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Synthesis, Characterization and Antibacterial Activity against Gram Positive and Gram Negative Bacteria of Biomimetically Coated Silver Nanoparticles

In the present work, we describe a simple procedure to produce biomimetically coated silver nanoparticles (Ag NPs), based on the postfunctionalization and purification of colloidal silver stabilized by citrate. Two biological capping agents have been used (cysteine Cys and glutathione GSH). The composition of the capped colloids has been ascertained by different techniques and antibacterial tests on GSH-capped Ag NPs have been conducted under physiological conditions, obtaining values of Minimum Inhibitory Concentration (MIC) of 180 and 15 μg/mL for Staphylococcus aureus and Escherichia coli, respectively. The antibacterial activity of these GSH capped NPs can be ascribed to the direct action of metallic silver NPs, rather than to the bulk release of Ag(+).

Assessment of airborne microorganism contamination in an industrial area characterized by an open composting facility and a wastewater treatment plant

In order to assess the potential exposure hazard to workers and people living in the immediate surroundings of an area characterized by an open composting facility and a wastewater treatment plant, a quantitative and a qualitative analysis of airborne microorganisms were carried out. Air sampling was performed once a week for four consecutive weeks in summer and winter. Six sites were selected as air sampling sites: one was upwind at approximately 40 m from the facilities; the other five were downwind at increasing distances from the facilities, with the furthest at 100 m away. Monitoring permitted us to verify the influence that the composting activities and wastewater treatment had on the bacterial and fungal contamination of the air. The results obtained have been expressed by means of contamination indexes that have already been used in previous works: a major microbiological contamination near the plants was evidenced. Near the facilities, mesophilic bacteria, psychrophilic bacteria and microfungi showed the highest median concentrations, respectively, of 307.5, 327.5 and 257.5 CFU/m(3). Moreover, the season generally influenced the concentration of the bacteria as well as of the fungi; higher in summer than in winter. The contamination index global index of microbial contamination (GIMC/m(3)) showed mean values of 4058.9 in summer and 439.7 in winter and the contamination index-amplification index (AI) showed values of 4.5 and 1.1 in the same seasons, respectively. Controlling the seasonal effect, mesophilic bacteria, Pseudomonas spp. and Enterobacteriaceae showed a significant decline in concentration with respect to upwind air samples and with increasing distance. Both GIMC and AI showed a significant decline with respect to upwind air samples by increasing the distance from facilities after adjusting for the seasonal effect. In conclusion, even if these plants do not represent a potential risk for nearby populations, they may pose a potential health risk for workers.

Thermally sensitive gels based on chitosan derivatives for the treatment of oral mucositis

The aim of the present work was the development of a thermally sensitive mucoadhesive gel based on chitosan derivatives for the treatment of oral mucositis. Trimethyl chitosan (TMC) and methylpyrrolidinone chitosan (MPC) were considered. They were mixed with glycerophosphate (GP) according to different polymer/GP molar ratios and characterized for gelation properties by means of rheological analysis in comparison with chitosan. The influence of molecular weight and substitution degree (SD) of TMC on gelation temperature and time was investigated. The mucoadhesive properties of the mixtures were also assessed using porcine buccal mucosa. The best properties were shown by TMC with high MW and low SD mixed with GP according to 1:2molar ratio. Such mixture was loaded with benzydamine hydrochloride, an anti-inflammatory drug with antimicrobial properties and subjected to in vitro drug release and wash away test. The formulation based on TMC/GP mixture was able to prolong drug release and to withstand the removal physiological mechanisms. The antimicrobial properties of both vehicle and formulation were investigated. Also in absence of drug, TMC/GP mixture was characterized by antimicrobial properties.

Determination of aerial microbiological contamination in scholastic sports environments

Aims: To assess the microbiological indoor air quality (IAQ) of high school and college gyms during physical training lessons and to evaluate the effective microbiological exposure of students.

Isolation of an antibacterial component from roasted coffee

A coffee beverage obtained from instant dark coffee that had been previously shown to possess high antibacterial activity, was acidified (pH 2) and extracted with ethyl acetate. After alkalinization (pH 12) the aqueous phase was re-extracted with the organic solvent. The acidic and basic extracts were evaporated to dryness and the aqueous phase freeze-dried. Residues were dissolved in sterile water and assayed for antibacterial activity against two reference bacteria (Staphylococcus aureus ATCC 25923 and Streptococcus mutans 9102). The acidic extract was found to be highly active and was separated by gel permeation chromatography (GPC) into five fractions. Fractions GPC4 and GPC5 were found to possess antibacterial activity: most of the activity was evident in fraction GPC5. These fractions were separated by RP-HPLC using a gradient elution with methanol water as mobile phase. Both GPC fractions gave an active subfraction with methanol-water (70:30, v/v). The experimental conditions used to separate the antibacterial compound that originates during the roasting process, indicate that it possesses low molecular mass (probably no more than 200 Da), weak acidic properties and an lambda(max) at 205 nm. The very small amount of this compound isolated from roasted coffee, indicates that it may be a very strong antibacterial agent.

Micro‐organisms and dust exposure in an Italian grain mill

Aims:  In order to assess possible occupational risk for workers in a grain mill, we evaluated aerial microbiological contamination in different areas of the mill and at different points of the production line. We also measured the concentration of aerodispersed dust particles.

Pyrogenic activity of air to characterize bioaerosol exposure in public buildings: a pilot study

Aims:  The aim of our study was to investigate indoor air quality (IAQ) by comparing pyrogen concentration and microbiological contamination in offices in public buildings.

Validation of use of a traditional remedy from Bridelia grandis (Pierre ex Hutch) stem bark against oral Streptococci

AIM OF THE STUDY Bridelia grandis (Pierre ex Hutch) (Euphorbiaceae) is a medicinal plant traditionally used in Cameroon by pygmies Baka as a remedy for oral cavity affection. Bioassay-guided stem bark extracts were investigated for their in vitro antimicrobial properties as well as their phytochemical constituents. MATERIALS AND METHODS The first extraction was carried out according to the traditional use. Further extractions were carried out with solvents of different polarity such as methanol (MeOH), ethyl acetate (EtOAc) and mixtures of MeOH-H2O. The antimicrobial activity of the extracts against oral Streptococci was evaluated on the basis of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) by the macrodilution method; the bacterial surface hydrophobicity was also evaluated. RESULTS Water, methanol and mixtures methanol-water extracts, exhibited antibacterial activity with MIC between 0.5 and 2mg/ml justifying the traditional use of Bridelia grandis stem bark for oral cavity affection. Preliminary phytochemical analysis was performed on the most active extract (methanol) using appropriate tests and well established analytical screening methods, such as TLC and RP-HPLC/DAD. CONCLUSIONS The data obtained indicate that tannins constitute the chemical family responsible for the biological activity.

Comparison of functional and biological properties of chitosan and hyaluronic acid, to be used for the treatment of mucositis in cancer patients

Functional and bioactive properties of a selection of chitosan and hyaluronic acid grades were compared to enable a rational choice of the best candidate for the future development of mucoadhesive systems intended for the treatment of buccal or vaginal mucositis. Chitosan or hyaluronic acid molecular weight, type of salt and the pH of the administration site were considered as critical variables for functional and bioactive polymer properties. Two grades of chitosan, salified with ascorbic acid or hydrochloric acid, and two grades of sodium hyaluronate were examined. Aqueous solutions (1 % w/w) of each polymer grade or salt were prepared and compared for viscosity, mucoadhesive (tensile stress measurements), antimicrobial, antioxidant and tissue repairing properties. The overall comparison of the results indicates that the high molecular weight of chitosan ascorbate is the more promising candidate for the development of mucoadhesive formulations, characterized by bioactive properties.

Evaluation of microbiological air quality and of microclimate in university classrooms.

The proliferation of air-diffused microorganisms inside public buildings such as schools, hospitals, and universities, is often indicated as a possible health risk. In this research, we have illustrated the results of an investigation realized to determine the health of the air in some university classrooms, both from a microbiological and a microclimatic viewpoint, during the normal didactic activity of direct lessons. The results obtained have been expressed by means of contamination indices, already used in previous works. Very little contamination was recorded in the different phases of air treatment, which underlines the efficiency of the system and of the maintenance protocols. The Global Index of Microbial Contamination (GIMC per cubic meter) showed a value greater than the mean during the heating period (290), while the highest values (95th percentile 1,138.45) were recorded in the period using air conditioning. The index of mesophilic bacterial contamination, though it did not show any significant differences in the various modes of air treatment, showed a mean value (1.34) and the 95th percentile value (4.14), which was greater in the air-conditioning phase. Finally, the mean value of the amplification index underlined a decrease in the microbial contamination in comparison to the outside, while showing situations of increased microbial amplification during the period of simple ventilation (95th percentile 4.27). The 95th percentile values found for GICM in the three sampling periods, however, permitted us to identify the value of GIMC per cubic meter equal to 1,000 as a guide to provide a means of self-monitoring the quality of the air inside the classrooms. From a microclimatic viewpoint, two periods of the year manifested discomfort situations: during the heating phase (winter) and during the simple ventilation phase (spring). The results obtained indicate, therefore, a need to intervene on the environmental parameters, not being able, in this particular case, to intervene on other aspects that influence the microclimate.