This protocol describes two biological assays to evaluate pathogenicity of Burkholderia cepacia complex (Bcc) strains against the nematode Caenorhabditis elegans. Specifically, these two assays allow one to identify if the under-investigated Bcc strains are able to kill the nematodes by intestinal colonization (slow killing assay, SKA) or by toxins production (fast killing assay, FKA). The principal differences between the two assays rely on the different killing kinetics for worms.
[Background] The Burkholderia cepacia complex (Bcc) occupies a critical position among Gram-negative multi-drug resistant bacteria. It consists of at least 20 closely related species. Many Bcc strains are multi drug and pandrug-resistant opportunistic human pathogens caused problematic lung infections in immune-compromised individuals, including cystic fibrosis (CF) patients. The use of non-vertebrate host model can be useful for dissecting virulence and pathogenicity determinants as well as identifying novel therapeutic targets (Kothe et al., 2003).
There are a good number of assays for detecting Bcc virulence against a large panel of host models, in liquid or in solid surface. However, some of those are mostly focused on phenotypic observations, which are difficult to detect and have a low reproducibility (Cardona et al., 2005). Herein, we developed two assays based on the analysis of surviving worms, which is a more reproducible and allows easy and fast comparison among the Bcc strains tested. In addition, these assays permit the detection of death mechanisms of Bcc towards nematode.
These killing assays allow us to identify bacterial strains that are able to colonize the nematode intestine and produce diffusible toxins capable of killing the host.
Thanks for your further question/comment. It has been sent to the author(s) of this protocol. You will receive a notification once your question/comment is addressed again by the author(s).
Meanwhile, it would be great if you could help us to spread the word about Bio-protocol.