Influence of Legionella pneumophila and other water bacteria on the survival and growth of Acanthamoeba polyphaga
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S H O R T CO M MU N I C A T I O N
InXuence of Legionella pneumophila and other water bacteria on the survival and growth of Acanthamoeba polyphaga I. Anacarso · E. Guerrieri · M. Bondi · S. de Niederhäusern · R. Iseppi · C. Sabia · M. Contri · P. Borella · P. Messi
Received: 26 January 2010 / Revised: 29 June 2010 / Accepted: 10 August 2010 / Published online: 21 August 2010 © Springer-Verlag 2010
Abstract We investigated in solid medium, in water microcosm co-cultures and by light and transmission electron microscopy the inXuence of Legionella pneumophila Lp-1, Pseudomonas aeruginosa ATCC 27853, Burkholderia cepacia ATCC 25416 and Pseudomonas Xuorescens SSD35 on the growth and survival of Acanthamoeba polyphaga. The infection with L. pneumophila was microscopically characterized by the presence of few bacteria inside protozoa at 4th h, and by the beginning of disruptive eVects in late phase of trial. In water microcosm studies, performed at diVerent temperature, the more signiWcant interactions were observed at 30°C. In these conditions, L. pneumophila caused a marked reduction in trophozoite and cyst counts from the 4th day until the end of incubation (11 days). B. cepacia showed, by microscopic observation, few and generally single rods within protozoan phagosomes and caused a light reduction of trophozoite viability and cyst formation in co-cultures. A more invasive type of endocytosis, characterized by an early invasion with the presence of a high bacteria number inside amoebae, was observed for Pseudomonas strains. P. Xuorescens produced a violent lysis of the host, whereas P. aeruginosa did not
Communicated by Erko Stackebrandt. I. Anacarso · E. Guerrieri · M. Bondi · S. de Niederhäusern · R. Iseppi · C. Sabia · M. Contri · P. Messi (&) Department of Biomedical Sciences, University of Modena and Reggio Emilia, Via Campi 287, 41100 Modena, Italy e-mail: [email protected] P. Borella Department of Public Health Sciences, University of Modena and Reggio Emilia, Via Campi 287, 41100 Modena, Italy
cause lysis or suVering. These results underline that water bacteria other than legionella are capable of intracellular survival in Acanthamoeba, inXuencing the protozoa viable cycle. Keywords Acanthamoeba polyphaga · Legionella pneumophila · Pseudomonas · Water bacteria
Introduction Many naturally occurring bacteria in water environments can interact with protozoa, inhibiting or promoting their survival and multiplication, since bacteria could serve as a nutrient source or parasite cells. The interactions between bacteria and protozoa, after contact, prey-capture and phagocytosis, are characterized by two types of predator–prey trends: (1) digestion into a food vacuole and killing of the ingested bacteria used as food source; (2) bacterial adaptation, survival and multiplication. In the latter case, some of the internalized bacteria, mainly of water origin, may avoid phagosomal lysis and persist intracellularly, establishing a coadaptation (Pagnier et al. 2008) that facilitates the spreading and colonization
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