[Outbreak of six cases of nosocomial Legionella pneumophila pneumonia].

OBJECTIVE

To describe the clinical characteristics, diagnosis, treatment and the causes of outbreak of nosocomial pneumonia due to Legionella pneumophila.

METHODS

The medical records of 6 cases of nosocomial Legionella pneumophila pneumonia were retrospectively reviewed, and the clinical data of clinical presentation, treatment, and etiologic diagnosis were analyzed.

RESULTS

The 6 patients were health care providers of the Department of Respiratory and Critical Care Medicine of the Affiliated Hospital of Logistics University of PAPF. There were 5 female and 1 male patients, aged 23 to 27 years. The diagnosis of Legionella pneumonia was made based on a positive Legionella urinary I antigen test. In all the 6 cases, the disease was attributable to inhaling contaminated aerosols produced by the air conditioning system in our hospital. All the 6 patients presented with fever of 37.5-39 °C, and productive cough. One patient had anorexia, dyspnoea, and pleuritic chest pain, while headache was reported in 3 patients. Physical examinations revealed lung rales in 3 patients. Single or multiple patchy infiltrates were found on Chest CT in all patients. However, the typical extrapulmonary manifestations of Legionnaires' disease, including relative bradycardia, hyponatremia, hypophosphatemia and diarrhea, were not present in the 6 patients. Neither neurological abnormalities nor renal involvement were observed.

CONCLUSIONS

Our data demonstrated that Legionella pneumonia may be mild with atypical laboratory findings and clinical manifestations, with fever, cough, chest tightness, headache, etc. The radiologic manifestations of Legionella pneumonia were single or multiple patchy infiltrates, similar to those of viral pneumonia, and therefore their differential diagnosis was needed. Legionella pneumophila can outbreak through the respiratory tract, in public places with central air-conditioning system, hot water piping systems and hospitals, and therefore microbiological monitoring, cleaning and disinfection of the water system was required for prevention of the outbreaks of Legionnaires' disease.