Urinary antigene and PCR can both be used to detect Legionella pneumophila in children's hospital-acquired pneumonia

Legionella pneumophila is the causative agent of more than 95% cases of severe Legionella pneumonia. Nosocomial pneumonias in different hospital wards is an important medical and pharmaceutical concern. This study aimed to detect Legionella with two methods: polymerase chain reaction (PCR) and detection of urine antigenic test (UAT) in patients suffering from nosocomial pneumonia admitted to pediatric intensive care unit (PICU) of children hospitals. This study was conducted in PICU wards of Rasool Akram and Bahrami children hospitals, Tehran, Iran during 2013-2014. In patients diagnosed with hospital-acquired pneumonia, intratracheal secretion samples for PCR and urine sample for UAT were taken. Simultaneously, PCR and urinary antigen test were conducted using commercial kits. The results of urinary antigen test and PCR were analyzed by SPSS v.19 for statistical comparison. In this study, 96 patients aging 2.77 years on average with two age peaks of less than 1 year and 7-8 year were enrolled. More than half of the patients were under 1 year old. The most common underlying diseases were seizure, Acute Lymphoblastic Lymphoma, Down syndrome and metabolic syndromes. The positivity rate of Legionella urinary antigen test was 16.7% and positivity rate of PCR test was 19.8%. There were no significant associations between the results obtained by both assays with age, gender or underlying diseases. In conclusion, PCR is a better detection method for Legionella infection than urinary antigen test, but the difference between the two methods was not significant.