Which of the following is a true statement regarding Enterobacteriaceae:
Motility is by polar flagellum
Glucose is not fermented by all members of the family
All members are oxidase positive
Nitrate reduction negative
Ans. (c) Shigella does not ferments mannitol "Members of enterobacteriaceae rcduce nitrates to nitrites, form catalase but not oxidase." Enterobacteriaceae: lmpoant features Features Escherichia Salmonella Shigella Motility by peritrichous flagella + + - Gas from glucose + + - Acid from lactose + - - Acid from sucrose d - - Growth in KCN - d - lndole + - d MRA/VP + + + Citrate - + - H2S - + - Urease - - - Phenylalanine deaminase (PPA) - - - Arginine dehydrolase d + - Lysine decarboxylase + + - Omithine decarboxylase d + d (d = result different in different species or strains) Remember: - Polar flagella: Vibrio, pseudomonas, legionella, spirilla, campylobacter, H. pylon, spirochetes. - V. parahemolytic produce both polar and peritrichous flagella.