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Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a risk factor for patients in general population and particularly in immunocompromised patients. As a matter of fact, it can produce serious infections that may then evolve in septicaemia. However, transmission of MRSA from food to people can represent a serious problem only for immunocompromised people. Vancomycin is the elective antimicrobial commonly used in case of MRSA infection, but S. aureus strains with reduced sensibility to vancomycin are emerging worldwide. We isolated 42 strains of S. aureus from 176 samples of raw meat (poultry, pork and beef) during a one-year survey. Each strain was tested against twelve antimicrobial to verify antibiotic resistance. We found no evidence of methicillin-, teicoplanin-or vancomycin-resistance, but a lot of multiresistant microorganisms, i.e. resistant to three or more antibiotics. These results confirm the hypothesis that antibiotics resistance is present not only in nosocomial bacteria, but also in community environments microorganisms.

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Motivated by recent advances in the physical and chemical basis of the Hofmeister effect, we measured the rate cell growth of S. aureus--a halophilic pathogenic bacterium--and of P. aeruginosa, an opportunistic pathogen, in the presence of different aqueous salt solutions at different concentrations (0.2, 0.6 and 0.9 M). Microorganism growth rates depend strongly on the kind of anion in the growth medium. In the case of S. aureus, chloride provides a favorable growth medium, while both kosmotropes (water structure makers) and chaotropes (water structure breakers) reduce the microorganism growth. In the case of P. aeruginosa, all ions affect adversely the bacterial survival. In both cases, the trends parallel the specific ion, or Hofmeister, sequences observed in a wide range of physico-chemical systems. The correspondence with specific ion effect obtained in other studies, on the activities of a DNA restriction enzyme, of horseradish peroxidase, and of Lipase A (Aspergillus niger) is particularly striking. This work provides compelling evidence for Hofmeister effects, physical chemistry in action, in these organisms.

Silver−poly(acrylate) clusters have been synthesized in water by reduction of AgNO3 in the presence of poly(acrylates) of different molecular weights through two different methods, NaBH4 reduction and UV exposure. The structure of the clusters and the effect of the synthesis parameters on the size and polydispersity of the particles were evaluated by means of small-angle X-ray scattering (SAXS) and confirmed by UV−visible absorption and transmission electron microscopy (TEM). The results clearly show that the reduction method and the polymer chain length play key roles in the achievement of few-nanometer-sized nanoparticles. The effect of the pH was also investigated. The nanoparticle dispersions were then used to functionalize cotton, wool, and polyester samples in order to obtain antimicrobial textiles for biomedical applications. The antimicrobial activity of the as-treated samples has been tested against Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Candida albicans.

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