First Case of Legionnaire's Disease Caused by Legionella anisa in Spain and the Limitations on the Diagnosis of Legionella non-pneumophila Infections

Legionnaires' disease is a severe form of pneumonia, with worldwide relevance, caused by Legionella spp. Approximately 90% of all cases of legionellosis are caused by Legionella pneumophila, but other species can also be responsible for this infection. These bacteria are transmitted by inhalation of aerosols or aspiration of contaminated water. In Spain, environmental studies have demonstrated the presence of Legionella non-pneumophila species in drinking water treatment plants and water distribution networks. Aware that this evidence indicates a risk factor and the lack of routine assays designed to detect simultaneously diverse Legionella species, we analyzed 210 urine samples from patients presenting clinical manifestations of pneumonia using a semi-nested PCR for partial amplification of the 16S rDNA gene of Legionella and a diagnostic method used in hospitals for Legionella antigen detection. In this study, we detected a total of 15 cases of legionellosis (7.1%) and the first case of Legionnaires' disease caused by L. anisa in Spain. While the conventional method used in hospitals could only detect four cases (1.9%) produced by L. pneumophila serogroup 1, using PCR, the following species were identified: Legionella spp. (10/15), L. pneumophila (4/15) and L. anisa (1/15). These results suggest the need to change hospital diagnostic strategies regarding the identification of Legionella species associated with this disease. Therefore, the detection of Legionella DNA by PCR in urine samples seems to be a suitable alternative method for a sensitive, accurate and rapid diagnosis of Legionella pneumonia, caused by L. pneumophila and also for L. non-pneumophila species.