A field study of the survival of Legionella pneumophila in a hospital hot-water system.
The colonization, survival and control of Legionella pneumophila in a hospital hot-water system was examined. The organism was consistently isolated from calorifier drain-water samples at temperatures of 50 degrees C or below, despite previous chlorination of the system. When the temperature of one of two linked calorifiers was raised to 60 degrees C, by closing off the cold-water feed, the legionella count decreased from c. 10(4) c.f.u./l to an undetectable level. However, 10 min after turning on the cold-water feed which produced a fall in calorifier temperature, the count in the calorifier drain water returned to its original level. Investigations revealed that the cold-water supply was continually feeding the calorifiers with L. pneumophila. Simple modifications in the design of the system were made so that the cold-water feed no longer exceeds 20 degrees C; these measures have considerably reduced the number of L. pneumophila reaching the calorifiers.
Farrell
I D
ID
Regional Public Health Laboratory, East Birmingham Hospital.
Barker
J E
JE
Miles
E P
EP
Hutchison
J G
JG
D003080:Cold Temperature; D015169:Colony Count, Microbial; D005455:Fluorescent Antibody Technique; D006757:Hospital Units; D006358:Hot Temperature; D006801:Humans; D007875:Legionella / Q000145:classification / Q000254:growth & development*; D012703:Serotyping; D014871:Water Microbiology; D014881:Water Supply