Health  Vol.7 No.7 , July 2015
Evaluation of the Effectiveness of a 4-Months Continuous Injection of a Gas Mixture (CO2 and Inert Gases) on Legionella Contamination of a Hot Water Distribution System
ABSTRACT
Within the biofilm and scales Legionella is less far susceptible to the effects of the most frequently used biocides. The objective of this study was to evaluate the effect of a 4-months continuous injection of a gas mixture (CO2 and inert gas) in the hot water distribution system of a large hotel colonized by L. pneumophila sg3 on limiting biofilm formation and scales and in turn Legionella growth. Before the continuous injection of the gas mixture, out of the 15 sampling points examined every month 60% were colonized by Legionella (mean concentrations of 102 cfu/L in the boilers and the return loop, and 104 cfu/L in taps and showers). One week after the injection of the gas mixture and daily fluxing of the distal outlets, the level of colonization decreased (<103 cfu/L). When it was decided to flux all the distal outlets only 1 day per week the mean concentration of Legionella increased again (>104 cfu/L) in all the sampling points. Thus, cleaning of the boilers was performed and distal outlets were again fluxed daily. One week after the level of contamination decreased again (<102 cfu/L). Nonetheless, the colonization was not eliminated and when fluxing of the distal outlets was not performed every day the mean concentrations of Legionella raised up to >104 cfu/L. Results indicate that the gas mixture was able to reduce the level of colonization by Legionella only because associated to the fluxing of the distal outlets.

Cite this paper
Coniglio, M. (2015) Evaluation of the Effectiveness of a 4-Months Continuous Injection of a Gas Mixture (CO2 and Inert Gases) on Legionella Contamination of a Hot Water Distribution System. Health, 7, 819-823. doi: 10.4236/health.2015.77096.
References
[1]   ECDC (2011) Survellance Report. Legionnaires’ Disease in Europe, 2011.

[2]   World Tourism Organization. UNWTO. Tourism Highlights. 2013 Edition.
www.unwto.org

[3]   Taylor, M., Ross, K. and Bentham, R. (2009) Legionella, Protozoa, and Biofilms: Interactions within Complex Microbial Systems. Microbial Ecology, 58, 538-547.
http://dx.doi.org/10.1007/s00248-009-9514-z

[4]   Kandiah, S., Yassin. M.H. and Stout, J. (2013) Monochloramine Use for Prevention of Legionella in Hospital Water Systems. Infectious Disorders—Drug Targets, 13, 18-190.
http://dx.doi.org/10.2174/1871526511313030006

[5]   Coniglio, M.A., Melada, S. and Yassin, M.H. (2015) Mono-chloramine for Controlling Legionella in Biofilms: How Much We Know? Journal of Nature and Science, 1, e44.

[6]   Melada, S. and Coniglio, M.A. (2015) Monochloramine for Remediation of Legionella Only in Domestic Hot Water Systems: An Iron Fist in a Velvet Glove. Open Journal of Preventive Medicine, 5, 143-150.
http://dx.doi.org/10.4236/ojpm.2015.53017

[7]   Borella, P., Guerrieri, E., Marchesi, I., Bondi, M. and Messi, P. (2005) Water Ecology of Legionella and Protozoan: Environmental and Public Health Perspectives. Biotechnology Annual Review, 11, 355-380.
http://dx.doi.org/10.1016/S1387-2656(05)11011-4

[8]   Roeder, R.S., Lenz, J., Tarne, P., Gebel, J., Exner, M. and Szewzyk, U. (2010) Long-Term Effects of Disinfectants on the Community Composition of Drinking Water Biofilms. International Journal of Hygiene and Environmental Health, 213, 183-189.
http://dx.doi.org/10.1016/j.ijheh.2010.04.007

[9]   Pitt, W.G., Mcbride, M.O., Barton, A.J. and Sagers, R.D. (1993) Air-Water-Interface Displaces Adsorbed Bacteria. Biomaterials, 14, 605-608.
http://dx.doi.org/10.1016/0142-9612(93)90179-6

[10]   Parini, M.R. and Pitt, W.G. (2006) Dynamic Removal of Oral Biofilms by Bubbles. Colloids and Surfaces B, 52, 39-46.
http://dx.doi.org/10.1016/j.colsurfb.2006.06.005

[11]   International Standard Organization (1998) Water Quality Detection and Enumeration of Legionella. ISO 11731, Geneva.

[12]   International Standard Organization (2006) ISO 19458:2006 Water Quality-Sampling for Microbiological Analysis. International Organization for Standardization, Geneva.

 
 
Top