Mycobacterium abscessus promotes Pseudomonas aeruginosa biofilm formation and antibiotic tolerance

Abstract

Modulator therapies have improved outcomes for people with Cystic Fibrosis (pwCF), and currently more than 50% of pwCF are over the age of 18. This has resulted in an increased prevalence of atypical pathogens, including non-tuberculous mycobacteria (NTM). CF-isolation rates of NTM and Pseudomonas aeruginosa (Pa) are high, and those co-colonized have worse clinical outcomes. We therefore investigated the behavior of these two organisms in a dual-species biofilm. We found that coculture of Mycobacterium abscessus (MAB) promoted biofilm formation by Pa. Confocal imaging revealed changes in biomass and structural organization of the Pa biofilm during coculture with MAB. DNase treatment slightly decreased dual-species biofilm, but biofilm formation was completely abrogated in Pel- and Psl-deficient mutants of Pa. Moreover, dual-species cultures promoted tolerance of Pa to tobramycin treatment. Overall, our findings highlight an interaction between P. aeruginosa and M. abscessus that may result in bacterial persistence for pwCF during antibiotic therapy.