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e. leoni, g. de luca, p.p. legnani, r. sacchetti, s. stampi and f. zanetti. 2004.An evaluation was made of the prevalence ofLegionellaspecies in hot water distribution systems in the city of Bologna (Italy) and their possible association with bacterial contamination (total counts and Pseudomonadaceae) and the chemical characteristics of the water (pH, Ca, Mg, Fe, Mn, Cu, Zn and Total Organic Carbon, TOC).A total of 137 hot water samples were analysed: 59 from the same number of private apartments, 46 from 11 hotels and 32 from five hospitals, all using the same water supply.Legionellaspecies were detected in 40·0% of the distribution systems,L. pneumophilain 33·3%. The highest colonization was found in the hot water systems of hospitals (93·7% of samples positive forL. pneumophila, geometric mean: 2·4 × 103 CFU l−1), followed by the hotels (60·9%, geometric mean: 127·3 CFU l−1) and the apartments with centralized heating (41·9%, geometric mean: 30·5 CFU l−1). The apartments with independent heating systems showed a lower level of colonization (3·6% forLegionellaspecies), with no evidence ofL. pneumophila. Correlation analysis suggests that copper exerts an inhibiting action, while the TOC tends to favour the development ofL. pneumophila. No statistically significant association was seen with Pseudomonadaceae, which were found at lower water temperatures than legionellae and in individual distribution points rather than in the whole network.The water recirculation system used by centralized boilers enhances the spreading of legionellae throughout the whole network, both in terms of the number of colonized sites and in terms of CFU count.Differences inLegionellacolonization between types of buildings are not due to a variation in water supply but to other factors. Besides the importance of water recirculation, the study demonstrates the inhibiting action of copper and the favourable action of TOC on the development ofL. pneumophila. [ABSTRACT FROM AUTHOR]

Focuses on a study that evaluated the effect of microwave heating and gamma irradiation on microbiological quality of spices and herbs. Materials and methods; Results.