Dictionary.com
definitions

Sonne bacillus

[sŏn′ə]
n.
  1. A gram-negative bacterium Shigella sonnei that causes a mild form of dysentery in adults and children.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.