels of the antibiotic effective against planktonic populations in standard medium. Time-dependent and dose-dependent viability curves revealed that more than one mechanism was involved in high S. aureus tolerance to vancomycin in viscous media. Increased viscosity affects antibiotic susceptibility by reducing diffusion and the mass transfer rate; this mechanism alone, however, cannot explain the increased tolerance demonstrated by S. aureus in viscous media, suggesting that viscosity may also alter the phenotype of the planktonic bacteria to one more resistant to antimicrobials, as seen in biofilms. However, these latter changes are not yet understood and will require further study.