An investigation of virulence factors of Legionella pneumophila environmental isolates

Abstract

Nine Legionella pneumophila strains isolated from cooling towers and a standard strain (L. pneumophila serogroup 1, ATCC 33152, Philadelphia 1) were analyzed and compared in terms of motility, flagella structure, ability to form biofilms, enzymatic activities (hemolysin, nucleases, protease, phospholipase A, phospholipase C, acid phosphatase, alkaline phosphatase and lipase), hemagglutination capabilities, and pathogenicity in various host cells (Acanthamoeba castellanii ATCC 30234, mouse peritoneal macrophages and human peripheral monocytes). All the isolates of bacteria appeared to be motile and polar-flagellated and possessed the type-IV fimbria. Upon the evaluation of virulence factors, isolate 4 was found to be the most pathogenic strain, while 6 out of the 9 isolates (the isolates 1, 2, 3, 4, 5, and 7) were more virulent than the ATCC 33152 strain. The different bacterial strains exhibited differences in properties such as adhesion, penetration and reproduction in the hosts, and preferred host type. To our knowledge, this is the first study to compare the virulence of environmental L. pneumophila strains isolated in Turkey, and it provides important information relevant for understanding the epidemiology of L. pneumophila.

Intracellular Behaviour of Three Legionella pneumophila Strains within Three Amoeba Strains, Including Willaertia magna C2c Maky

“…Strain Philadelphia is a clinical isolate that is historically responsible for the very first outbreak. It possesses gene traits that allow for multiplication in a number of hosts such as peripheral blood mononuclear cells, peritoneal macrophages, and A. castellanii, A. polyphaga, or A. lenticulate [26][27][28][29]. The Philadelphia strain is, according to the EN 13623 European standard, the only strain for which testing is required to validate a disinfectant against Legionella in Europe.…”

Assessing the impact, genomics and evolution of type II secretion across a large, medically important genus: the Legionella type II secretion paradigm

“…Some apparatus proteins such as LspJ may undergo diversifying selection within L. pneumophila [217], which may help to explain the varying degrees of secreted activity of environmental isolates despite encoding an intact T2SS [218]. Turning attention to the prevalence of the secreted substrates, it is clear that the genes for all 25 confirmed T2SS effectors (Table 1) are present and intact within the 90 annotated L.…”

Investigation of Virulence Genes and Biofilm Formation Among Legionella Pneumophila Isolated from Hospital Water Sources

“…There was a signi cant difference between PCR and culture results for detection of Legionella. Several studies described PCR to have a higher rate of detection than culture methods [24][25][26]. Molecular methods were suggested to be fundamental when an outbreak occurs.…”

“…This bacterial super cial protein also plays a role in the binding and entry of bacteria to the Acanthamoeba castellanii protozoan and its survival in nature. In rtxa mutants, the ability to bind and entery of the bacterium into epithelial cells and monocytes is reduced [17]. The L. pneumophila major outer membrane protein (MOMP) is involved in the attachment to host cells [18].…”