Scanning electron micrograph of E. coli 'bacteria'.
Source: NIAID: These high-resolution (300 dpi) images may be downloaded directly from this site. All the images, except specified ones from the World Health Organization (WHO), are in the public domain. For the public domain images, there is no copyright, no permission required, and no charge for their use. http://en.wiktionary.org/wiki/File:EscherichiaColi_NIAID.jpg
Author: Credit: Rocky Mountain Laboratories, NIAID, NIH