The cell envelope structure and properties of Mycobacterium smegmatis mc 2 155: is there a clue for the unique transformability of the strain? Mycobacterium smegmatis is often used as a surrogate host for pathogenic mycobacteria, especially since the isolation of the transformable smooth morphotype strain mc 2 155 from the isogenic rough wild-type strain ATCC 607. Biochemical analysis of the cell envelope components revealed a lack of polar glycolipids, namely the lipooligosaccharides and the polar subfamilies of glycopeptidolipids, in the mc 2 155 strain. In addition, the latter strain differs from its parent by the distribution of various species of glycolipids and phospholipids between the outermost and deeper layers of the cell envelope. The presence of filamentous and rope-like structures at the cell surface of mc 2 155 cells grown in complex media further supported an ultrastructural change in the cell envelope of the mutant. Importantly, a significantly more rapid uptake of the hydrophobic chenodeoxycholate was observed for the mutant compared to wild-type cells. Taken together, these data indicate that the nature of the surface-exposed and envelope constituents is crucial for the surface properties, cell wall permeability and bacterial phenotype, and suggest that the transformable character of the mc 2 155 strain may be in part explained by these profound modifications of its cell envelope.
Significance and Impact of study: Due to the emergence of multi-drug-resistant (MDR) uropathogenic Escherichia coli (UPEC), the treatment of urinary tract infection with conventional antibiotics has now become limited or ineffective. This study provides evidence that colistin (COL) could enhance the antibacterial activity of fosfomycin (FOS), nitrofurantoin (NIT) and trimethoprim (TRI) by decreasing their minimum inhibitory concentrations (MICs) to less than the suspectable breakpoints. Additionally, the combinations of COL with these antibiotics exert synergistic and bactericidal effects against MDR UPEC. These findings may help in choosing more promising treatments against multi-drug-resistant MDR UPEC infections.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.