Occurrence of the Legionella species in the respiratory samples of patients with pneumonia symptoms from Ahvaz, Iran; first detection of Legionella cherrii.

Abstract

This study aimed to investigate the occurrence of Legionella species in the respiratory samples of patients with pneumonia symptoms from Ahvaz, Iran by culture and the real-time PCR of 23S-5S rRNA gene spacer region. A total of 123 clinical respiratory samples including 63 pleural aspirates, 57 bronchoalveolar lavage (BAL), and 3 sputum were collected from 65 males and 58 females with pneumonia symptoms. All samples were cultured on the Modified Wadowsky-Yee (MWY) agar. The Legionella species was identified by routine bacteriological tests. The presence of the 16S-23S rRNA spacer region gene was investigated by real-time PCR. The Legionella species were differentiated by sequencing of 16S-23S rRNA gene. A total of 2 (1.6%) BAL specimens were positive for Legionella species by culture method. No Legionella spp. were identified in pleural aspirates and sputum samples by the culture method. Using real-time PCR, 9 (7.3%) samples including 6 BAL, 1 sputum, and 2 pleural aspirates were positive for legionella species. These species were detected in 3 (5.2%) females and 6 males (9.2%). The results of sequencing showed that eight species were L. pneumophila while one was L. cherrii. Also, the 2 isolates that were identified by culture method, were confirmed as L. pneumophila by sequencing. The results showed that using the real-time PCR has a more efficacy for detecting of Legionella species in respiratory samples. Also, L. pneumophila was the most prevalent species circulating in the southwest region of Iran. So, periodic monitoring programs is recommended to prevent epidemics due to this bacterium.