Identification of Legionella from clinically diagnosed pneumonia patients and environmental samples

Abstract

Legionnaires disease is a multisystem disease with life-threatening acute and severe form of pneumonia which is responsible for 2-9% pneumonia with high mortality. Eighty six respiratory tract samples and urine were collected from clinically diagnosed pneumonia patients and 12 water samples were collected from different environment. Identification of Legionella was done by culture and Polymerase Chain Reaction (PCR) of respiratory tract samples and environmental samples and Legionella Antigen (Ag) in urine was detected by Immunochromatographic test (ICT). Legionella was identified from 4 (4.65%) clinically diagnosed pneumonia patients  of which 1 (1.16%) case was culture positive, 1 (1.16%) case was urine ICT positive and PCR was positive in all four cases. Of the 12 water samples tested, 4 (33.33%) samples were Legionella positive by PCR but culture results of these samples were negative. Identification of Legionella should be done by PCR in parallel with culture and urine ICT. Detection of Legionella in environmental samples is also needed to explore possible links between the water sources and disease transmission in population.