Indeed, in water from coolers Escherichia coli and Enterococcus spp. were absent [10, 12] and Pseudomonas aeruginosa has been detected in 24.1% of the water samples [10]. Furthermore, in contrast in a survey conducted in Canada on the microbiological GDC-0068 quality of water from coolers located in residences and workplaces with respectively 28% and 36% of the collected samples contaminated by at least one coliform or indicator bacterium and/or one pathogenic bacterium [9]. In addition, we were interested to determine whether the tap water used was responsible for the

contamination CP673451 in vitro of the water dispensed by coolers. None of the tap water samples had a bacterial count higher than the water coolers and none of the samples were contaminated with coliforms. Thus, tap water was not directly responsible of water coolers contamination. These findings suggest that the contamination may be caused by the accumulation of small quantity of microorganisms from tap water or from Captisol faucet surface which are concentrated at filters. It was interesting to find out that the results of the statistical analysis indicated that strongly and highly significant differences in quality and quantity of the microbiological parameters between the water coolers samples

and the tap water samples. Indeed, the aerobic plate counts were higher in the coolers compared with the tap water and Pseudomonas aeruginosa was more frequently detected in the non-carbonated and carbonated water coolers samples than in those of tap water. These findings are in accordance with the two already mentioned studies, since the aerobic plate counts was higher in coolers compared with spring water [10] and a significantly higher proportion of water cooler samples resulted contaminated than tap water [9]. Therefore, a periodic adequate disinfection of water dispensers had to be indicated in order to keep the level of microbiological contamination under control. The validity of this recommendation is supported by the results of a study Amisulpride that showed

that the periodic application of hydrogen peroxide (3%) of microfiltered water dispensers led to a reduction in the concentrations of Pseudomonas aeruginosa and to obtain water with bacteria counts conforming to Italian regulations for drinking water [12]. Furthermore, the data from this study demonstrated that no significant differences in bacterial counts occur between the non-carbonated and carbonated water in relation with the time since the last filter was substituted. Conclusion The data presented here raise concern about the microbiological quality of the drinking water plumbed in water coolers and highlights the importance of adopting appropriate monitoring system with changing filters according to their use and the disinfection of the water in order to prevent or to diminish the chances of contamination of this water source.