Legionnaires' Disease Associated With a Hospital Water System
A Five-Year Progress Report on Continuous Hyperchlorination
- Charles M. Helms, MD, PhD;
- R. Michael Massanari, MS, MD;
- Richard P. Wenzel, MD, MSc;
- Michael A. Pfaller, MD;
- Nelson P. Moyer, PhD;
- Nancy Hall, MT(ASCP);
- Legionella Monitoring Committee;
- Stephen Streed, MS;
- William Johnson, PhD;
- William J. Hausler, Jr, PhD;
- Laverne A. Wmtermeyer, MD
- Program of Epidemiology, University of Iowa Hospitals and Clinics; Department of Microbiology, University of Iowa College of Medicine; University Hygienic Laboratory; Iowa Department of Public Health.
- From the Departments of Internal Medicine (Drs Helms, Massanari, and Wenzel) and Pathology (Dr Pfaller), University of Iowa College of Medicine; the Program of Epidemiology, University of Iowa Hospitals and Clinics (Drs Massanari and Wenzel); and the University Hygienic Laboratory (Dr Moyer and Ms Hall), Iowa City.
Abstract
In 1981, sixteen cases of nosocomial legionellosis occurred among 456 patients admitted to a new hematology-oncology unit (35 per 1000 admissions). Monoclonal antibody typing and restriction endonuclease plasmid analysis identified a unique strain (09,04) of Legionella pneumophila serogroup 1 isolated from both patients and water outlets. Continuous hyperchlorination of the hot and cold water began in January 1982, and chlorine levels of 3 to 5 mg/L have been maintained most recently. Water samples have been consistently negative for Legionella for more than five years. Four sporadic cases of nosocomial legionellosis have occurred in the hematology-oncology unit during the same period (one per 1000 admissions) associated with a different strain of L pneumophila serogroup 1 (09,00). The environmental reservoir(s) of L pneumophila serogroup 1 in these cases has not been identified. Levels of trihalomethanes (potential carcinogens) were high (>100 μg/L) when chlorine levels of hot water exceeded 4 mg/L. Some corrosion damage to the water distribution system has occurred: the average number of leaks per month increased steadily from zero in 1982 to 5.2 in 1986. The chlorinator installation costs were $75 800, and annual operation expenses were $12 500. Continuous hyperchlorination is a promising but still experimental technique for control of nosocomial legionellosis. In our experience, epidemic disease has been controlled, but sporadic cases have continued to occur.
(JAMA 1988;259:2423-2427)
Footnotes
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Reprint requests to Division of Infectious Diseases, Department of Internal Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA 52242 (Dr Helms).
