Eradicating Legionella from hospital water.

To the Editor. —The report by the Centers for Disease Control and Prevention (CDC) on transmission of nosocomial legionnaires disease 1 documents failure to eradicate Legionella organisms from the water distribution systems of 2 hospitals despite the use of hyperchlorination, thermal disinfection, and/ or metal ionization. The efficacy of these decontamination methods can be compromised by a variety of factors. The duration of thermal decontamination (160°F/71°C at the tap) used in hospital Y was only 5 minutes. The original report on the use of this method specified a 30-minute flush at the tap. 2 Thus, failure to maintain the elevated temperature for a sufficient period undoubtedly contributed to this failure to eradicate Legionella . In fact, when one California hospital applied thermal eradication with a flush time of 5 minutes, as recommended by the CDC, distal site colonization by Legionella organisms was unaffected. When the process was repeated using a 30-minute flush