Investigation of Bacterial Interactions Using Lab on Chips

Many infections, such as pulmonary infections occurring in cystic fibrosis (CF) patients, are polymicrobial and caused by a combination of different bacterial species. Sometime, a micro-organism predisposes the host to colonisation by other species, and the microbial cooperation or antagonism govern the infectious sequelae. Staphylococcus aureus is one of the first pathogens infecting CF airways, but during adolescence up to 80% of patients become chronically colonised by Pseudomonas aeruginosa, which causes a progressive pulmonary destruction, although antibiotic therapies can improve life expectancy. To investigate the antagonistic interactions between S. aureus and P. aeruginosa, we have designed and fabricated two different lab-on-chips. The first device consists of three parallel compartments, two are filled with different bacterial species while the central one is an agarose barrier, to avoid direct interaction between bacteria. Also the second microfluidic device is composed of three compartments, but the central one is connected to the other two by 260 microchannels; a cell trap is placed at the center of each microchannel to avoid physical contact between bacterial cells in different compartments. We use fluorescent-tagged bacteria and monitor their growth rate inside the microchannels using confocal microscopy.