Legionella pneumophila is frequently found in hospital hot water mains. To prevent Legionella infection, numerous methods have been applied to eradicate Legionella pneumophila from the hospital water circuit, hyperchlorinization through the use of sodium hypochlorite, calcium hypochlorite and chlorine dioxide, overheating and flushing, copper and silver ionization, UV radiation and ozonization. Nevertheless, the above methods are not always effective, at times achieving only temporarily solving the problem. Installation of anti-bacterial filters at the points where water is used (taps and shower heads) offers some indisputable advantages: installation can be limited to the high risk areas; installation and maintenance are simple and inexpensive. Nevertheless, it is worth noting that most filters last a maximum of 15 days and this constitutes a significant drawback to their use. Recently, however, a filter to protect showerheads from passage of Legionella has been created with a porosity of 0.2 m (Pall – Aquasafe Shower Head Filter, AQL3). The filter membrane resists a maximum recommended water temperature of 60°C and has an operating lifespan of one month. The purpose of the present research was to evaluate whether installation of this filter in 8 showers found in different departments located in different areas of the S. Orsola Malpighi Hospital in Bologna, Italy could prevent the presence of this microorganism in the water over the period of one month. At the time of installation all showers showed the presence of Legionella contamination (102 – 104 cfu/l). Moreover, it is worth noting that, for the entire test period, no other water sanitation system was used. The samples were taken before installation of the filter and once a week thereafter for 4 weeks. After a month the filters were changed and additional samples were taken after 15 and 30 days. All colonies fell under serum group 3. After installation of the filter, no Legionella colonies were found in the water downstream of the filter nor was it possible to detect Legionella 15 and 30 days after the filters were replaced. For the quantities sampled and the dilutions used, the lower limit for Legionella detection was 50 cfu/l. The results lead one to conclude that, prior to installation of the filter, the number of Legionella bacteria present in the hot water mains was at limit levels. As in most countries, Italian Guidelines permit possible water contamination containing between 102-104 cfu/l of Legionella. Therefore it is clear that use of the filters made it possible to eliminate the potential risk of infection.
Effectiveness of installing an anti-bacterial filter at water taps to prevent legionella infections
SALVATORELLI, Germano;DE LORENZI, Sonia;
2005
Abstract
Legionella pneumophila is frequently found in hospital hot water mains. To prevent Legionella infection, numerous methods have been applied to eradicate Legionella pneumophila from the hospital water circuit, hyperchlorinization through the use of sodium hypochlorite, calcium hypochlorite and chlorine dioxide, overheating and flushing, copper and silver ionization, UV radiation and ozonization. Nevertheless, the above methods are not always effective, at times achieving only temporarily solving the problem. Installation of anti-bacterial filters at the points where water is used (taps and shower heads) offers some indisputable advantages: installation can be limited to the high risk areas; installation and maintenance are simple and inexpensive. Nevertheless, it is worth noting that most filters last a maximum of 15 days and this constitutes a significant drawback to their use. Recently, however, a filter to protect showerheads from passage of Legionella has been created with a porosity of 0.2 m (Pall – Aquasafe Shower Head Filter, AQL3). The filter membrane resists a maximum recommended water temperature of 60°C and has an operating lifespan of one month. The purpose of the present research was to evaluate whether installation of this filter in 8 showers found in different departments located in different areas of the S. Orsola Malpighi Hospital in Bologna, Italy could prevent the presence of this microorganism in the water over the period of one month. At the time of installation all showers showed the presence of Legionella contamination (102 – 104 cfu/l). Moreover, it is worth noting that, for the entire test period, no other water sanitation system was used. The samples were taken before installation of the filter and once a week thereafter for 4 weeks. After a month the filters were changed and additional samples were taken after 15 and 30 days. All colonies fell under serum group 3. After installation of the filter, no Legionella colonies were found in the water downstream of the filter nor was it possible to detect Legionella 15 and 30 days after the filters were replaced. For the quantities sampled and the dilutions used, the lower limit for Legionella detection was 50 cfu/l. The results lead one to conclude that, prior to installation of the filter, the number of Legionella bacteria present in the hot water mains was at limit levels. As in most countries, Italian Guidelines permit possible water contamination containing between 102-104 cfu/l of Legionella. Therefore it is clear that use of the filters made it possible to eliminate the potential risk of infection.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
