MICROBIOLOGICAL AND BIOCHEMICAL INVESTIGATIONS OF EFFLUX AND LIPID BIOSYNTHESIS IN MYCOBACTERIUM ABSCESSUS BIOFILMS

Mycobacterium abscessus is a nontuberculous mycobacterium found in the environment that is becoming an emerging infectious pathogen capable of causing numerous types of infections. It is more antibiotic resistant than Mycobacterium tuberculosis and is becoming more prevalent in developed nations. Current treatments are not standardized and have poor success records and there is no definitive method in properly treating these infections. We tested an in vitro model that mimics the reducing environment that M. abscessus experiences during an infection by subjecting it to thiol-reductive stress. We observed that thiol reductive stress stabilized biofilms formed by M. abscessus. We found that M. abscessus in biofilms became tolerant to the antibiotics: clarithromycin, amikacin, and streptomycin. We postulated that efflux pumps might be involved in transport of the precursors of lipids associated with biofilm formation. Therefore, we investigated whether the efflux pump inhibitors affected biofilm formation and found that verapamil, CCCP and reserpine inhibited the formation of biofilms. We investigated the biosynthesis of lipids during biofilm formation by metabolic radiolabeling with ¹⁴C-acetate, the building block of fatty acids. We found that the biosynthesis of several phospholipids were elevated during biofilm formation and that the efflux pump inhibitor verapamil and exogenous fatty acids inhibited their biosynthesis. Further studies are needed to understand the roles of these lipids in biofilm formation.