Insights into Cystic Fibrosis Polymicrobial Consortia: The Role of Species Interactions in Biofilm Development, Phenotype, and Response to In-Use Antibiotics

Cystic Fibrosis (CF) airways disease involves complex polymicrobial infections where different bacterial species can interact and influence each other and/or even interfere with the whole community. To gain insights into the role that interactions between in co-culture with , and may play in infection, the reciprocal effect during biofilm formation and the response of dual biofilms toward ciprofloxacin under atmospheres with different oxygen availabilities were evaluated. Biofilm formation kinetics showed that the growth of , and was disturbed in the presence of , under both aerobic and anaerobic environments. On the other hand, under aerobic conditions, led to a decrease in biofilm mass production by , although biofilm-cells viability remains unaltered. The interaction between and positively influenced dual biofilm development by increasing its biomass. Compared with monocultures, biomass of + biofilms was significantly reduced by reciprocal interference. When grown in dual biofilms with , ciprofloxacin was less effective against , with increasing antibiotic doses leading to drastic inhibitions of cultivability. Therefore, might be responsible for the protection of the whole dual consortia against ciprofloxacin activity. Based on the overall data, it can be speculated that reciprocal interferences occur between the different bacterial species in CF lung, regardless the level of oxygen. The findings also suggest that alterations of bacterial behavior due to species interplay may be important for disease progression in CF infection.