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INVESTIGATING THE INFLUENCE OF EFFLUX PUMP INHIBITORS ON BIOFILM FORMATION, ANTIBIOTIC RESISTANCE AND LIPID BIOSYNTHESIS IN MYCOBACTERIUM ABSCESSUS

thesis
posted on 2024-04-23, 02:21 authored by Toe Ko Ko HtayToe Ko Ko Htay

Mycobacterium abscessus (Mab) is a type of mycobacterium that is known for its remarkable resistance to a variety of antibiotics. This pathogen poses a significant risk for individuals with weakened immune systems as it can cause skin and soft tissue infections, pulmonary disease and disseminated infections. Mab's ability to expel antibiotics through efflux pumps and form strong biofilms makes it even more challenging to treat infections. Lipids form a major part of the extracellular matrix of Mab biofilms. Efflux pumps have been shown to export lipids to the cell surface. Despite ongoing research into Mab's antibiotic tolerance, there is still much to learn about the impact of efflux pump inhibitors (EPIs) on antibiotic resistance and lipid biosynthesis during biofilm development in Mab. In this study, we investigated the impact of the EPIs; CCCP (carbonyl cyanide m-chlorophenyl hydrazone), piperine (PIP), reserpine (RES), berberine (BER), and verapamil (VER) on efflux activity, biofilm formation, antibiotic resistance, and lipid biosynthesis in Mab during planktonic and biofilm growth conditions. We found that Mab cells had a higher tolerance to EPIs in biofilm-stimulating medium and that the presence of EPIs led to a decrease in minimum inhibitory concentrations of frontline antibiotics, reduced efflux activity within Mab cells, and significantly inhibited biofilm formation. We examined the effects of EPIs that inhibited biofilm formation on lipid metabolism in Mab using radiolabeling with 14C?palmitic acid and 14C-acetic acid which are precursors of lipid biosynthesis. We observed that the EPI berberine inhibited the incorporation of 14C-palmitic acid into glycopeptidolipids in the surface lipids of planktonic cells and increased cellular glycopeptidolipid (GPL) in biofilm cells. Verapamil-treated cells showed a 55 % increase in cellular trehalose monomycolate (TMM) compared to controls. Piperine-treated cells exhibited a 50 % increase in cardiolipin. The incorporation of 14C-acetate into biofilm cells showed that piperine-treated biofilm cells showed a 146 % increase in surface glycopeptidolipids. Overall, our study enhances our understanding of lipid biosynthesis in Mab, the effects of EPIs on Mab biofilms, efflux mechanisms, and antibiotic resistance and offers insights for combating Mab-related infections.

History

Degree Type

  • Master of Science

Department

  • Biological Sciences

Campus location

  • Fort Wayne

Advisor/Supervisor/Committee Chair

Jaiyanth Daniel

Additional Committee Member 2

Arturo Lopez Villalobos

Additional Committee Member 3

Jose Thekkiniath

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