Detection of rokitamycin-induced morphostructural alterations in Helicobacter pylori by atomic force microscopy.

The subinhibitory and suprainhibitory concentrations of many antibiotics are capable of interfering with the morphology of bacteria, thus disrupting the integrity of their structures and reducing bacterial virulence. Studies of this type have so far been performed using optical or scanning electron microscopes, but a new type of lens-free microscope, the atomic force microscope (AFM), has recently been introduced which is capable of investigating fine three-dimensional surface topography. The present study made use of this new technique to investigate the morphological alterations in Helicobacter pylori as a bacterial specimen exposed or not to different concentrations of rokitamycin. The produced images clearly show that AFM is a very useful tool for obtaining fine-quality three-dimensional images of bacterial morphology. The breakthrough in applying this new type of microscopy is also due to the fact that the images can be digitally collected at very high resolution in the z-axis, without the need to adopt the critical point-drying method or vacuum conditions, and without the need to coat the surface of the sample with a metal layer, a result not otherwise attainable with other microscopy techniques. Copyright 2000 S. Karger AG, Basel