Ethambutol-induced alterations inMycobacterium bovisBCG imaged by atomic force microscopy

Abstract

Progress in understanding the structure-function relationships of the mycobacterial cell wall has been hampered by its complex architecture as well as by the lack of sensitive, high-resolution probing techniques. For the first time, we used atomic force microscopy (AFM) to image the surface topography of hydrated Mycobacterium bovis bacillus Calmette Guérin cells and to investigate the influence of the antimycobacterial drug ethambutol on the cell wall architecture. While untreated cells showed a very smooth and homogeneous surface morphology, incubation of cells in the presence of ethambutol caused dramatic changes of the fine surface structure. At 4 micro g mL(-1), the drug created concentric striations at the cell surface and disrupted a approximately 8 nm thick cell wall layer, attributed to the outer electron-opaque layer usually seen by electron microscopy, while at 10 micro g mL(-1) an underlying approximately 12 nm thick layer reflecting the thick electron-transparent layer was also altered. These noninvasive ultrastructural investigations provide novel information on the macromolecular architecture of the mycobacterial envelope as well as into the destructuring effects of ethambutol.

Organization of the mycobacterial cell wall: a nanoscale view

“…2e). High-resolution images revealed a very smooth and homogeneous surface, consistent with previous work [28].…”

“…Early investigations performed in air demonstrated the ability of AFM to visualize drug-induced alterations in the cell walls of Escherichia coli [7], Helicobacter pylori [8], and Staphylococcus aureus [6]. However, attempts to probe cell-drug interaction in situ, i.e., in relevant hydrated conditions, have been very limited so far [28].…”

An Isoniazid Analogue Promotes Mycobacterium tuberculosis-Nanoparticle Interactions and Enhances Bacterial Killing by Macrophages

“…Taken together, these data demonstrate that it is possible to generate nanosystems to target intra-and extracellular mycobacteria, which could contribute to increase bacterial killing within granulomas at lower drug doses. Although we have not investigated the ultrastructure of mycobacteria treated with JVA-NP, it has been previously demonstrated that antibiotic treatment promotes changes in the bacterium (3,47). Moreover, physical and biochemical mechanisms by which JVA-NP interacts with M. tuberculosis merits further investigation.…”

Past, present and future of atomic force microscopy in life sciences and medicine

“…Non-destructive attachment may be achieved by immobilizing cells mechanically in a polymer membrane with pore size comparable to the dimensions of the cell (Kasas and Ikai, 1995). This method permitted the observation of bacterial cell surface dynamics, such as cell growth and division (Touhami et al, 2004), as well as structural changes resulting from cell wall-drug interactions (Verbelen et al, 2006).…”