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Gold nanoparticles (NP) were synthesized inside ordered mesoporous TiO2thin films (MTTF) by stepwise reduction of AuCl4–with NaBH4. This leads to an optical material (Au@TiO2) of interest for plasmonic applications. The films (pure titania or gold-titania nanocomposites) were thoroughly characterized by UV–visible and ellipsometry spectroscopies. The dielectric function of the MTTF, considered as the dielectric environment in which the NP are embedded, was acquired by ellipsometry and rationalized by the asymmetric Bruggeman model as an effective medium formed by the mixture of dense TiO2and air. Nanocomposite Au@TiO2systems present an isotropic dispersion of Au NP in the 5–8 nm range. The UV–visible spectra obtained with a low nanoparticle filling fraction of the pore volume (fNP< 2%) are accurately reproduced by both Maxwell–Garnett (MG) and Mie theories. Accurate and coincident values of fNPand NP size are obtained by this method. The dielectric function of Au NP used in this work was studied in detail; in particular, the interface damping parameter related to the NP/MTTF interface was determined by comparison with TEM microscopy. The potential of the ellipsometry technique to determine the material plasmonic response, and its correspondence with the UV–visible spectra, are discussed. This spectroscopy technique opens the possibility to study the plasmon response of the material to changes in the environment due to the presence of vapors, and other in situ experiments, as well as to provide nanostructural information of metallic nanoparticles (NP size, interparticle distance, number of NP) with well-defined spatial localization in a multilayered system.

In 2004, an outbreak of legionnaires disease occurred in a hospital in northern Italy with a water system that had been disinfected multiple times since 1990 and equipped with a continuous disinfecting system. Molecular typing linked the outbreak to contamination of the hospital water system and demonstrated the persistence of a predominant strain of Legionella pneumophilafor 15 years.

Between August and October 2003, 15 cases of Legionnaires' disease were detected in the 9th district of Rome. To identify possible sources of Legionella exposure, a matched case-control study was conducted and environmental samples were collected. Hospital discharge records were also retrospectively analysed for the period July–November 2003, and results were compared with the same period during the previous 3 years. The case-control study revealed a significantly increased risk of disease among those frequenting a specific department store in the district (OR 9·8, 95% CI 2·1–46·0), and Legionella pneumophila was isolated from the store's cooling tower. Genotypic and phenotypic analysis of human and environmental isolates demonstrated that the cluster was caused by a single strain of L. pneumophila serogroup 1, and that the cooling tower of the store was the source of infection. The increased number of hospital admissions for microbiologically undiagnosed pneumonia during the study period may indicate that some legionellosis cases were not identified.

The bacterial growth and the production of tumor necrosis factor alpha (TNF-alpha) and TNF receptors (TNF-Rs) in the spleen and blood of BALB/c mice challenged with Mycobacterium avium complex (MAC) were monitored. Infection developed in two phases: the first, up to day 21, was associated with rapid MAC multiplication in the spleen and a drop in the mycobacteremia, and the second was associated with control of the infection in both compartments. In the spleen, TNF-alpha and TNF-RII mRNA levels peaked on day 21 and then slowly decreased; however, no increase in the level of TNF-RI mRNA was observed throughout these experiments. The level of circulating soluble TNF-RII (sTNF-RII) was transiently increased after day 21. In a model in which overproduction of bioactive TNF-alpha was triggered in response to a second infection with MAC, an increased production of sTNF-RII by cultured splenocytes was also observed. Administration of an antagonist anti-TNF-RII monoclonal antibody (MAb 6G1) to infected mice inhibited the bacterial growth in the spleen, suggesting that the TNF-RII and/or sTNF-RII was functionally involved in the mechanisms that control the infection. Overall, these observations suggest that upregulation of TNF-RII or sTNF-RII contributes to modulation of the TNF-alpha antibacterial activity in MAC infections.

MICs of clarithromycin, amikacin, isoniazid, rifabutin, ciprofloxacin, sparfloxacin, ethambutol, and clofazimine were determined for six isolates of Mycobacterium avium complex (MAC) from AIDS patients both by the radiometric method and by an ex vivo model of infection in human macrophages. The median MICs in macrophages were similar or slightly lower than values found in broth, except for amikacin, which had slightly higher MICs inside the cells. Combinations of clarithromycin with other antimicrobial agents showed that clarithromycin-clofazimine and clarithromycin-rifabutin were synergistic on five of six strains while clarithromycin-amikacin and clarithromycin-isoniazid were antagonistic on one and two strains, respectively. The addition of amikacin made the combinations of clarithromycin-clofazimine and clarithromycin-ethambutol synergistic against all the MAC strains. In the macrophage model, the combination of clarithromycin-clofazimine (mean survival, 21%) and clarithromycin-rifabutin (mean survival, 29%) showed a strong reduction in viable counts compared with single drugs, while clarithromycin-amikacin was less active than single drugs alone. In general, the addition of amikacin did not improve the activity of the combinations, except for clarithromycin-isoniazid-amikacin (mean survival, 19%), which was significantly more active than either clarithromycin-isoniazid or clarithromycin-amikacin. The use of the macrophage model can suggest new combinations of antimicrobial agents with anti-MAC activity which, on the basis of their in vitro effectiveness, would probably be disregarded for assay in animal models.

We examine quasiperiodic multilayers arranged in m-bonacci sequences, which combine ordinary positive-index materials and dispersive metamaterials with negative index in a certain frequency range. When the volume-averaged refractive index of the nonperiodic multilayer equals zero, the structure does not propagate light radiation and exhibits a forbidden band. We identify some analytical expressions to determine the upper and lower limits of the above zero-average refractive-index bandgap. We recognize that these limits are not explicitly dependent on the geometrical parameters of the stack of layers.

ABSTRACTIn the summer of 2003 a community-acquired outbreak of Legionella pneumophilaoccurred in Rome, Italy. Three molecular typing methods, pulse-field gel electrophoresis, amplified fragment length polymorphism analysis, and sequence-based typing (SBT), were used to establish the clonal correlation among the isolates of the epidemic cluster. By comparison of the methods, SBT was the most rapid and the easiest to perform and provided unambiguous results.

Mutations of rpoB associated with rifampin resistance were studied in 37 multidrug-resistant (MDR) clinical strains of Mycobacterium tuberculosis isolated in Italy. At least one mutated codon was found in each MDR strain. It was always a single-base substitution leading to an amino acid change. Nine different rpoB alleles, three of which had not been reported before, were found. The relative frequencies of specific mutations in this sample were different from those previously reported from different geographical areas, since 22 strains (59.5%) carried the mutated codon TTG in position 531 (Ser-->Leu) and 11 (29.7%) had GAC in position 526 (His-->Asp).

ABSTRACTMutations of rpoBassociated with rifampin resistance were studied in 37 multidrug-resistant (MDR) clinical strains ofMycobacterium tuberculosisisolated in Italy. At least one mutated codon was found in each MDR strain. It was always a single-base substitution leading to an amino acid change. Nine differentrpoBalleles, three of which had not been reported before, were found. The relative frequencies of specific mutations in this sample were different from those previously reported from different geographical areas, since 22 strains (59.5%) carried the mutated codon TTG in position 531 (Ser?Leu) and 11 (29.7%) had GAC in position 526 (His?Asp).