Xiao-Yong Zhan, Chao-Hui Hu and Qing-Yi Zhu
Legionella is the causative agent of legionellosis or Legionnaires’disease. Infection with Legionella spp. is an important cause of community and hospital-acquired pneumonia. Infection with Legionella is also one of the most common causes of severe pneumonia in community settings, and Legionella is isolated in 40% of hospital-acquired pneumonia cases. Intense research on Legionella pneumophila (L. pneumophila) and other Legionella spp. over the last two decades provided insights into the evolution, ecology, epidemiology, and pathogenesis of this opportunistic pathogenic and facultative intracellular bacterium. An in-depth understanding of the ecology and virulence factors of Legionella spp. will contribute to an in-depth comprehension of its pathogenesis and efficient, sustainable elimination of the bacteria from anthropogenic water systems and might lead to the development of novel therapeutics. This review summarizes available information regarding the cellular microbiology, pathogenesis and virulence factors of Legionella spp. with an emphasis on the potential virulence factors and the contribution of these factors to the pathogenesis.
