More than 10 Years of Unrecognized Nosocomial Transmission of Legionnaires' Disease among Transplant Patients

• Published in: Infection control and hospital epidemiology Vol. 19; no. 12; pp. 898 - 904
• Main Authors: Kool, Jacob L., Fiore, Anthony E., Kioski, Clare M., Brown, Ellen W., Benson, Robert F., Pruckler, Janet M., Glasby, Constance, Butler, Jay C., Cage, Gary D., Carpenter, Joseph C., Mandel, Richard M., England, Bob, Breiman, Robert F.
• Format: Journal Article
• Language: English
• Published: Thorofare, NJ SLACK Incorporated 01-12-1998; Slack; Cambridge University Press
• Subjects: Bacterial diseases; Bacterial diseases of the respiratory system; Biological and medical sciences; Bone marrow; Case-Control Studies; Cooling towers; Cross Infection - epidemiology; Cross Infection - mortality; Cross Infection - transmission; Disease Outbreaks; Disease risk; Disease transmission; Drinking water; Environmental monitoring; Epidemiology; Equipment Contamination; Heart diseases; Hospitals, University; Human bacterial diseases; Humans; Infection Control; Infectious diseases; Legionella; Legionella pneumophila - isolation & purification; Legionnaire's disease; Legionnaires disease; Legionnaires' Disease - epidemiology; Legionnaires' Disease - mortality; Legionnaires' Disease - transmission; Medical sciences; Microbiology; Nosocomial infection; Nursing; Potable water; Preventive medicine; Prospective Studies; Radiology; Retrospective Studies; Risk Factors; Southwestern United States - epidemiology; Transplantation; Water Microbiology; Water Supply; Southwestern United States; Human; Lung disease; Nosocomial infection; Pneumonia; Legionellaceae; Respiratory disease; Feed water; Serogroup; Legionella pneumophila; Transplantation; Legionellosis; Homotransplantation; Bacteriological investigation; Retrospective; Infection; Immunosuppression; Microbiological investigation; Bacteriosis; Bacteria; Complication; Environment; Hospital; Cooling tower
• ISSN: 0899-823X; 1559-6834
• DOI: 10.1086/647760

Objective: To investigate a cluster of cases of legionnaires' disease among patients at a hospital. Setting: A university hospital that is a regional transplant center. Design: Retrospective review of microbiology and serology data from the hospital laboratories and prospective surveillance via the radiology department; a case-control study and environmental sampling within the hospital and from nearby cooling towers. Results: Diagnosis of seven cases of legionnaires' disease in the first 9 months of 1996 led to recognition of a nosocomial outbreak that may have begun as early as 1979. Review of charts from 1987 through September 1996 identified 25 culture-confirmed cases of nosocomial or possibly nosocomial legionnaires' disease, including 18 in bone marrow and heart transplant patients. Twelve patients (48%) died. During the first 9 months of 1996, the attack rate was 6% among cardiac and bone marrow transplant patients. For cases that occurred before 1996, intubation was associated with increased risk for disease. High-dose corticosteroid medication was strongly associated with the risk for disease, but other immunosuppressive therapy or cancer chemotherapy was not. Several species and serogroups of Legionella were isolated from numerous sites in the hospital's potable water system. Six of seven available clinical isolates were identical and were indistinguishable from environmental isolates by pulsed-field gel electrophoresis. Initial infection control measures failed to interrupt nosocomial acquisition of infection. After extensive modifications to the water system, closely monitored repeated hyperchlorinations, and reduction of patient exposures to aerosols, transmission was interrupted. No cases have been identified since September 1996. Conclusions: Legionella can colonize hospital potable water systems for long periods of time, resulting in an ongoing risk for patients, especially those who are immunocompromised. In this hospital, nosocomial transmission possibly occurred for more than 17 years and was interrupted in 1996, after a sudden increase in incidence led to its recognition. Hospitals specializing in the care of immunocompromised patients (eg, transplant centers) should prioritize surveillance for cases of legionnaires' disease. Aggressive control measures can interrupt transmission of this disease successfully.