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Aims: To investigate the potent control of microbial surface contamination of an innovative process which consists in incorporating metal oxide microspheres homogeneously into materials., Methods and Results: Spherical microspheres containing zinc and magnesium oxides synthesized via a one-step manufacturing process (Pyrolyse Pulvérisée ® ) and incorporated into different plastic matrices were evaluated for their antimicrobial activity according to JIS Z 2801 standard. A significant activity was observed for microsphere-added polyethylene coupons with a reduction of all tested bacteria populations, including Gram negative and Gram positive even expressing acquired antibiotic resistance (Escherichia coli ESBL, Staphylococcus aureus metiR). An antiviral activity higher than 2 log of reduction was also observed on H1N1 and HSV-1 viruses. This antimicrobial effect was dose-dependent and time-dependent for both polyethylene and polypropylene matrices. Antimicrobial activity was maintained after exposition to disinfectants and totally preserved 50 months after the preparation of the coupons., Conclusions: Incorporated into plastic matrices, metal oxide microspheres showed significant antibacterial and antiviral activities., Significance and Impact of Study: This is, to our knowledge, the first report on an original process incorporating metal oxide microspheres, which have specific physico-chemical and antimicrobial properties, into materials that could be used for surface contamination prevention., (© 2018 The Society for Applied Microbiology.)

New agents that are effective against common pathogens are needed particularly for those resistant to conventional antimicrobial agents. Essential oils (EOs) are known for their antimicrobial activity. Using the broth microdilution method, we showed that (1) two unique blends of Cinnamomum zeylanicum, Daucus carota, Eucalyptus globulus and Rosmarinus officinalis EOs (AB1 and AB2; cinnamon EOs from two different suppliers) were active against the fourteen Gram-positive and -negative bacteria strains tested, including some antibiotic-resistant strains. Minimal inhibitory concentrations (MICs) ranged from 0.01% to 3% v/v with minimal bactericidal concentrations from <0.01% to 6.00% v/v; (2) a blend of Cinnamomum zeylanicum, Daucus carota, Syzygium aromaticum, Origanum vulgare EOs was antifungal to the six Candida strains tested, with MICs ranging from 0.01% to 0.05% v/v with minimal fungicidal concentrations from 0.02% to 0.05% v/v. Blend AB1 was also effective against H1N1 and HSV1 viruses. With this dual activity, against H1N1 and against S. aureus and S. pneumoniae notably, AB1 may be interesting to treat influenza and postinfluenza bacterial pneumonia infections. These blends could be very useful in clinical practice to combat common infections including those caused by microorganisms resistant to antimicrobial drugs., (© 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.)

The effects of grazing pressure and inorganic nutrient availability on the direct carbon transfer from freshly produced phytoplankton exudates to heterotrophic bacteria biomass production were studied in Mediterranean coastal waters. The short-term incorporation of ¹³C (H¹³CO₃) in phytoplankton and bacterial lipid biomarkers was measured as well as the total bacterial carbon production (BP), viral lysis and the microbial community structure under three experimental conditions: (1) High inorganic Nutrient and High Grazing (HN + HG), (2) High inorganic Nutrient and Low Grazing (HN + LG) and (3) under natural in situ conditions with Low inorganic Nutrient and High Grazing (LN + HG) during spring. Under phytoplankton bloom conditions (HN + LG), the bacterial use of freshly produced phytoplankton exudates as a source of carbon, estimated from ¹³C enrichment of bacterial lipids, contributed more than half of the total bacterial production. However, under conditions of high grazing pressure on phytoplankton with or without the addition of inorganic nutrients (HN + HG and LN + HG), the ¹³C enrichment of bacterial lipids was low compared with the high total bacterial production. BP therefore seems to depend mainly on freshly produced phytoplankton exudates during the early phase of phytoplankton bloom period. However, BP seems mainly relying on recycled carbon from viral lysis and predators under high grazing pressure.

Biofilms formed in aerobic seawater on stainless steel are known to be efficient catalysts of the electrochemical reduction of oxygen. Based on their genomic analysis, seven bacterial isolates were selected and a cyclic voltammetry (CV) procedure was implemented to check their electrocatalytic activity towards oxygen reduction. All isolates exhibited close catalytic characteristics. Comparison between CVs recorded with glassy carbon and pyrolytic graphite electrodes showed that the catalytic effect was not correlated with the surface area covered by the cells. The low catalytic effect obtained with filtered isolates indicated the involvement of released redox compounds, which was confirmed by CVs performed with adsorbed iron-porphyrin. None of the isolates were able to form electro-active biofilms under constant polarization. The capacity to catalyze oxygen reduction is shown to be a widespread property among bacteria, but the property detected by CV does not necessarily confer the ability to achieve stable oxygen reduction under constant polarization., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Antiseptic activity of five mouthrinses containing 0.10%, 0.12% and 0.20% chlorhexidine, as well as aqueous chlorhexidine solutions at the same concentrations were determined under usual conditions (advocated dilutions by the manufacturers and short contact time) and according to French Pharmacopoeia recommendations. The three aqueous solutions and two mouthrinses containing 0.12% chlorhexidine were not antiseptic according to the fixed criteria. Bactericidal activities of the different dilutions of products were tested with an appropriate micromethod against nine-bacterial species involved in periodontal disease. Efficacity of mouthrinses were variable and were not agreed with the aqueous chlorhexidine-corresponding solutions: the mouthrinse containing 0.10% chlorhexidine reached 0.20% aqueous solution efficacy, and the mouthrinses containing 0.12% chlorhexidine were generally less active than the 0.12% aqueous chlorhexidine solution. Therefore, antibacterial activity of this type of product cannot be anticipated with the sole concentration factor, excipients playing essential part in the chlorhexidine activity.

Some monoterpenes and their carbonylated products were evaluated for their antibacterial and antifungal properties. The carbonylation of tested monoterpenes was shown to increase the bacteriostatic and fungistatic activities specifically by the contact method. Concerning the killing effects, only (1R,2S,5R)-isopulegol, its carbonylated products, and (R)-carvone showed significant bactericidal activities, particularly against Enterococcus faecium and Escherichia coli above a concentration of 10 microliters/ml. A fungicidal efficiency of (1R,2S,5R)-isopulegol and (R)-carvone against Aspergillus niger was also noted. It seems that the presence of an oxygenated function in the framework increases the antimicrobial properties. However, monoterpenes were more active using a micro-atmosphere method.

Bactericidal activities of five mouthrinses containing cetylpyridinium chloride, hexetidine or chlorhexidine have been tested in vitro, against the main microorganisms involved in buccal affections. Mouthrinses containing hexetidine or chlorhexidine are effective, but chlorhexidine activity appears more extensive and homogeneous.