Spirillum minus
{{Short description|Species of bacterium}}
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Spirillum minus is an organism associated with rat-bite fever (specifically sodoku){{DorlandsDict|seven/000099459|Spirillum}}{{cite journal | vauthors = Gaastra W, Boot R, Ho HT, Lipman LJ | title = Rat bite fever | journal = Veterinary Microbiology | volume = 133 | issue = 3 | pages = 211–28 | date = January 2009 | pmid = 19008054 | doi = 10.1016/j.vetmic.2008.09.079 | url = https://hal.science/hal-00532514/file/PEER_stage2_10.1016%252Fj.vetmic.2008.09.079.pdf }}{{cite journal | vauthors = Dendle C, Woolley IJ, Korman TM | title = Rat-bite fever septic arthritis: illustrative case and literature review | journal = European Journal of Clinical Microbiology & Infectious Diseases | volume = 25 | issue = 12 | pages = 791–7 | date = December 2006 | pmid = 17096137 | doi = 10.1007/s10096-006-0224-x | s2cid = 12345288 }} that has never been fully identified and was assigned to the genus Spirillum in 1887 based on morphology, although it is not a validly published name. As Spirillum species are generally obligately microaerophiles and not found in mammals, this organism may be misclassified. Sequencing data should help to resolve this question.
This organism is presumed to be a bacterium. It stains gram-negative and has a coiled rod shape. It does not grow in vitro, and requires inoculation in animals for growth. No attempts to sequence the organism are known as of 2015.{{cite book | vauthors = Washburn RG |date=2015|title=Mandell, Douglas, and Bennett's principles and practice of infectious diseases |location=Philadelphia, PA |isbn=978-1-4557-4801-3 |pages=2629–2632 |edition=Eighth |chapter=Rat-Bite Fever: Streptobacillus moniliformis and Spirillum minus |doi=10.1016/B978-1-4557-4801-3.00233-2}}