Detection of Legionella pneumophila by sputum culture, direct immunoflurscence and PCR

Community acquired pneumonia (CAP) is the main cause of mortality and morbidity world wide. Legionella pneumophila is identified as the fourth agent that causes CAP. The aim of this study was to define the prevalence of L. pneumophila among hospitalized children by culture, direct immune-fluorescence, (DFA) and PCR.

In this study 210 sputum samples were collected from hospitalized children diagnosed with CAP. Samples were cultured on selective buffered charcoal-yeast extract agar (BCYE). Existence of L. pneumophila among sputum samples was confirmed by culture, direct immune-fluorescence and PCR.

Our results for 210 hospitalized children showed that the sputum of 12 children, (5.7%) with acute respiratory infections was positive for L. pneumophila. Of the 12 positive samples 3, (25%) were detected by culture; 5 by DFA, (41.6%); and 9 by PCR, (75%).

PCR is more sensitive than culture and DFA for detection of Legionella pneumonia in sputum samples.