A Preliminary study on the prevalence of Legionella pneumophila infection in Lebanon

After the first outbreak of Legionnaire disease was described for the first time in1976, legionellosis has been increasingly recognized in association with many outbreaks, both community and hospital acquired. This disease remains a model of water borne transmission. In Lebanon, no report has yet been published on the prevalence of Legionella pneumophila infections. This study aims to evaluate the prevalence of legionellosis in hospitalized patients with community acquired pneumonia (CAP) and in patients with nosocomial pneumonia (HAP). The study was conducted between April 2004 and August 2007. Eleven community hospitals participated to this endeavour. Laboratory evaluation was conducted in two centers (Middle East Health Institute, Bsalim, Lebanon and Nini Hospital, Tripoli, Lebanon). Two hundred and forty two urinary samples and ninety one pulmonary samples from 242 patients were analyzed. The age range was 16 to 71 years. Two hundred and fifteen were from community acquired pneumonias and twenty seven were nosocomially acquired in intensive care units. The urinary antigen was investigated in 242 patients; the Binax kit® was used in this research. In lung secretions of 91 patients, the presence of Legionella pneumophila was searched for using direct immunofluorescence method and culture. Among the 215 urinary samples from patients with CAP, three were positive for Legionella antigen with a prevalence of 1.4 %. Among the 27 patients with HAP, one was positive for Legionella antigen with a prevalence of 3.7%. This preliminary study reveals the fact that legionellosis is indeed present in Lebanon, hence the importance of considering it in the work-up and the management of patients with pneumonia. Hospital laboratories should therefore routin ely search for this pathogen through at least urinary antigen detection. Health authorities should also enforce microbiological regulations concerning water sanitation in hospitals and in the community to prevent the establishment of this pathogen and prevent outbreaks such as those witnessed recently in many countries.(author)