Identification of Legionella Pneumophila in Intubated Patients With TaqMan Real Time PCR

Background: Legionellaceae contains Legionella genus with over 52 species and 64 serogroups. It is one of the most important causes of respiratory disease in human. More than 30% of hospital-acquired pneumonia is caused by Legionella. Ventilator-associated pneumonia (VAP) is an infection acquired in hospital wards, particularly in intensive care unit (ICU). This disease approximately affects 9% to 20% of intubated patients. Mortality in these patients varies between 8% and 76%. Legionella is one of the important factors for infection in intubated patients. Objectives: The present study was aimed to investigate the use of molecular methods in diagnosis of infection caused by Legionella pneumophila. Materials and Methods: In this study, 109 samples of lung secretions collected from intubated patients admitted to ICU wards of four university hospitals in a three-month period were examined. Cultivation and Real time Polymerase Chain Reaction (PCR) methods were used to assess L. pneumophila colonization in these samples. Results: Eleven samples had positive results using real time PCR analysis of 16s rRNA gene fragments specific for L. pneumophila, but according to culture method on specific buffered charcoal-yeast extract medium (BCYE), no positive cases were detected. Of the total positive cases, six were males, one female and four infants. The seven adults aged 40-65 years. Conclusions: Using molecular methods in diagnosis of infection caused by L. pneumophila has a great value because of its high specificity and rapid diagnosis potency.