Molecular Epidemiologic Investigation of Hospital-Acquired Legionellosis with Multiple Serogroups of Legionella in Chiayi County

Lei-Ron Tseng, Jui-Hsin Chang, Jei-Kai Tan, Ying-Yan Chen, Jung-Jung Mu,Chuen-Sheue Chiang, Ho-Sheng Wu

2010 Vol.26 NO.17

Correspondence Author: Lei-Ron Tseng


Hospital-acquired Legionellosis has received significant attention in western countries. The major source of hospital-acquired Legionellosis is the potable water supply system and micro-aspiration of contaminated water is the mode of transmission. The fatality rate of hospital-acquired Legionellosis is twice as much as that of community-acquired infection. Patients with chronic illnesses and organ transplant recipients are at greater risk of infection. Few cases of hospital-acquired legionellosis have been reported in Taiwan and the actual incidence might be underestimated. Water quality monitoring and the routine cultures from environmental water samples have emerged as an effective strategy for prevention of hospital-acquired legionellosis. Taiwan Centers for Disease Control (Taiwan CDC) received a case report of Legionella pneumophila from a hospital in Chiayi County in August, 2007, later confirmed as serogroup 1 infection. Isolates of Legionella pneumophila serogroup 1 and serogroup 6 had also been cultured from tap water of that hospital. When comparing the genetic fingerprints of bacterial isolates from environments with those from the patient using pulsed field gel electrophoresis (PFGE), the results were quite similar. Another case had been reported to Taiwan CDC in January 2008, and Legionella pneumophila serogroup 6 had been isolated from the patient’s sputum. The second patient was treated in the same hospital as the first case for 22 days prior to the onset of illness, and the genetic fingerprint of the second patient’s bacterial isolate was almost identical with the isolate from environmental culture of the hospital. Molecular subtyping of the clinical and environmental isolates revealed high possibility of hospital-acquired infection of these two patients. This study is the first published case report of hospital-acquired infection with multiple serogroups of Legionella in Taiwan. Based on this study, appropriate surveillance of water supply systems in hospitals has proved to play an important role in controlling hospital acquired infection, and molecular subtyping has also made it easier to identify the source of infection.