How to prevent an outbreak of Legionnaires' disease

Nosocomial Legionnaire's disease in a children's hospital

BACKGROUND

Only a few cases of nosocomial Legionella sp. infection have been reported in children. We report the clinical and epidemiologic data of five nosocomial legionellosis cases that occurred in the Pediatric Nephrology Service between August, 1994, and December, 1998, and the control measures adopted.

METHODS

The Hospital Materno-Infantil Vall d'Hebron, Barcelona, is a 407-bed tertiary care hospital. The pediatric kidney transplant unit has three isolated beds in the same ward within the Pediatric Nephrology Service. Diagnostic workup to establish Legionella pneumophila infection included culture, fluorescent antibody and serologic studies. Macrorestriction analysis of genomic DNA was used as epidemiologic markers of the isolated strains.

RESULTS

In May, 1996, a case of L. pneumophila serogroup 6 pneumonia was identified in a 19-year-old youth who had received a kidney transplant 16 days earlier. Retrospective and prospective analysis of legionellosis cases diagnosed at our center up to August, 1994, yielded four additional cases. Four patients had had a kidney transplant and were receiving immunosuppressive therapy, and the fifth had been diagnosed with systemic lupus erythematosus with renal involvement. L. pneumophila serogroup 6 was isolated in bronchial secretions in four cases; in the fifth patient the diagnosis was made by serology. L. pneumophila serogroup 6 was isolated from potable water of the hospital. Molecular epidemiologic methods revealed the identity of the environmental and clinical isolates. Showering was implicated as the most feasible means of exposure to contaminated water.

CONCLUSIONS

Nosocomial legionellosis, albeit rare in children, should be considered in the differential diagnosis of pneumonias, particularly in immunosuppressed children, because the fatality rate may be high without early diagnosis and treatment.

Combined monoclonal antibody typing, multilocus enzyme electrophoresis, soluble protein profiles and plasmid analysis of clinical and environmental Legionella pneumophila serogroup 1 isolated in a Portuguese hospital

Sixteen strains of Legionella pneumophila serogroup 1 isolated from patients and the environment at Santa Cruz Hospital were examined using four typing methods. Monoclonal antibodies showed that all the isolates belonged to subgroup Pontiac and mainly to subtype Allentown. With multilocus enzyme electrophoresis nine subtypes (ETs) were revealed; each strain had the same profile with electrophoresis of soluble proteins, and plasmid analysis revealed that only two of the strains studied contained plasmids. Among these methods, multilocus enzyme electrophoresis was the most discriminative as a single epidemiological marker. Problems concerning the microbiological examination of environmental specimens and correlation with clinical strains confirmed the difficulty of investigating an outbreak source of legionellosis and the need for careful evaluation of the results.

Electric showers as a control measure for Legionella spp. in a renal transplant unit in São Paulo, Brazil. Legionellosis Study Team

After an outbreak of legionnaires' disease Legionella pneumophila serogroup 1 in a renal transplant unit in São Paulo, Brazil, periodic hyperchlorination and flushing of pipes were instituted as control measures. These were only partially effective as every two to five months water cultures turned positive or new cases of the disease occurred. In November 1993 the hot water was disconnected from the unit and small, plastic electric showers were installed in each bathroom. Over a period of 12 months water from showers and taps was cultured for Legionella spp. every two weeks. On only one occasion was a water culture positive for L. pneumophila from a sink tap. No water sample obtained from showers was positive during the study period. No cases of legionnaires' disease occurred. We considered the use of electric showers an inexpensive and effective method of controlling the problem of Legionella spp. in the water system of our renal transplant unit.