The Collaborative International Dictionary
Spirobacterium
Spirobacteria \Spi`ro*bac*te"ri*a\, n. pl.; sing. Spirobacterium. [NL. See 4th Spire, and Bacterium.] (Biol.) See the Note under Microbacteria.
Wiktionary
spirobacterium
n. (context biology dated English) Any bacterium found in spiral filaments, such as the genus ''Vibrio''.