engleski

The pathogenic potential of Legionella cells exposed to desiccation

Legionella species are prevalent within both natural and man-made aquatic enviroments where they reside and multiply in aquatic free living amoebae. Legionella are capable of causing human disease and the vast majority of legionellosis in the world is caused by L. pneumophila. L. longbeache is the only soil-dwelling pathogenic Legionella which is the leading cause of legionellosis in Australia. The purpose of our study was to examine the effect of the desiccation on L. pneumophila and L. longbeache. Also, the pathogenic potential of Legionella cells exposed to desiccation in Acanthamoeba castellanii was tested. In this study clinical isolates of L. pneumophila (strain 130b) and L. longbeachae (strain NSW150) were used. The ability of L. pneumophila and L. longbeachae to replicate in A. castellanii were tested. The number of bacteria per well was determined at different time points p.i. For desiccation study, bacteria were prepared in sterile water and 5x20µl of bacterial suspension (~108 cfu/ml) were deposited in 96 wells plates and dried for 1 hour under laminar flow hood. At different time points, bacteria were rehydrated and cultivated in CYE broth or BCYE agar. Non-culturable Legionella cells exposed to desiccation were added to A. castellanii monolayers and incubated for 48 hours under nutrient–limiting conditions. The results of co-cultivation of L. pneumophila and L. longbeachae showed that both Legionella strains were able to replicate in A. castellanii. The Legionella strains, exposed to desiccation were culturable up to 4 days. Our result show that although L. pneumophila and L. longbeachae become non-culturable after desiccation, co-culture with A. castellanii resuscitates the bacteria and bouth Legionella strains were able to infect and proliferate within amoeba after 15 days of desiccation. Legionella pneumophila and Legionella longbeachae exposed to desiccation loss their culturability but are able to infect and replicate in Acanthamoeba castellanii.

Legionella; virulence; desiccation

nije evidentirano