Which of the following shigella doesn't ferment mannitol?
Ans. A. S. dysenteriae. (Ref. Textbook of Microbiology by Ananthanarayan 7th/Pg. 285)SubgroupABCDSpeciesSh. DysenteriaeSh. FlexineriSh. BoydiiSh. SonneiMannitol-AcidAcidAcidLactose---A LateSucrose---A LateDulcitol--Variable-IndoleVariableVariableVariable-Orithine decarboxylase---+Serotypes106 + Variants15Only 1SHIGELLA# S. dysentriae does not produce ctalase & does not ferment manitol# S. Sonnie is late lactose fermentor# S. Flexinerri produces gas.# S. dysenteriae Type 1 forms a toxin, the earliest example of a exotoxin produced by a gram-negative bacillus.# All except Shigella dysenteria ferment mannitol.# All except S. dysenteriae Type 1 produces catalase.# Colonies on MacConkey agars are colorless due to absence of lactose fermentation except S. sonnie, which ferments lactose late and forms pink colonies.# DCA and Wilson and Blair selective media are the selective media.# Infective dose of Shigella is 10-100 bacteria, while that of Salmonella is 102-105.S. boydii does not produce H2S, does not hydrolyze urea and does not grow in KCN broth. Carbohydrates are usually fermented and these include glucose (in the absence of gas production), D-mannitol, arabinose, trehalose and mannose.# Lactose fermentation is a biochemical property commonly used for to distinguish Shigella from the closely related bacterium E. coli. However, S. sonnei isolates ferment lactose at a lot slower process than other species of Shigella. S. sonnei is known to be less virulent than other Shigella species.# S. dysenteriae type 1 differs from most of the Enterobacteriaceae in that it does not produce catalase. Shigella dysenteriae type 1 produces severe disease symptoms collectively called shigellosis, which may be associated with life-threatening complications.# Shigella flexneri is a facultative anaerobe. It makes ATP via aerobic respiration in the presence of oxygen and via fermentation in the absence of oxygen. Although it is closely related to Escherichia coli, Shigella flexneri can be differentiated because it fails to ferment lactose or decarboxylate lysine.# 5. boydii, when found in the intestine, go though anaerobic metabolic pathways but can survive outside of the body due to its ability to utilize aerobic pathways. More specifically, 5. boydii, typically does not have oxidase enzymes but rather catalase enzymes (catalyzes the reduction of H2O2->H20). Methyl red testing is positive, meaning that the bacteria uses a mixed acid fermentation pathway. Voges-Proskauer and Simmons' citrate reactions are negative, meaning that this organism does not utilize the butylene glycol pathway or produce acetoin. Lysine decarboxylase, arginine dihydrolase and ornithine decarboxylase are not present. S. boydii does not produce H2S, does not hydrolyze urea and does not grow in KCN broth. Carbohydrates are usually fermented and these include glucose (in the absence of gas production), D-mannitol, arabinose, trehalose and mannose.
S.dysenteriae
S. flexneri
S.boydii
S. sonnei
Bacteria