Imaging bacterial shape, surface, and appendages before and after treatment with antibiotics.

Antibiotics are particular type of drugs that are able to interfere in different ways to the metabolic -pathways of bacteria. This causes also morphostructural alterations of cell wall and surface appendages (flagella, fimbriae or pili, and filaments).Atomic force microscopy (AFM) is extremely useful for analyzing the three-dimensional structure of the surface of biological specimens, particularly bacteria. A step-by-step AFM methodology to be applied to different type of bacteria is reported and visual examples of the action of antibiotics are shown. Although scanning electron microscopy is still frequently used, the introduction of the AFM technique offers substantial benefits in real quantitative data acquisition in three dimensions, minimal sample preparation times, flexibility in ambient operating conditions (i.e., no vacuum is necessary), and effective three-dimensional magnification at submicron level.