Shi.gel' la
. M.L. dim. ‐
ella
ending; M.L. fem. n.
Shigella
named after K. Shiga, the Japanese bacteriologist who first discovered the dysentery bacillus.
Proteobacteria / Gammaproteobacteria / Enterobacteriales / Enterobacteriaceae / Shigella
Straight rods, 1–3 × 0.7–1.0 µm, that conform to the general definition of the family
Enterobacteriaceae
and contain the enterobacterial common antigen. Gram negative. Nonmotile. Non‐pigmented. Facultatively anaerobic, having both a respiratory and a fermentative type of metabolism. Catalase positive (with exceptions in
Shigella dysenteriae
). Oxidase negative. Chemoorganotrophic.
Ferment sugars without gas production
(a few exceptions produce gas).
Salicin, adonitol, and
myo
‐inositol are not fermented
. Strains of
Shigella sonnei
ferment lactose and sucrose upon extended incubation; however, other species do not utilize these substances in conventional medium.
Do not utilize citrate, malonate, or sodium acetate
(with exceptions in
Shigella flexneri
for sodium acetate) as a sole carbon source.
Do not grow in KCN or produce H
2
S. Do not decarboxylate lysine
. Reduce nitrates to nitrites. Intestinal pathogens of humans and other primates, causing bacillary dysentery. Based on 16S rDNA sequencing, shigellae belong in the
Gammaproteobacteria
.
The mol
%
G
+
C of the DNA is
: 49–53 (Laskin and Lechevalier, 1981).
Type species
:
Shigella dysenteriae
(Shiga 1898) Castellani and Chalmers 1919, 935, Epit. Spec. Cons. Opinion 11 of the Jud. Comm. 1954a, 149 (
Bacillus dysenteriae
Shiga 1898, 817.)