Examining the Intraspecific Interactions in Mixed-Strain Biofilms Containing the Prairie Epidemic Strain and Unique Clinical Pseudomonas aeruginosa Isolates




Garnier, Nicole

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University of Guelph


The prairie epidemic strain (PES) of Pseudomonas aeruginosa causes infections in cystic fibrosis (CF) patients that lead to an increase in morbidity and mortality. The PES can cause superinfections and outcompete previously existing P. aeruginosa isolates within the lungs of CF patients, however, the interactions that occur to allow this to happen are currently unknown. This work examines biofilms formed when PES isolates are cocultured with clinical P. aeruginosa isolates that either remained stable (P637) or were replaced by the PES during a superinfection (P261). Biofilms were quantified using a crystal violet assay, imaged using fluorescence microscopy, and the isolates within the coculture biofilms were quantified using Droplet Digital™ PCR. The results of this project combined with recent sequence data suggests that there may be alterations in the regulation of biofilm formation in these cocultures, potentially due to changes in bacterial quorum sensing.



Pseudomonas, aeruginosa, epidemic strain, Prairie epidemic strain, PES, biofilm, microscopy, ddPCR, Droplet Digital PCR, P. aeruginosa, intraspecific interactions, coculture